© 2019, © 2019 The Author(s). Published by National Institute for Materials Science in partnership with Taylor & Francis Group. The collected end-of-life (EoL) silicon wafers from the discharged photovoltaic (PV) panels are easily contaminated by impurities such as doping elements and attached materials. In this study, the thermodynamic criteria for EoL silicon wafers refining using three most typical metallurgical refining processes: oxidation refining, evaporation refining, and solvent refining were systemically and quantitatively evaluated. A total of 42 elements (Ag, Al, Au, B, Be, Bi, C, Ca, Ce, Co, Cr, Cu, Fe, Ga, Gd, Ge, Hf, In, La, Mg, Mn, Mo, Na, Nb, Ni, Os, P, Pb, Pd, Pt, Re, Ru, Sb, Sn, Ta, Ti, U, V, W, Y, Zn, Zr) that are likely to be contained in the collected EoL silicon-based PV panels were considered. The principal findings are that the removal of aluminum, beryllium, boron, calcium, gadolinium, hafnium, uranium, yttrium, and zirconium into the slag, and removal of antimony, bismuth, carbon, lead, magnesium, phosphorus, silver, sodium, and zinc into vapor phase is possible. Further, solvent refining process using aluminum, copper, and zinc as the solvent metals, among the considered 14 potential ones, was found to be efficient for the EoL silicon wafers refining. Particularly, purification of the phosphorus doped n-type PV panels using solvent metal zinc and purification of the boron doped p-type PV panels using solvent metal aluminum are preferable. The efficiency of metallurgical processes for separating most of the impurity elements was demonstrated, and to promote the recycling efficiency, a comprehensive management and recycling system considering the metallurgical criteria of EoL silicon wafers refining is critical.

© 2019, The Minerals, Metals & Materials Society. Because high-purity silicon is one of the core materials for use in cleaner energy industry, silicon purification techniques have taken on greater importance. An understanding of the thermodynamics of impurity elements in silicon is therefore of great scientific and industrial importance. Experimental and assessment works on the thermodynamics of 23 impurity elements (Ag, Al, Au, B, Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Ni, P, Pb, Sb, Ta, Ti, V, W, Zn, and Zr) in silicon melts are reviewed herein, and their activity coefficients in dilute silicon melts are discussed. The parameters suggested for use in assessing the liquid phase in each of the silicon binary systems are selected based on this discussion. The segregation coefficients of impurity elements calculated using the activity coefficients agree well with reported values and are used to evaluate silicon purification by directional solidification. The purpose of this paper is to provide fundamental and systemic thermodynamics knowledge for the development of silicon purification processes.

© 2018 Elsevier Ltd The potential feasibility of steel slag as a low cost removal agent for heavy metal ions Pb(II), Cu(II) and Cd(II) in acidic conditions was investigated in this study. The initial pH effect on heavy metal ion removal efficiency, the compounds formed after heavy metal ion removal, and the binding force of metals with the compounds were determined. The results showed that the efficiency of removing heavy metal ions by steel slag was low at low initial pH levels, yet it sharply increased and then became stable as the initial pH increased. The pseudo-second order model provided the best description for the removal of Pb, Cu, and Cd ions, indicating that the predominant heavy metal ion removal mechanism was chemisorption. The images obtained by the Fourier transform infrared spectroscopy (FTIR) and the X-ray diffraction (XRD) analysis indicated that the main compounds formed after the removal of Pb, Cu, and Cd ions by steel slag in an aqueous solution were heavy metal ferrites, silicates, carbonates, hydroxides and oxides. Sequential extraction experiments showed that these three heavy metals bond to the compounds mainly in the carbonate fraction (F2), the Fe oxide bound fractions (F3 (a) and F3 (c)), and the residual fraction (F4) in which F2 corresponded to the carbonates, and F3(a), F3(c) and F4 corresponded to the amorphous or crystalline ferrites and silicates, respectively. The F3 (a), F3 (c) and F4 are relatively stable and do not tend to re-release metal ions in acidic solutions. However, F2 and heavy metal hydroxides have relatively low stability and dissolve readily, re-leaching heavy metal ions into the acid solution. When these three heavy metal ion mixtures were removed by steel slag, the Pb, Cu and Cd deposits were at higher levels in the F3 and F4 fractions. Therefore, it was concluded that the co-existence of heavy metal ions in an aqueous solution is beneficial for their removal by steel slag in acidic conditions.

Importance of end-of-life vehicles (ELVs) as an urban mine is expected to grow, as more people in developing countries are experiencing increased standards of living, while the automobiles are increasingly made using high-quality materials to meet stricter environmental and safety requirements. While most materials in ELVs, particularly steel, have been recycled at high rates, quality issues have not been adequately addressed due to the complex use of automobile materials, leading to considerable losses of valuable alloying elements. This study highlights the maximal potential of quality-oriented recycling of ELV steel, by exploring the utilization methods of scrap, sorted by parts, to produce electric-arc-furnace-based crude alloy steel with minimal losses of alloying elements. Using linear programming on the case of Japanese economy in 2005, we found that adoption of parts-based scrap sorting could result in the recovery of around 94-98% of the alloying elements occurring in parts scrap (manganese, chromium, nickel, and molybdenum), which may replace 10% of the virgin sources in electric arc furnace-based crude alloy steel production.

Economic growth is associated with a rapid rise in the use of natural resources within the economy, and has potential environmental impacts at local and/or global scales. In today's globalized economy, each country has indirect flows supporting its economic activities, and natural resource consumption through supply chains influences environmental impacts far removed from the place of consumption. One way to control environmental impacts associated with consumption of natural resources is to identify the consumption of natural resources and the associated environmental impacts through the global supply chain. In this study, we used a global link input-output model (GLIO, a hybrid multiregional input-output model) to detect the linkages between national nickel consumption and mining-associated global land-use changes. We focused on nickel, whose global demand has risen rapidly in recent years, as a case study. The estimated area of land-use change around the world caused by nickel mining in 2005 was 1.9 km(2), and that induced by Japanese final demand for nickel was 0.38 km(2). Our modeling also revealed that the areas of greatest land-use change associated with nickel mining were concentrated in only a few countries and regions far removed from the place of consumption. For example, 57.7% of the world's land-use changes caused by nickel mining were concentrated in five countries in 2005: Australia, 13.7%; Russia, 12.9%; Indonesia, 12.5%; New Caledonia, 10.4%; and Colombia, 8.2%. The mining-associated land use change induced by Japanese final demand accounted for 19.5% of the total area affected by land-use change caused by nickel mining. The top three countries accounted for 70.6% (Indonesia: 47.0%, New Caledonia: 16.0%, and Australia: 7.7%), and the top five accounted for 82.4% (the Philippines: 7.5%, and Canada: 4.3%, in addition to the top three countries and regions). (C) 2017 The Authors. Published by Elsevier B.V.

To design optimal pyrometallurgical processes for nickel and cobalt recycling, and more particularly for the end-of-life process of Ni-Co-Fe-based end-of-life (EoL) superalloys, knowledge of their activity coefficients in slags is essential. In this study, the activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag, a candidate slag used for the EoL superalloy remelting process, were measured using gas/slag/metal equilibrium experiments. These activity coefficients were then used to consider the recycling efficiency of nickel and cobalt by remelting EoL superalloys using CaO-Al2O3-SiO2 slag. The activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag both show a positive deviation from Raoult's law, with values that vary from 1 to 5 depending on the change in basicity. The activity coefficients of NiO and CoO peak in the slag with a composition near B = (%CaO)/(%SiO2) = 1, where B is the basicity. We observed that controlling the slag composition at approximately B = 1 effectively reduces the cobalt and nickel oxidation losses and promotes the oxidation removal of iron during the remelting process of EoL superalloys.

Special steel materials, including alloy steel and stainless steel, are among the most widely utilized materials in our society. Many kinds of metals other than iron accompany the special steel materials. Therefore, to achieve sustainable metals use in the steel industry, it is important to untangle the logistics of special steel materials in society. In conventional material flow analysis (MFA) studies based on a top down approach, primary inputs of materials into industries tend to be regarded as "end use" of material. However, materials are often traded between industries or even exported as intermediate or final products to foreign countries. In this study, discrepancies in requirements for materials between their primary and final versions are revealed by means of a waste input-output MFA (W10-MFA) model for special steel materials made in Japan in 2005. The result shows that only 45% of the primary demand is domestically consumed as finished product because exports of products such as automobiles and machinery contain significant amounts of special steel materials. In addition, non-negligible inter-industrial transactions are observed. The results imply a need for the careful accounting and precise understanding of material usages, and their sustainable management is crucial.

Metal extraction and smelting cause considerable impacts on the environment. Consumption-based impact accounting highlights the responsibility of metal-consuming industries for the impacts and may drive a system-wide improvement in the structure of related supply chains. To drive the improvements, policies at national level coordinated for respective product types across the nations is needed. However, nationwide responsibility for specific use of metals is difficult to identify because metals are manufactured into composite products (e.g., vehicles) in a country that is in many cases, different from the country where mining is practiced. The final product environmental footprints would not reveal the location where the various impacts are caused. This study presents a method to support the policy coordination by identifying the magnitude of the responsibility of metal-consuming countries for environmental impacts occurred in mining countries so that the countries sharing large responsibilities can find partner countries to jointly work on reduction in environmental impacts effectively. An input–output-based material flow analysis model is used to track the flows of metals included in products made in Japan throughout the international supply chain. In 2005, Japanese industries collected steel alloying elements (manganese, chromium, nickel, molybdenum) embodying 3200 kt-CO2eq and distributed them as both intermediate and final products. For steel mill products, Asian countries were the main destination, while alloying elements contained in other products were relatively evenly exported to Asia, Europe, and North America. By consuming products made in Japan, South Korea, China, the USA, and Taiwan shared approximately 10% each in terms of share of responsibility for greenhouse gas emission embodied in alloying element collected by Japan. Japan shared 40% of the responsibility with domestic consumption of own products. These findings suggest that Japan, a collector and distributor of steel alloying elements, must work on its own resource use reduction policies coordinating with these countries to globally develop sustainable resource use system.

Cobalt and nickel are high-value commodity metals and are mostly used in the form of highly alloyed materials. The alloying elements used may cause contamination problems during recycling. To ensure maximum resource efficiency, an understanding of the removability of these alloying elements and the controllability of some of the primary alloying elements is essential with respect to the recycling of end-of-life (EoL) nickel- and cobalt-based superalloys by remelting. In this study, the distribution behaviors of approximately 30 elements that are usually present in EoL nickel- and cobalt-based superalloys in the solvent metal (nickel, cobalt, or nickel-cobalt alloy), oxide slag, and gas phases during the remelting were quantitatively evaluated using a thermodynamic approach. The results showed that most of the alloying elements can be removed either in the slag phase or into the gas phase. However, the removal of copper, tin, arsenic, and antimony by remelting is difficult, and they remain as tramp elements during the recycling. On the other hand, the distribution tendencies of iron, molybdenum, and tungsten can be controlled by changing the remelting conditions. To increase the resource efficiency of recycling, preventing contamination by the tramp elements and identifying the alloying compositions of EoL superalloys are significantly essential, which will require the development of efficient prior alloy-sorting systems and advanced separation technologies. (C) The Minerals, Metals & Materials Society and ASM International 2016

Zinc ferrite (ZnFe2O4), one of the major forms of zinc in Electric Arc Furnace (EAF) dust, is very difficult to chemically dissolve in aqueous solutions. In our previous work, a pretreatment process referred to as "CaO treatment" was proposed as a key technology for transforming the ZnFe2O4 in EAF dust to ZnO and Ca2Fe2O5 without carbothermic reduction. Because this CaO treatment also enables the preferential removal of chloride, fluoride and heavy metals during heating with essentially no evaporation loss of zinc or iron, the CaO treated product, or "CaO treated dust", consists mainly of ZnO and Ca2Fe2O5, and contains no chloride, fluoride or heavy metals. Zinc leaching, which involves dissolving ZnO into either acidic or alkaline solutions, makes it possible to recover zinc from the CaO treated dust. In this study, the feasibility of the alkaline leaching of CaO treated dust was investigated using a NaOH solution for the selective leaching of zinc over iron and calcium, and the effect of temperature, reaction time, NaOH concentration and solid/liquid (S/L) ratio were examined. It was found that significantly more zinc was extracted from the CaO treated dust than the as-supplied raw dust by the NaOH solution. Nearly complete zinc extraction from the CaO treated dust was achieved without any notable dissolution of iron and calcium, which remained as Ca2Fe2O5 and Ca3Fe2(OH)(12) in the leach residue. These residues can be supplied to the steel making industry as flux for the dephosphorization of hot metal or a raw material for the blast furnace. (C) 2015 Elsevier B.V. All rights reserved.

Zinc in Electric Arc Furnace dust or EAF dust mainly exists as ZnFe(2)O4 and ZnO. While ZnO can be simply dissolved into either an acidic or alkaline solution, it is difficult to dissolve ZnFe(2)O4. In our previous work, we introduced a process called "CaO treatment", a preliminary pyrometallurgical process designed to transform the ZnFe(2)O4 in the EAF dust into ZnO and Ca2Fe2O5. The halogens and others heavy metals were favorably vaporized during CaO treatment with no essential evaporation loss of zinc and iron, leaving CaO treated dust which consisted mainly of ZnO and Ca2Fe2O5 and no problematic ZnFe2O4 compound. In this work, the selective leaching of zinc over iron and calcium in the CaO treated dust was investigated using an NR4Cl solution. The effects of temperature, reaction time and NH4Cl concentration on dissolution behavior were examined. While most of the zinc in the CaO treated dust was extracted after 2 h at 70 degrees C with 2 M Na4Cl, only about 20% of calcium was leached in NH4Cl solution. However, the iron did not dissolve and remained as Ca2Fe2O5 in residue. It was confirmed that zinc can be effectively recovered using NH4Cl solution. (C) 2015 Elsevier B.V. All rights reserved.

This article will outline the historical transition in the flow of phosphorus in steelmaking technology, and examine the current and future phosphorus flow in steel production and the peripheral steelmaking processes. History provides many instances of innovative changes in steelmaking processes driven by various issues associated with raw materials which emerged over time, such as supply, quality and cost issues. The major steel countries with a long history, including Sweden and Japan, have shown flexibility in their ability to adapt to the changes in the value of resources and geopolitical conditions over times, and have enacted survival resource utilization measures over many centuries, leading to improvements in their respective steelmaking processes. Considering these success stories, it stands to reason that the ideal state of steelmaking is one with a clear stance with regard to resource policy. (C) 2015 Elsevier B.V. All rights reserved.

Due to the impact of increasing global demand for high-grade steel for a variety of applications at a time when high grade iron ore reserves are becoming depleted, the removal of impurities, and especially phosphorus, has become essential. Demand in the rapidly growing car industry, in particular, is increasing pressure on steelmakers to provide high quality steel. The dephosphorization step presents new opportunities to steelmakers: besides producing high-quality steels not prone to cracking or corrosion, and improving production efficiency, steelmakers are presented with the opportunity to recover phosphorus and market it as a value-added product. Another industry with potential to recover P as a secondary product is the surface treatment industry. Surface treatment and the galvanization of metal products requires phosphoric acid and generates waste containing phosphorus, which is typically not well recovered or recycled. In this study, we focus on the potential of steelmaking slag and waste sludge from nickel plating and metal surface treatment processes as non-traditional phosphorus resources. An MFA on the hidden phosphorus flow behind global iron ore trade showed that, that the hidden flow of phosphorus from the three major iron ore export countries to China alone was 331 kt in 2013, which is equivalent to 1.7% of the global consumption of P in fertilizers consumed that year. In 2013, 3.6 kilo ton of phosphorus was wasted in acid waste from the metal surface treatment industry. (C) 2015 Elsevier B.V. All rights reserved.

The non-carbothermic zinc pyrometallurgical processing of electric arc furnace (EAF) dust was investigated on a laboratory scale. The main objective of this process was to convert highly stable zinc ferrite (ZnFe2O4), which accounts for more than half of total zinc in the EAF dust, into ZnO and Ca2Fe2O5 by CaO addition. The EAF dust was mixed with CaO powder in various ratios, pressed into pellets, and heated in a muffle furnace in air at temperatures ranging from 700 to 1100A degrees C for a predetermined holding time. All ZnFe2O4 was transformed into ZnO and Ca2Fe2O5 at a minimum temperature of 900A degrees C within 1 h when sufficient CaO to achieve a Ca/Fe molar ratio of 1.1 was added. However, at higher temperatures, excess CaO beyond the stoichiometric ratio was required because it was consumed by reactions leading to the formation of compounds other than ZnFe2O4. The evaporation of halides and heavy metals in the EAF dust was also studied. These components could be preferentially volatilized into the gas phase at 1100A degrees C when CaO was added.

The changes in the food supply over a period of almost 50 years in the three biggest economies in Asia were examined to estimate the change in the virtual phosphorus requirements in each country over time with regard to food consumption. While the overall food supply in the rapidly growing economies of India and China grew rapidly, there are some remarkable differences in the food supply in these two emerging giant economies over time. Having undergone rapid development in the late 1970s and 1980s, Japan’s food supply stabilized with the stagnation of the Japanese economy in the mid 1990s. The implications of the changes in the food supply of these three economies are discussed in terms of the phosphorus demand for producing food for these three countries using the concept of the virtual phosphorus. Future projections were made to create a likely case scenario for the virtual phosphorus requirements in these countries in the lead up to 2050 by extrapolation and by incorporating the latest population predictions.

There has been a sharp increase in the production of automobiles over the past decade. In 2010, one billion automobiles were in circulation worldwide. The automobile industry is one of the largest metals consumers and plays an important role in their sustainable use. Steel materials, including alloy steels that contain alloying elements (AEs) such as manganese, chromium, nickel, and molybdenum, are the main component of automobiles. The recycling of end-of-life vehicles (ELVs) significantly affects the cycling of iron, steel, and AEs. Currently, ELV recycling is performed using the electric arc furnace (EAF). In this method, losses of AEs are likely to occur because their presence is rarely considered. This study evaluated the environmental and economic benefits of alternative ELV recycling schemes, which allow more efficient utilization of AEs found in ELV-derived steel scrap (ELV-dSS). The AE contents in ELV-dSS (as car-parts) were estimated by means of a waste input-output material flow analysis (WIO-MFA) model extended for the detailed analysis of automobile composition. Using Japanese data, it was found that sorting ELV-dSS by parts can result in a significant recovery of AEs; more specifically, a 10-fold saving in AEs was achieved by sorting exhaust parts. The recoverable mass of AEs from sorted ELV-dSS was found to correspond to 8.2% of the annual consumption of AEs in Japan, as virgin resources in EAF steelmaking. ELV-dSS sorting was found to be significantly effective in the conservation of AE resources. (C) 2015 Elsevier B.V. All rights reserved.

Metallic aluminum in aluminum dross is recovered in Japan generally by physical separation, using the so-called Metal Reclamate Machine (MRM). A large amount of the residue containing oxides, metallic aluminum, nitrides and salts is unavoidably generated as a by-product of the MRM process. Since the metallic aluminum is much more viscous than the relatively brittle oxides and nitrides, it remains larger after crushing in the MRM. Using of an easier separation process for the recovery of metallic aluminum from the residue would promote sustainable recycling. The relationship between the composition and the grain size of the residue was investigated to develop an easier technique for upgrading aluminum dross residue. The mean sizes of studied residues were 100-200 A mu m. The residues larger than about 200 A mu m had higher metallic aluminum content, whereas their aluminum nitride and chlorine contents were lower. It was confirmed that the metallic aluminum content of the residue could be easily increased by the proposed screening process.

The aim of this article is to propose a method for forecasting future secondary material flows by combining a product lifetime distribution analysis with a waste input-output analysis and present a simple case study of automobiles. The case study demonstrates that the proposed method enables us to estimate replacement demand of new vehicles, number of end-of-life (EOL) vehicles arising from the aging of vehicles, volume of shredder scraps recovered from EOL vehicles, and volume of shredder scraps required to meet final consumption in the future.

Phosphorus is an important strategic resource for agricultural food production and the chemical industry. Natural phosphate ore is traded worldwide as a raw material for fertilizers however, owing to the growing demand for fertilizers worldwide, its deposits could deplete within the next century. The average price of the ore in 2008 was approximately twice that in 2007. Considering the limited supplies of phosphorus, it is important to evaluate the quantity and availability of currently untapped phosphorus resources. Thus, we developed the Integrated Phosphorus Cycle Input Output (IPCIO) model to estimate the phosphorus requirements for economic activities and to evaluate the recycling effects of reutilizing currently untapped phosphorus resources. The model’s accounting framework includes four natural resources, 25 phosphorus-related commodities in physical terms, and 389 intermediate sectors of the Japanese economy for 2005.

The removability of impurities during the aluminum remelting process by oxidation was previously investigated by our research group. In the present work, alternative impurity removal with chlorination has been evaluated by thermodynamic analysis. For 43 different elements, equilibrium distribution ratios among metal, chloride flux and oxide slag phases in the aluminum remelting process were calculated by assuming the binary systems of aluminum and an impurity element. It was found that the removability of impurities isn't significantly affected by process parameters such as chloride partial pressure, temperature and flux composition. It was shown that Ho, Dy, Li, La, Mg, Gd, Ce, Yb, Ca and Sr can be potentially eliminated into flux by chlorination from the remelted aluminum. Chlorination and oxidation are not effective to remove other impurities from the melting aluminum, due to the limited parameters which can be controlled during the remelting process. It follows that a proper management of aluminum scrap such as sorting based on the composition of the products is important for sustainable aluminum recycling.

Even for metals, open-loop recycling is more common than closed-loop recycling due, among other factors, to the degradation of quality in the end-of-life (EoL) phase. Open-loop recycling is subject to loss of functionality of original materials, dissipation in forms that are difficult to recover, and recovered metals might need dilution with primary metals to meet quality requirements. Sustainable management of metal resources calls for the minimization of these losses. Imperative to this is quantitative tracking of the fate of materials across different stages, products, and losses. A new input-output analysis (IO) based model of dynamic material flow analysis (MFA) is presented that can trace the fate of materials over time and across products in open-loop recycling taking explicit consideration of losses and the quality of scrap into account. Application to car steel recovered from EoL vehicles (ELV) showed that after 50 years around 80% of the steel is used in products, mostly buildings and civil engineering (infrastructure), with the rest mostly resided in unrecovered obsolete infrastructure and refinery losses. Sensitivity analysis was conducted to evaluate the effects of changes in product lifespan, and the quality of scrap.

リンは農業生産および食糧供給に欠かせない必須の栄養元素である。リン資源の主たる供給源はリン鉱石であるが、近年、供給国の地政学的 リスクが懸念されている。将来にわたった人口増大、経済的な発展を背景としてアジアにおいて、リン資源の重要性はますます高まることは予想される。中国はリン鉱石の供給においても重要な役割を担っている。本研究は貿易統計を通じて、アジアにおけるリン資源の国際依存度の解析を行った。

Alloying elements in steel add a wide range of valuable properties to steel materials that are indispensable for the global economy. However, they are likely to be effectively irretrievably blended into the steel when recycled because of (among other issues) the lack of information about the composition of the scrap. This results in the alloying elements dissipating in slag during steelmaking and/or becoming contaminants in secondary steel. We used the waste input-output material flow analysis model to quantify the unintentional flows of alloying elements (i.e., chromium, nickel, and molybdenum) that occur in steel materials and that result from mixing during end-of-life (EOL) processes. The model can be used to predict in detail the flows of ferrous materials in various phases, including the recycling phase by extending steel, alloying element source, and iron and steel scrap sectors. Application of the model to Japanese data indicates the critical importance of the recycling of EOL vehicles (ELVs) in Japan because passenger cars are the final destination of the largest share of these alloying elements. However, the contents of alloying elements are rarely considered in current ELV recycling. Consequently, the present study demonstrates that considerable amounts of alloying elements, which correspond to 7% to 8% of the annual consumption in electric arc furnace (EAF) steelmaking, are unintentionally introduced into EAFs. This result suggests the importance of quality-based scrap recycling for efficient management of alloying elements.

Recently, sustainable management of resources has become an increasingly recognized issue. Accordingly, interest in understanding the relationship between natural resources consumption and the global product supply chain has also been increasing. Material flow analysis (MFA) is a useful tool for understanding resource consumption and material cycles in national economies. However, detailed MFA studies of the materials embedded in foreign trade flows are rare. This study identified global trade flow of iron embedded in bilateral trade between 231 countries by multiplying the trade volume of the commodities in the BACI (Base pour l'Analyse du Commerce International) database and the iron content of each commodity. We focused on the cases of Japan, China, and United States, and estimated the mass of iron embedded in imports and export. The identified total flows of iron embedded in international trade were 1.15 x 10(9) t-Fe with 35.2% of the flows concentrated in three countries, Japan, China and United States, which are major crude steel production countries.

Recently, the issue of sustainable resource management has been increasingly recognized. Economic growth of human activity is associated with a rapid rise in the use of resources in our economy, and society has a potential environmental impact. The UNEP International Resource Panel (IRP) pointed out the importance of decoupling resource use and negative environmental impacts from economic activity (UNEP IRP 2011). In order to optimize the material cycles and increase resource efficiency, material flow analysis (MFA) is a powerful tool to understand the resource consumption and material cycle in the national economy. In this study, we present the results of global material flow analysis of nickel, which is one of the important resources for reducing energy use and CO2 emission in our society, and discuss the importance and possibility of controlling its resource logistics. This study also introduces the challenge of identifying the land-use changes in nickel mining sites by a remote-sensing technique, and knowledge to increase the resource efficiency in metal recycling based on the metallurgical thermodynamic approach. The results indicated the importance of recovery of nickel in recycling policies for end-of-life (EoL) vehicles and constructions. Improvement in EoL sorting technologies and implementation of designs for recycling/disassembly at the manufacturing phase are needed. Possible solutions include development of sorting processes for steel scrap and introduction of easier methods for identifying the composition of secondary resources. Recovery of steel scrap with a high alloy content will reduce primary inputs of alloying elements and contribute to more efficient resource use.

Urban ores can be classified into two typesthose made up of items that were in the possession of consumers, such as end-of-life home appliances, and those that were not, such as manufacturing wastes. The dephosphorization slag generated at some steelmaking plants is an example of a manufacturing waste. In this study, the potential for this slag to become a new phosphorous resource is evaluated in terms of total material requirement (TMR). To do this, we compare two types of TMRnatural ore TMR (NO-TMR) and urban ore TMR (UO-TMR)defined respectively as the TMR to obtain or recycle 1 kilogram of phosphoric acid from natural phosphate ore or dephosphorization slag. In the dephosphorization slag process, the slag is magnetically separated into a phosphorous-rich (PR) phase and an iron-rich (IR) phase, and the phosphorous in the PR phase is subsequently converted to phosphoric acid. We included case studies that considered generation of potentially useful by-products, such as phosphogypsum and the IR phase. The effect of declines in natural phosphate ore grade on the potential recyclability of phosphoric acid from dephosphorization slag was also explored. In addition, the effect of changes in the slag's contribution to the UO-TMR of phosphoric acid was considered. We found that, in many scenarios, the UO-TMR for phosphoric acid was lower than its NO-TMR. This indicates that dephosphorization slag has the potential to be a new phosphorous resource. We also found that recycling of the IR phase by recharging it to the blast furnace plays an important role in improving the potential feasibility of slag as a new phosphorous resource. The value of the slag stream, relative to the value of the pig iron stream, is also a key parameter, with low relative values improving the potential for production of phosphoric acid. Evaluating the UO-TMR of materials recovered from manufacturing waste streams promises to be a useful tool for assessing the potential of these waste streams to serve as urban ores.

Steel is not elemental iron but rather a group of iron-based alloys containing many elements, especially chromium, nickel, and molybdenum. Steel recycling is expected to promote efficient resource use. However, open-loop recycling of steel could result in quality loss of nickel and molybdenum and/or material loss of chromium. Knowledge about alloying element substance flow is needed to avoid such losses. Material flow analyses (MFAs) indicate the importance of steel recycling to recovery of alloying elements. Flows of nickel, chromium, and molybdenum are interconnected, but MFAs have paid little attention to the interconnected flow of materials/substances in supply chains. This study combined a waste input-output material flow model and physical unit input-output analysis to perform a simultaneous MFA for nickel, chromium, and molybdenum in the Japanese economy in 2000. Results indicated the importance of recovery of these elements in recycling policies for end-of-life (EoL) vehicles and constructions. Improvement in EoL sorting technologies and implementation of designs for recycling/disassembly at the manufacturing phase are needed. Possible solutions include development of sorting processes for steel scrap and introduction of easier methods for identifying the composition of secondary resources. Recovery of steel scrap with a high alloy content will reduce primary inputs of alloying elements and contribute to more efficient resource use. © 2013 American Chemical Society.

In order to improve the coke combustion efficiency during iron ore sintering, the effect of coke granule structure was investigated with a TG-DTA and a new combination heating equipment capable of establishing similar heating pattern to the actual sintering bed. The results were analyzed as a function of granule type and neighboring specie as follows: The granule type was crucial to the combustion behavior of granules. On the other hand, the effect of neighbors was distinct over core coke particles; meanwhile, the effect remained uncertain in pellet type granules. The authors recommend composite type granules (fine coke particles adhering on a core particle) for the best choice. The type should bring 1.2% save of coke consumption and 2.3% increase in the heat front speed in comparison to coke particles of single type.

Oxidation behavior of CaS in oxidizing atmosphere has been investigated for the regeneration process of desulfurization slag by oxidation. The temperature range of oxidation of CaS reagent with Ar-21%O-2 gas was 973 to 1423 K. The weight gain was observed in the lower temperature range and reached at the maximum value at 1173 K while weight gain turned to decrease when the reaction temperature was higher than 1173 K. It was clarified that CaS was oxidized to CaSO4 under 1173 K or to CaO over 1373 K by the measurement of oxidation rate, XRD and thermodynamic analysis. The results strongly suggested that sulfur removal from the sulfur containing slag may be possible at temperatures of 1223 K or higher by the oxidation of with air.

Metals can in theory be infinitely recycled in a closed-loop without any degradation in quality. In reality, however, open-loop recycling is more typical for metal scrap recovered from end-of-life (EoL) products because mixing of different metal species results in scrap quality that no longer matches the originals. Further losses occur when meeting the quality requirement of the target product requires dilution of the secondary material by adding high purity materials. Standard LCA usually does not address these losses. This paper presents a novel approach to quantifying quality- and dilution losses, by means of hybrid input-output analysis. We focus on the losses associated with the recycling of ferrous materials from end-of-life vehicle (ELV) due to the mixing of copper, a typical contaminant in steel recycling. Given the quality of scrap in terms of copper density, the model determines the ratio by which scrap needs to be diluted in an electric arc furnace (EAF), and the amount of demand for EAF steel including those quantities needed for dilution. Application to a high-resolution Japanese IO table supplemented with data on ferrous materials including different grades of scrap indicates that a nationwide avoidance of these losses could result in a significant reduction of CO2 emissions.

The oxidation behavior of sulfur in desulfurization slag generated from the secondary steelmaking process with air has been investigated in the temperature range of 973 K to 1373 K (700 A degrees C to 1100 A degrees C). Although a high removal rate of sulfur is not achieved at temperatures lower than 1273 K (1000 A degrees C) because of the formation of CaSO4, most of the sulfur is rapidly removed from slag as SO2 gas in the 1273 K to 1373 K (700 A degrees C to 1100 A degrees C) range. This finding indicates that the desulfurization slag generated from the secondary steelmaking process can be reused as a desulfurized flux through air oxidation, making it possible to reduce significantly the amount of desulfurization slag for disposal.

Waste electrical and electronic equipment (WEEE) has become an important target in managing material cycles from the viewpoint of not only waste management and control of environmental pollution but also resource conservation. This study investigated the distribution tendency of trace elements in municipal solid waste (MSW) or incinerator ash, including valuable non-ferrous metals (Ni, Co, Cr, Mn, Mo, Ti, V, W, Zr), precious group metals (PGMs) originated from WEEE (Ag, Au, Pd, Pt), and others (Al, B, Pb, Si), between Fe-rich and Cu-rich metal phases by means of simple thermodynamic calculations. Most of the typical alloying elements for steel (Co, Cr, Mo, Nb, Ni, Si, Ti, V. and W) and Rh were preferentially distributed into the Fe-rich phase. PGMs, such as Au, Ag, and Pd, were enriched in the Cu-rich phase, whereas Pt was almost equally distributed into both phases. Since the primary metallurgical processing of Cu is followed by an electrolysis for refining, and since PGMs in crude copper have been industrially recovered from the resulting anode slime, our results indicated that Ag, Au, and Pd could be effectively recovered from MSW if the Cu-rich phase could be selectively collected. (c) 2012 Elsevier Ltd. All rights reserved.

The separation and control of undesired elements are key to recycling scrap or end-of-life (EoL) metal products, as the quality of regenerated metals is often impaired by contamination from the alloying elements in the scrap. However, little is known of their removability or controllability because they are normally absent in the production of primary metal from natural ore. Here, the distribution ratios of 31 kinds of alloying element among the metal, slag, and gas phases in the re-melting of EoL titanium products were quantitatively discussed. Our results clarified that the typical titanium alloying elements - Al, Fe, and V - are essentially uncontrollable in re-melted titanium by oxidation or evaporation. This suggests that the mixing of commercially pure titanium (CP-Ti) and other titanium alloys should be avoided. Hence, the development of new technologies to separate alloying elements from titanium scraps for sustainable titanium recycling is highly anticipated. (C) 2012 Elsevier B.V. All rights reserved.

Zinc is a widely utilized industrial metal and has numerous applications such as galvanization, production of brass, and die casting. However, zinc has been identified as one of the elements whose supply may potentially be limited in nature. Zinc recycling from end-of-life products has been employed as a method of increasing zinc supplies, but this alone cannot be expected to satisfy industrial demands due to the chemical nature of recycling processes. In this study, we have examined the flow of zinc cycle in Taiwan in 2009, which encompasses manufacturing, usage, and wastage stages. The electric arc furnace (EAF) dust plays an essential role as the sole recovery path of zinc from end-of-life products, and hence, an intermediate dust treatment process, the Waelz process, is a key technology to promote the efficiency of the zinc cycles. Hence, we have applied the substance flow analysis (SFA) to the Taiwanese zinc cycle (i.e., at the national level) as well as to the most important zinc recycling process, i.e., EAF dust management during steelmaking, and discussed the results in considerable detail. Our results demonstrate that Taiwan is a net importer of zinc in the form of ingots, and its zinc applications to galvanized steel, brass, and zinc-based alloys amount to 61.4%, 15.9%, and 13.5%, respectively. However, in the steelmaking sector, more than 148.5 ktons of EAF dust were generated in 2009; this exceeded all the intermediate treatment capacities of 85 ktons and led to the accumulation of more than 500 ktons of EAF dust in temporary storages without proper treatments. Only 32.3% of the total zinc input to the steelmaking process (galvanization) returned to the economy. In this manner, we have demonstrated a problematic situation in the Taiwanese zinc flow cycle, and we believe that it is highly probable that such an unsustainable state may contribute to further resource depletions of zinc. (C) 2011 Elsevier By. All rights reserved.

Zinc is a widely utilized industrial metal and has numerous applications such as galvanization, production of brass, and die casting. However, zinc has been identified as one of the elements whose supply may potentially be limited in nature. Zinc recycling from end-of-life products has been employed as a method of increasing zinc supplies, but this alone cannot be expected to satisfy industrial demands due to the chemical nature of recycling processes. In this study, we have examined the flow of zinc cycle in Taiwan in 2009, which encompasses manufacturing, usage, and wastage stages. The electric arc furnace (EAF) dust plays an essential role as the sole recovery path of zinc from end-of-life products, and hence, an intermediate dust treatment process, the Waelz process, is a key technology to promote the efficiency of the zinc cycles. Hence, we have applied the substance flow analysis (SFA) to the Taiwanese zinc cycle (i.e., at the national level) as well as to the most important zinc recycling process, i.e., EAF dust management during steelmaking, and discussed the results in considerable detail. Our results demonstrate that Taiwan is a net importer of zinc in the form of ingots, and its zinc applications to galvanized steel, brass, and zinc-based alloys amount to 61.4%, 15.9%, and 13.5%, respectively. However, in the steelmaking sector, more than 148.5 ktons of EAF dust were generated in 2009; this exceeded all the intermediate treatment capacities of 85 ktons and led to the accumulation of more than 500 ktons of EAF dust in temporary storages without proper treatments. Only 32.3% of the total zinc input to the steelmaking process (galvanization) returned to the economy. In this manner, we have demonstrated a problematic situation in the Taiwanese zinc flow cycle, and we believe that it is highly probable that such an unsustainable state may contribute to further resource depletions of zinc. (C) 2011 Elsevier By. All rights reserved.

Coal fly ash emitted from coal-fired electric power stations generally contains environmentally regulated trace elements. In particular, boron, arsenic, and selenium have been recognized as troublesome trace elements because elutions from the fly ash contain them. In order to design an effective removal process for these trace elements, we have developed and investigated an acid-washing process. The dissolution behavior of selenium from coal fly ash particles was focused on for the improvement of the process, and was found to greatly depend on the pH of the acid solutions. The species of selenium in solutions with a pH of around 0-1 was determined to be H(2)SeO(3). The dissolved H(2)SeO(3) transformed into HSeO(3)(-) and adsorbed onto the surface of the ash particles in solution upon elevation of the pH. The re-elution of the absorbed HSeO(3)(-) as SeO(3)(2-) at a pH of 10 was also confirmed, and will cause the elution of the excess selenium from the acid-washed ash. (C) 2011 Elsevier Ltd. All rights reserved.

Coal fly ash emitted from coal-fired electric power stations generally contains environmentally regulated trace elements. In particular, boron, arsenic, and selenium have been recognized as troublesome trace elements because elutions from the fly ash contain them. In order to design an effective removal process for these trace elements, we have developed and investigated an acid-washing process. The dissolution behavior of selenium from coal fly ash particles was focused on for the improvement of the process, and was found to greatly depend on the pH of the acid solutions. The species of selenium in solutions with a pH of around 0-1 was determined to be H(2)SeO(3). The dissolved H(2)SeO(3) transformed into HSeO(3)(-) and adsorbed onto the surface of the ash particles in solution upon elevation of the pH. The re-elution of the absorbed HSeO(3)(-) as SeO(3)(2-) at a pH of 10 was also confirmed, and will cause the elution of the excess selenium from the acid-washed ash. (C) 2011 Elsevier Ltd. All rights reserved.

Phosphorus is indispensable for agricultural production. Hence, the consumption of imported food indirectly implies the import of phosphorus resources. The global consumption of agricultural products depends on a small number of ore-producing countries. For sustainable management of phosphorus resources, the global supply and demand network should be clarified. In this study, we propose the virtual phosphorus ore requirement as a new indicator of the direct and indirect phosphorus requirements for our society. The virtual phosphorus ore requirement indicates the direct and indirect demands for phosphorus ore transformed into agricultural products and fertilizer. In this study, the virtual phosphorus ore requirement was evaluated for the Japanese economy in 2005. Importantly, the results show that our society requires twice as much phosphorus ore as the domestic demand for fertilizer production. The phosphorus contained in "eaten" agricultural products was only 12% of virtual phosphorus ore requirement. (C) 2011 Elsevier Ltd. All rights reserved.

This study presents the results of chemical thermodynamic analysis on the distribution of elements in the smelting process of metallic materials to examine the controllability of impurities in the pyrometallurgical technique. The results of the present work can give an answer against the frequently given question; "Which impurity element can be removable in metallurgical process?" or "How far can the impurity level be controlled?". The proposed method was applied to estimate the distribution of 29 elements for a copper converter and 26 elements for a steel-making process and shows the distribution tendency of elements among the gas, slag, and metal phases as well as clarifying which metals can be recovered or removed from secondary resources in metallurgical processes. The effects of temperature, oxygen partial pressure, and slag composition on the distribution ratio of elements were also evaluated, and the removal limit or controllability of impurity in these two processes was presented. This study results in thermodynamic features of various elements in the pyrometallurgical process and also shows, even by varying process parameters such as temperature and oxygen partial pressure, no drastic improvement of removal efficiency should be expected, except for lead and tin in copper.

In this paper, the possibility of removing impurities during magnesium recycling with pyrometallurgical techniques has been evaluated by using a thermodynamic analysis. For 25 different elements that are likely to be contained in industrial magnesium alloys, the equilibrium distribution ratios between the metal, slag and gas phases in the magnesium remelting process were calculated assuming binary systems of magnesium and an impurity element. It was found that calcium, gadolinium, lithium, ytterbium and yttrium can be removed from the remelted end-of-life (EoL) magnesium products by oxidization. Calcium, cerium, gadolinium, lanthanum, lithium, plutonium, sodium, strontium and yttrium can be removed by chlorination with a salt flux. However, the other elements contained in magnesium alloy scrap are scarcely removed and this may contribute toward future contamination problems. The third technological option for the recycling of EoL magnesium products is magnesium recovery by a distillation process. Based on thermodynamic considerations, it is predicted that high-purity magnesium can be recovered through distillation because of its high vapor pressure, yet there is a limit on recoverability that depends on the equilibrium vapor pressure of the alloying elements and the large energy consumption. Therefore, the sustainable recycling of EoL magnesium products should be an important consideration in the design of advanced magnesium alloys or the development of new refining processes.

Boron-containing compounds have been listed as one of environmentally hazardous substances in Japan since 2001, and known to condense in coal fly ash particles during coal combustion and coal fly ash formation in coal-fired electric power stations. So far, the authors have revealed that the speciation of boron-containing compounds in coal fly ash particles is mostly a calcium orthoborate or pyroborate. In this research, the speciation of boron compounds in standard coals and their char generated by laboratory-scale combustion test has been investigated by using a microwave-assisted acid digestion method and a Magic-Angle-Spinning Nuclear Magnetic Resonance (MAS-NMR) in order to reveal the vaporization behavior of boron in standard coals during combustion at relatively low temperature. Three isolated peaks are observed in (11)B MAS-NMR spectra of standard coals, and all of them are attributed to four-oxygen-coordinated boron atom. Around 50% of boron vaporizes even though heating condition is 200 degrees C and O(2) = 25%, and the percentage of vaporization reaches higher value than 80% at 400 degrees C and O(2) = 25%. The remaining boron contents in ash components are relatively small, and it suggests that most of boron in standard coals exist with relatively volatile carbon contents, and they volatilize in the very early stage of coal combustion. (C) 2010 Elsevier Ltd. All rights reserved.

Atomic scale chemical environments of boron in coal has been studied by solid state NMR spectroscopy including magic angle spinning (MAS), satellite transition magic angle spinning (STMAS), and cross-polarization magic angle spinning (CPMAS). The 11B NMR spectra can be briefly classified according to the degree of coalification. On the 11B NMR spectra of lignite, bituminous, and sub-bituminous coals (carbon content of 70-90mass%), three sites assigned to four-coordinate boron [4]B with small quadrupolar coupling constants (≥0.9 MHz) are observed. Two of the [4]B sites in downfield are considered organoboron complexes with aromatic ligands, while the other in the most upper field is considered inorganic tetragonal boron (BO4). By contrast, on the 11B NMR spectra of blindcoal (carbon content &gt 90 mass%), the [4]B which substitutes tetrahedral silicon of Illite is observed as a representative species. It has been considered that the organoboron is decomposed and released from the parent phase with the advance of coal maturation, and then the released boron reacts with the inorganic phase to substitute an element of inorganic minerals. Otherwise boron contained originally in inorganic minerals might remain preservedevenunder the high temperature condition that is generated during coalification. © 2011 American Chemical Society.

The demand for iron and steel materials has been increasing mainly because of the rapid economic growth of the BRIC countries. The annual worldwide production of crude steel is approximately 2 billion tons. There has been a corresponding increase in the production of crude steel in Japan. As a result, the significance of Japan as a source of iron and steel scraps has also increased.(1)) Scrap recycling, however, is subject to some problems, such as unstable supply conditions and contamination by impurities.(2)) A significant part of these problems can be attributed to the increasing use of electric devices, such as circuit boards, motors, and wiring harnesses, in high-tech products. These electric devices/equipments contain many kinds of metals, such as copper, lead, and zinc, which can become a source of contamination of steel scrap recovered from end-of-life vehicles (ELVs) or home appliances. Here the contamination of tramp elements was analyzed using a Waste Input Output model, considering the following points: (1) the amount of ferrous scrap usage in iron and steel production process, (2) copper elimination from ELV scraps, and (3) contamination of copper in iron and steel products. The results of scenario analysis indicated that copper contamination in crude steel production associated with the use of scrap from ELVs could be reduced by 2 % by the use of a more recycle-oriented ELV treatment. The effects of copper elimination on CO2 emission were more significant for ordinary steel production than special steel production.

This study proposes a method of combining a waste input-output material flow analysis (WIO-MFA) model with trade statistical data to identify the flows of substances embedded in trade commodities. We focused on the case of Japan as a typical processing and trading country, and we estimated each mass of iron and aluminum embedded in the imports and exports of 300 product items categorized in the WIOMFA. We found that iron ore imported from Australia, Brazil, and India as a raw material is processed and exported to South Korea, China, and other Asian countries as steel materials and to the United States as steel materials and automobiles. Primary aluminum imported from Russia, Australia, and Brazil as a raw material is processed and exported to Asia as rolled materials and to the United States as rolled materials and automobiles. © 2011 ISIJ.

This paper investigates the effect of de-oxidation inclusions on micro-structure in low carbon (0.07 mass%), high Mn (0.9 mass%) steel. De-oxidation tests were carried out by adding either aluminum (0.05 mass%) or titanium (0.05, 0.03 or 0.015 mass%) to an iron melt in a 400 g-scale vacuum furnace. A Confocal Scanning Laser Microscope (CSLM) was used to evaluate the effect of cooling rate by re-melting and quenching during solidification. Fine secondary de-oxidation particles were obtained in the Ti-killed samples, and the particle density increased with increasing oxygen content, and their size decreased with increasing the cooling rate during solidification. The secondary Ti de-oxidation particles were found to have an effect on microstructure evolution, such as solidifying microstructure, austenite grain growth and austenite decomposition. The de-oxidation particles were examined through FE-TEM and were identified to be TiO, MnTiO(3) and Mn(2)TiO(4), in low oxygen ([O]=7 ppm) and high oxygen ([O]=56, 81 ppm) Ti-killed steels respectively, which were qualitatively same as those predicted by thermodynamic calculations. Stabilities of TiO, MnTiO(3) and Mn(2)TiO(4) are influenced by Mn presence. Composition change and decomposition of oxide were estimated through thermodynamic calculations. The effect of the particles on ferrite formation was evaluated through thermo-mechanical treatments. TiO was the most effective for promoting ferrite formation through heterogeneous nucleation. The particles contributed to ferrite formation in the following order, TiO>TiN>MnS> MnTiO(3)>Ti(2)O(3). It was found that the secondary Ti de-oxidation particles work are engulfed by the advancing solid phase during solidification based on analysis with PET (Pushing Engulfment Transition) velocity, particle sizes and solidification rates. The particles at dendrite tips and inter-dendritic regions are likely restraining the molten steel flow resulting in a finer solidification microstructure.

Coal fly ash emitted from coal thermal power plants generally contains tens ppm of arsenic, one of the hazardous elements in coal, during combustion and their elution to soil or water has become a public concern. In this study, the acid washing process developed by the authors was applied to the removal of arsenic from coal fly ash. Laboratory- and bench-scale investigations on the dissolution behavior of arsenic from various coal fly ash samples into dilute H2SO4 were conducted. Arsenic in the coal fly ash samples were dissolved into H2SO4 solutions rapidly. However, its concentrations decreased with an increase in the pH of H2SO4 solution in some cases. The species of arsenic in the dilute H2SO4 was estimated as H3AsO4, and its anionic species was considered to adsorb with the elevation of pH under the presence of ash particle. Such adsorption behavior was enhanced under the presence of Fe ion in the solution. The sufficient removal of arsenic was achieved by controlling pH and avoiding the adsorption of arsenic on the surface of coal fly ash particles, and the elution of arsenic from coal fly ash sample was successfully below the regulation limit. (C) 2010 Elsevier B.V. All rights reserved.

The chemical states of boron in coal fly ash, which may control its leaching into the environment, were investigated by focused-ion-beam time-of-flight secondary ion mass spectrometry (FIB-TOF-SIMS) and satellite-transition magic angle spinning nuclear magnetic resonance (STMAS NMR) spectroscopy. The distribution of boron on the surface and in the interior of micron-sized fly ash particles was directly observed by FIB-TOF-SIMS. Coordination numbers of boron and its bonding with different atoms from particles of bulk samples were investigated by STMAS NMR. Boron in coal fly ash with relatively poor leaching characteristics appears as trigonal BO(3) and coexists with Ca and Fe at the outer layer of every particle and inside CaO-MgO particles. In contrast, boron in coal fly ash with better leaching characteristics appears as CaO- or MgO-trigonal BO(3) and tetragonal BO(4), and it is distributed only on the outer surface of each ash particle without showing any correlation with a particular element. (C) 2010 Elsevier Ltd. All rights reserved.

In previous studies on the physical chemistry of pyrometallurgical processing of aluminum scrap, only a limited number of thermodynamic parameters, such as the Gibbs free energy change of impurity reactions and the variation of activity of an impurity in molten aluminum, were taken into account In contrast, in this study we thermodynamically evaluated the quantitative removal limit of impurities during the remelting of aluminum scrap; all relevant parameters, such as the total pressure, the activity coefficient of the target impurity, the temperature, the oxygen partial pressure, and the activity coefficient of oxidation product, were considered. For 45 elements that usually occur in aluminum products, the distribution ratios among the metal, slag, and gas phases in the aluminum remelting process were obtained. Our results show that, except for elements such as Mg and Zn, most of the impurities occurred as troublesome tramp elements that are difficult to remove, and our results also indicate that the extent to which the process parameters such as oxygen partial pressure, temperature, and flux composition can be changed in aluminum production is quite limited compared to that for iron and copper production, owing to aluminum's relatively low melting point and strong affinity for oxygen. Therefore, the control of impurities in the disassembly process and the quality of scrap play important roles in suppressing contamination in aluminum recycling.

Boron and its compounds are environmentally hazardous substance and are well-known condensed products that appear in coal fly ash during combustion of coal in coal-fired electric power stations. In a previous study, we suggested that boron in coal fly ash obtained from Nantun coal in China, identified as Ash-N, may exist on the surface of relatively large coal fly ash particles or as very fine particles generated by homogeneous nucleation. Although the characterization of boron in coal fly ash is important for its effective stabilization or removal, its detection is quite difficult because of its low concentration in coal fly ash and its light atomic weight. In the present work, solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) technique has been applied to reveal the local chemical structures of boron in Ash-N. In the B-11 MAS-NMR spectrum of Ash-N, two peaks which are attributed to a three-oxygen coordinated boron unit (BO3) and a four-oxygen coordinated boron unit (BO4) were observed with high resolution. We have estimated quadrupole parameters of the BO3 unit in Ash-N using computer simulation, and we have fingerprinted these moieties with the parameters of borates. The result of the present analysis shows that calcium-or magnesium-bearing orthoborate or pyroborate are the most likely forms of boron in Ash-N. (C) 2009 Elsevier Ltd. All rights reserved.

In a previous study, the authors found that phosphorus exhibits remarkable segregations in industrial hot metal pretreatment slag where it exists as a Ca₃P₂O₈–Ca₂SiO₄ solid solution together with a FeO–CaO–SiO₂–MnO–MgO matrix. Since the magnetic property of each phase is significantly different, it is possible to separate the phases with the aid of a superconducting strong magnetic field. By applying a strong magnetic field of 0.5 to 2.5 T to the crushed slag, more than 60% of the concentrated phosphorus phase in the slag was recovered. If most of the phosphorus can be removed from the slag, the residual slag will comprise FeO–CaO–SiO₂–MnO–MgO with less P₂O₅, and thus may be recycled to iron- and steel-making processes, such as sintering, hot-metal desiliconization, and hot-metal dephosphorization processes. In the present work, the recycling effect of subjecting the residual slag to the dephosphorization process was simulated based on a mass balance calculation. A significant reduction in total slag generation and CaO input was demonstrated by the mathematical model considering phosphorus recovery and recycling of residual slag as a dephosphorization agent. Using the waste input–output model, it was shown that phosphorus recovery from dephosphorization slag and the recycling of residual slag in a hot-metal dephosphorization process have potentially great environmental and economic benefits.

The authors have found that phosphorus exhibits remarkable segregation in exhausted actual hot-metal pretreatment slag (dephosphorization slag), and it exists as a 3CaO·P₂O₅–2CaO·SiO₂ solid solution with the FeO–CaO–SiO₂ matrix. Since their magnetic properties are significantly different, it is possible to separate them with the aid of a superconducting strong magnetic field. To investigate the effects of magnetic field strength, the particle size of the slag, <i>etc.</i>, an experiment on magnetic separation has been carried out using simulated dephosphorization slag (18.1Fe_tO–45.9CaO–20.3SiO₂–6.6P₂O₅–2.5MnO–5.5MgO in mass%) and a superconducting magnet with 0.5–2.5 T. In a stronger magnetic field, the quality of the recovered slag becomes better due to less contamination of the Fe_tO matrix phase, while its quantity worsens and the amount of recovered slag declines. However, the quantity of the recovered slag can be improved by repeating the procedure. In the present experiment, about 65% of the phosphorus enriched phase can be recovered with less than 10% of Fe_tO matrix phase contamination at conditions of 0.5 T, a particle size of less than 35 μm, and a water/slag ratio of 32 with a single procedure. The P₂O₅ content in the recovered slag is close to that in the phosphorus-enriched phase in the initial slag, and the FeO content decreases markedly with magnetic separation.

P&gt;The demand for biofuels has recently increased because of rising prices of fossil fuels and diversification of energy resources. As a result, the demand for sugarcane and corn has been increasing, not only for food production, but also as sources of energy. In this context, securing supplies of phosphorus, required as an essential nutrient in agricultural production, has considerable implications that extend beyond food and agricultural policy. It is therefore important to consider the quantity and availability of phosphorus resources that remain untapped, because the demand and supply of phosphate ore is currently becoming very tight, and Japan has no domestic phosphorus resources. To identify potential phosphorus resources, we have investigated the material flow of phosphorus within Japan, including that in the iron and steel industry, on the basis of statistical data for 2002. Our major finding is that the quantity of phosphorus in iron and steelmaking slag is almost equivalent to that in imported phosphate ore in terms of both the amount and concentration. We also found, by means of a waste input-output analysis and a total materials requirement study, that the phosphorus potentially recoverable from steelmaking slag by a new process that we have proposed has considerable environmental and economic benefits. Concerning the restricted supplies of phosphorus resource, it is important to consider the quantity and availability of phosphorus resources that currently remain untapped. From that viewpoint, steelmaking slag would be expected to be a great potential resource for phosphorus.

Thermodynamic evaluation of Cu-Cu3P system has been conducted by applying subregular solution model with Gibbs energy of CUR formation that was newly determined by means of triple Knudsen cell mass spectrometry. Both the calculated vapor pressure of phosphorus and phase diagram of Cu-P system are excellently consistent with the literature data in the composition range of Cu-Cu3P, indicating that there is no significant thermodynamic inconsistency between the present work based on the Gibbs energy of Cu3P formation determined and the literature data. (C) 2009 Elsevier Ltd. All rights reserved.

Boron as an environmentally regulated substance is well known to condense in the coal fly ash generated from coal combustion plants. Since boron in the coal fly ash tends to elute into the soil easily, a technology for its stabilization or removal from fly ash is required. An acid washing process is proposed and studied as one of the candidate technologies for the removal of boron from coal fly ash. A laboratory-scale investigation is conducted on the dissolution behavior of boron in the coal fly ash in a diluted HCl solution. The dissolution of boron and alkaline species is considerably fast and exhibits a behavior different from that of aluminum and silicon, which are major components of the ash. From the kinetic model, it is expected that boron in the ash may mainly be in the form of alkaline or alkaline earth borates that are deposited on the surface of relatively large ash particles of alumino-silicate or may be precipitated,as fine particles during coal combustion. This acid washing process is extended to a bench-scale plant and boron is successfully removed from the coal fly ash until its content is less than the regulation limit. (C) 2009 Elsevier Ltd. All rights reserved.

Security of resources becomes more important than ever as the upward trend in the prices of mineral and natural resources continues. Phosphorus and manganese are important minerals to many countries. Phosphorus is in global demand, particularly for making fertilizers,and manganese is an indispensable element in industrial and consumer products. However, the raw materials for these two elements are restricted to certain geographical regions and countries. More importantly, they are not produced in South Korea, although domestic use of each is increasing. In this paper the authors examine domestic phosphorus and manganese flows in South Korea, focusing on the iron and steel industries and using statistical data for 2005. The total phosphorus and manganese usage in South Korea are evaluated to be 380 kt-P/year and 303 kt-Mn/year (manganese ore + manganese alloy). Further, the amounts of phosphorus and manganese lost to steelmaking slag are estimated to be 35.7 kt-P/year and 162 kt-Mn/year. These losses correspond to about 10% of the domestic phosphorus consumption and approximately 53% of the manganese added in steelmaking processes as an alloying element or deoxidation agent. The results from these substance flow analyses suggest that a significantly large ripple effect can be expected if recovery of phosphorus and manganese from slag becomes possible. The potential for converting steelmaking slags into new phosphorus and manganese resources is also discussed from the viewpoint of recovery technology. (C) 2009 Elsevier B.V. All rights reserved.

The authors have found in their previous work that phosphorus exhibits remarkable segregations in the industrial hot metal pretreatment slag and it exists as Ca3P2O8-Ca2SiO4 solid Solution together with FeO-CaO-SiO2-MnO-MgO matrix. Since their magnetic property of each phase is significantly different, it is possible to separate each phase with the aid of superconducting strong magnetic field. By applying strong magnetic field of 0.5 to 2.5 T to the crushed slag, more than 60% of phosphorus concentrated phase in the slag has been recovered. If the most of phosphorus can be removed from the slag, the residual slag is basically FeO-CaO-SiO2-MnO-MgO with less P2O5 and thus it may be recycled to iron and steelmaking processes such as the sintering, hot-metal desiliconization, and hot-metal dephosphorization processes. In the present work, the recycling effect of the residual slag to the dephosphorization process is simulated based on the mass balance calculation. The significant reduction of total slag generation and CaO input has been demonstrated by the mathematical model considering phosphorus recovery and recycling of residual slag as a dephosphorization agent. It has also been indicated by the Waste Input-Output model that the phosphorus recovery from dephosphorization slag and the recycling of residual slag to hot metal dephosphorization process have great environmental and economical benefits.

Currently, several metals are commercially recycled from by-products and wastes by metallurgical processing. However, the metallurgical process has each characteristic, which causes limitation for resource recovery. The combinations of elements in secondary resources, such as byproducts and wastes, are often different from those in natural resources. There are even combinations that are not present in natural resources. Conventional metallurgical processes have been optimized for economical and efficient extraction of desired elements only from large amount of ores under constant grade. Therefore, in order to extract metals from secondary resources by the conventional metallurgical process, it is necessary to estimate the recoverability of the constituent elements by taking into account their chemical properties well in advance. In particular, analysis for combination of elements is significantly important. In this study, we developed the evaluation method of metal resources recyclability based on thermodynamic analysis, and made clear the element distribution among gas, slag and metal phases during metal recovery based on thermodynamic analysis. In an application of the method shows that Cu, and precious metals (Ag, Au, Ft, Pd) present in mobile phones can be recovered as metals in the pyrometallurgy process of Cu in a converter, while Pb and Zn can be recovered as vapor. Other elements distributed in the slag phase are difficult to recover. The result of our analysis reflects the trends observed in the distribution of metals in copper metallurgy, thereby indicating the validity of our proposed evaluation method. © 2009 The Japan Institute of Metals.

現在工業的に利用されている高品質のリン鉱石は、現在のペースで消費が進むと100 年以内に枯渇することが懸念されており、新たなリン資源の開発が強く望まれている。本研究では、詳細なリンの国内マテリアルフロー分析を行い、製鋼スラグと下水汚泥に濃縮されるリンは、質および量において輸入リン鉱石とほぼ同等であり、人工リン資源として極めて高いポテンシャルを有することを示した。また、これら廃棄物からのリン回収技術開発を行った。廃棄物産業連関モデルを用いて、これらの新技術が与える環境負荷および経済影響を定量的に示した。

The production process of metals such as copper, lead, and zinc is characterized by mutual interconnections and interdependence, as well as by the occurrence of a large number of byproducts, which include precious or rare metals, such as gold, silver, bismuth, and indium. On the basis of the framework of waste input-output (WIO), we present a hybrid IO model that takes full account of the mutual interdependence among the metal production processes and the interdependence between them and all the other production sectors of the economy as well. The combination of a comprehensive representation of the whole national economy and the introduction of process knowledge of metal production allows for a detailed analysis of different materials-use scenarios under the consideration of full supply chain effects. For illustration, a hypothetical case study of the introduction of lead-free solder involving the production of silver as a by product of copper and lead smelting processes was developed and implemented using Japanese data. To meet the increased demand for the recovery and recycling of silver resources from end-of-life products, the final destination of metal silver in terms of products and user categories was estimated, and the target components with the highest silver concentration were identified.

Substance flow analysis (SFA) of indium has been conducted in this study. The purpose of this study is to identify the relevant issues for the development of an efficient indium recycling system by performing SFA of indium supplied for ITO processing as transparent electrodes, which accounts for 86.9% of the total indium demand. In this study, as part of the development of substance and material flow data, (1) data on the flow of indium was collected and reviewed, (2) the amount of dissipated indium associated with the production of flat-panel displays (FPDs) were estimated and (3) its environmental impact was also assessed. The major conclusions are (a) 470 t-In is used in ITO for transparent electrodes, out of which 220 t-In is dissipated or potentially dissipated in Japan, and (b) 220 t-In of dissipated indium is equivalent to 11.4 TJ of energy consumption, 0.5 x 10(3) t of CO2 emissions, and 1.0 X 10(6) t of Total Materials Requirement (TMR).

Approximately 400,000 tons per year of aluminum dross (Al dross) are generated during a melting process of aluminum metal in Japan. The Al dross and the residue, which have high concentration of metallic Al, are mostly used as an Al resource for Al production or as a deoxidizer in the steel industry. On the other hand, the residue with the Al content is less than 20%, is difficult to be recycled and is therefore land filled. This paper deals with (1) a material flow analysis (MFA) of the domestic Al dross in order to achieve clear targets for recycling of Al dross and residue, and (2) an environmental assessment of newly developed technologies for its recycling, such as the process of hydrogen production from residue. The result of material flow analysis on the domestic Al dross in 2003 shows that 2.344 X 10(5) t of aluminum is recovered and 2.150 X 10(5) t of residue is generated from the dross. The residue is mostly used in the steelmaking process, whereas 5.0 X 10(4) t of residue is landfilled in the final disposal site. As the result of the environmental assessment through the material flow, there is a possibility of reduction of CO2 emission and waste emissions by using residue (Al content: 10%) as a hydrogen resource, which is presently landfilled.

This paper presents a study on desulfurization technology in the steel industry, with attention focused on the removal of sulfur that forms acid rain, which has been creating various global problems. The study was confined to the technology that injects a mixture of serpentine and pulverized coals. Thermodynamically, a magnesium gas producing reaction occurs when magnesium oxide is turned into a hot strongly reducing atmosphere and the resulting magnesium gas forms magnesium sulfide by reaction with the sulfur in the molten iron. By dividing this desulfurization process into a magnesium gas producing reaction and a desulfurization reaction by the magnesium gas, the desulfurization effect of the magnesium oxide flux was confirmed through laboratory experiment. A thermodynamic study on the desulfurization reaction in which SiO gas resulting from the reduction of SiO2 produces a silicon sulfide gas by reaction with the sulfur in the molten iron revealed that the possibility of desulfurization of the molten iron by the silicon sulfide gas is not negligible.

This study conducts the substance flow analysis (SFA) of Manganese (Mn) with regard to the iron and steel cycle, which accounts for 95 % of the demand for Mn, along with the data collection and assessment of material/substance flow; as a result, an efficient material cycle system is formulated for the Mn flow. The main conclusions are (1) Mn charged as iron ore and the Mn content of other ferrous raw materials reached 266.2 X 10(3) t-Mn of which 208.9X10(3) t-Mn was discharged as pig iron and 55.4X10(3) t-Mn as blast furnace slag in the ironmaking process, and (2) 530.7 X 10(3) t-Mn was discharged as steelmaking slag and 5776 X 10(3) t-Mn was charged in the secondary refining process as Ferro-Mn, Si-Mn, and metal Mn for the purpose of adding them as constituents of alloy in the steelmaking process.

The technology using waste wood from construction and thinned wood that are not recycled in the woody biomass as one of raw materials for producing metallurgical coke was examined in detail by adding them to coal and carbonizing them. In the carbonization tests, four types of woody biomasses showed substantially almost the same results in respect to material balance and composition of carbonized products. Compared with raw woods, woody biomasses compressively formed to not smaller than 10 mm permit an increase in the addition rate to 1.5% while inhibiting the lowering of coke strength. Hot compressive forming at 200-350 degrees C where pyrolysis of woody biomass occurs inhibits the lowering of coke strength and will therefore permit an increase in the use of woody biomasses. As a result, the possibility to use as a raw material for the coke manufacturing by adding the compressively formed woody biomass was found.

Japanese zinc production in 2005 was 6.75x10(5) t, and domestic demand of zinc was 4.82x10(5)t. The main use of metallic zinc is in the surface coating of steel and the metal accounts for 62.8 % of the domestic demand. The purposes of this study are as follows: (1) to identify the material flow of zinc associated with steel production, and (2) to estimate the environmental effects (energy consumption and CO2 emission reduction) of some intermediate dust treatment processes. The major conclusions are (a) in Japan, 6.16x10(6) t of blast furnace/converter dust was generated in 2000, and this product contained 2.20x10(4) t-Zn. 0.433x10(6) t of EAF dust was generated and this dust contained 8.86x10(4) t-Zn, and (b) 9.57 MJ of energy is required for producing I kg of zinc oxide by the Waelz process using EAF dust, and the estimated amount of CO, emission in this process is 1.49 kg-CO2. On the other hand, if the LAMS process proposed by the authors is employed, it is estimated that there will be a reduction of 1.70 MJ in energy consumption and a reduction of 0.14 kg-CO2 in CO2 emissions.

A new EAF dust treatment process named as "Lime Addition and Magnetic Separation Process (LAMS Process)" has been proposed to recover zinc oxide from the dust and to use solid residue as a flux for steel refining. The LAMS Process consists of the reaction of EAF dust with CaO followed by the adequate crushing and high gradient magnetic separation. The basic principle of this process has been established by revealing the phase equilibria in the CaO-Fe2O3-ZnO system where Ca2Fe2O5 can be in equilibrium with pure ZnO rather than ZnFe2O4, which is the major component of EAF dust, at higher CaO region. The conversion of zinc ferrite in EAF dust to ZnO and Ca2Fe2O5 has been experimentally demonstrated by heating the dust with double molar amount of CaO at 1 173 and 1 373 K. It has also been demonstrated that the formed ZnO and Ca2Fe2O5 can be separated by the strong magnetic field. Therefore, it may be possible to recover ZnO from EAF dust without the carbothermic reduction like Waelz process.

Substance flow analysis (SFA) of indium has been conducted in this study. The purpose of this study is to identify the relevant issues for the development of an efficient indium recycling system by performing SFA of indium supplied for indium-tin oxide (ITO) processing as transparent electrodes, which accounts for 86.9% of the total indium demand. In this study, as part of the development of substance and material flow data, (1) data on the flow of indium was collected and reviewed, (2) the amount of dissipated indium associated with the production of flat-panel displays (FPDs) were estimated and (3) its environmental impact was also assessed. . The major conclusions are (a) 470t-In is used in ITO for transparent electrodes, out of which 220 t-In is dissipated or potentially dissipated in Japan, and (b) 220 t-In of dissipated indium is equivalent to 11.4 TJ of energy consumption, 0.5 x 10(3) t Of CO2 emissions, and 1.0 x 10(6) t of Total Materials Requirement (TMR).

A general analytical model of materials flow analysis (MFA) incorporating physical waste input-output is proposed that is fully consistent with the mass balance principle. Exploiting the triangular nature of the matrix of input coefficients, which is obtained by rearranging the ordering of sectors according to degrees of fabrication, the material composition matrix is derived, which gives the material composition of products. A formal mathematical definition of materials (or the objects, the flow of which is to be accounted for by MFA) is also introduced, which excludes the occurrence of double accounting in economy-wide MFAs involving diverse inputs. By using the model, monetary input-output (IO) tables can easily be converted into a physical material flow account (or physical input-output tables [PIOT]) of an arbitrary number of materials, and the material composition of a product can be decomposed into its input origin. The first point represents substantial saving in the otherwise prohibitive cost that is associated with independent compilation of PIOT. The proposed methodology is applied to Japanese IO data for the flow of 11 base metals and their scrap (available as e-supplement on the JIE Web site). © 2007 by the Massachusetts Institute of Technology and Yale University.

Approximately 400,000 tons per year of aluminum dross are generated during a melting process of aluminum metal in Japan. The Al dross and the residue, which have high concentration of metallic Al, are mostly used as an Al resource for Al production or as a deoxidizer in the steel industry. On the other hand, the lower grade residue with the Al content less than 20%, is difficult to be recycled and is therefore landfilled. This paper deals with (1) a material flow analysis (MFA) of the domestic aluminum dross in order to achieve clear targets for recycling of aluminum dross and residue, and (2) an environmental assessment of newly developed technologies for its recycling, such as the process of hydrogen production from residue. The result of material flow analysis on the domestic aluminum dross in 2003 shows that 234.4 x 10(3) t of aluminum is recovered and 215.0 x 10(3) t of residue is generated from the dross. The residue is mostly used in the steelmaking process, whereas 50.0 x 10(3) t of residue is landfilled in the final disposal site. As the result of the environmental assessment through the material flow, there is a possibility of reduction of CO2 emission and waste emissions by using residue (Al content: 10%) as a hydrogen resource, which is presently landfilled.

Substance flow analysis of molybdenum associated with iron and steel flow has been conducted in this study. The demand of molybdenum in iron and steel section reaches approximately 85 % of total molybdenum consumption in Japan. Total demand of special steel products in final commodity is 18.4x10(6)t (for domestic: 12.4x10(6)t), and that contains 14.3x10(3) Mo-t (for domestic: 9.6x10(3) Mo-t) of molybdenum in 2004 fy. In addition, crude steel for special steel (23.8x10(6)t) contains 18.5x10(3) Mo-t of molybdenum. Approximately 70% (12.3x10(3) Mo-t) of molybdenum in the crude steel flows into domestic market, and about 45% of that is used for motor vehicles production. Improvement of dismantling technology and standardizing of special steel scrap will help to promote rare metal recycling.

Microwave heating has been applied to the oxidation in the new rutile extraction process developed by the authors in which rutile is extracted from a natural ilmenite ore by oxidation and magnetic separation followed by leaching with diluted acid. Since ilmenite FeTiO3 and pseuclobrookite Fe2TiO5 strongly absorb 28 GHz microwave, Australian ilmenite ore mainly composed of FeTO3 was rapidly heated up to about 1 273 K and oxidized in air with keeping almost constant temperature. As a result, two equilibrium phases of rutile TiO2 and pseuclobrookite were quickly formed at microwave power of 1.5 kW. The growth rate of the pseudobrookite phase in the microwave irradiation was found to be much faster than that of the rutile phase in the conventional resistance furnace, indicating a drastic enhancement of the growth rate by the microwave irradiation.

In order to make sure the great potential of steelmaking slag as a new phosphorus resource, domestic phosphorus material flow in Japan including iron and steel industry has been investigated based on the statistical data on 2002. It has been demonstrated that phosphorus in the steelmaking slag is almost equivalent with that in the imported phosphate rock in the view points of the amount and the concentration. Phosphorus exists mainly in the form of calcium-phosphate or its solid solution with calcium-silicate rather than the FetO rich liquid phase in the slag and exhibits remarkable segregation in the solidified slag. If the strong magnetic field is applied to the crushed slag, precipitated calcium-phosphate solution phase can be separated from FetO matrix phase due to the large difference of each magnetic property. It has also been indicated by the Waste Input-Output model that the phosphorus recovery from steelmaking slag by the new process proposed in the present work has great environmental and economical benefits.

Phase relations in the Fe2O3-FeTiO3-TiO2 System were investigated by equilibrating synthetic samples in evacuated sealed quartz tubes at a temperature of 1373 K. The equilibrium partial pressure of oxygen was measured by the electromotive force (EMF) method in the temperature range of 1273 to 1373 K. The phase diagram and oxygen partial pressure diagram in the titanium-iron-oxygen ternary system were then constructed at 1373 K. Rutile extraction from natural ilmenite ore was discussed from the thermodynamic viewpoint. It is found that rutile can be produced from common natural ilmenite ores not only by the reduction as the conventional titanium-rich stag process but also by an oxidation. Then, the oxidation experiment was conducted in air using Australian ilmenite ore to obtain rutile as one of the coexistent phases. Magnetic separation and leaching experiments for synthesized pseudobrookite and reagent rutile were conducted to confirm the possibility of separation of rutile from pseudobrookite. A new rutile extraction process was then proposed.

In order to make sure the great potential of steelmaking slag as a new phosphorus resource, domestic phosphorus material flow in Japan including iron and steel industry has been investigated based on the statistical data on 2002. It has been demonstrated that phosphorus in the steelmaking slag is almost equivalent with that in the imported phosphate rock in the view points of the amount and the concentration. Phosphorus exists mainly in the form of calcium-phosphate or its solid solution with calcium-silicate rather than the FetO rich liquid phase in the slag and exhibits remarkable segregation in the solidified slag. If the strong magnetic field is applied to the crushed slag, precipitated calcium-phosphate solution phase can be separated from FetO matrix phase due to the large difference of each magnetic property. It has also been indicated by the Waste Input-Output model that the phosphorus recovery from steelmaking slag by the new process proposed in the present work has great environmental and economical benefits.

as keynote

1.91 million t of steel scrap was exported from Japan to Korea in 2003, which accounted for more than 30% of the total steel scrap exported to other countries from Japan. Change in steel scrap demand in Korea in the future will make a great influence on the amount of Japan's steel scrap domestic consumption and export. In this work, quantitative data about the steel production, steel scrap demand and consumption during 1977-2003 in Korea were collected to analyze the amounts of inhouse, industrial and obsolete scrap generatiom, and total steel accumulation in Korea. Then, the steel scrap demand in Korea in the future was estimated. The total accumulation of steel in Korea was estimated as 380 million I in 2003 and 548 million t in 2010, respectively. The amount of obsolete scrap generation in Korea was 7.1 million t in 1996 and 9.0 million t in 2003, which was about 3.0% and 2.4% of the total steel accumulation in each year. Supposing that the amount of crude steel production, scrap consumption percentages in B.O.F and E.A.F will be stable, the obsolete scrap generation in Korea in 2010 were estimated as 13-17 million t. This significant increase in obsolete scrap generation in Korea could exceed the current amount of the scrap import. So, self-sufficiency of steel scrap could be achieved in around 2010 in Korea.

Quantitative data on development of steel production in China were collected and examined to estimate the scrap demand in 2010. Taking several influential factors into consideration, it is speculated the amount of scrap increase from 2003 is 15 million tons. This will be covered by in-house scrap, suggesting little increase of scrap import. Moreover, the scrap will used mainly for basic oxygen converter and hence high quality scrap will be requested.

TMR (Total materials requirement), which refers to the total amount of overburden and rock, were estimated as a fundamental data in this study. 10 kinds of TMR of energy resource and power generation and 62 kinds of TMR of industrial material were approximately estimated based on LCI data. Moreover, a recycle flow analysis based on TMR was proposed. From a result of a study on ELV (End-of-Life Vehicle) recycle flow, followings were shown. 1) A dismantling process which is a pretreatment process for shredding was main process for ELV recycle. Most of Metals, which have large amount of TMR, were collected in the dismantling process. 2) Copper is main component of ASR (Automobile Shredder Residue).

The equilibrium between Ti and O has been investigated in molten Fe-Ti alloy saturated with various kinds of titanium oxides at 1873 K. The present results have been thermodynamically analyzed applying Wagner's formalism as well as Darken's quadratic formalism with the excess Gibbs free energy change of mixing described by Redlich-Kister type polynomial. The equilibrium constants and the interaction parameters of Wagner's formalism were given as follows at 1873 K in the present work. Ti2O3(s)=2Ti+3O (0.5 &lt; mass%Ti &lt; 6.2) logK=-10.17, e(O)(Ti)=-0.34 'Ti3O5'(s)=3Ti+5O (0.0004 &lt; mass%Ti &lt; 0.36) log K=-16.86, e(O)(Ti)=-0.34 The Henry constant of Ti in liquid Fe-T alloy was assessed as follows at 1873 K. gamma(o)(Ti(I))=0.0090 The interaction parameters of Redlich-Kister type polynomial for molten Fe-T-O alloy were given by the following values at 1873 K in the present work. (0)Omega(Fe-Ti)=-73360/J (0)Omega(Ti-O)=-1035900/J The estimated results based on Wagner's formalism as well as Darken's quadratic formalism polynomials were well agreed with the experimental results which were observed between Ti and O equilibrium contents in molten Fe-Ti alloy.

From the viewpoint of recycling and recovery of metal values from used lead-batteries, especially from lead anode slime, recovery of antimony has been studied experimentally. First, oxidation kinetics has been investigated for pure liquid antimony in the temperature range between 973 and 1373 K to elucidate the reaction mechanism. Since lead anode slime generally consists of antimony, lead and bismuth, oxidation experiments have also been carried out using antimony-lead-bismuth alloy. It was found that gas phase mass transfer step mainly controls the overall oxidation rate. The overall rate was expressed as the sum of antimony oxide and metallic antimony evaporation rates. The oxide evaporation is dominant at lower temperature around 1073 K with higher oxygen partial pressure. In the experiment of the antimony-lead-bismuth alloy simulated for anode slime, only the oxide Sb406 evaporation was observed, indicating that antimony was preferentially oxidized followed by evaporation of antimony oxide. The oxidation rate of the alloy was substantially identical with that of pure antimony. This is the advantage of oxidation treatment for anode slime.

The problems concerned with non-proportionality between the absorbance and the vapor density and its dependence on the vapor temperature, which are inherently encountered by vacuum-sealed quartz cell/atomic absorption spectrophotometry combination, were solved through model calculations in this study. Model calculations revealed that "colligated analytical-curve" is useful. Activities of Bi and In in the Bi-In liquid alloy were measured over the entire composition range at the temperature from 850 to 1050 K. An alloy was vacuum-sealed in a quartz cell and heated at the temperature of interest. The absorption for Bi 307 nm radiation from Bi lamp was measured for Bi atom vapor in the cell. By heating a pure metal as a standard and measuring the absorbance as a function of the temperature, a colligated analytical-curve for Bi atom vapor was constructed and used for conversion of the absorbance to the vapor density. Bi activity was determined as the ratio of the Bi atom vapor density over the alloy to that over a pure metal. The same procedure was applied to the In 304 nm radiation from In lamp and In activity was determined independently of Bi. Thermodynamic behavior of the Bi-In liquid alloy was optimized with a sub-regular solution model by taking into account activity data obtained in this study. The agreement between activities optimized in this study and those in the literature was fairly good. The model also well predicted the liquidus curve on the Bi side and the heat of mixing in Bi-In binary, both of which are comparable with the literature values. Finally it was concluded that by constructing colligated analytical-curves the vacuum-sealed quartz cell/atomic absorption spectrophotometer combination was established as a useful technique to measure the activities of elements in alloy systems.

Phase equilibria of two-liquid CaO-MgO-FetO-P2O5 slag saturated with (Mg, Fe)O solid solution and the distribution ratio of phosphorus between the slag and liquid iron were measured at steelmaking temperatures by chemical equilibration. It is known that this slag system has wide liquid miscibility gap at steelmaking temperature and this two-liquid phase slag has many advantages, such as high activities of both FetO and CaO and high amount of phosphoric oxide. It was made clear that the phosphorus distribution ratio between the slag system and molten iron was higher than that of the CaOsat-FetO-P2O5 system and the twoliquid slag phase was very useful for dephosphorization of molten steel and reduction of slag volume.

Suppression of CO, and waste such as slags discharged from iron- and steelmaking processes are some of the typical biggest issues for the protection of global environment and sustainable growth of steelmaking industry. Utilization of active phytoplankton growth will be one of the best options to stabilize and suppress carbon dioxide at high-efficiency. Inorganic minerals such as C, O, N, Si, P and le are necessary for phyloplankton multiplication, It is crucial for supply of nutrition into seawater effectively for phytoplankton multiplication to understand the dissolution behavior of some elements from steelmaking slags into seawater. Firstly, the morphology of the precipitated phases in steelmaking slags during cooling period was investigated in the present work. Secondary, the dissolution behavior of some elements from steelmaking slags and pure substances such as 4CaO . P2O5 (8.5 mass% P), 3CaO . P2O5 (10.0 mass% P) and 2CaO . SiO2-3CaO . P2O5 (2.8 mass% P) solid solution phase into artificial seawater has also been studied. Thirdly, the dissolution mechanism of elements from steelmaking slags was discussed by using stability diagrams of Si, P and Fe in seawater.

Steelmaking slag contains nutrition such as Si, P and Fe for acceleration of phytoplankton growth. Phytoplankton can fixate carbon dioxide more than any other creatures on the earth. Hence, suppression of CO, can be achieved by educing the potential of steelmaking slag as the nutrition for their propagation. When it is considered to supply nutrition from steelmaking slag to seawater, we must avoid hazardous elements dissolution from steelmaking slag into seawater. In the present work, the dissolution behavior of Ca, Mg, Mn and F from steelmaking slags into artificial seawater was studied continuously with our previous paper. The dissolution mechanism of elements from steelmaking slags was discussed again by using stability diagram in seawater.

Soldering material widely used is Sn-Pb alloy, which have low melting point and excellent electrical, strength properties and wettability. However, Pb is one of the toxic elements, which is undesirable due to environmental and safety reasons, thus Pb-free alternative alloy is preferred for new soldering material. Sn-Ag and Sn-Zn based alloys have been viewed as very promising candidates, among many potential substitutes. Addition of third element to these alloys will decrease melting point of the alloys. Hence, Sn-Ag-In and Sn-Zn-Mg alloys are expected to be suitable for replacing Sn-Pb solder alloy. In order to design new Pb-free soldering materials, it is crucial to understand precise thermodynamic properties and phase diagrams of alloy systems. In the present work, ion current ratios of Ag to In and Mg to Zn were measured for Sn-Ag-In and Sn-Zn-Mg alloys by mass spectrometry, respectively. Also, the authors reviewed the thermodynamic properties of terminal binary, alloys determined by other researchers and evaluated a thermodynamic functions to express the excess Gibbs free energy of each binary alloy. Thermodynamic functions to express the excess Gibbs free energy of liquid Sn-Ag-In and Sn-Zn Mg ternary alloys were determined, utilizing the assessed Gibbs free energy of terminal binary alloys with the measured ion current ratios using mass spectrometer.

Activities of Bi and In in the Bi-In liquid alloy were measured over the whole range of composition at the temperatures from 850K to 1050K. An alloy was vacuum-sealed in a quartz cell and heated at the temperature of interest. The absorption for 307nm radiation from Bi lamp was-measured for Bi atom vapor in the cell. By heating a pure metal as a standard and measuring the absorbance as a function of the temperature, an analytical curve for Bi atom vapor was constructed and used for conversion of the absorbance to the vapor density. Bi activity was determined as the ratio of the Bi atom vapor density over the alloy to that over a pure metal. The same procedure was applied to the In 304nm radiation from In lamp and In activity was determined independently of Bi. Results showed that the liquid Bi-In system behaves like a regular solution.

It is recently recognized, that the iron reduction and melting as well as the slag separation of a composite of granular iron ore and coal are completed in a very short period of about 10 minutes when the composite is rapidly heated up to approximately 1673K. These phenomena are expected to be applied to a new iron-making process. The mechanism of iron ore reduction and iron-slag separation during rapid heating has not yet been revealed and the fundamental research has just started. Carburization of the reduced iron is regarded as one of the most important steps in this process. In the present work, the composite was prepared from four kinds of coal or graphite as a carbon source and electrolytic iron powder as a completely reduced iron ore. The temperature at which the liquid formation and iron carburization occurred was monitored. Direct observation of smelting reduction behavior was made by a confocal laser-scanning microscope combined with the infiared image-heating furnace to clarify the effect of molten ash on iron carburization. It was found that the meltdown temperature of composite became lower as the melting temperature of coal ash decreased. From. the, observed result, it was presumed that the liquid slag would act, as an important media for the carbon transfer from coal to iron. The carburization mechanism during the smelting reduction was estimated as follows. When slag containing iron oxide melted down and contacted, carbon, iron oxide in the slag was reduced and the formation of the metallic iron particle. as Well, as the its carburization occurred simultaneously at the slag carbon interface. Carburized iron particle, was carried from slag carbon to slag-iron interfaces due to the slag convection flow. caused by. the difference of the interfacial tension between the carbon-slag and iron slag interfaces. Carburization of reduced iron could proceed with a repeat of the above-mentioned process.

The contents of gangue minerals, such as Al2O3, P2O5, crystalline water and so forth in the iron ore imported to Japan tend to increase year by year. Though the increments of such gangue contents are approximately 0.1-0.2 mass%, some problems for the blast furnace operation in ironmaking process have already been reported. In order to clarify the mechanism of harmful effect caused by the small increment of gangue minerals, mainly Al2O3, on the blast furnace :,operation, the dripping behavior of Fe1C-CaO-SiO2-Al2O3-MgO slag from the iron funnel, which simulated the micro-porosity in sinter ore, has been observed with the wide range of basicity, Al2O3,.FetO and MgO contents. The effect of MgO on the dripping behavior of slag has been summarized in this paper. It was found that the addition of 2mass% MgO resulted in large increase of hold-up on the most of the conditions. When FetO content was less than 20mass% and the basicity was lower than 0.8, MgO lowered the hold-up even if the slag contained 10mass% Al2O3. Every slag hold-up showed the minimum at the basicity of less than unity on the conditions of constant FetO and Al2O3 contents. This trend became remarkable when the slag contained 2 mass% MgO.

Some physico-chemical studies have been conducted to utilize steelmaking slag for the fixation of CO2 with the multiplication of the marine phytoplankton. The targets of present work are to reveal the morphology of the industrial steelmaking slags, the control of crystal size of each phase precipitated in the slag by heat treatment, and the dissolution behavior of elements from the slags into the artificial seawater. The dissolution limit of each element has been thermodynamically discussed based on the stability diagram.

Crude high Cr containing steel such as tool steel, heat-resistant steel or stainless steel is produced by dissolution of high carbon ferro-chromium into molten crude steel. In the refining process, decarburization is performed at the first stage, and deoxidation is followed in the next stage. Therefore, the equilibrium relation between dissolved Cr and O in molten Fe-Cr alloy after decarburization is very important when yield of deoxidizer is considered for the overall control and optimization of the process. It is well known that the yield of deoxidizer does strongly depend on the kinds of refractories of furnace in the secondary refining process. In the present work, the equilibrium relation between dissolved Cr and O in molten Fe-Cr alloy has been measured in a Cr2O3, MgO or Al2O3 crucible at steelmaking temperature. O contents at given Fe-Cr components have been lower in order of Cr2O3, Al2O3 and MgO crucible. The present results have been discussed based on the activities of the constituents in pure solid Cr2O3, and (FeOCr2O3)-Cr-., (MgOCr2O3)-Cr-. and (Al,Cr)(2)O-3 solid solutions.

Activities of the constituents in an alloy proposed for the Pb-free solder, Sn-Mg-Zn, were studied experimentally using a mass spectrometer. The ion current ratios of Mg to Zn were measured in the temperature range 700-800 K. From the experimental results and the assessed thermodynamic properties of molten Sn-Mg, Sn-Zn, and Mg-Zn binary alloys, the excess Gibbs free energy of liquid Sn-Mg-Zn ternary alloy was determined. Also, phase diagram of Sn-Mg-Zn ternary system was determined.

Oxidation and reduction are utilized in the refining process of iron and steel. Therefore, the most important thermodynamic property is the activity of FetO in slag and especially in refractories, which contact with liquid iron and steel. It is well known that refractories easily form solid solutions with FetO, so that molten iron and steel would react with FetO in the refractories, non-metallic inclusions and slag coexisting in the iron and steel production process. In the present work, the reaction of molten steel with the solid oxide phase will be discussed based on the activity of the constituents in MnO-FetO and FetO.Cr2O3-FetO solid solutions by way of examples of FetO-containing solid solution.

Some new melting processes for the ash have been developed to solve the problems on increasing volume of ash generated from municipal waste incinerators. The metal phase formed in this melting process generally consists of Fe-Cu-Si-P-C containing a small amount of other heavy metals, but their phase equilibria and physico-chemical properties are unknown. The present work aimed at determining the thermochemical properties of liquid Fe-Cu-Si alloys, which establish the basic system in this melting process. The heat contents of liquid Fe, Fe-Cu and Fe-Cu-Si alloys have been directly measured with a drop calorimeter at mainly 2073 K in the present work. The observed heat content and the enthalpy of mixing of the alloys were assessed by a thermodynamic model. The input energy which should be supplied to melt the metal phase in the new melting treatment process was also discussed.

Oxidation and reduction are utilized in the refining process of iron and steel. Therefore, the most important thermodynamic property is the activity of FetO in slag and especially in refractories, which contact with liquid iron and steel. It is well known that refractories easily form solid solutions with FetO, so that molten iron and steel would react with FetO in the refractories, non-metallic inclusions and slag coexisting in the iron and steel production process. In the present work, the reaction of molten steel with the solid oxide phase will be discussed based on the activity of the constituents in MnO-FetO and FetO.Cr2O3-FetO solid solutions by way of examples of FetO-containing solid solution.

Oxygen control in liquid stainless steel production is extremely important for the removal of impurities and improvement of Cr yield. Precise information on the thermodynamics of oxygen in liquid Fe-Cr alloy is necessary for this purpose. The equilibrium relation between dissolved Cr and 0 in liquid iron saturated with pure solid Cr2O3 or FeO . Cr2O3 solid solution and thermodynamic behavior of FeO . Cr2O3 solid solution had been established in our previous works. Following these studies, the deoxidation equilibrium of Si in liquid Fe-Cr alloy was thermodynamically discussed in this paper. Mutual solubility between SiO2 and (Fe,Mg)O . (Cr,Al)(2)O-3 solid solution was observed at 1 573 and 1 873 K, in order to know the activity of SiO2 coexisted with Cr2O3, based oxide solid solution after Si deoxidation of liquid Fe-Cr alloy. It was found that Si deoxidation equilibrium of liquid Fe-Cr alloy could be thermodynamically evaluated based on unit activity of SiO2 due to negligibly small mutual solubility between SiO2 and FetO-Cr2O3 based solid solution. As the result, the deoxidation power of Si would not enough high to produce low oxygen high Cr steel because of the attraction between Cr and Si in liquid iron.

The activity of Si in molten Cu-Si alloy was determined by a new experimental technique, that is, the combination of chemical equilibration technique and mass spectrometry. The ion current ratio of SiO to Cu at 1600-1700 K was measured for Cu-Si alloy equilibrated with SiO2 by mass spectrometry. Since the vapor pressure of Si is relatively low, the formation reaction of volatile suboxide, SiO2 was utilized in the present work. The activity coefficient of Si in liquid copper at 1623 K was also determined by equilibrating a Cu-Si alloy with SiO2 saturated CaO-Al2O3-SiO2 slag in a graphite crucible under CO atmosphere. From these results, the activity coefficient of Si in copper at 1600-1700 K was determined. The thermodynamic property of Cu-Si alloy was assessed and it was confirmed that the present work agreed with the reported phase diagram of Cu-Si binary system.

Activities of the constituents in one of the ph-free solder systems, Ag-In-Sn, were studied experimentally using a mass spectrometer. Ion current ratios of Ag to In were measured in the temperature range 1273-1523 K. From the experimental results and the assessed thermodynamic properties of molten Ag-Sn,AS-In, and In-Sn binary alloys, the excess Gibbs energy of liquid Ag-In. Sn ternary alloy wets determined.

A new melting system is being developed to solve the problems in the treatment of ash from municipal waste incinerators. The viscosity of Liquid Fe-Cu-Si ternary melt has been measured in the present work by the oscillation crucible technique in the temperature range from 1523 to 1673 K in order to obtain the basic information on the fluidity of the typical alloy system generated in the ash melting furnace. The relation between the viscosity of Fe-Cu-Si ternary alloys and 1/T can be expressed by Arrhenius-type formula in the temperature range from 1523 to 1673 K. Viscosity of the alloy is in the range of 5 to 7 mPa s in the composition range of 0 similar to 5 mass%Cu and 10 similar to 20 mass%Si at 1723 K. These values are approximately double of that in pure Cu melt at 1723 K. From the result obtained. the appropriate condition is discussed for the operation of the melting furnace for ash from municipal solid waste incinerator.

Previously, the present authors have investigated the effects of temperature and pressure on the evaporation rates of Pb and Zn from liquid copper under reduced pressure. Oxygen does easily contaminate molten metal during high temperature processing and is known as a strong surface active element. In this study, the effect of oxygen on the evaporation rate of Pb from liquid copper was discussed at 1 473 K and 1.3 kPa. The rate constant was supposed to be slower with oxygen content due to lowering the interfacial chemical reaction rate. However, the rate constant increased with oxygen content in the present experiment. Assuming that the acceleration of vaporization is due to the volatile lead oxide, the rate equation was derived for the evaporation of lead oxide together with that of metallic Pb. As a result of the analysis for the present experiment, it was found that Pb evaporated from copper melt containing higher oxygen in the form of PbO. The presence of PbO in the vapor phase was confirmed by the mass spectroscopy. The rate mechanism of vaporization of Sn and Cu from liquid steel containing oxygen have also been discussed.

A mass spectrometer has been used to study activities of the constituents in liquid Cu-Mg and Cu-Ca alloys. Activities and heats of mixing have been determined from a series of measurements of the ratios of the ion current intensity of the solution components according to the Belton-Fruehan treatment. The activities in both systems exhibit negative deviation from ideality and tend to approach an ideal behavior at higher temperatures. The terms of RT In gamma (Cu) and RT In gamma (Mg) show very small temperature dependence within the present experimental range and agree well with the values reported by Garg et al, for the Cu-Mg system. The terms of RT In gamma (Ca) and RT In gamma (Cu) are independent of temperature and in excellent agreement with the values assessed by Risold et al, for the Cu-Ca system. Relative partial molar enthalpy and integral heat of mixing in the liquid Cu-Mg and Cu-Ca systems were also estimated.

Interfacial kinetics on the hydrogen reduction of liquid Fe(t)O in Fe(t)O-M(x)O(y) slag (M(x)O(y) = CaO, SiO(2), Al(2)O(3), and TiO(2)) has been studied at 1673 K. Because the rate of hydrogen reduction was very fast, the rate was controlled by gas-phase mass transfer under most of the experimental conditions. The effect of CaO or SiO(2) addition on the interfacial chemical reaction rate of hydrogen reduction was empirically evaluated as a function of the ferrous-ferric ratio in the slag. The observed interfacial chemical reaction rates in Fe(t)O-CaO and Fe(t)O-SiO(2) slags showed reasonable agreement with the estimated values. Most of the available literature data on the reduction rate of liquid iron oxide by solid carbon, hot metal, and reducing gases were also reviewed and compared with the results of the present work. It was found that the rate of hydrogen reduction of liquid iron oxide slag is much faster than that with other reducing agents such as solid carbon, carbon dissolved in the Liquid iron, and CO gas.

The kinetics of several gas-metal reactions relevant to bath smelting have been investigated. The rate of carburization of liguid iron by C2H6 gas was measured between 1 400 and 1 600 degrees C under conditions in which partial pressure of C2H6 was in the range of 0.016 to 0.04 atm and sulfur content in the iron was in the range of 0.003 to 0.5 wt%. The experimental results indicate that the rate is controlled by the dissociation of C2H6 on the surface of iron and gas phase mass transfer in Series. The gas phase mass transfer can be corrected with reasonable accuracy and the chemical rate constants were obtained. The rate was retarded by sulfur in liquid iron and there was evidence of a large residual rate at high sulfur contents. The rate of carburization of pure liquid iron (a(s)=0.01) by CH4-CO2 gas mixture was measured at 1 600 degrees C under conditions at which the rate is controlled by gas phase mass transfer and chemical reaction in series. The gas was 6% CH4 and up to 2.5 % CO2 in Ar. It was concluded that CH4 and CO2 reached the surface of the iron before they reacted with each other and carburization by CH4 and decarburization by CO2 occurred independently for the present experimental conditions. The rate of decarburization of carbon saturated liquid iron by CO-CO2-O-2 gas mixture was measured at 1 600 degrees C. The partial pressure of O-2 in 90%CO/10%CO2 gas was in the range of 0 to 0.03 atm and sulfur content in the metal was 0.1 wt%. The measured rate shows that the gases reached the surface of metal before they reacted with each other and decarburization by CO2 and O-2 proceeded independently at a high gas flow rate (5 l/min), but there may have been some gas phase reaction at lower flow rate (2 l/min).

Equilibrium between Cr and O in the high Cr steel melt is one of the most important information to control Cr content in the stainless steel. In spite of such importance, there are some uncertainties in the literature values including the recommended values of the Japan Society for the Promotion of Science (JSPS) on deoxidation equilibrium constant and interaction parameters. The main reason of Such uncertainties of the previous works is referred to the insufficient consideration on the thermodynamic properties of oxide phase in equilibrium with liquid Fe-Cr alloy. The present work deals with the equilibrium relation between dissolved Cr and O in liquid high Cr steel saturated with pure solid Cr2O3. The equilibrium constant of reaction and the interaction parameter between Cr and O in liquid iron saturated with pure solid Cr2O3 is given by the following equations in the present work. Cr2O3 (s)=2Cr+3O log K= -36 200/T+ 16.1 (1 823 K&lt;T&lt;1 923 K) e(o)(Cr)=-123/T+0.034 (mass% Cr&lt;46, 1 823 K&lt;T&lt;1 923 K) The activity of O can be expressed by above thermodynamic function without the second order interaction paramer up to 46 mass%Cr.

The alumina content in the iron ore imported to Japan is increasing year by year, and some problems in blast furnace operation, due to the use of the high-alumina-containing sinter, have already been reported. In order to clarify the mechanism of the harmful effect of alumina on the blast furnace operation, the behavior of the primary melt, which is formed in the sinter at the cohesive zone of the blast furnace, has been simulated by dripping slag through an iron or oxide funnel. The effects of basicity, Al2O3, and FetO contents in the five slag systems on the dripping temperature and weight of slag remaining on the funnel have been discussed. It was found that the eutectic melt formed in the sinter would play an important role in the dripping behavior of the slag in the blast furnace through the fine poreosity of the reduced iron and ore particles. Al2O3 increased the weight of the slag remaining on the funnel, and its effect became very significant in the acidic and low-FetO-containing slag. It was estimated that the increase of the weight of the slag remaining on the funnel by Al2O3 in the ore could result in a harmful effect on the permeability resistance and an indirect reduction rate of the sinter in the blast furnace.

Removal of tramp elements from the remelted scrap is one of the important subjects for the recycling process of base metals such as copper. The present work was aimed to establish fundamental knowledge on the evaporation kinetics of Zn and Pb from inductively stirred liquid copper under reduced pressure. It was found that the evaporation rates of Zn and Pb from liquid copper follow the first-order rate equation with respect to Zn and Ph contents in the metal. The apparent first-order rate constant obtained is in proportional to the reciprocal of the total pressure in the reactor and is independent of the stirring condition of the melt under most of the experimental conditions. The rate of free evaporation calculated by the Hertz-Knudsen-Langmuir equation was found to be much faster than the observed rate. It was, therefore, concluded that the mass transfer in the gas phase would be the rate-limiting step in this case. However, the rate of Zn evaporation at 1693 K tended to be independent of pressure and to approach a constant value at a lower total pressure due to the effect of the mass transfer in the liquid phase. The mass transfer coefficient in the liquid phase was evaluated to be k(l) = 3.0 x 10(-4) mis. The possibility of the removal of Zn and Pb by evaporation from liquid copper was discussed on the basis of the present experimental results and considerations.

Fe-Cu-Si ternary alloy phases are commonly formed during melting in a treatment process of domestic waste incineration that is currently being developed. The alloy phases appear in the incineration residue. Experiments were performed to observe phase equilibria in solid Fe+liquid, solid Si+liquid, the compound of FeSi liquid, and so forth, in the range 1523 to 1723 K. Then the phase diagram of Fe-Cu-Si ternary was thermodynamically assessed based on the present experimental results and literature data. It was found that this system has a wide liquid miscibility gap, and this two-liquid region is stable up to about 1900 K. The phase diagram of Fe-Cu-Si system assessed in the present work is much different from an earlier proposed diagram, but is very close to one recently evaluated. From the results obtained, the appropriate condition is discussed for the operation of the melting furnace for ash from municipal solid waste incinerators.

Heat transfer in continuous casting mold is important to decide the surface quality of the cast slab of middle carbon steel. Many researchers have recently studied the mechanism of reducing the heat transfer between the mold and the solidified shell, and some of them have pointed out that the interfacial thermal resistance between the mold and surface of solidified mold flux has caused decreasing heat transfer. In the present study, the surface roughness of solidified mold fluxes used for low carbon and middle carbon steel casting, Na2O-CaO-SiO2 and Li2O-CaO-SiO2 slag systems, was measured by a confocal scanning laser microscope combined with an infrared image furnace. It was found that the surface roughness was in the range of approximately 10-30 mu m when the crystalline phase precipitated. Furthermore, the faster the cooling rate, the smoother the surface roughness of the solidified mold flux became. In the contrast, the surface roughness of the slag, of which critical cooling rate is faster, increased. The surface roughness of the mold flux for middle carbon steel casting became rougher than that for low carbon steel casting. As a result, the surface roughness was related to normalized cooling rate, which is the ratio of actual experimental cooling rate to critical cooling rate. The experimental data of surface roughness were fairly in agreement with calculated values on the assumption of one dimensional heat transfer in the continuous casting mold.

The thermodynamics for reduction of iron-chromium ore by carbon is discussed. The thermodynamic properties of iron-chromium ore were evaluated from our previous work on the activities of constituents in the FeO . Cr(2)O(3)-MgO . Cr(2)O(3)-MgO . Al(2)O(3) iron-chromite spinel-structure solid solution saturated with (Cr, Al)(2)O(3), and those of the Fe-Cr-C alloy were estimated by a sublattice model. The stability diagrams were drawn for carbon reduction of pure FeO . Cr(2)O(3), (Fe(0.5)Mg(0.5))O . (Cr(0.8)Al(0.2))(2)O(3) iron-chromite solid solution, and South African iron-chromium ore. The evaluated stability diagrams agreed well with the literature data. It was concluded that the lowest temperature for reduction of FeO . Cr(2)O(3) in the iron-chromium ore was 1390 K and a temperature higher than 1470 K would be necessary to reduce Cr(2)O(3) in MgO . (Cr,Al)(2)O(3) in the prereduction process of iron-chromium ore. The composition of liquid Fe-Cr-C alloy in equilibrium with iron-chromium ore was also estimated under 1 atm of CO at steelmaking temperature. The predicted metal composition showed reasonable agreement with the literature values.

The recycling of valuable resources has currently became a major worldwide subject in the industries from the viewpoint of saving energy and protection of environment. Since the accumulated amount of steel product is reaching almost one billion ton in Japan, it is very important to develop the technology for the removal of tramp-elements such as tin, copper and zinc from steel scrap. In the present work, the rate of tin removal by the evaporation from carbon saturated liquid Fe-Sn-S alloy has been studied at 1, 673 K under reduced pressure.<BR>Tin evaporates from molten iron and equimolar amount of sulfur is also removed together with tin. The evaporation rate of tin increases with increasing initial sulfur content in the melt. It is confirmed that tin dissolved in liquid iron is removed in the form of SnS under the presence of sulfur in the metal. The rate of tin evaporation becomes faster with reducing the pressure in the reaction chamber. This indicates that the rate is controlled mainly by the mass transfer of SnS in the gas phase.

Some laboratory studies have been done to discuss the possibility of copper, tin and zinc removal from molten steel scrap. At first, the equilibrium copper distribution ratio between FeS-based sulfide flux and Fe-C-sat melt at 1673K is reviewed. The copper distribution ratio, L-Cu increases with the addition of alkaline- or alkaline earth sulfide into FeS and reaches the maximum, while the sulfur content in metal decreases at the same time. The maximum value of L-Cu of approximately 20-30 is obtained in FeS-M2S (M: Li, Na, and K) and FeS-MS (M: Sr and Ba) fluxes. In the second, the vaporization rate of zinc from liquid Fe-Zn alloy is discussed at 1873K by impinging Ar onto the surface of inductively stirred melt. The evaporation rate of zinc is found to be mainly controlled by the liquid phase mass transfer on the condition. The evaporation rate of tin from Fe-S-C-sat bath is also studied at 1673K under reduced pressure. The evaporation rate of tin is controlled mainly by the gas phase mass transfer and becomes drastically faster by adding sulfur in the metal, and it indicates that tin dissolved in liquid iron could be removed by evaporation in the form of SnS. The removal rate of tin, zinc or other residual elements from molten steel in the conventional practical operations or vacuum treatment is also discussed based on the present results.

Some laboratory studies have been done to discuss the possibility of copper, tin and zinc removal from molten steel scrap. At first, the equilibrium copper distribution ratio between FeS-based sulfide flux and Fe-C-sat melt at 1673K is reviewed. The copper distribution ratio, L-Cu, increases with the addition of alkaline- or alkaline earth sulfide into FeS and reaches the maximum, while the sulfur content in metal decreases at the same time. The maximum value of L-Cu of approximately 20-30 is obtained in FeS-M2S (M: Li, Na, and K) and FeS-MS (M: Sr and Ba) fluxes. In the second, the vaporization rate of zinc from liquid Fe-Zn alloy is discussed at 1873K by impinging Ar onto the surface of inductively stirred melt. The evaporation rate of zinc is found to be mainly controlled by the liquid phase mass transfer on the condition. The evaporation rate of tin from Fe-S-C-sat bath is also studied at 1673K under reduced pressure. The evaporation rate of tin is controlled mainly by the gas phase mass transfer and becomes drastically faster by adding sulfur in the metal, and it indicates that tin dissolved in liquid iron could be removed by evaporation in the form of SnS. The removal rate of tin, zinc or other residual elements from molten steel in the conventional practical operations or vacuum treatment is also discussed based on the present results.

In iron bath smelting and other processes that use coal, the effective use of volatile matter can improve the energy efficiency of the process. The reaction of simulated volatile (CH4) with iron was studied. The rate of carburization of liquid iron by CH4 gas was measured between 1400 degrees C and 1700 degrees C under conditions for which the effect of mass transfer can be corrected with reasonable accuracy. The rate was measured for partial pressures of CH4 in Ar in the range of 0.02 to 0.06 atm and sulfur contents in the metal from 0.0006 to 0.5 mass pct. The results indicate that the rate of carburization may be controlled by the dissociation of CH4 on the surface. Sulfur was found to decrease the rate, and the residual rate phenomenon was observed for high sulfur contents. The rate constant may be represented by the following equation: k(C) = k(o)/1 + K(S)a(S) + K(s)a(S)k(r)/1 + K(S)a(S) where k(o), k(r), K-S, and a(S) are the bare surface rate constant, residual rate constant, adsorption coefficient for sulfur, and activity of sulfur in the metal, respectively. The second term in the rate equation represents the rate of dissociation on the adsorbed sulfur. The rate constants and adsorption coefficient were determined as functions of temperature to be log k(o) = -12,000/T + 2.95 (mole/cm(2) s atm) log k(r) = -14,000/T + 3.45 (mole/cm(2) s atm) log K-S = 1800/T + 1.04

The activity of iron chromite in solid FeO.Cr2O3-MgO.Cr2O3-MgO.Al2O3 spinels, saturated with (Cr,Al)(2)O-3, was determined at 1573 K, by the equilibrium of iron dissolved into liquid silver in the spinel crucible with CO-CO2 gas mixture, to clarify the thermodynamic properties of chromium ores used in ferrochromium industry. The phase relation between (Cr,Al)(2)O-3 and FeO.Cr2O3-MgO.Cr2O3-MgO.Al2O3 spinel phase was studied, and the solubility of (Cr,Al)(2)O-3 in FeO.Cr2O3-MgO.Al2O3, MgO.Cr2O3-MgO.Al2O3, and FeO.Cr2O3-MgO.Cr2O3-MgO.Al2O3 spinel phases was found to be small. The activity of FeO.Cr2O3 in FeO.Cr2O3-MgO.Cr2O3-MgO.Al2O3 spinel solid solution coexisted with (Cr,Al)(2)O-3 shows negative deviation from ideality. It was observed that the spinel solid solution took regular solution behavior, and alpha-function of each pseudo-binary in FeO.Cr2O3-MgO.Cr2O3-MgO.Al2O3 system was determined as follows; alpha(FeO.Cr2O3-Mgo.Al2O3) = -92,000 (J), alpha(MgO.CR2O3-MgO.Al2O3) = -30,000 (J).

The activity of iron chromite in solid FeO.Cr2O3-MgO.Cr2O3 spinel, saturated with Cr2O3, was determined at 1573 K, by the equilibrium measurement of iron dissolved in liquid silver held in the spinel crucible with CO-CO2 gas mixture, to clarify the thermodynamic properties of chromium ores used in ferrochromium industry. The solubility of Cr2O3 in FeO.Cr2O3-MgO.Cr2O3 spinel phase was found to be negligibly small. The free energy of formation of FeO.Cr2O3 was determined as follows; Fe(s) + 1/2O2(g) + Cr2O3(s) = FeO.Cr2O3(s), DELTAG(degrees) = -307600 + 66.82T (J/mol). (1423-1723K) The activities of constituents in FeO.Cr2O3-MgO.Cr2O3 spinel solid solution coexisted with Cr2O3 showed negative deviation from ideality. It was observed that the spinel solid solution took regular solution behavior, and alpha-function of FeO.Cr2O3-MgO.Cr2O3 system was determined as follows; alpha(FeO.Cr2O3) = RTlngamma(FeO.Cr2O3)/(1 - N(FeO.Cr2O3)2 = alpha(MgO.Cr2O3) = RTlngamma((MgO.Cr2O3)/(1 - N(MgO.Cr2O3))2 = -12800 (J).

The rate of the decarburization of carbon-saturated liquid iron by H2O gas between 1673 and 1873 K has been studied under conditions in which the effect of mass transfer is negligible, or a reasonable correction for its effect can be made. The rate was measured for water vapor pressures in the range 0.002 to 0.3 atm and sulfur contents in the metal from 0.005 to 0.5 mass pct. The measured rates are consistent with the rate-controlling reaction being the dissociation of H2O on the surface. Sulfur was found to significantly decrease the rate, and the residual rate phenomenon was observed at high sulfur content. The rate constant for the dissociation of H2O on liquid iron is given by k = k-degrees/1 + K(S)a(S) + k(r) where k-degrees, k(r), K(S), and a(S) are the rate constant for pure iron, residual rate constant, the adsorption coefficient of sulfur, and the activity of sulfur in the metal relative to 1 mass pct in carbon-saturated liquid iron, respectively. The rate constants and adsorption coefficient were determined to be log k-degrees = -4860/T + 0.57 (mol/cm2 s atm) log k(r) = -5350/T - 1.03 (mol/cm2 s atm) log K(S) = 3870/T + 0.51

The rate of decarburization of carbon-saturated liquid iron with CO2-H2O gas mixtures has been studied to better understand the reaction mechanism between liquid iron containing carbon with post-combusted gas in an iron bath smelting reactor. The measurements were done under conditions in which the effect of mass transfer is negligible. The experimental temperature was 1 773 K and the sulfur content in the metal was fixed at 0.2 mass%. The rate was measured for a partial pressure of CO2 in the range of 0.5 to 1 atm for CO2-Ar, 0.7 to 0.9 atm for CO2-H2O and 0 to 0.95 atm for CO2-5%H2O-Ar gas mixtures. The measured rates agreed well with the predicted rates by assuming an ideal additivity of CO2 and H2O reaction rates individually measured in previous work. It was concluded that there were no special effects retarding or accelerating the reaction rate with liquid iron and the rates were simply additive. It was also found that iron oxide did not form on the surface as long as the surface concentration of carbon did not become very low. The critical carbon content at which FeO forms on the surface was expressed as a function of partial pressure of oxidant, sulfur content in the metal, mass transfer coefficient and temperature and was found to be in agreement with experimental observations.

An investigation of evaporation rate of Zn from liquid iron has been undertaken at 1 873 K by impinging Ar onto the surface of inductively melted iron containing Zn. The evaporation rate of Zn was found to be first order with respect to Zn content in the metal. No measurable effects of the Ar flowrate and carbon or sulfur content in the metal on the rate were observed with Ar flowrate above 5//min, but the rate was strongly affected by stirring condition of the melt. It was, therefore, concluded that the evaporation rate of Zn was controlled by the liquid phase mass transfer under the condition. The mass transfer coefficient in the liquid phase was estimated to be 0.032 cm/s at 1 873 K. The removal rate of Zn or other tramp elements in the conventional practical operations or vacuum treatment was also discussed based on the present result.

An attempt has been made to estimate the hydroxyl capacities of some molten silicates by the regular solution model of Lumsden, which has been extensively developed to be applied to slag-metal reactions in steelmaking process by the authors. The slag systems discussed were of Na2O-SiO2, K2O-SiO2, Li2O-SiO2, CaO-SiO2 binaries and CaO-SiO2-Al2O3, CaO-SiO2-MgO, CaO-SiO2-MnO and CaO-SiO2-P2O5 ternaries. In the present work, it was assumed that the water vapor is dissolved in the slag as C(OH)' = X(HO0.5)/(P(H2O)/P-degrees)1/2, where, P(H2O), P-degrees are partial pressure of water vapor in the gas phase and the atmospheric pressure (Pa), respectively. The interaction energies between hydrogen ion and other cation i, alpha(H-i), have been derived based on the regular solution model in the present work. As the result, it has been confirmed that the model has been applicable to predict the hydroxyl capacities over the wide range of slag composition discussed. It has been found that C(OH)' calculated by the model showed the minimum value at the slag composition of about unit basicity. The hydroxyl capacities calculated by the model have agreed with the measured within +/- 0.002.

Phase equilibria of Fe-S-C ternary melt has been studied to establish fundamental knowledge on the copper removal from iron melt by sulfide fluxes. Measurements were made to clarify the solubility of carbon and the miscibility gap between iron and FeS melts in Fe-S-C system at the temperature range from 1 473 to 1 873 K. Thermodynamic analysis was tried by applying interstitial solution model. Activity of iron in liquid Fe-C binary alloy was determined by distributing iron between liquid iron and silver phases to determine the interaction parameter between iron and carbon in Fe-C melt. It was concluded that interstitial solution model was applicable to express thermodynamic relation in this system. Phase diagram and activity contours of constituents in Fe-S-C ternary melt were calculated by the model.

Copper distribution between FeS-NaS0.5 flux and carbon saturated liquid iron has been studied at 1 673 K. Copper distribution ratio, L(Cu) = (mass%Cu)flux/[mass%Cu]iron, was about 9 when FeS only was used as sulfide flux. The addition of NaS0.5 to FeS increased the copper distribution ratio. The L(Cu) showed the maximum value of about 24, at around X(NaS0.5) = 0.4, and became nearly constant at the range of higher NaS0.5 content than 0.4 of NaS0.5. The addition of NaS0.5 also lowered sulfur content in liquid iron from 1.9 mass% at X(NaS0.5) = 0 to 0.004 mass% at X(NaS0.5) = 0.8 CuS0.5 dissolved in flux decreased L(Cu) at high concentration range of NaS0.5. In order to discuss the effect of NaS0.5 and CuS0.5 on the copper distribution ratio, the activity coefficient of CUS0.5 in flux was evaluated. It was found that NaS0.5 decreased the activity coefficient of CuS0.5 in flux, so that the L(Cu) increased in spite of the significant decrease of sulfur potential in the system by the addition of NaS0.5.

Measurements have been made to study the effect of the addition of alkaline or alkaline earth metal sulfide such as Li2S, K2S, MgS, CaS, SrS or BaS to FeS on the copper distribution ratio between FeS flux and carbon saturated liquid iron at 1 673 K. Since each solubility of MgS and CaS in liquid FeS was limited, no apparent effect of MgS or CaS on the copper distribution ratio was observed. Similar to the effect of Na2S studied in our previous work, the addition of Li2S, K2S, SrS or BaS to FeS increased the copper distribution ratio, L(Cu) = (mass%Cu)flux/[mass%Cu]Fe, and L(Cu) reached maximum value at certain content of these additives in each flux. The maximum values of L(Cu) measured in each flux were 30, 20, 22 and 19 in FeS-LiS0.5, -KS0.5, -SrS and -BaS fluxes, respectively. The sulfur content in liquid iron also decreased by the addition of these sulfides to FeS.

The activities of tin and antimony in liquid Fe-S alloy saturated with carbon were determined at 1 673 to 1 873 K by the distribution method using liquid silver. The concentration range of tin and antimony measured in the iron melt was less than 2 mass% and that of sulfur was up to FeS saturation (about 1.9 mass% at 1 673 K). The activity coefficients of tin and antimony, gamma-Sn(Fe-C(sat.)) and gamma-Sb(Fe-C(sat.)), and the solubility of carbon, [C]sat., in iron melt measured could be empirically expressed as the function of tin, antimony and sulfur contents in liquid iron saturated with carbon and temperature as follows: [GRAPHICS] The activity coefficients of SnS and SbS1.5 in FeS-Na2S flux were estimated to explain the distribution behavior of tin and antimony between the flux and liquid Fe-C(sat.) by combining the results of the present work with the distribution ratios of tin and antimony between FeS-Na2S flux and Fe-C(sat.) melt determined in our previous work. Equilibrium partial pressure of SnS in Fe-C-S-Sn melt was also estimated by using the activities of tin and sulfur and free energy of formation of SnS, and the possibility of tin removal from iron melt as SnS gas was quantitatively evaluated.

The reduction rate of liquid wustite contained in an iron crucible under Ar-CO, CO-CO_2 or Ar-CO-CO_2 gas mixtures has been measured by using thermobalance at 1400 and 1450℃. The experimental region of partial pressure of CO was P_<CO>=0.02-0.18 atm (Ar-CO) and P_<CO>=0.07-0.84 atm (Ar-CO-CO_2 and CO-CO_2). The apparent reduction rate became constant in the region of gas flow rate above 2.5 l/min. Under this experimental condition, the rate of reduction was controlled by the chemical reaction at the interface, and was expressed by the following equation : r=k_c(k_e-α)P_<CO> (g-oxygen/cm^2・s), where K_e and α are the equilibrium constant of the reaction among gas, liquid wustite and solid iron, and P_<CO_2>/P_<CO> in the gas phase, respectively. The apparent rate constant of the chemical reaction, k_c, was expressed by the following equation : k_c=1.18exp(-24300/RT)(g-oxygen/cm^2・s・atm). The reduction rate of liquid wustite with CO was 6 times larger than that of solid wustite.