The Experts below are selected from a list of 1668 Experts worldwide ranked by ideXlab platform
Fumitaka Tsukihashi - One of the best experts on this subject based on the ideXlab platform.
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Nutrient Supply to Seawater from Steelmaking Slag: The Coupled Effect of Gluconic Acid Usage and Slag Carbonation
Metallurgical and Materials Transactions B, 2020Co-Authors: Yuta Sakurai, Xiao Yang, Yuta Hisaka, Fumitaka TsukihashiAbstract:Vanishing of seaweeds in coastal areas has become a serious environmental problem. Part of the reason is nutrient deficiency in seawater, especially iron. Steelmaking Slag is probably one of the best nutrient suppliers in terms of cost and quantity. Utilizing Steelmaking Slag to fertilize coastal seaweeds may simultaneously address the two challenges of seaweed restoration and byproduct treatment. However, direct usage of Slag from a basic oxygen furnace is not practical because of negative effects such as a sharp pH increase and magnesium loss. To address the disadvantages, this work investigated the leaching behavior of a practical Steelmaking Slag in an artificial seawater and clarified the coupled effect of gluconic acid usage and Slag carbonation on aiding the nutrient supply. Slag carbonation prevents a drastic pH increase and Mg loss, while gluconic acid induces formation of stable chelated complexes. The combination of Slag carbonation and gluconic acid usage results in significant improvements in the nutrient supply. By leaching the Slag, the maximum concentration of Fe in seawater increases to 0.29 mg L^−1, 193 times larger than the value in the initial seawater (1.5 μ g L^−1).
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generation behavior of syngas between coal and feo containing Slag under co2 ar atmosphere
Applied Thermal Engineering, 2017Co-Authors: Hiroyuki Matsuura, Yan Wu, Zhangfu Yuan, Fumitaka TsukihashiAbstract:Abstract In this study, Steelmaking Slag was utilized as heat carrier and catalyst to perform the coal gasification; meanwhile, CO 2 was used as gasifying agent rather than steam from the viewpoint of carbon circulation. An overview on research activities and technology development on the effect of Steelmaking Slag on coal gasification are provided. The effects of coal type, Slag composition, CO 2 gas ratio and temperature on the gas producing behavior were discussed through the high temperature experiment. The results showed that coal gasification was remarkably enhanced and the produced CO amount increased considerably with the addition of Slag. On the contrary, with the increase of the Slag amount, the produced CO amount has the decreasing trend. Coal combined with higher FeO content Slag presented higher CO generation rate and less CO generation amount. Moreover, the increase of the CO 2 gas ratio and reaction temperature would promote the gasification of coal.
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Long-Term Dissolution Behavior of Steelmaking Slag and Its Composite Materials in Seawater
Journal of Sustainable Metallurgy, 2017Co-Authors: Yusheng Lang, Hiroyuki Matsuura, Fumitaka TsukihashiAbstract:Steelmaking Slag is considered to be a suitable candidate material for rehabilitating marine environments damaged by sea desertification because it can supply nutrient elements, and its positive effects have been phenomenologically proven. To fully understand the role of Steelmaking Slag in the rehabilitation process and maximize its efficiency, elucidation of the dissolution mechanism of nutrient elements from Slag-based materials is essential. The present study focused on the long-term dissolution behaviors of Steelmaking Slag, a Slag–soil composite material, and a Slag–humic substance composite material. Column experiments with a duration of 1152 h clarified that a marked increase in the pH value as well as the significant dissolution of elements occurred in the initial stage, while the subsequent increase in the concentrations of elements was small, and the Fe contained in the original seawater precipitated owing to the locally high pH in the column.
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Dissolution mechanisms of Steelmaking Slags in sea water
Mineral Processing and Extractive Metallurgy, 2016Co-Authors: Hiroyuki Matsuura, Likun Zang, Guohua Zhang, Xiaorui Zhang, Fumitaka TsukihashiAbstract:ABSTRACTNew methods to further utilize Steelmaking Slag must be developed from the viewpoint of not only the stable consumption of Steelmaking Slag but also the establishment of sustainable and environmental friendly Steelmaking process. It is well known that the lack of iron in sea water, which is an essential minor nutrient for seaweeds, is a major reason for the severe deterioration of coastal environment all over the world. The trial application of Steelmaking Slag as a material to supply such mineral nutrients has revealed the positive effects on the improvement of coastal ecological system. Dissolution mechanisms of various elements from Steelmaking Slag into sea water must be clarified in order to apply the rehabilitation technology to seriously damaged coasts. In the present paper, the dissolution behaviours of nutrient elements from Steelmaking Slag and Steelmaking Slag blended with dredged soil into sea water, or sea water containing gluconic acid which have been previously studied through labor...
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Advances in Molten Slags, Fluxes, and Salts - Dissolution Mechanisms of Nutrient Elements from Steelmaking Slag into Seawater
Advances in Molten Slags Fluxes and Salts: Proceedings of the 10th International Conference on Molten Slags Fluxes and Salts 2016, 2016Co-Authors: Hiroyuki Matsuura, Qian Zhou, Fuminori Katabe, Likun Zang, Guohua Zhang, Fumitaka TsukihashiAbstract:Steelmaking Slag is one of major by-products from Steelmaking process and its efficient recycling is essential to establish the environmentally-friendly Steelmaking industry. Recently Steelmaking Slag has been recognized as an effective supplier of nutrient elements to recover the ocean environment from sea desertification. It is believed that the efficient dissolution of iron ion is critical to rehabilitate the damaged sea coast, while the solubility of iron ion in seawater is much below the required concentration. Therefore, the simultaneous addition of humic acids to Steelmaking Slag is necessary to produce the stable chelated iron ion in seawater. In the present paper, the effect of natural substances containing humic acids or a chemical organic acid on the dissolution behavior of nutrient elements from Steelmaking Slag was studied and the dissolution mechanisms of Steelmaking Slag into seawater were discussed.
Hiroyuki Matsuura - One of the best experts on this subject based on the ideXlab platform.
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generation behavior of syngas between coal and feo containing Slag under co2 ar atmosphere
Applied Thermal Engineering, 2017Co-Authors: Hiroyuki Matsuura, Yan Wu, Zhangfu Yuan, Fumitaka TsukihashiAbstract:Abstract In this study, Steelmaking Slag was utilized as heat carrier and catalyst to perform the coal gasification; meanwhile, CO 2 was used as gasifying agent rather than steam from the viewpoint of carbon circulation. An overview on research activities and technology development on the effect of Steelmaking Slag on coal gasification are provided. The effects of coal type, Slag composition, CO 2 gas ratio and temperature on the gas producing behavior were discussed through the high temperature experiment. The results showed that coal gasification was remarkably enhanced and the produced CO amount increased considerably with the addition of Slag. On the contrary, with the increase of the Slag amount, the produced CO amount has the decreasing trend. Coal combined with higher FeO content Slag presented higher CO generation rate and less CO generation amount. Moreover, the increase of the CO 2 gas ratio and reaction temperature would promote the gasification of coal.
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Long-Term Dissolution Behavior of Steelmaking Slag and Its Composite Materials in Seawater
Journal of Sustainable Metallurgy, 2017Co-Authors: Yusheng Lang, Hiroyuki Matsuura, Fumitaka TsukihashiAbstract:Steelmaking Slag is considered to be a suitable candidate material for rehabilitating marine environments damaged by sea desertification because it can supply nutrient elements, and its positive effects have been phenomenologically proven. To fully understand the role of Steelmaking Slag in the rehabilitation process and maximize its efficiency, elucidation of the dissolution mechanism of nutrient elements from Slag-based materials is essential. The present study focused on the long-term dissolution behaviors of Steelmaking Slag, a Slag–soil composite material, and a Slag–humic substance composite material. Column experiments with a duration of 1152 h clarified that a marked increase in the pH value as well as the significant dissolution of elements occurred in the initial stage, while the subsequent increase in the concentrations of elements was small, and the Fe contained in the original seawater precipitated owing to the locally high pH in the column.
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Dissolution mechanisms of Steelmaking Slags in sea water
Mineral Processing and Extractive Metallurgy, 2016Co-Authors: Hiroyuki Matsuura, Likun Zang, Guohua Zhang, Xiaorui Zhang, Fumitaka TsukihashiAbstract:ABSTRACTNew methods to further utilize Steelmaking Slag must be developed from the viewpoint of not only the stable consumption of Steelmaking Slag but also the establishment of sustainable and environmental friendly Steelmaking process. It is well known that the lack of iron in sea water, which is an essential minor nutrient for seaweeds, is a major reason for the severe deterioration of coastal environment all over the world. The trial application of Steelmaking Slag as a material to supply such mineral nutrients has revealed the positive effects on the improvement of coastal ecological system. Dissolution mechanisms of various elements from Steelmaking Slag into sea water must be clarified in order to apply the rehabilitation technology to seriously damaged coasts. In the present paper, the dissolution behaviours of nutrient elements from Steelmaking Slag and Steelmaking Slag blended with dredged soil into sea water, or sea water containing gluconic acid which have been previously studied through labor...
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Advances in Molten Slags, Fluxes, and Salts - Dissolution Mechanisms of Nutrient Elements from Steelmaking Slag into Seawater
Advances in Molten Slags Fluxes and Salts: Proceedings of the 10th International Conference on Molten Slags Fluxes and Salts 2016, 2016Co-Authors: Hiroyuki Matsuura, Qian Zhou, Fuminori Katabe, Likun Zang, Guohua Zhang, Fumitaka TsukihashiAbstract:Steelmaking Slag is one of major by-products from Steelmaking process and its efficient recycling is essential to establish the environmentally-friendly Steelmaking industry. Recently Steelmaking Slag has been recognized as an effective supplier of nutrient elements to recover the ocean environment from sea desertification. It is believed that the efficient dissolution of iron ion is critical to rehabilitate the damaged sea coast, while the solubility of iron ion in seawater is much below the required concentration. Therefore, the simultaneous addition of humic acids to Steelmaking Slag is necessary to produce the stable chelated iron ion in seawater. In the present paper, the effect of natural substances containing humic acids or a chemical organic acid on the dissolution behavior of nutrient elements from Steelmaking Slag was studied and the dissolution mechanisms of Steelmaking Slag into seawater were discussed.
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Dissolution Mechanisms of Steelmaking Slag–Dredged Soil Mixture into Seawater
Journal of Sustainable Metallurgy, 2016Co-Authors: Xiaorui Zhang, Hiroyuki Matsuura, Fumitaka TsukihashiAbstract:A Steelmaking Slag–dredged soil mixture has been applied to develop or recover the sea coast. In recent years, the side effect of its utilization has been reported, in which the coastal environment has been rehabilitated from sea desertification. It is considered that the mixture can provide various nutrient elements essential for the growth of seaweeds which are lacking in the natural seawater. In the present research, the dissolution behaviors of Steelmaking Slag–dredged soil mixture into seawater were investigated at laboratory-scale experiments, and the mechanisms were discussed. Variation of pH and the dissolution of Ca were significantly dependent on the CaO/SiO_2 ratio of the Slag, and simultaneously, a slight buffering action on the pH of seawater was provided by the dredged soil. When the pH of seawater increased to a certain extent, Mg contained in seawater precipitated and hindered the further increase of the pH. After the complete precipitation of Mg, pH started to increase again. Dissolution of Si and P greatly depended on the CaO/SiO_2 ratio of the Slag and also slightly depended on the ratio of Steelmaking Slag to dredged soil. According to the CaO/SiO_2 ratio of the Slag, the existing forms of Si were considered to change, while those of P were considered to be the HPO_4 ^2− ion in the whole range. A reasonable dissolution mechanism of Fe from Steelmaking Slag–dredged soil mixture was estimated based on the variation of ORP value, dissolved Fe concentration and its solubility diagram in seawater condition.
Xiaorui Zhang - One of the best experts on this subject based on the ideXlab platform.
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Dissolution mechanisms of Steelmaking Slags in sea water
Mineral Processing and Extractive Metallurgy, 2016Co-Authors: Hiroyuki Matsuura, Likun Zang, Guohua Zhang, Xiaorui Zhang, Fumitaka TsukihashiAbstract:ABSTRACTNew methods to further utilize Steelmaking Slag must be developed from the viewpoint of not only the stable consumption of Steelmaking Slag but also the establishment of sustainable and environmental friendly Steelmaking process. It is well known that the lack of iron in sea water, which is an essential minor nutrient for seaweeds, is a major reason for the severe deterioration of coastal environment all over the world. The trial application of Steelmaking Slag as a material to supply such mineral nutrients has revealed the positive effects on the improvement of coastal ecological system. Dissolution mechanisms of various elements from Steelmaking Slag into sea water must be clarified in order to apply the rehabilitation technology to seriously damaged coasts. In the present paper, the dissolution behaviours of nutrient elements from Steelmaking Slag and Steelmaking Slag blended with dredged soil into sea water, or sea water containing gluconic acid which have been previously studied through labor...
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Dissolution Mechanisms of Steelmaking Slag–Dredged Soil Mixture into Seawater
Journal of Sustainable Metallurgy, 2016Co-Authors: Xiaorui Zhang, Hiroyuki Matsuura, Fumitaka TsukihashiAbstract:A Steelmaking Slag–dredged soil mixture has been applied to develop or recover the sea coast. In recent years, the side effect of its utilization has been reported, in which the coastal environment has been rehabilitated from sea desertification. It is considered that the mixture can provide various nutrient elements essential for the growth of seaweeds which are lacking in the natural seawater. In the present research, the dissolution behaviors of Steelmaking Slag–dredged soil mixture into seawater were investigated at laboratory-scale experiments, and the mechanisms were discussed. Variation of pH and the dissolution of Ca were significantly dependent on the CaO/SiO_2 ratio of the Slag, and simultaneously, a slight buffering action on the pH of seawater was provided by the dredged soil. When the pH of seawater increased to a certain extent, Mg contained in seawater precipitated and hindered the further increase of the pH. After the complete precipitation of Mg, pH started to increase again. Dissolution of Si and P greatly depended on the CaO/SiO_2 ratio of the Slag and also slightly depended on the ratio of Steelmaking Slag to dredged soil. According to the CaO/SiO_2 ratio of the Slag, the existing forms of Si were considered to change, while those of P were considered to be the HPO_4 ^2− ion in the whole range. A reasonable dissolution mechanism of Fe from Steelmaking Slag–dredged soil mixture was estimated based on the variation of ORP value, dissolved Fe concentration and its solubility diagram in seawater condition.
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dissolution mechanisms of Steelmaking Slag dredged soil mixture into seawater
Journal of Sustainable Metallurgy, 2016Co-Authors: Hiroyuki Matsuura, Xiaorui Zhang, Fumitaka TsukihashiAbstract:A Steelmaking Slag–dredged soil mixture has been applied to develop or recover the sea coast. In recent years, the side effect of its utilization has been reported, in which the coastal environment has been rehabilitated from sea desertification. It is considered that the mixture can provide various nutrient elements essential for the growth of seaweeds which are lacking in the natural seawater. In the present research, the dissolution behaviors of Steelmaking Slag–dredged soil mixture into seawater were investigated at laboratory-scale experiments, and the mechanisms were discussed. Variation of pH and the dissolution of Ca were significantly dependent on the CaO/SiO2 ratio of the Slag, and simultaneously, a slight buffering action on the pH of seawater was provided by the dredged soil. When the pH of seawater increased to a certain extent, Mg contained in seawater precipitated and hindered the further increase of the pH. After the complete precipitation of Mg, pH started to increase again. Dissolution of Si and P greatly depended on the CaO/SiO2 ratio of the Slag and also slightly depended on the ratio of Steelmaking Slag to dredged soil. According to the CaO/SiO2 ratio of the Slag, the existing forms of Si were considered to change, while those of P were considered to be the HPO4 2− ion in the whole range. A reasonable dissolution mechanism of Fe from Steelmaking Slag–dredged soil mixture was estimated based on the variation of ORP value, dissolved Fe concentration and its solubility diagram in seawater condition.
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Enhancement of the Dissolution of Nutrient Elements from Steelmaking Slag into Seawater by Gluconic Acid
Journal of Sustainable Metallurgy, 2015Co-Authors: Xiaorui Zhang, Hiroyuki Matsuura, Fumitaka TsukihashiAbstract:Steelmaking Slag has been buried in coast to provide nutrient elements, especially iron, into seawater for the seaweeds’ growth. However, the solubility of iron is extremely low under the oxic seawater conditions. In order to stabilize soluble iron which is dissolved from Steelmaking Slag into seawater, the addition of gluconic acid was investigated in the present study. By using two kinds of synthesized Steelmaking Slag with different CaO/SiO_2 ratios, the effect of gluconic acid on the dissolution behavior of various elements into seawater, while varying the concentration of gluconic acid and pH, was studied. The dissolution of Ca, Si, P, and Fe was greatly enhanced by the addition of gluconic acid and their concentration increased for increasing gluconic acid concentration. The dissolution mechanisms of each element were discussed using their stability diagrams and the dissolution reactions.
A Ramachandran - One of the best experts on this subject based on the ideXlab platform.
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Direct mineral carbonation of Steelmaking Slag for CO_2 sequestration at room temperature
Environmental Science and Pollution Research, 2016Co-Authors: T. D. Rushendra Revathy, Krishnamoorthy Palanivelu, A RamachandranAbstract:Rapid increase of CO_2 concentration in the atmosphere has forced the international community towards adopting actions to restrain from the impacts of climate change. Moreover, in India, the dependence on fossil fuels is projected to increase in the future, implying the necessity of capturing CO_2 in a safe manner. Alkaline solid wastes can be utilized for CO_2 sequestration by which its disposal issues in the country could also be met. The present work focuses to study direct mineral carbonation of Steelmaking Slag (SS) at room temperature and low-pressure conditions (
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direct mineral carbonation of Steelmaking Slag for co2 sequestration at room temperature
Environmental Science and Pollution Research, 2016Co-Authors: T Rushendra D Revathy, Krishnamoorthy Palanivelu, A RamachandranAbstract:Rapid increase of CO2 concentration in the atmosphere has forced the international community towards adopting actions to restrain from the impacts of climate change. Moreover, in India, the dependence on fossil fuels is projected to increase in the future, implying the necessity of capturing CO2 in a safe manner. Alkaline solid wastes can be utilized for CO2 sequestration by which its disposal issues in the country could also be met. The present work focuses to study direct mineral carbonation of Steelmaking Slag (SS) at room temperature and low-pressure conditions (<10 bar). Direct mineral carbonation of SS was carried out in a batch reactor with pure CO2 gas. The process parameters that may influence the carbonation of SS, namely, CO2 gas pressure, liquid to solid ratio (L/S) and reaction time were also studied. The results showed that maximum sequestration of SS was attained in the aqueous route with a capacity of 82 g of CO2/kg (6 bar, L/S ratio of 10 and 3 h). In the gas-solid route, maximum sequestration capacity of about 11.1 g of CO2/kg of SS (3 bar and 3 h) was achieved indicating that aqueous route is the better one under the conditions studied. These findings demonstrate that SS is a promising resource and this approach could be further developed and used for CO2 sequestration in the country. The carbonation process was evidenced using FT-IR, XRD, SEM and TG analysis.
Shin-ya Kitamura - One of the best experts on this subject based on the ideXlab platform.
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Selective Leaching of P from Steelmaking Slag in Sulfuric Acid Solution
Journal of Sustainable Metallurgy, 2019Co-Authors: Chuanming Du, Shigeru Ueda, Shin-ya KitamuraAbstract:Steelmaking Slag contains considerable quantities of valuable elements such as P and Mn; however, its intrinsic value has not been fully exploited. In Steelmaking Slag, P is primarily distributed in the 2CaO·SiO2–3CaO·P2O5 solid solution, which can be dissolved readily in the aqueous solution compared with other phases. To separate and recover P from Steelmaking Slag, selective leaching of the P-containing solid solution was proposed. In this study, sulfuric acid was used as the leaching agent to reduce production costs. The effects of the cooling method of the molten Slag, valence of Fe in Slag, pH, and particle size on the dissolution characteristic of Steelmaking Slag were investigated. To achieve an improved selective leaching of P, the molten Slag should be oxidized into the Fe2O3-containing Slag and cooled slowly. As the pH decreased, the dissolution of the Slag was promoted, resulting in a higher extraction efficiency of P. The majority of the solid solution was separated without dissolving the Fe-rich magnesioferrite at pH 3, indicating an improved selective leaching of P. Through selective leaching, the P2O5 content in the residue decreased significantly. If the formation of CaSO4 can be suppressed, this residue has the potential to be reused in the steel plant. Decreasing the particle size increased the dissolution rate of Slag. A shrinking core model was used to describe the kinetics of Slag dissolution. The dissolution of P in the sulfuric acid solution was controlled by diffusion in the residue layer.
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Separation and recovery of phosphorus from Steelmaking Slag via a selective leaching–chemical precipitation process
Hydrometallurgy, 2019Co-Authors: Chuanming Du, Shigeru Ueda, Shin-ya KitamuraAbstract:Abstract Steelmaking Slag, a significant by-product of Steelmaking, contains a certain amount of phosphorus, which makes it a potential phosphate source. To achieve its high value-added utilization, the P-concentrated C 2 S–C 3 P solid solution in Slag is commonly separated. In this study, we adopted a selective leaching–chemical precipitation process to recover P from Steelmaking Slag. The effects of the acid, pH, and valence of Fe in Slag on the leaching characteristics of P were first investigated. Chemical precipitation was then adopted to extract P from the leachate. The characteristics of the final product were evaluated. The results indicate that the P-concentrated solid solution was readily leached, whereas the Fe-rich magnesioferrite was resistant to dissolution in each acid solution. In view of the utilization of the residue and reducing the production costs, hydrochloric acid was considered the optimum leaching agent for dissolving the Slag. The dissolution of Steelmaking Slag in the hydrochloric acid solution increased with a decrease in pH. In addition, 81.6% of the P in Slag was dissolved at pH 3, whereas the Fe leaching was negligible, exhibiting an improved selective leaching. Further, the P-removed Steelmaking Slag can be reutilized in a steel plant to achieve waste-free Steelmaking. In the following precipitation at pH 7, most of the P in the leachate was transformed into an insoluble calcium phosphate. This process provides more than a 70% P recovery from Steelmaking Slag. The P 2 O 5 content in the product obtained reached 20.2 mass%, which can be applied as a fertilizer.
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Separation of Phosphorus and Manganese from Steelmaking Slag by Selective Reduction
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2019Co-Authors: Dong Jun Shin, Shigeru Ueda, Shin-ya KitamuraAbstract:Steelmaking Slag contains considerable amount of manganese (Mn) and phosphorus (P), and recycling them is an important issue. Since Mn is an alloy added to enhance the steel quality, while P is a harmful impurity in the steel product, they need to be separated for recycling. We have already found the possibility of separating Mn and P from Steelmaking Slag by selectively reducing P2O5 and FeO while suppressing the reduction of MnO. As a fundamental study for the selective reduction of P from Steelmaking Slag, in this study, we vary the Slag basicity, graphite mixing ratio, temperature, and crucible type to find the optimum condition. Artificial Steelmaking Slag with various compositions is synthesized and mixed with graphite powder in an Al2O3 or a MgO crucible. The reduction is conducted at 1673 K, 1773 K, and 1873 K for 20 to 80 minutes. As a result, carbon saturated metal is formed from the Slag, and the reduced metal and Slag were separated easily. We find that a decrease in Slag basicity suppressed the reduction rate of Mn while enhancing that of P. The activation energy for the reduction rate constant of P is found to be close to that of the diffusion of P in Slag.
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Measures to Decrease and Utilize Steelmaking Slag
Journal of Sustainable Metallurgy, 2019Co-Authors: Chuanming Du, Shin-ya KitamuraAbstract:Steelmaking Slag is artificially produced to remove, among others, the phosphorus from molten steel; approximately 120 kg of Slag is formed per ton of steel. At present, Steelmaking Slag is mostly used for road construction and civil engineering materials. However, the Slag cannot be sold at a high price and, in advanced countries, its market for civil work is shrinking and regulations to protect the environment are becoming more severe. There are two solutions to the problem of Steelmaking Slag: one is to decrease the generation of Slag, and the other is the development of reuse methods. In this paper, the measures to decrease Slag formation are first discussed based on the mass-balance calculation, and then the present and future states of Slag valorization in Japan are reviewed. In the first part, the importance of the hot-metal dephosphorization process and the recycling of decarburized Slag is clarified. In the second part, as a new field of Slag valorization, the use of Slag in marine environments is explained. Several studies to extract phosphorus and manganese from Slag were also introduced.
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Alkali Elution of Various Mineralogical Phases in Steelmaking Slag
REWAS 2019, 2019Co-Authors: Shigeru Ueda, Shin-ya KitamuraAbstract:To suppress alkaline elution from Steelmaking Slag, the dissolution behaviors of mineralogical phases in Slag need to be studied. In this paper, primary crystal phases (CaO·SiO2, CaO·SiO2·FeO, and CaO·SiO2·2MgO) of CaO–SiO2–FeOx and CaO–SiO2–MgO systems were synthesized, and their dissolution behaviors and the change in pH were investigated. The results showed that CaO·SiO2 caused the increase in pH by the dissolution of alkali. Therefore, the alkali elution from Steelmaking Slag is caused by not only free CaO and 2CaO·SiO2 but also CaO·SiO2. Then, Slags corresponding to actual Steelmaking composition in the system CaO–SiO2–FeOx and CaO–SiO2–MgO systems were synthesized and their dissolution behaviors were observed. The result showed that the pH values after the dissolution of every Slag were lower than that of CaCO3, even though water soluble phases were contained in Slag. Therefore, alkali elution from Slag containing soluble phases can be suppressed when the mass fractions of these phases in Slag are low enough.
