Pub Date : 2024-07-17DOI: 10.1007/s40831-024-00883-6
Jiahai Bai, Chengfeng Li, Qingyang Du, Cheng Dong
Self-foamed glass ceramics were fabricated using red mud and ceramic tile polishing waste as main starting materials. Effects of red mud content in ceramics, sintering temperature and soaking time on pore structure, pore size distribution, total porosity, compressive strength and thermal conductivity were elaborately investigated. Experimental results revealed that the as-prepared self-foamed glass ceramics all exhibited homogenous foam-like structure. When the red mud content rose from 15 to 25 wt% and then up to 30 wt%, mean pore size and total porosity of the samples increased markedly and then decreased sharply, while compressive strength and thermal conductivity first decreased and then increased. As sintering temperature rose from 1110 to 1140 °C and soaking time extended from 30 to 60 min, respectively, mean pore size and total porosity increased remarkably, while compressive strength and thermal conductivity decreased appreciably. The self-foamed glass ceramics from 25 wt% red mud sintered at 1130 °C for 45 min exhibited many excellent properties including mean pore size of 0.99 mm, bulk density of 0.48 g/cm3, total density of 79.6%, high compressive strength of 8.3 MPa and low thermal conductivity of 0.08 W/m K, which made the as-fabricated self-foamed glass ceramics a good candidate material for external thermal insulator in buildings.
{"title":"Fabrication and Properties of Self-foamed Glass Ceramics from Red Mud and Ceramic Tile Polishing Waste","authors":"Jiahai Bai, Chengfeng Li, Qingyang Du, Cheng Dong","doi":"10.1007/s40831-024-00883-6","DOIUrl":"https://doi.org/10.1007/s40831-024-00883-6","url":null,"abstract":"<p>Self-foamed glass ceramics were fabricated using red mud and ceramic tile polishing waste as main starting materials. Effects of red mud content in ceramics, sintering temperature and soaking time on pore structure, pore size distribution, total porosity, compressive strength and thermal conductivity were elaborately investigated. Experimental results revealed that the as-prepared self-foamed glass ceramics all exhibited homogenous foam-like structure. When the red mud content rose from 15 to 25 wt% and then up to 30 wt%, mean pore size and total porosity of the samples increased markedly and then decreased sharply, while compressive strength and thermal conductivity first decreased and then increased. As sintering temperature rose from 1110 to 1140 °C and soaking time extended from 30 to 60 min, respectively, mean pore size and total porosity increased remarkably, while compressive strength and thermal conductivity decreased appreciably. The self-foamed glass ceramics from 25 wt% red mud sintered at 1130 °C for 45 min exhibited many excellent properties including mean pore size of 0.99 mm, bulk density of 0.48 g/cm<sup>3</sup>, total density of 79.6%, high compressive strength of 8.3 MPa and low thermal conductivity of 0.08 W/m K, which made the as-fabricated self-foamed glass ceramics a good candidate material for external thermal insulator in buildings.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"27 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-17DOI: 10.1007/s40831-024-00880-9
A. Shikika, F. A. Muvundja, M. C. Mugumaoderha, M. Aâtach, St. Gaydardzhiev
Results from purification and separation of Ta and Nb from bifluoride-based leachates aiming to produce high-purity Ta and Nb oxides are reported. The leachates have been generated through ammonium bifluoride (NH4F⋅HF) fluorination (5/1 ratio to ore), followed by sulfuric acid (1 M) leaching of the fluorinated product. Under these conditions, leachate concentration in Nb was 4.2 g/L, while Ta varied between 15 and 17 g/L. Contact time, organic/aqueous (O/A) ratio, and sulfuric acid concentration of the aqueous phase were investigated on their influence on the level of Ta/Nb extraction and separation efficiencies of methyl isobuthyl ketone (MIBK), 2-octanol (OCL), and Aliquat®336 used as solvent extractants. Results show that Ta and Nb could be successfully separated from ammonium bifluoride using the three studied extractants. In the case of MIBK and OCL (100% concentration), the optimum conditions for Ta/Nb separation were found as follows: leachate acidity—3 M, contact time—15 min, and O/A ratio—1. Separation factors of Ta against Nb (SFTa/Nb) of about 280 (MIBK) and 51 (OCL) were accordingly reached. When 3% Aliquat®336 was used, the highest Ta vs. Nb separation factor (SFTa/Nb = 180) was obtained at O/A ratio of 1 employing 2-min contact time without acidity adjustment. The separation performance of the three extractants could be ranked in the following order: MIBK > Aliquat®336 > OCL. MIBK could nevertheless be substituted at industrial scale by Aliquat®336 due to its known process relevant advantages (higher flash point (132 °C) and lower solubility < 0.5%). After stripping of the loaded Aliquat®336, Ta and Nb were precipitated and precipitates calcinated. Ta and Nb oxide powders with purity around 93% were, thus, obtained and their morphology examined by SEM.
{"title":"Separation and Purification of Ta and Nb from Ammonium Bifluoride Leachates Using Methyl Isobuthyl Ketone, 2-Octanol, and Aliquat® 336","authors":"A. Shikika, F. A. Muvundja, M. C. Mugumaoderha, M. Aâtach, St. Gaydardzhiev","doi":"10.1007/s40831-024-00880-9","DOIUrl":"https://doi.org/10.1007/s40831-024-00880-9","url":null,"abstract":"<p>Results from purification and separation of Ta and Nb from bifluoride-based leachates aiming to produce high-purity Ta and Nb oxides are reported. The leachates have been generated through ammonium bifluoride (NH<sub>4</sub>F⋅HF) fluorination (5/1 ratio to ore), followed by sulfuric acid (1 M) leaching of the fluorinated product. Under these conditions, leachate concentration in Nb was 4.2 g/L, while Ta varied between 15 and 17 g/L. Contact time, organic/aqueous (O/A) ratio, and sulfuric acid concentration of the aqueous phase were investigated on their influence on the level of Ta/Nb extraction and separation efficiencies of methyl isobuthyl ketone (MIBK), 2-octanol (OCL), and Aliquat®336 used as solvent extractants. Results show that Ta and Nb could be successfully separated from ammonium bifluoride using the three studied extractants. In the case of MIBK and OCL (100% concentration), the optimum conditions for Ta/Nb separation were found as follows: leachate acidity—3 M, contact time—15 min, and O/A ratio—1. Separation factors of Ta against Nb (SF<sub>Ta/Nb</sub>) of about 280 (MIBK) and 51 (OCL) were accordingly reached. When 3% Aliquat®336 was used, the highest Ta vs. Nb separation factor (<i>SF</i><sub>Ta/Nb</sub> = 180) was obtained at O/A ratio of 1 employing 2-min contact time without acidity adjustment. The separation performance of the three extractants could be ranked in the following order: MIBK > Aliquat®336 > OCL. MIBK could nevertheless be substituted at industrial scale by Aliquat®336 due to its known process relevant advantages (higher flash point (132 °C) and lower solubility < 0.5%). After stripping of the loaded Aliquat®336, Ta and Nb were precipitated and precipitates calcinated. Ta and Nb oxide powders with purity around 93% were, thus, obtained and their morphology examined by SEM.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"14 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-17DOI: 10.1007/s40831-024-00884-5
Zulfiadi Zulhan, Muhammad A’an, Fauzan Kamal, Sonny Djatnika Sunda Djaja, Taufiq Hidayat, R. M. Nabiel Salmanhakim, Bouman Tiroi Situmorang, Nilus Rahmat
The growth of the global population has led to a substantial increase in municipal solid waste (MSW) generation. Various methods have been suggested and implemented to address this issue, including waste processing by dry fermentation using aerobic bio-drying, resulting in treated municipal solid waste (TMSW) that can serve as an energy source. The potential application of TMSW as a reducing agent in the production of ferronickel from lateritic nickel ore was investigated. Experiments were conducted in a muffle furnace by mixing lateritic nickel ore with TMSW and heating according to specific temperature patterns. Ferronickel was produced in the form of metal nuggets, with nickel content ranging from 7–12% and iron from 84–88%, with a yield of 87% for both nickel and iron. From these results, it can be concluded that TMSW can substitute coal as a reducing agent, enabling MSW utilization and enhancing the sustainability of ferronickel production.
{"title":"Municipal Solid Waste as a Potential Reducing Agent for Substituting Coal in Ferronickel Production","authors":"Zulfiadi Zulhan, Muhammad A’an, Fauzan Kamal, Sonny Djatnika Sunda Djaja, Taufiq Hidayat, R. M. Nabiel Salmanhakim, Bouman Tiroi Situmorang, Nilus Rahmat","doi":"10.1007/s40831-024-00884-5","DOIUrl":"https://doi.org/10.1007/s40831-024-00884-5","url":null,"abstract":"<p>The growth of the global population has led to a substantial increase in municipal solid waste (MSW) generation. Various methods have been suggested and implemented to address this issue, including waste processing by dry fermentation using aerobic bio-drying, resulting in treated municipal solid waste (TMSW) that can serve as an energy source. The potential application of TMSW as a reducing agent in the production of ferronickel from lateritic nickel ore was investigated. Experiments were conducted in a muffle furnace by mixing lateritic nickel ore with TMSW and heating according to specific temperature patterns. Ferronickel was produced in the form of metal nuggets, with nickel content ranging from 7–12% and iron from 84–88%, with a yield of 87% for both nickel and iron. From these results, it can be concluded that TMSW can substitute coal as a reducing agent, enabling MSW utilization and enhancing the sustainability of ferronickel production.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"74 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1007/s40831-024-00868-5
Fuqiang Zheng, Yuqi Zhao, Hongyang Wang, Bin Hu, Chen Liu
Reduction roasting‒magnetic separation was adopted to extract iron in red mud containing 47.45% Fe and 11.58% Al2O3. The process mineralogy and phase transformation of red mud during reduction roasting with CaO were studied using advanced mineral identification and characterization system, X-ray diffraction, scanning electron microscope, and energy-dispersive spectrometer. Results show that the main Fe-bearing minerals in red mud are hematite and alumogeothite, with corresponding contents of 47.99% and 37.81%, respectively. After reduction roasting with CaO, red mud is converted into metallic iron and Ca–Al compounds, and the iron grain size increases with roasting temperature. After roasting at 1175 °C for 60 min, the iron grain size reaches 18.85 μm. Under the conditions of grinding size of − 44 μm of 86.57%, and magnetic intensity of 1000 Gs, a concentrate with Fe grade of 90.14% and Fe recovery of 85.68% is obtained. Meanwhile, there are 40.01% of CaO and 23.96% of Al2O3 in magnetic tailing, which can be used as cement raw materials. This study lays the foundation for the resource utilization of red mud.
{"title":"Preparation of Reduced Iron Powder and Cement Raw Material from Red Mud Using Reduction Roasting with CaO","authors":"Fuqiang Zheng, Yuqi Zhao, Hongyang Wang, Bin Hu, Chen Liu","doi":"10.1007/s40831-024-00868-5","DOIUrl":"https://doi.org/10.1007/s40831-024-00868-5","url":null,"abstract":"<p>Reduction roasting‒magnetic separation was adopted to extract iron in red mud containing 47.45% Fe and 11.58% Al<sub>2</sub>O<sub>3</sub>. The process mineralogy and phase transformation of red mud during reduction roasting with CaO were studied using advanced mineral identification and characterization system, X-ray diffraction, scanning electron microscope, and energy-dispersive spectrometer. Results show that the main Fe-bearing minerals in red mud are hematite and alumogeothite, with corresponding contents of 47.99% and 37.81%, respectively. After reduction roasting with CaO, red mud is converted into metallic iron and Ca–Al compounds, and the iron grain size increases with roasting temperature. After roasting at 1175 °C for 60 min, the iron grain size reaches 18.85 μm. Under the conditions of grinding size of − 44 μm of 86.57%, and magnetic intensity of 1000 Gs, a concentrate with Fe grade of 90.14% and Fe recovery of 85.68% is obtained. Meanwhile, there are 40.01% of CaO and 23.96% of Al<sub>2</sub>O<sub>3</sub> in magnetic tailing, which can be used as cement raw materials. This study lays the foundation for the resource utilization of red mud.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"78 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.1007/s40831-024-00872-9
Steven King, Alberto Striolo
The current pyrometallurgical silver refining process involves high energy consumption and a proportional carbon footprint. Developmental work conducted by Glencore at Britannia Refined Metals, UK, has achieved a fundamental redesign of the silver refining process. The new process, tested at the pilot plant scale, has removed the liquation stage in the original process and introduced a vacuum dezincing unit with significantly superior energy efficiency to the original vacuum induction dezincing operation. The redesigned dezincing unit demonstrates dezincing kinetics 44% greater than the original unit, as well as a higher purity and recovery efficiency of zinc. Utilizing a pilot plant at nominally ¼ scale of the full-scale process, the new Britannia Silver Process has been operated as an experimental facility to examine all aspects of the new operation and its integration into larger full-scale plant. The extended operation demonstrated a 37% reduction in energy usage and a 31% reduction in carbon footprint, as assessed at Scope 1 resolution, compared to the original process, per unit of produced silver, at equal or better purity. The favorable results have secured the approval of construction of a demonstration plant.
{"title":"Performance Metrics of the Newly Introduced Britannia Silver Process: Significant Reductions in Operating Costs, Energy Usage, and Scope 1 Carbon Emissions in the Industrial-Scale Refining of Silver","authors":"Steven King, Alberto Striolo","doi":"10.1007/s40831-024-00872-9","DOIUrl":"https://doi.org/10.1007/s40831-024-00872-9","url":null,"abstract":"<p>The current pyrometallurgical silver refining process involves high energy consumption and a proportional carbon footprint. Developmental work conducted by Glencore at Britannia Refined Metals, UK, has achieved a fundamental redesign of the silver refining process. The new process, tested at the pilot plant scale, has removed the liquation stage in the original process and introduced a vacuum dezincing unit with significantly superior energy efficiency to the original vacuum induction dezincing operation. The redesigned dezincing unit demonstrates dezincing kinetics 44% greater than the original unit, as well as a higher purity and recovery efficiency of zinc. Utilizing a pilot plant at nominally ¼ scale of the full-scale process, the new Britannia Silver Process has been operated as an experimental facility to examine all aspects of the new operation and its integration into larger full-scale plant. The extended operation demonstrated a 37% reduction in energy usage and a 31% reduction in carbon footprint, as assessed at Scope 1 resolution, compared to the original process, per unit of produced silver, at equal or better purity. The favorable results have secured the approval of construction of a demonstration plant.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"86 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141568278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reduction shaft furnace process is one of the future directions for low-carbon ironmaking. Different parameters can affect the yield and CO2 emissions. In the present work, the effect of metallization degree (MD) of direct reduced iron (DRI) on the yield and CO2 emission in reduction shaft furnace process was calculated by thermodynamics, considering the partial oxidation of coke oven gas (COG). The results indicate that (1) at a reduction temperature of 850 °C and an MD of 90%, COG partial oxidation in shaft furnace can increase DRI yield by 0.266 kg/100mol COG and reduce CO2 emissions by 72.664 kg/t-DRI compared to heating furnace; (2) reducing reduction temperature and MD will increase DRI yield and reduce CO2 emission. At 800 °C with a 90% MD, the highest DRI yield (2.599 kg/100mol COG) and lowest CO2 emission (626.406 kg/t-DRI) were achieved, which mark a significant 0.138 kg/100mol COG increase in DRI yield and a notable 43.331 kg/t-DRI decrease in CO2 emission compared to 950 °C with a 100% MD; (3) high CO2 removal rates from the top gas not only slightly reduces the heat load of the heating furnace but also provides more heat and reducing gas for top gas recycling. The results of this study may provide guidance in selecting optimal parameters for practical shaft furnace processes and reducing CO2 emissions.
{"title":"Effects of Metallization Degree of DRI on the Yield and CO2 Emission in Reduction Shaft Furnace Process","authors":"Yulu Zhou, Xin Jiang, Xiaoai Wang, Haiyan Zheng, Qiangjian Gao, Fengman Shen","doi":"10.1007/s40831-024-00824-3","DOIUrl":"https://doi.org/10.1007/s40831-024-00824-3","url":null,"abstract":"<p>Reduction shaft furnace process is one of the future directions for low-carbon ironmaking. Different parameters can affect the yield and CO<sub>2</sub> emissions. In the present work, the effect of metallization degree (MD) of direct reduced iron (DRI) on the yield and CO<sub>2</sub> emission in reduction shaft furnace process was calculated by thermodynamics, considering the partial oxidation of coke oven gas (COG). The results indicate that (1) at a reduction temperature of 850 °C and an MD of 90%, COG partial oxidation in shaft furnace can increase DRI yield by 0.266 kg/100mol COG and reduce CO<sub>2</sub> emissions by 72.664 kg/t-DRI compared to heating furnace; (2) reducing reduction temperature and MD will increase DRI yield and reduce CO<sub>2</sub> emission. At 800 °C with a 90% MD, the highest DRI yield (2.599 kg/100mol COG) and lowest CO<sub>2</sub> emission (626.406 kg/t-DRI) were achieved, which mark a significant 0.138 kg/100mol COG increase in DRI yield and a notable 43.331 kg/t-DRI decrease in CO<sub>2</sub> emission compared to 950 °C with a 100% MD; (3) high CO<sub>2</sub> removal rates from the top gas not only slightly reduces the heat load of the heating furnace but also provides more heat and reducing gas for top gas recycling. The results of this study may provide guidance in selecting optimal parameters for practical shaft furnace processes and reducing CO<sub>2</sub> emissions.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"169 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1007/s40831-024-00877-4
Özge Özgün, Imants Dirba, Oliver Gutfleisch, Yan Ma, Dierk Raabe
Hydrogen-based direct reduction (HyDR) of iron ores has attracted immense attention and is considered a forerunner technology for sustainable ironmaking. It has a high potential to mitigate CO2 emissions in the steel industry, which accounts today for ~ 8–10% of all global CO2 emissions. Direct reduction produces highly porous sponge iron via natural-gas-based or gasified-coal-based reducing agents that contain hydrogen and organic molecules. Commercial technologies usually operate at elevated pressure, e.g., the MIDREX process at 2 bar and the HyL/Energiron process at 6–8 bar. However, the impact of H2 pressure on reduction kinetics and microstructure evolution of hematite pellets during hydrogen-based direct reduction has not been well understood. Here, we present a study about the influence of H2 pressure on the reduction kinetics of hematite pellets with pure H2 at 700 °C at various pressures, i.e., 1, 10, and 100 bar under static gas exposure, and 1.3 and 50 bar under dynamic gas exposure. The microstructure of the reduced pellets was characterized by combining X-ray diffraction and scanning electron microscopy equipped with electron backscatter diffraction. The results provide new insights into the critical role of H2 pressure in the hydrogen-based direct reduction process and establish a direction for future furnace design and process optimization.
Graphical Abstract
铁矿石的氢基直接还原（HyDR）技术引起了广泛关注，被认为是可持续炼铁的先驱技术。目前，钢铁行业的二氧化碳排放量约占全球总排放量的 8-10%。直接还原法通过含氢和有机分子的天然气还原剂或气化煤还原剂生产高孔隙海绵铁。商业技术通常在高压下运行，例如 MIDREX 工艺在 2 bar 压力下运行，HyL/Energiron 工艺在 6-8 bar 压力下运行。然而，在氢基直接还原过程中，氢气压力对赤铁矿球团的还原动力学和微观结构演变的影响尚未得到很好的了解。在此，我们介绍了一项关于氢气压力对赤铁矿球团在不同压力（静态气体暴露下为 1、10 和 100 巴，动态气体暴露下为 1.3 和 50 巴）、700 °C、纯 H2 还原动力学的影响的研究。通过结合 X 射线衍射和配备电子反向散射衍射的扫描电子显微镜，对还原颗粒的微观结构进行了表征。研究结果为氢气压力在氢基直接还原过程中的关键作用提供了新的见解，并为未来的熔炉设计和工艺优化指明了方向。
{"title":"Green Ironmaking at Higher H2 Pressure: Reduction Kinetics and Microstructure Formation During Hydrogen-Based Direct Reduction of Hematite Pellets","authors":"Özge Özgün, Imants Dirba, Oliver Gutfleisch, Yan Ma, Dierk Raabe","doi":"10.1007/s40831-024-00877-4","DOIUrl":"https://doi.org/10.1007/s40831-024-00877-4","url":null,"abstract":"<p>Hydrogen-based direct reduction (HyDR) of iron ores has attracted immense attention and is considered a forerunner technology for sustainable ironmaking. It has a high potential to mitigate CO<sub>2</sub> emissions in the steel industry, which accounts today for ~ 8–10% of all global CO<sub>2</sub> emissions. Direct reduction produces highly porous sponge iron via natural-gas-based or gasified-coal-based reducing agents that contain hydrogen and organic molecules. Commercial technologies usually operate at elevated pressure, e.g., the MIDREX process at 2 bar and the HyL/Energiron process at 6–8 bar. However, the impact of H<sub>2</sub> pressure on reduction kinetics and microstructure evolution of hematite pellets during hydrogen-based direct reduction has not been well understood. Here, we present a study about the influence of H<sub>2</sub> pressure on the reduction kinetics of hematite pellets with pure H<sub>2</sub> at 700 °C at various pressures, i.e., 1, 10, and 100 bar under static gas exposure, and 1.3 and 50 bar under dynamic gas exposure. The microstructure of the reduced pellets was characterized by combining X-ray diffraction and scanning electron microscopy equipped with electron backscatter diffraction. The results provide new insights into the critical role of H<sub>2</sub> pressure in the hydrogen-based direct reduction process and establish a direction for future furnace design and process optimization.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"31 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-26DOI: 10.1007/s40831-024-00873-8
Alireza Habibzadeh, Mehmet Ali Kucuker, Öznur Çakır, Mertol Gökelma
Due to continuously increasing demand and limited resources of rare-earth elements (REEs), new solutions are being sought to overcome the supply risk of REEs. To mitigate the supply risk of REEs, much attention has recently been paid to recycling. Despite the more common recycling methods, including hydrometallurgical and pyrometallurgical processes, hydrogen processing of magnetic scrap (HPMS) is still in the development stage. Magnet-to-magnet recycling via hydrogenation of discarded NdFeB magnets provides a fine powder suitable for the production of new magnets from secondary sources. One of the crucial aspects of HPMS is the degree of recovery of the magnetic properties, as the yield efficiency can easily reach over 95%. The amount, morphology, and distribution of the Nd-rich phase are the key parameters to achieve the excellent performance of the magnet by isolating the matrix grain. Therefore, a better insight into the microstructure of the matrix grains and the Nd-rich phase before and after hydrogenation is essential. In this study, a low-temperature hydrogenation process in the range of room temperature to 400 °C was conducted as the first step to recycle NdFeB magnets from discarded hard disk drives (HDDs), and the hydrogenated powder was characterized by electron microscopy and X-ray diffraction. The results show that there are three different morphologies of the Nd-rich phase, which undergo two different transformations through oxidation and hydride formation. While at lower temperatures (below 250 °C) the degree of pulverization is higher and the experimental evidence of hydride formation is less clear, at higher temperatures the degree of pulverization decreases. The formation of neodymium hydride at higher temperatures prevents further oxidation of the Nd-rich phase due to its high stability.
{"title":"Microstructural Investigation of Discarded NdFeB Magnets After Low-Temperature Hydrogenation","authors":"Alireza Habibzadeh, Mehmet Ali Kucuker, Öznur Çakır, Mertol Gökelma","doi":"10.1007/s40831-024-00873-8","DOIUrl":"https://doi.org/10.1007/s40831-024-00873-8","url":null,"abstract":"<p>Due to continuously increasing demand and limited resources of rare-earth elements (REEs), new solutions are being sought to overcome the supply risk of REEs. To mitigate the supply risk of REEs, much attention has recently been paid to recycling. Despite the more common recycling methods, including hydrometallurgical and pyrometallurgical processes, hydrogen processing of magnetic scrap (HPMS) is still in the development stage. Magnet-to-magnet recycling via hydrogenation of discarded NdFeB magnets provides a fine powder suitable for the production of new magnets from secondary sources. One of the crucial aspects of HPMS is the degree of recovery of the magnetic properties, as the yield efficiency can easily reach over 95%. The amount, morphology, and distribution of the Nd-rich phase are the key parameters to achieve the excellent performance of the magnet by isolating the matrix grain. Therefore, a better insight into the microstructure of the matrix grains and the Nd-rich phase before and after hydrogenation is essential. In this study, a low-temperature hydrogenation process in the range of room temperature to 400 °C was conducted as the first step to recycle NdFeB magnets from discarded hard disk drives (HDDs), and the hydrogenated powder was characterized by electron microscopy and X-ray diffraction. The results show that there are three different morphologies of the Nd-rich phase, which undergo two different transformations through oxidation and hydride formation. While at lower temperatures (below 250 °C) the degree of pulverization is higher and the experimental evidence of hydride formation is less clear, at higher temperatures the degree of pulverization decreases. The formation of neodymium hydride at higher temperatures prevents further oxidation of the Nd-rich phase due to its high stability.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"9 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Global concerns about climate change are driving increased demand of electric vehicles for sustainable transportation and turbines in emerging energy solutions, where permanent magnets (PMs) and rare earth elements (REEs) play a critical role. However, global REEs recycling rates are only 3% and 8% for light and heavy REEs, respectively. This work proposes an effective approach to separate the REEs and iron via high-pressure selective leaching by low-concentrated nitric acid from the end-of-life NdFeB magnet and investigates the impurities behavior during the leaching and precipitation steps. The results from the optimized leaching conditions demonstrated over 95% REEs leaching efficiency with less than 0.3% Fe dissolution. Approximately 70% of Al and B were leached as well, while other elements (Co, Ni, Cu) had leaching efficiencies below 40%, leaving a hematite rich residue. Adjusting the pH removes Al and Fe in leachate but minimally affects Cu, Co, and Ni. Na2S addition is more effective against transition metals, but both methods result in around 10% REEs loss. Direct oxalate precipitation is suggested for the obtained leachate, which can yield over 97.5% REEs oxides with approximately 1.0% alumina, which is acceptable for magnet remanufacturing due to the aluminum content commonly found in magnets. The technology developed in this study offers opportunities for closed-loop recycling and remanufacturing of PMs, benefiting the environment, economy, and supply chain security.
{"title":"NdFeB Magnets Recycling via High-Pressure Selective Leaching and the Impurities Behaviors","authors":"Zhiming Yan, Zushu Li, Mingrui Yang, Wei Lv, Anwar Sattar","doi":"10.1007/s40831-024-00871-w","DOIUrl":"https://doi.org/10.1007/s40831-024-00871-w","url":null,"abstract":"<p>Global concerns about climate change are driving increased demand of electric vehicles for sustainable transportation and turbines in emerging energy solutions, where permanent magnets (PMs) and rare earth elements (REEs) play a critical role. However, global REEs recycling rates are only 3% and 8% for light and heavy REEs, respectively. This work proposes an effective approach to separate the REEs and iron via high-pressure selective leaching by low-concentrated nitric acid from the end-of-life NdFeB magnet and investigates the impurities behavior during the leaching and precipitation steps. The results from the optimized leaching conditions demonstrated over 95% REEs leaching efficiency with less than 0.3% Fe dissolution. Approximately 70% of Al and B were leached as well, while other elements (Co, Ni, Cu) had leaching efficiencies below 40%, leaving a hematite rich residue. Adjusting the pH removes Al and Fe in leachate but minimally affects Cu, Co, and Ni. Na<sub>2</sub>S addition is more effective against transition metals, but both methods result in around 10% REEs loss. Direct oxalate precipitation is suggested for the obtained leachate, which can yield over 97.5% REEs oxides with approximately 1.0% alumina, which is acceptable for magnet remanufacturing due to the aluminum content commonly found in magnets. The technology developed in this study offers opportunities for closed-loop recycling and remanufacturing of PMs, benefiting the environment, economy, and supply chain security.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"16 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-25DOI: 10.1007/s40831-024-00870-x
Jesse Franklin White, Luis Miguel López Renau, Björn Glaser
The chemical and thermophysical properties of carbon make it essentially irreplaceable for non-reductant uses in many high-temperature metallurgical processes. At present, biocarbon substitutes are not technically feasible for large-scale application in electrode and refractory materials that are such vital consumables in the steel, aluminum, and non-ferrous metal industries. Carbon electrodes of all types, including Söderberg, prebaked, and anodes/cathodes for Al, graphite electrodes, as well as carbon lining pastes are all similar in that they are comprised of a granular carbon aggregate bonded in a carbon-based binder matrix. Similarly, refractories such as MgO–C utilize both natural (mined) graphite and carbon-based binders. Replacement of fossil carbon materials with biocarbon substitutes has the potential to dramatically reduce the carbon footprints of these products. However, there are considerable materials engineering challenges that must be surmounted. The technological demands for these applications and potential for substitution with biogenic carbon are explored.
{"title":"A Review of Biocarbon Substitutes in Electrodes and Refractories for the Metallurgical Industries","authors":"Jesse Franklin White, Luis Miguel López Renau, Björn Glaser","doi":"10.1007/s40831-024-00870-x","DOIUrl":"https://doi.org/10.1007/s40831-024-00870-x","url":null,"abstract":"<p>The chemical and thermophysical properties of carbon make it essentially irreplaceable for non-reductant uses in many high-temperature metallurgical processes. At present, biocarbon substitutes are not technically feasible for large-scale application in electrode and refractory materials that are such vital consumables in the steel, aluminum, and non-ferrous metal industries. Carbon electrodes of all types, including Söderberg, prebaked, and anodes/cathodes for Al, graphite electrodes, as well as carbon lining pastes are all similar in that they are comprised of a granular carbon aggregate bonded in a carbon-based binder matrix. Similarly, refractories such as MgO–C utilize both natural (mined) graphite and carbon-based binders. Replacement of fossil carbon materials with biocarbon substitutes has the potential to dramatically reduce the carbon footprints of these products. However, there are considerable materials engineering challenges that must be surmounted. The technological demands for these applications and potential for substitution with biogenic carbon are explored.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"224 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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