Pub Date : 2024-05-17DOI: 10.1007/s40831-024-00844-z
L. Jiang, R. K. W. Marceau, T. Dorin
Recycled aluminum alloys are pivotal for sustainable manufacturing, offering strength, durability, and environmental advantages. However, the presence of iron (Fe) impurities poses a major challenge, undermining their properties and recyclability. Conventional manufacturing processes result in coarse Fe-rich intermetallic compounds that limit the tolerance of Fe content and negatively influence performance of advanced aluminum alloys. To address this, rapid solidification techniques like direct strip casting have been explored. In this work, a detailed study of the strip cast microstructure was conducted by scanning electron microscopy, electron backscattered diffraction and atom probe tomography. Our results reveal that alloys produced by direct strip casting exhibit significantly refined microstructures and are free from coarse Fe-rich intermetallics, thereby retaining the majority of Fe in solid solution. These findings indicate that strip casting significantly enhances Fe-tolerance in aluminum alloys, making it an attractive process for future aluminum recycling, with implications for sustainable high-performance applications.
{"title":"Improved Iron-Tolerance in Recycled Aluminum Alloys via Direct Strip Casting Process","authors":"L. Jiang, R. K. W. Marceau, T. Dorin","doi":"10.1007/s40831-024-00844-z","DOIUrl":"https://doi.org/10.1007/s40831-024-00844-z","url":null,"abstract":"<p>Recycled aluminum alloys are pivotal for sustainable manufacturing, offering strength, durability, and environmental advantages. However, the presence of iron (Fe) impurities poses a major challenge, undermining their properties and recyclability. Conventional manufacturing processes result in coarse Fe-rich intermetallic compounds that limit the tolerance of Fe content and negatively influence performance of advanced aluminum alloys. To address this, rapid solidification techniques like direct strip casting have been explored. In this work, a detailed study of the strip cast microstructure was conducted by scanning electron microscopy, electron backscattered diffraction and atom probe tomography. Our results reveal that alloys produced by direct strip casting exhibit significantly refined microstructures and are free from coarse Fe-rich intermetallics, thereby retaining the majority of Fe in solid solution. These findings indicate that strip casting significantly enhances Fe-tolerance in aluminum alloys, making it an attractive process for future aluminum recycling, with implications for sustainable high-performance applications.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"54 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141063083","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 : 2024-05-09DOI: 10.1007/s40831-024-00788-4
Yannan Wang, Min Gan, Xiaohui Fan, Zhiyun Ji, Wei Lv, Ganesh Pilla, Mingfeng Ye
In this study, a mixture rich in K, Na, and Pb, composed of undesired elements rich iron ore A, sinter dust, and blast furnace dust (ore-dust mix,), is sintered along with the regular iron ore. The K, Na, and Pb compounds within the ore-dust mix are identified as alkali chlorides, alkali aluminosilicates, PbO, and PbSO4 using X-ray diffraction. The primary objective is to investigate the impact of three distinct sintering technologies: regular (pre-reduction) sintering, double-layer sintering, and hearth-layer sintering, on the removal degrees of K, Na, and Pb. In both the regular and double-layer sintering processes, the K, Na, and Pb contents within the blend of raw materials was measured approximately 0.430 wt%, 0.105 wt%, and 0.033 wt%, respectively. Moreover, the ratio of ore-dust mix to the regular ore was 0.54. In the regular sinter pot test, sinter feed was uniformly placed in the pot. In the run of the regular sinter pot test with the optimal coke breeze ratio of 20 wt%, the removal degrees of K, Na, and Pb were 79.5%, 67.5% and 92.7%, respectively. In comparison, the double-layer sintering technology resulted in a slight increase in the removal degrees for alkali metals and a similar removal degree for Pb, while utilizing a reduced coke breeze ratio of only 8.10 wt%. The removal mechanism of the hearth-layer and double-layer sintering processes are similar. However, the coke breeze ratio decreases to 6.63 wt% as the fraction of ore-dust mix within the blend of raw materials is reduced to 7 wt% during the hearth-layer sintering process.
{"title":"Enhanced Removal of Potassium, Sodium, and Lead During the Iron Ore Sintering Process","authors":"Yannan Wang, Min Gan, Xiaohui Fan, Zhiyun Ji, Wei Lv, Ganesh Pilla, Mingfeng Ye","doi":"10.1007/s40831-024-00788-4","DOIUrl":"https://doi.org/10.1007/s40831-024-00788-4","url":null,"abstract":"<p>In this study, a mixture rich in K, Na, and Pb, composed of undesired elements rich iron ore A, sinter dust, and blast furnace dust (ore-dust mix,), is sintered along with the regular iron ore. The K, Na, and Pb compounds within the ore-dust mix are identified as alkali chlorides, alkali aluminosilicates, PbO, and PbSO<sub>4</sub> using X-ray diffraction. The primary objective is to investigate the impact of three distinct sintering technologies: regular (pre-reduction) sintering, double-layer sintering, and hearth-layer sintering, on the removal degrees of K, Na, and Pb. In both the regular and double-layer sintering processes, the K, Na, and Pb contents within the blend of raw materials was measured approximately 0.430 wt%, 0.105 wt%, and 0.033 wt%, respectively. Moreover, the ratio of ore-dust mix to the regular ore was 0.54. In the regular sinter pot test, sinter feed was uniformly placed in the pot. In the run of the regular sinter pot test with the optimal coke breeze ratio of 20 wt%, the removal degrees of K, Na, and Pb were 79.5%, 67.5% and 92.7%, respectively. In comparison, the double-layer sintering technology resulted in a slight increase in the removal degrees for alkali metals and a similar removal degree for Pb, while utilizing a reduced coke breeze ratio of only 8.10 wt%. The removal mechanism of the hearth-layer and double-layer sintering processes are similar. However, the coke breeze ratio decreases to 6.63 wt% as the fraction of ore-dust mix within the blend of raw materials is reduced to 7 wt% during the hearth-layer sintering process.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"155 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929214","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}
The reclamation of exhausted Fluid Catalytic Cracking (FCC) catalysts has attracted considerable interest. However, the leaching rates of valuable metals in waste can be influenced by the pretreatment and calcination process. This study focuses on investigating the impact of pretreatment temperature on the metal-leaching process of spent FCC catalysts. After calcination at 1200 °C, the Al2O3 carrier transformed from γ-Al2O3 to α-Al2O3 with a denser structure. Subsequently, the valuable metals react with the carrier to form regular acid salts, which are averse to the leaching process. While the pretreatment roasting of spent FCC catalysts at 600 °C could not only remove the surface impurities effectively but also keep the original γ-Al2O3 structure, promoting the leaching process. Finally, the kinetic model is studied with the aim of achieving the high-efficiency leaching of Ni in spent FCC catalysts. The leaching kinetics model of Ni accords with the ash diffusion model, and the reaction activation energy is 53.05 kJ/mol, in the temperature range of 60–90 °C, sulfuric acid concentration of 2 mol/L, particle size of less than 200 mesh (75μm). Specifically, for spent FCC catalysts, pretreatment at high temperatures is not conducive to subsequent leaching, while pretreatment at low temperatures is conducive to subsequent leaching of valuable metals.
Graphical Abstract
流化催化裂化（FCC）催化剂用完后的回收利用引起了人们的极大兴趣。然而，废料中有价金属的浸出率会受到预处理和煅烧过程的影响。本研究主要探讨预处理温度对催化裂化废催化剂金属浸出过程的影响。在 1200 °C 煅烧后，Al2O3 载体从 γ-Al2O3 转变为结构更致密的 α-Al2O3。随后，有价金属会与载体发生反应，形成对浸出过程不利的常规酸盐。而对废催化裂化催化剂进行 600 °C 的预处理焙烧，不仅能有效去除表面杂质，还能保持原有的 γ-Al2O3 结构，促进浸出过程。最后，研究了动力学模型，以期实现废催化裂化催化剂中 Ni 的高效浸出。镍的浸出动力学模型符合灰扩散模型，在温度为 60-90 ℃、硫酸浓度为 2 mol/L、粒度小于 200 目（75μm）的条件下，反应活化能为 53.05 kJ/mol。具体而言，对于催化裂化废催化剂，高温预处理不利于后续浸出，而低温预处理则有利于后续有价金属的浸出。
{"title":"Study on Pretreatment and Leaching Behaviors of Spent Fluid Catalytic Cracking Catalysts","authors":"Mingshuai Wu, Wenbo Cheng, Fengshan Yu, Maolin Tian, Xueli Wang, Yongjie Bu, Jiawei Wen, Guoyong Huang","doi":"10.1007/s40831-024-00831-4","DOIUrl":"https://doi.org/10.1007/s40831-024-00831-4","url":null,"abstract":"<p>The reclamation of exhausted Fluid Catalytic Cracking (FCC) catalysts has attracted considerable interest. However, the leaching rates of valuable metals in waste can be influenced by the pretreatment and calcination process. This study focuses on investigating the impact of pretreatment temperature on the metal-leaching process of spent FCC catalysts. After calcination at 1200 °C, the Al<sub>2</sub>O<sub>3</sub> carrier transformed from γ-Al<sub>2</sub>O<sub>3</sub> to α-Al<sub>2</sub>O<sub>3</sub> with a denser structure. Subsequently, the valuable metals react with the carrier to form regular acid salts, which are averse to the leaching process. While the pretreatment roasting of spent FCC catalysts at 600 °C could not only remove the surface impurities effectively but also keep the original γ-Al<sub>2</sub>O<sub>3</sub> structure, promoting the leaching process. Finally, the kinetic model is studied with the aim of achieving the high-efficiency leaching of Ni in spent FCC catalysts. The leaching kinetics model of Ni accords with the ash diffusion model, and the reaction activation energy is 53.05 kJ/mol, in the temperature range of 60–90 °C, sulfuric acid concentration of 2 mol/L, particle size of less than 200 mesh (75μm). Specifically, for spent FCC catalysts, pretreatment at high temperatures is not conducive to subsequent leaching, while pretreatment at low temperatures is conducive to subsequent leaching of valuable metals.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"22 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929382","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 : 2024-05-08DOI: 10.1007/s40831-024-00834-1
Mustapha A. Raji, Alafara A. Baba, Abhilash, Ajeet Gangwar, Jude O. Majasan
The continuous rise of the population cum standard of living has resulted in Nigerians looking for a profound solution to the fast-growing demand for electrical energy with sustainability concerns including greenhouse gas emissions limitation. Thus, the investigation of uranium leaching kinetics and thermodynamics has become one of the most crucial topics in leach technology, where many distinct results have been obtained. In this study, the influence of sulfuric acid concentration, reaction temperature, solid-to-liquid ratio, and leaching time were all investigated. At established experimental conditions (2.5 mol/L H2SO4, 75 °C, 75 µm), the uranium ore dissolution efficiency recorded was 89.1% within 120 min. The kinetic and thermodynamic tests of the leaching process coupled with the reaction mechanism between sulfuric acid and uranium were discussed. Hence, the results confirm that the dissolution mechanism of uranium was diffusion controlled, exothermic, and spontaneous.
{"title":"Optimization of the Leaching Kinetics for Uranium Recovery from a Boltwoodite Ore as Emerging Solution to Nigerian Power Sector","authors":"Mustapha A. Raji, Alafara A. Baba, Abhilash, Ajeet Gangwar, Jude O. Majasan","doi":"10.1007/s40831-024-00834-1","DOIUrl":"https://doi.org/10.1007/s40831-024-00834-1","url":null,"abstract":"<p>The continuous rise of the population <i>cum</i> standard of living has resulted in Nigerians looking for a profound solution to the fast-growing demand for electrical energy with sustainability concerns including greenhouse gas emissions limitation. Thus, the investigation of uranium leaching kinetics and thermodynamics has become one of the most crucial topics in leach technology, where many distinct results have been obtained. In this study, the influence of sulfuric acid concentration, reaction temperature, solid-to-liquid ratio, and leaching time were all investigated. At established experimental conditions (2.5 mol/L H<sub>2</sub>SO<sub>4</sub>, 75 °C, 75 µm), the uranium ore dissolution efficiency recorded was 89.1% within 120 min. The kinetic and thermodynamic tests of the leaching process coupled with the reaction mechanism between sulfuric acid and uranium were discussed. Hence, the results confirm that the dissolution mechanism of uranium was diffusion controlled, exothermic, and spontaneous.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"128 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929097","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}
Rapid development of the fluorine industry has led to mass production of fluorine-containing waste, and direct discharge of this waste will cause serious environmental pollution of water, atmosphere, soil, and so on. Recycling and treatment of fluorine-containing waste are required for environmental protection and to utilize the fluorine resources. Because of decreases in fluorite reserves and inefficient fluorine resource recovery, cryolite has become a potential resource for fluorine recovery. This paper summarizes research on the preparation of cryolite from fluorine-containing substances produced in various industries, mechanisms of contamination under different conditions, and commonly used methods for controlling the product particle size. The results indicate that cryolite prepared in acidic or weakly alkaline solutions with a fluorine–aluminum molar ratio of 5.4–6.6 has high purity. The particle size of the cryolite increases with the addition of a seed during precipitation. This review provides insight for future production of cryolite with regard to purity problems and particle size control.
{"title":"Review on the Preparation of Cryolite from Industry Waste Containing Fluorine","authors":"Xiaomeng Cao, Jianping Peng, Wenxiong Dong, Yifei Li, Yaowu Wang, Yuezhong Di","doi":"10.1007/s40831-024-00835-0","DOIUrl":"https://doi.org/10.1007/s40831-024-00835-0","url":null,"abstract":"<p>Rapid development of the fluorine industry has led to mass production of fluorine-containing waste, and direct discharge of this waste will cause serious environmental pollution of water, atmosphere, soil, and so on. Recycling and treatment of fluorine-containing waste are required for environmental protection and to utilize the fluorine resources. Because of decreases in fluorite reserves and inefficient fluorine resource recovery, cryolite has become a potential resource for fluorine recovery. This paper summarizes research on the preparation of cryolite from fluorine-containing substances produced in various industries, mechanisms of contamination under different conditions, and commonly used methods for controlling the product particle size. The results indicate that cryolite prepared in acidic or weakly alkaline solutions with a fluorine–aluminum molar ratio of 5.4–6.6 has high purity. The particle size of the cryolite increases with the addition of a seed during precipitation. This review provides insight for future production of cryolite with regard to purity problems and particle size control.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"21 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929105","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 : 2024-05-08DOI: 10.1007/s40831-024-00836-z
Han Zhang, Ke Liu, Hongxin Zhao, Yue Tian, Jianye Liang, Zhangfu Yuan
The innovative slag splashing technology can significantly reduce CO2 emissions in the steel industry. However, conventional oxygen lances are no longer sufficient due to the gas-slag reactions involved. Hence, the feasibility of applying nozzle-twisted oxygen lances to the innovative slag splashing process was investigated in this work. Numerical simulation was employed to compare the CO2 jet, its impact characteristics on the slag, and the slag splashing performance of both the nozzle-twisted and conventional oxygen lances. It was found that the nozzle-twisted jet has higher radial and tangential velocities and a more significant impact region compared with the conventional jet. Furthermore, it exhibited superior stirring capability for the melt pool, enhancing the average velocity of the slag and reducing the size of dead zones. This facilitated the mixing of carbon powder and the interfacial reaction between CO2 and the slag. However, the slag splashing performance deteriorated after the oxygen lance was replaced. Fortunately, the slag still reached the vicinity of the slag line. Furthermore, the addition of bottom blowing compensated for the disadvantages, elevating the slag mass flow rate and further enhancing the stirring of the slag. Therefore, utilizing nozzle-twisted oxygen lances is feasible in this scenario.
{"title":"Numerical Simulation of Innovative Slag Splashing Process in a Converter Using a Nozzle-Twisted Oxygen Lance","authors":"Han Zhang, Ke Liu, Hongxin Zhao, Yue Tian, Jianye Liang, Zhangfu Yuan","doi":"10.1007/s40831-024-00836-z","DOIUrl":"https://doi.org/10.1007/s40831-024-00836-z","url":null,"abstract":"<p>The innovative slag splashing technology can significantly reduce CO<sub>2</sub> emissions in the steel industry. However, conventional oxygen lances are no longer sufficient due to the gas-slag reactions involved. Hence, the feasibility of applying nozzle-twisted oxygen lances to the innovative slag splashing process was investigated in this work. Numerical simulation was employed to compare the CO<sub>2</sub> jet, its impact characteristics on the slag, and the slag splashing performance of both the nozzle-twisted and conventional oxygen lances. It was found that the nozzle-twisted jet has higher radial and tangential velocities and a more significant impact region compared with the conventional jet. Furthermore, it exhibited superior stirring capability for the melt pool, enhancing the average velocity of the slag and reducing the size of dead zones. This facilitated the mixing of carbon powder and the interfacial reaction between CO<sub>2</sub> and the slag. However, the slag splashing performance deteriorated after the oxygen lance was replaced. Fortunately, the slag still reached the vicinity of the slag line. Furthermore, the addition of bottom blowing compensated for the disadvantages, elevating the slag mass flow rate and further enhancing the stirring of the slag. Therefore, utilizing nozzle-twisted oxygen lances is feasible in this scenario.</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":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929386","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}
The global annual industrial waste production is enormous, influencing the environmental parameters affecting the whole universe. Due to rapid industrialization, cement production is increasing to meet the demand of the construction industries, harming the atmosphere and prompting scarcity of natural resources. Thus, the need for a supplementary cementitious material is essential, replacing cement either partially or completely. In the current investigation, red mud, which has some cementitious and hydraulic characteristics, is being utilized as a supplementary cementitious material and is used as a partial replacement to cement in concrete production at different percentage levels like 0% (the control concrete), 5%, 10%, 15%, 20%, and 25% with an intension to establish the optimal replacement level established on various fresh and hardened concrete characteristics. All workable mixes are subjected to physical tests (density measurement), mechanical tests (ultrasonic pulse velocity test, rebound hammer test, compressive and tensile strength test), and durability tests (acid resistance test, sulfate resistance test, and chloride resistance test). The discussions on the concrete characterization variations can be substantiated through various microstructure level tests like scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD) tests. The detailed characterization tests mutually confirmed that the optimal red mud replacement level in conventional concrete is evaluated to be 15%, leading to a sustainable production evolving reasonable waste management.
Graphical Abstract
全球每年产生的工业废物数量巨大，影响着整个宇宙的环境参数。随着工业化进程的加快，水泥产量不断增加，以满足建筑业的需求，这不仅破坏了大气环境，而且导致自然资源匮乏。因此，需要一种补充胶凝材料来部分或完全替代水泥。在当前的研究中，具有一定胶凝和水力特性的赤泥被用作一种补充胶凝材料，并在混凝土生产中以不同的百分比水平部分替代水泥，如 0%（对照混凝土）、5%、10%、15%、20% 和 25%，目的是根据各种新拌和硬化混凝土的特性确定最佳替代水平。所有可施工混合料都要经过物理测试（密度测定）、机械测试（超声波脉冲速度测试、回弹锤测试、抗压和抗拉强度测试）和耐久性测试（耐酸测试、耐硫酸盐测试和耐氯化物测试）。通过各种微观结构测试，如扫描电子显微镜（SEM）、能量色散 X 射线光谱（EDX）和 X 射线衍射分析（XRD）测试，对混凝土特性变化的讨论得到了证实。详细的表征测试相互证实，传统混凝土中最佳的赤泥替代水平被评估为 15%，从而实现了可持续生产和合理的废物管理。
{"title":"Optimal Red Mud Replacement Level Evaluation in Conventional Concrete Based on Fresh and Hardened Concrete Characteristics","authors":"Soumyaranjan Panda, Monalin Pradhan, Saubhagya Kumar Panigrahi","doi":"10.1007/s40831-024-00837-y","DOIUrl":"https://doi.org/10.1007/s40831-024-00837-y","url":null,"abstract":"<p>The global annual industrial waste production is enormous, influencing the environmental parameters affecting the whole universe. Due to rapid industrialization, cement production is increasing to meet the demand of the construction industries, harming the atmosphere and prompting scarcity of natural resources. Thus, the need for a supplementary cementitious material is essential, replacing cement either partially or completely. In the current investigation, red mud, which has some cementitious and hydraulic characteristics, is being utilized as a supplementary cementitious material and is used as a partial replacement to cement in concrete production at different percentage levels like 0% (the control concrete), 5%, 10%, 15%, 20%, and 25% with an intension to establish the optimal replacement level established on various fresh and hardened concrete characteristics. All workable mixes are subjected to physical tests (density measurement), mechanical tests (ultrasonic pulse velocity test, rebound hammer test, compressive and tensile strength test), and durability tests (acid resistance test, sulfate resistance test, and chloride resistance test). The discussions on the concrete characterization variations can be substantiated through various microstructure level tests like scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD) tests. The detailed characterization tests mutually confirmed that the optimal red mud replacement level in conventional concrete is evaluated to be 15%, leading to a sustainable production evolving reasonable waste management.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"32 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929098","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}
Recovering fluoride from industrial alkaline solutions will benefit the environmental protection and improve product quality. This paper presented a novel approach to fluoride recovery by precipitating the coarse NaF from sodium aluminate solution. The equilibrium concentration of fluoride ion in the sodium aluminate solution was first presented as a function of caustic soda concentration and temperature. Coarse NaF and high NaF precipitation efficiency were obtained by the fine particle agglomeration under conditions of inhomogeneously distributed at weak agitation (IDWA) and the addition of activated seeds. Based on particle number calculated from the particle size distribution curves, the agglomeration rate was linearly dependent on the supersaturation of NaF in sodium aluminate solution. The agglomeration mechanism was described by the fresh ultrafine particles acting as a “binder” to agglomerate the fine particles (< 10 μm) into the coarse particles (> 30 μm). Therefore, 91.15% precipitation efficiency of NaF was achieved by adding the activated seeds, adopting the special schedule of decreasing temperature, and regulating the supersaturation under IDWA. Furthermore, about 65 μm NaF with more than 98% purity was received. These results provide a novel approach for recovering NaF from the sodium aluminate solution and benefit the green development of the alumina industry.
{"title":"Seeded Precipitation of the Coarse Sodium Fluoride with High Purity for Efficient Removal of Fluoride Ion from Sodium Aluminate Solutions","authors":"Jie Tang, Guihua Liu, Tiangui Qi, Qiusheng Zhou, Zhihong Peng, Xiaobin Li, Yilin Wang, Leiting Shen","doi":"10.1007/s40831-024-00833-2","DOIUrl":"https://doi.org/10.1007/s40831-024-00833-2","url":null,"abstract":"<p>Recovering fluoride from industrial alkaline solutions will benefit the environmental protection and improve product quality. This paper presented a novel approach to fluoride recovery by precipitating the coarse NaF from sodium aluminate solution. The equilibrium concentration of fluoride ion in the sodium aluminate solution was first presented as a function of caustic soda concentration and temperature. Coarse NaF and high NaF precipitation efficiency were obtained by the fine particle agglomeration under conditions of inhomogeneously distributed at weak agitation (IDWA) and the addition of activated seeds. Based on particle number calculated from the particle size distribution curves, the agglomeration rate was linearly dependent on the supersaturation of NaF in sodium aluminate solution. The agglomeration mechanism was described by the fresh ultrafine particles acting as a “binder” to agglomerate the fine particles (< 10 μm) into the coarse particles (> 30 μm). Therefore, 91.15% precipitation efficiency of NaF was achieved by adding the activated seeds, adopting the special schedule of decreasing temperature, and regulating the supersaturation under IDWA. Furthermore, about 65 μm NaF with more than 98% purity was received. These results provide a novel approach for recovering NaF from the sodium aluminate solution and benefit the green development of the alumina industry.</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":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929402","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 : 2024-05-06DOI: 10.1007/s40831-024-00829-y
I. Adhiwiguna, K. Vellayadevan, Y. Tekneci, M. Walz, D. Algermissen, R. Deike
This study comprehensively assesses the ecotechnological consideration and perspective of implementing a lime-based desulfurization process in the cast iron industry to replace the utilization of magnesium partially. By adopting an injection process to introduce the lime powder into molten cast iron, this research elucidated that the new alternative concept can successfully be integrated with daily operations without any disparities in cast iron quality, as proved by the production of cast iron products with vermicular graphite. A mixture of lime powder and carbon was utilized, and it was substantiated that the aim of a sulfur content lower than 0.015% can be reliably achieved. Furthermore, an ecological analysis was also conducted to justify the possible environmental advantages. The results indicated that considering the cradle-to-gate approach, the maximum amount of CO2eq connected to the lime-based desulfurization is approximately 43 g for 1 kg of desulfurized cast iron. This amount of calculated emission is still expected to be lower than the minimum calculated emission associated with the magnesium-based process, which can reach an amount of 76 g for a similar functional unit.
{"title":"Industrial Ecotechnological Assessment of Lime as a Sustainable Substitute for Desulfurization of Cast Iron","authors":"I. Adhiwiguna, K. Vellayadevan, Y. Tekneci, M. Walz, D. Algermissen, R. Deike","doi":"10.1007/s40831-024-00829-y","DOIUrl":"https://doi.org/10.1007/s40831-024-00829-y","url":null,"abstract":"<p>This study comprehensively assesses the ecotechnological consideration and perspective of implementing a lime-based desulfurization process in the cast iron industry to replace the utilization of magnesium partially. By adopting an injection process to introduce the lime powder into molten cast iron, this research elucidated that the new alternative concept can successfully be integrated with daily operations without any disparities in cast iron quality, as proved by the production of cast iron products with vermicular graphite. A mixture of lime powder and carbon was utilized, and it was substantiated that the aim of a sulfur content lower than 0.015% can be reliably achieved. Furthermore, an ecological analysis was also conducted to justify the possible environmental advantages. The results indicated that considering the cradle-to-gate approach, the maximum amount of CO<sub>2</sub>eq connected to the lime-based desulfurization is approximately 43 g for 1 kg of desulfurized cast iron. This amount of calculated emission is still expected to be lower than the minimum calculated emission associated with the magnesium-based process, which can reach an amount of 76 g for a similar functional unit.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"37 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929301","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}
The utilization of coal fly ash has been of great concern in recent years due to the growing awareness of waste recycling and environmental protection. Alumina recycling from coal fly ash is a good path to realize the state-of-the-art utilization of coal fly ash. The present work proposes a novel strategy for recovering alumina and producing Fe–Si alloy from coal fly ash employing Na2SO4 as the additive. The enhancing mechanism of the Na2SO4 addition on the mullite (Al6Si2O13) decomposition and alumina extraction during vacuum carbothermic reduction of coal fly ash was systematically investigated. The thermodynamic calculation results show that the theoretical decomposition temperature of mullite can be decreased from 1048 to 683 K with the assistance of Na2SO4, which means that the addition of Na2SO4 can effectively eliminate the mullite phase. Furthermore, the aggregation of Fe–Si alloy particles was enhanced efficiently in the presence of Na2SO4, which was proved to be conducive to the alumina and Fe–Si alloy separation in the subsequent magnetic separation process. As the Na2SO4 addition amounts changed from 0 to 12 wt% at 1423 K for 4 h, the average size of the Fe–Si alloys particle exhibited an enlargement from 21.39 to 39.94 μm, by which the recovery efficiency of alumina increased from 61.03 to 75.26% correspondingly.
{"title":"The Enhancing Mechanism of Na2SO4 on Mullite Decomposition and Alumina Recovery During the Vacuum Carbothermic Reduction of Coal Fly Ash","authors":"Joseph Emmanuel Nyarko-Appiah, Wenzhou Yu, Lanjiang Song, Peng Wei, Hao Chen","doi":"10.1007/s40831-024-00832-3","DOIUrl":"https://doi.org/10.1007/s40831-024-00832-3","url":null,"abstract":"<p>The utilization of coal fly ash has been of great concern in recent years due to the growing awareness of waste recycling and environmental protection. Alumina recycling from coal fly ash is a good path to realize the state-of-the-art utilization of coal fly ash. The present work proposes a novel strategy for recovering alumina and producing Fe–Si alloy from coal fly ash employing Na<sub>2</sub>SO<sub>4</sub> as the additive. The enhancing mechanism of the Na<sub>2</sub>SO<sub>4</sub> addition on the mullite (Al<sub>6</sub>Si<sub>2</sub>O<sub>13</sub>) decomposition and alumina extraction during vacuum carbothermic reduction of coal fly ash was systematically investigated. The thermodynamic calculation results show that the theoretical decomposition temperature of mullite can be decreased from 1048 to 683 K with the assistance of Na<sub>2</sub>SO<sub>4</sub>, which means that the addition of Na<sub>2</sub>SO<sub>4</sub> can effectively eliminate the mullite phase. Furthermore, the aggregation of Fe–Si alloy particles was enhanced efficiently in the presence of Na<sub>2</sub>SO<sub>4</sub>, which was proved to be conducive to the alumina and Fe–Si alloy separation in the subsequent magnetic separation process. As the Na<sub>2</sub>SO<sub>4</sub> addition amounts changed from 0 to 12 wt% at 1423 K for 4 h, the average size of the Fe–Si alloys particle exhibited an enlargement from 21.39 to 39.94 μm, by which the recovery efficiency of alumina increased from 61.03 to 75.26% correspondingly.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\u0000","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":"4 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929314","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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