Materials

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14 pages, 4828 KiB

Open AccessArticle

Arsenic Removal and Iron Recovery from Arsenic-Bearing Iron Ores by Calcification-Magnetic Roasting and Magnetic Separation Process

by Mengbo Dai, Yongcheng Zhou, Qingfei Xiao, Jinfang Lv, Lingyun Huang, Xian Xie, Yiming Hu, Xiong Tong and Tiejun Chun

Materials 2023, 16(21), 6884; https://doi.org/10.3390/ma16216884 - 26 Oct 2023

Viewed by 970

Abstract

Extracting iron while minimizing the health and environmental risks associated with arsenic contamination necessitates the removal of arsenic from arsenic-bearing iron ores to ensure a safe and sustainable supply of this metal for industries. The beneficiation of iron minerals and arsenic-bearing minerals from [...] Read more.

Extracting iron while minimizing the health and environmental risks associated with arsenic contamination necessitates the removal of arsenic from arsenic-bearing iron ores to ensure a safe and sustainable supply of this metal for industries. The beneficiation of iron minerals and arsenic-bearing minerals from arsenic-bearing iron ores with a calcification-magnetizing roasting and low-intensity magnetic separation (CMR-LMS) process is investigated in this work. The results show that the process is successful in extracting iron minerals and eliminating arsenic-containing minerals. The roasting involves two key steps: calcification and magnetizing, which change hematite and goethite into magnetite and arsenic-bearing minerals into calcium arsenates. The process’s separation efficiency of the CMR-LMS is closely linked to the parameters such as roasting temperature, roasting time, coke, alkalinity, and the liberation of gangue minerals from iron minerals. Through grinding and secondary magnetic separation, the iron minerals and gangue components, as well as arsenic, in roasted sand can be further separated. The optimum procedure results in a high-grade iron concentrate with an iron assay of 65.65%, an Fe recovery rate of 80.07%, and an arsenic content of 0.085%, while achieving a 93.29% As removal rate from the original ore that has 45.32% Fe and 0.70% As. Full article

(This article belongs to the Special Issue Frontier of Environmental Friendly Recycling Technology for Metals)

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16 pages, 8753 KiB

Open AccessArticle

Study on Magnetization Roasting Kinetics of High-Iron and Low-Silicon Red Mud

by Lei Xie, Jiao Hao, Chaojie Hu and Hanquan Zhang

Materials 2023, 16(18), 6178; https://doi.org/10.3390/ma16186178 - 12 Sep 2023

Viewed by 795

Abstract

High-iron and low-silicon red mud is not only an alkaline solid waste from Bayer process alumina production, but it is also a very important secondary iron resource. Magnetization roasting is considered as an effective and typical method for the iron recovery and removal [...] Read more.

High-iron and low-silicon red mud is not only an alkaline solid waste from Bayer process alumina production, but it is also a very important secondary iron resource. Magnetization roasting is considered as an effective and typical method for the iron recovery and removal of impurities in red mud. In this work, based on the characteristics of large specific surface area and high porosity of red mud, the kinetics of magnetization roasting and phase transformation of red mud were studied. Thermodynamic analysis results show that the reduction of iron oxide in red mud is more easily promoted by CO as reducing agent at low roasting temperature. The reduction reaction is prone to overreduction, and fayalite and ferrospinel can be formed in the reaction system. The phase transformation and iron reduction mechanism during the roasting process were evaluated. Most of hematite and goethite in the red mud decomposed in the process of magnetization roasting, released CO₂, and transformed into strongly magnetic magnetite. The reaction process has some characteristics controlled by homogeneous reaction. The process of magnetization roasting reduction with CO was controlled by the hybrid control dynamics model, and the apparent activation energy was 38.31 kJ·mol⁻¹. Full article

(This article belongs to the Special Issue Frontier of Environmental Friendly Recycling Technology for Metals)

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16 pages, 14010 KiB

Open AccessArticle

Mineral Phase Reconstruction and Separation Behavior of Zinc and Iron from Zinc-Containing Dust

by Zeqiang Xie, Guang Li, Yufeng Guo, Shuai Wang, Feng Chen, Lingzhi Yang, Ganghua Fu and Tao Jiang

Materials 2023, 16(9), 3481; https://doi.org/10.3390/ma16093481 - 30 Apr 2023

Cited by 3 | Viewed by 1186

Abstract

Zinc-containing dust can be found in ironmaking and steelmaking, and it is an important secondary resource of zinc. Zinc-containing dust from an electric furnace was used as a raw material to study the phase transformation behavior of the dust using a calcification roasting [...] Read more.

Zinc-containing dust can be found in ironmaking and steelmaking, and it is an important secondary resource of zinc. Zinc-containing dust from an electric furnace was used as a raw material to study the phase transformation behavior of the dust using a calcification roasting process and the zinc–iron separation behavior by using ammonia leaching. The zinc-bearing dust was mixed with CaO and roasted to transform the zinc ferrite into zinc oxide. The results showed that increasing the calcium oxide to dust ratio could promote the conversion of zinc ferrite to zinc oxide. When the calcium oxide ratio reached 60%, the peak of zinc ferrite in the calcined-roasted product in the zinc-containing dust basically disappeared. As the temperature increased, the zinc oxide grains increased but were still smaller than 10 µm. The calcined-roasted product was crushed and ground, and the zinc was leached by ammonia. A zinc–iron recovery rate of 86.12% was achieved by the ammonia leaching. The leachate could be used for zinc extraction by electrolysis. The leaching residue was mainly calcium ferrate, which could be used in sintering production. The proposed process may achieve on-site recovery of zinc-containing dust in steel-making plants. Full article

(This article belongs to the Special Issue Frontier of Environmental Friendly Recycling Technology for Metals)

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14 pages, 4811 KiB

Open AccessArticle

Achieving Large-Capability Adsorption of Hg⁰ in Wet Scrubbing by Defect-Rich Colloidal Copper Sulfides under High-SO₂ Atmosphere

by Xiaofeng Xie, Hao Chen, Xudong Liu, Kaisong Xiang and Hui Liu

Materials 2023, 16(8), 3157; https://doi.org/10.3390/ma16083157 - 17 Apr 2023

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Abstract

This paper reports on a novel method to remove Hg⁰ in the wet scrubbing process using defect-rich colloidal copper sulfides for reducing mercury emissions from non-ferrous smelting flue gas. Unexpectedly, it migrated the negative effect of SO₂ on mercury removal performance, [...] Read more.

This paper reports on a novel method to remove Hg⁰ in the wet scrubbing process using defect-rich colloidal copper sulfides for reducing mercury emissions from non-ferrous smelting flue gas. Unexpectedly, it migrated the negative effect of SO₂ on mercury removal performance, while also enhancing Hg⁰ adsorption. Colloidal copper sulfides demonstrated the superior Hg⁰ adsorption rate of 306.9 μg·g⁻¹·min⁻¹ under 6% SO₂ + 6% O₂ atmosphere with a removal efficiency of 99.1%, and the highest-ever Hg⁰ adsorption capacity of 736.5 mg·g⁻¹, which was 277% higher than all other reported metal sulfides. The Cu and S sites transformation results reveal that SO₂ could transform the tri-coordinate S sites into S₂²⁻ on copper sulfides surfaces, while O₂ regenerated Cu²⁺ via the oxidation of Cu⁺. The S₂²⁻ and Cu²⁺ sites enhanced Hg⁰ oxidation, and the Hg²⁺ could strongly bind with tri-coordinate S sites. This study provides an effective strategy to achieve large-capability adsorption of Hg⁰ from non-ferrous smelting flue gas. Full article

(This article belongs to the Special Issue Frontier of Environmental Friendly Recycling Technology for Metals)

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11 pages, 2240 KiB

Open AccessArticle

Removal of Sodium from Vanadium Tailings by Calcification Roasting in Reducing Atmosphere

by Chao Wang, Yufeng Guo, Shuai Wang, Feng Chen, Lingzhi Yang and Yu Zheng

Materials 2023, 16(3), 986; https://doi.org/10.3390/ma16030986 - 20 Jan 2023

Cited by 1 | Viewed by 1031

Abstract

Vanadium tailings from vanadium extraction by a sodium roasting process are solid waste and cannot be used in sintering and ironmaking due to their high sodium content. In this paper, a calcification and reduction roasting process was proposed to remove sodium from vanadium [...] Read more.

Vanadium tailings from vanadium extraction by a sodium roasting process are solid waste and cannot be used in sintering and ironmaking due to their high sodium content. In this paper, a calcification and reduction roasting process was proposed to remove sodium from vanadium tailings. The effects of Ca(OH)₂ addition, reduction temperature, and roasting time on the sodium removal behavior and compression strength of pellets were studied. The addition of Ca(OH)₂ and the reduction of iron oxides promoted the sodium-containing phases to transform to be simpler, which could enhance sodium removal. The sodium removal rate was up to 93.47% and the compression strength of the reduced products was 4497 N/P, and the metallized ratio of the product was higher than 70% under the optimal conditions: roasting at 1200 °C for 2 h with the Ca(OH)₂ addition of 35%. The treated product after removing sodium can be recycled in the ironmaking process in a steel company. Full article

(This article belongs to the Special Issue Frontier of Environmental Friendly Recycling Technology for Metals)

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14 pages, 5715 KiB

Open AccessArticle

A Novel Technique for the Preparation of Iron Carbide and Carbon Concentrate from Blast Furnace Dust

by Dong Chen, Hongwei Guo, Peng Li, Feibao Wu, Yanan Lv, Bingji Yan, Wei Zhao and Yifan Su

Materials 2022, 15(22), 8241; https://doi.org/10.3390/ma15228241 - 20 Nov 2022

Cited by 1 | Viewed by 1358

Abstract

Blast furnace (BF) dust is a typical refractory iron resource. A novel technology-based utilization of BF dust as iron carbide and carbon concentrate by applying carburization roasting followed by magnetic separation and acid leaching is proposed. Under optimized conditions, an electric arc furnace [...] Read more.

Blast furnace (BF) dust is a typical refractory iron resource. A novel technology-based utilization of BF dust as iron carbide and carbon concentrate by applying carburization roasting followed by magnetic separation and acid leaching is proposed. Under optimized conditions, an electric arc furnace (EAF) burden assaying 80.79% Fe and 7.63% C with a corresponding iron recovery rate of 87.26% and a carbon concentrate assaying 67.06% C with a corresponding carbon recovery rate of 81.23% were prepared. Furthermore, the carburization behavior and separation mechanism were revealed using X-ray powder diffraction, scanning electron microscopy, and optical microscopy. The results show that the separation efficiency of iron carbide, gangue, and carbon is very low. Na₂SO₄ is a highly effective additive to strengthen the separation efficiency as it can enhance the carburization index, enlarge the iron carbide particle size, improve the embed embedded relationship of iron carbide and gangue, and promote the gangue leaching efficiency. The study demonstrates that preparation of iron carbide and carbon concentrate from BF dust using the proposed technology is a feasible method. Full article

(This article belongs to the Special Issue Frontier of Environmental Friendly Recycling Technology for Metals)

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14 pages, 3332 KiB

Open AccessArticle

Use of Hydrogen–Rich Gas in Blast Furnace Ironmaking of V–bearing Titanomagnetite: Mass and Energy Balance Calculations

by Xudong Gao, Run Zhang, Zhixiong You, Wenzhou Yu, Jie Dang and Chenguang Bai

Materials 2022, 15(17), 6078; https://doi.org/10.3390/ma15176078 - 1 Sep 2022

Cited by 4 | Viewed by 1638

Abstract

The iron and steel industry is a major CO₂ emitter and an important subject for the implementation of carbon emission reduction goals and tasks. Due to the complex ore composition and low iron grade, vanadium–bearing titanomagnetite smelting in a blast furnace consumes [...] Read more.

The iron and steel industry is a major CO₂ emitter and an important subject for the implementation of carbon emission reduction goals and tasks. Due to the complex ore composition and low iron grade, vanadium–bearing titanomagnetite smelting in a blast furnace consumes more coke and emits more carbon than in an ordinary blast furnace. Injecting hydrogen–rich gas into blast furnace can not only partially replace coke, but also reduce the carbon emission. Based on the whole furnace and zonal energy and mass balance of blast furnace, the operation window of the blast furnace smelting vanadium–bearing titanomagnetite is established in this study on the premise that the thermal state of the blast furnace is basically unchanged (raceway adiabatic flame temperature and top gas temperature). The effects of different injection amounts of hydrogen–rich gases (shale gas, coke oven gas, and hydrogen) on raceway adiabatic flame temperature and top gas temperature, and the influence of blast temperature and preheating temperature of hydrogen–rich gases on operation window are calculated and analyzed. This study provides a certain theoretical reference for the follow–up practice of hydrogen–rich smelting of vanadium–bearing titanomagnetite in blast furnace. Full article

(This article belongs to the Special Issue Frontier of Environmental Friendly Recycling Technology for Metals)

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10 pages, 3628 KiB

Open AccessArticle

A New Process of Direct Zinc Oxide Production by Carbothermal Reduction of Zinc Ash

by Jianjun Gao, Hong Wang, Jie Wang, Yingyi Zhang, Feng Wang, Shuang Yang and Shinan Li

Materials 2022, 15(15), 5246; https://doi.org/10.3390/ma15155246 - 29 Jul 2022

Cited by 5 | Viewed by 1925

Abstract

Zinc ash is a by-product of the hot-dip galvanizing process and the electrolytic zinc process, which is classified as a hazardous waste consisting predominately of zinc oxide that could be recovered as the useful main resource for ZnO preparation. In this work, in [...] Read more.

Zinc ash is a by-product of the hot-dip galvanizing process and the electrolytic zinc process, which is classified as a hazardous waste consisting predominately of zinc oxide that could be recovered as the useful main resource for ZnO preparation. In this work, in order to reduce the energy consumption of the direct reduction process and improve the resource-recovery rate. A new technology for zinc oxide production, by a carbothermal reduction of zinc ash, is proposed. This process includes two steps: high-temperature roasting of zinc ash for dechlorination and a carbothermal reduction of dechlorination ash. Zn in zinc ash is mainly presented in the form of zinc oxide (ZnO), basic zinc chloride (Zn₅(OH)₈Cl₂H₂O), and metallic zinc (Zn). Basic zinc chloride can be roasted and decomposed to reduce the chlorine content in zinc ash. The results of a chloride ion removal test show that the optimal roasting temperature is 1000 °C, with a holding time of 60 min. Under the modified conditions, the chloride content in the roasted zinc ash is reduced to 0.021 wt.%, and the dechlorination rate is more than 99.5%, which can meet the requirements of zinc oxide production. The best process conditions for zinc oxide production by carbothermic reduction are as follows: reduction temperature of 1250 °C, reduction time of 60 min, and reduction agent addition of 22 wt.%. Under the best reduction process, the purity of zinc oxide product is 99.5%, and the recovery of zinc is more than 99.25%. Needle-like zinc oxide obtained by carbothermic reduction has high purity and can replace zinc oxide produced by an indirect process. Full article

(This article belongs to the Special Issue Frontier of Environmental Friendly Recycling Technology for Metals)

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