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14 pages, 3961 KiB

Open AccessArticle

Extraction of Rare Earth and CaF₂ from Rare Earth Calcium Thermal Reduction Slag by Using CaO Roasting–Acid Leaching Method

by Jinqiu Huang, Lizhi Zhang, Wen Yu, Jiangan Chen, Chengtao Le and Sili Ren

Minerals 2024, 14(10), 1001; https://doi.org/10.3390/min14101001 - 30 Sep 2024

Viewed by 1351

Abstract

The rare earth calcium thermal reduction slag (RCS) generated during the production of heavy rare earth metal contains large amounts of rare earth and fluoride compounds. In this study, rare earth elements (REEs) and fluorine in the RCS were recovered by the CaO [...] Read more.

The rare earth calcium thermal reduction slag (RCS) generated during the production of heavy rare earth metal contains large amounts of rare earth and fluoride compounds. In this study, rare earth elements (REEs) and fluorine in the RCS were recovered by the CaO roasting–hydrochloric acid leaching method. Firstly, the thermodynamic feasibility of converting rare earth fluoride to rare earth oxides through CaO roasting was demonstrated. The influence of roasting conditions and leaching conditions on the leaching rate of the REEs was investigated. Optimal results, a 95.48% leaching rate of the REEs, were obtained under the following conditions: a CaO dosage of 15%, a roasting temperature of 1000 °C, and a roasting duration of 90 min. XRD, SEM, and EDS results revealed that during the calcination process, the REEs present in fluorite (CaF₂) in isomorphic form were transformed into acid-soluble rare earth oxides; furthermore, the rare earth metallic in the RCS remained unchanged even after roasting. In the leaching process, rare earth metals and rare earth oxides are efficiently extracted, while CaF₂ rarely dissolves. The leaching slag contained 97.31% CaF₂ with a F recovery of 96.92%. The kinetics of the rare earth leaching process was analyzed, and the results show that the three-dimensional diffusion control at the phase interface of the kinetic model best fits the process. The calculated apparent activation energy for the leaching rate of REEs is 20.869 kJ/mol. Therefore, efficient comprehensive recovery of rare earth and fluorite from RCS can be achieved by using the CaO roasting–hydrochloric acid leaching method. Full article

(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)

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15 pages, 4784 KiB

Open AccessArticle

Thermodynamic and Experimental Substantiation of Comprehensive Processing of Zinc Sulfide Ore and Its Concentration Tailings to Extract Non-Ferrous Metals and Produce a Silicon Ferroalloy

by Viktor Shevko, Baktygul Makhanbetova, Dosmurat Aitkulov, Alexandra Badikova and Daniel Amanov

Minerals 2024, 14(8), 819; https://doi.org/10.3390/min14080819 - 13 Aug 2024

Cited by 1 | Viewed by 1404

Abstract

This article presents the results of thermodynamic and experimental studies on the joint processing of a mixture of Shalkiya deposit zinc–lead sulfide ore and its concentration tailings in the presence of coke and magnetite. Using the HSC-6.0 software package, it was established by [...] Read more.

This article presents the results of thermodynamic and experimental studies on the joint processing of a mixture of Shalkiya deposit zinc–lead sulfide ore and its concentration tailings in the presence of coke and magnetite. Using the HSC-6.0 software package, it was established by thermodynamic modeling that the silicon-containing products of the SiO₂ reduction in the system under consideration are FeSi, Si, Fe₃Si, Fe₅Si₃, FeSi₂, FeSi_2.33, and SiOg, which, based on the starting reduction temperature, form an increasing series: Fe₃Si (1200 °C); Fe₅Si₃, Si (1400 °C); and SiOg, FeSi₂, FeSi_2.33 (1500 °C). The smelting of the zinc–lead sulfide ore and concentration tailings mixture in the case of replacing 55% of the iron contained in the magnetite concentrate with steel shavings iron allowed us to produce FeSi45 ferrosilicon (41.9%–42.1% Si), with the extraction of 85% of the silicon in it, and sublimates containing 26.03% zinc and 13.47% lead, with the extraction of 97% of the zinc and 99% of the lead in them. In comparison with the initial ore-tailings mixture, the resulting sublimates are 11.83 times richer in zinc. Full article

(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)

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15 pages, 4167 KiB

Open AccessArticle

Slag after Smelting of Anode Mud: Role of Sulphiding Sintering

by Lyudmila Sokolovskaya, Sergey Kvyatkovskiy, Sultanbek Kozhakhmetov, Anastassiya Semenova, Bulat Sukurov, Maral Dyussebekova and Alexander Shakhalov

Minerals 2024, 14(8), 781; https://doi.org/10.3390/min14080781 - 30 Jul 2024

Viewed by 877

Abstract

The study object was slag from the Balkhash copper smelter, obtained by re-melting anode mud containing nonferrous metals. The process flow for processing these slags includes sintering with Na₂SO₄, Na₂CO₃, and coal, followed by soda-alkaline [...] Read more.

The study object was slag from the Balkhash copper smelter, obtained by re-melting anode mud containing nonferrous metals. The process flow for processing these slags includes sintering with Na₂SO₄, Na₂CO₃, and coal, followed by soda-alkaline leaching of the sinter and extraction of metals from the solution into marketable products. Since sintering is the main operation providing high selectivity, the composition of the products of this process was studied. The main transformations during sintering were determined, and the optimal parameters were identified. The structures of slags and sintered materials obtained during the experiments were studied by electron-probe microanalysis. Sintering was performed at 600–800 °C. The best results for sulphidization of slag components were obtained at 800 °C; a further increase in temperature leads to the smelting of sinter particles and slows down sulphidization. The optimal quantities of additives, based on the weight of the slag, are Na₂SO₄—45%, Na₂CO₃—15%, and reducing agent—41%, with a sintering time of 2 h. These conditions enable the sulphidization of non-ferrous metals in the slag to the entire depth of the polymetallic globules. The distinct concentration of harmful impurities (Ni, As, and Sb) was observed in the fine structure of the polymetallic globules. Full article

(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)

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15 pages, 17275 KiB

Open AccessArticle

Numerical Modeling of Electron Beam Cold Hearth Melting for the Cold Hearth

by Yunpeng Wang, Lei Gao, Yuchen Xin, Shenghui Guo, Li Yang, Haohang Ji and Guo Chen

Minerals 2024, 14(6), 601; https://doi.org/10.3390/min14060601 - 7 Jun 2024

Cited by 2 | Viewed by 1488

Abstract

The electron beam cold hearth melting (EBCHM) process is one of the key processes for titanium alloy production. The unique characteristic of this pyrometallurgy process is the application of the cold hearth, which is responsible for controlling the Low-Density Inclusions (LDIs) and High-Density [...] Read more.

The electron beam cold hearth melting (EBCHM) process is one of the key processes for titanium alloy production. The unique characteristic of this pyrometallurgy process is the application of the cold hearth, which is responsible for controlling the Low-Density Inclusions (LDIs) and High-Density Inclusions (HDIs) in the melt. As a key process of inclusion removal, the information such as melt residence time in the cold hearth is directly related to the control of metallurgical defects in the ingot, and may also affect the composition distribution of the ingot. In this paper, the details for the physical phenomena, namely the evolution of the pool, the evolution of the flow, and the evolution of the component in the cold hearth during EBCHM are investigated using a modified multi-physical numerical model. The effects of melting temperature and melting speed on these phenomena were investigated. The purpose is to provide more fundamental knowledge and to further enhance the applications of EBCHM for more titanium alloys. Full article

(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)

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23 pages, 9658 KiB

Open AccessArticle

Reduction of an Ilmenite Concentrate by Using a Novel CO₂/CH₄ Thermal Plasma Torch

by Mohammed El Khalloufi, Gervais Soucy, Jonathan Lapointe and Mathieu Paquet

Minerals 2024, 14(5), 502; https://doi.org/10.3390/min14050502 - 10 May 2024

Cited by 2 | Viewed by 1715

Abstract

Plasma technology has emerged as a very helpful tool in a variety of sectors, notably metallurgy. Innovators and scientists are focused on the problem of finding a more ecologically friendly way of extracting titanium and iron metal from natural ilmenite concentrate for industrial [...] Read more.

Plasma technology has emerged as a very helpful tool in a variety of sectors, notably metallurgy. Innovators and scientists are focused on the problem of finding a more ecologically friendly way of extracting titanium and iron metal from natural ilmenite concentrate for industrial applications. A direct current (DC) plasma torch operating at atmospheric pressure is used in this study to describe a decarbonization process for reducing an ilmenite concentrate. The plasma gases employed in this torch are CO₂ and CH₄. The molar ratio of the gases may be crucial for achieving a satisfactory reduction of the ilmenite concentrate. As a result, two molar ratios for CO₂/CH₄ have been chosen: 1:1 and 2:1. During torch operation, a thin layer of graphite is formed on the cathode to establish a protective barrier, prolonging the cathode’s life. The material was analyzed using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). The output gases were analyzed using mass spectrometry (MS). In addition, a thermodynamic analysis was performed to predict the development of thermodynamically stable phases. An economic assessment (including capital expenditures (CAPEX) and operating expenditures (OPEX)) and a carbon balance were developed with the feasibility of the piloting in mind. Full article

(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)

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14 pages, 7359 KiB

Open AccessArticle

Phase Transformation of Arsenic, Antimony and Lead in High-Grade Copper Matte Converting

by Wenkai Qu, Yingbao Yang, Shiwei Zhou, Yonggang Wei and Bo Li

Minerals 2024, 14(5), 499; https://doi.org/10.3390/min14050499 - 9 May 2024

Viewed by 1466

Abstract

The duration of the high-grade matte converting process is short, the amount of slag is small, and it is difficult for the original impurity removal operation in the low-grade matte converting process to meet the current production demand. Because the removal method for [...] Read more.

The duration of the high-grade matte converting process is short, the amount of slag is small, and it is difficult for the original impurity removal operation in the low-grade matte converting process to meet the current production demand. Because the removal method for impurity elements during high-grade matte converting is unclear, the phase transformation of impurity elements during this process is investigated in this study. The results show that arsenic exists mainly in the form of FeAsO₄ and As₂O₅, antimony in the form of Sb and Sb₂O₅, and lead in the form of PbS and PbO in high-grade matte. During the converting process, arsenic and antimony mainly exist in the melt in the form of oxides and gradually aggregate into large particles with increasing copper content in the melt. Lead exists in matte in the form of PbS until the end of the converting process, and PbS is not completely oxidized until the matte converted to blister copper phase. The phase transformation characteristics of copper, iron, sulfur and impurity elements in the process of high-grade matte converting were revealed. This study provides a theoretical reference for the formulation of an efficient impurity removal scheme for the converting process. Full article

(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)

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20 pages, 12869 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Grinding of Australian and Brazilian Iron Ore Fines for Low-Carbon Production of High-Quality Oxidised Pellets

by Wuju Zhang, Qi Zhou, Jian Pan, Deqing Zhu and Congcong Yang

Minerals 2024, 14(3), 236; https://doi.org/10.3390/min14030236 - 26 Feb 2024

Cited by 3 | Viewed by 2655

Abstract

Oxidised pellets have become an indispensable high-quality charge for blast furnaces. Nevertheless, high-quality pellet feeds are becoming scarcer and scarcer. To broaden the range of sources of pellet feeds and reduce the production cost of pellets, more steel mills are predicted to use [...] Read more.

Oxidised pellets have become an indispensable high-quality charge for blast furnaces. Nevertheless, high-quality pellet feeds are becoming scarcer and scarcer. To broaden the range of sources of pellet feeds and reduce the production cost of pellets, more steel mills are predicted to use coarse iron ore fines with a relatively low iron grade and low impurities for the preparation of desirable pellet feeds through a typical wet grinding–settling–filtering process. In this work, the grinding, settling and filtering behaviour of Brazilian and Australian iron ore fines are studied and compared, with the aim of discovering the internal relationship between the mineralogical characteristics of different iron ore types and their grinding–settling–filtering performance. Additionally, the effects of ore blending on pellet preparation were investigated. The results show that, usually, the higher the hardness of the iron ore, the more grinding energy is required. Australian and Brazilian ore fines exhibit good grindability, with a Bond work index of about 10–15 kW·h/t. Furthermore, ore blending can reduce grinding energy consumption and improve settling and filtration rates, and the addition of finely ground Australian ores improves the balling performance of pellet mixtures. At the same bentonite content, the ball drop strength of the three blends with added Australian ore is significantly higher than that of the base blend, and the fired pellets obtained from Blend 1, Blend 2 and Blend 3 blends exhibit good metallurgical properties. Full article

(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)

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16 pages, 14402 KiB

Open AccessArticle

A Study on the Influence of Drying and Preheating Parameters on the Roasting Properties of Limonite Pellets

by Peng Chen and Xiaolei Zhou

Minerals 2024, 14(2), 166; https://doi.org/10.3390/min14020166 - 4 Feb 2024

Cited by 4 | Viewed by 1479

Abstract

In this experiment, a pellet preparation method was investigated to study the drying, preheating, and roasting properties of limonitic iron ore from a plant in Yunnan. The aim was to improve the subsequent iron-making process of limonitic iron ore and make it a [...] Read more.

In this experiment, a pellet preparation method was investigated to study the drying, preheating, and roasting properties of limonitic iron ore from a plant in Yunnan. The aim was to improve the subsequent iron-making process of limonitic iron ore and make it a substitute for sintered ore. This substitution would reduce the amount of blast furnace slag in the iron-making process. Bentonite is commonly used as a primary binder in many pelletizing plant operations. However, its excessive usage leads to a higher risk of slagging and coking in the furnace. In this paper, we aim to decrease the quantity of bentonite added, enhance the iron content in the pellets, and reduce impurities to improve the grade of limonite pellets. The results show that the optimal drying, preheating, and roasting temperatures of limonite pellets are 200 °C, 700 °C, and 1250 °C, respectively, and the optimal roasting time is 20 min, when the diameter of the pellets is 8–13 mm. The compressive strength of limonite pellets with the addition of 1.5% bentonite was the highest, meeting the demands of a general blast furnace, based on which the iron grade of limonite pellet ore was increased by 10.63%. Full article

(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)

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