Research

12 pages, 4092 KiB

Open AccessArticle

Purification of Copper Concentrate from Arsenic under Autoclave Conditions

by Kirill Karimov, Oleg Dizer, Maksim Tretiak and Denis Rogozhnikov

Metals 2024, 14(2), 150; https://0-doi-org.brum.beds.ac.uk/10.3390/met14020150 - 25 Jan 2024

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This study presents the results of a two-stage autoclave processing of a copper–arsenic concentrate. Copper concentrate is an important raw material to produce copper and other metals. However, in some cases, the concentrate may contain increased amounts of arsenic, which makes further processing [...] Read more.

This study presents the results of a two-stage autoclave processing of a copper–arsenic concentrate. Copper concentrate is an important raw material to produce copper and other metals. However, in some cases, the concentrate may contain increased amounts of arsenic, which makes further processing difficult. Therefore, the development of modern hydrometallurgical methods for processing copper concentrate with a high arsenic content is an urgent task, which could lead to the optimization of the raw material processing process and the improvement of the quality of the concentrate. It has been established that the optimal conditions for the sequential two-stage autoclave processing of copper–arsenic concentrate are: t = 220–225 °C, τ_oxidation = 20 min, τ_tot = 90 min, Po₂ = 0.4 MPa, and L:S = 10:1, [H₂SO₄]_initial = 40 g/dm³; in this case, 85% of zinc, 44% of iron, and 78% of arsenic, respectively, are extracted into the solution during both stages and the loss of copper was about 0.01%. This is explained by the fact that at the first stage (oxidation) of the autoclave processing of the copper–arsenic concentrate, copper, together with iron, leaches into the solution, and at the second stage (reduction), copper precipitates out of the solution in the form of chalcocite. Copper in the residue after autoclave leaching is in the form of Cu₂S, iron is in the form of pyrite (FeS₂), and lead is in the form of anglesite (PbSO₄), respectively. The obtained micrographs and EDX mappings clearly show no iron arsenates. This confirms that at the oxidative stage of the developed process, arsenic, removed by 78%, remains in the solution. The remaining arsenic is associated with tennantite, indicating the effectiveness of the treatment process in removing arsenic from the copper–arsenic concentrate. A second important observation is the presence of pronounced areas of copper sulfides in the microphotos without iron and arsenic impurities. This confirms that copper is deposited as chalcocite during the reduction phase of the process, which is the desired result. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy II)

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18 pages, 2520 KiB

Open AccessArticle

Towards Using MMO Anodes in Zinc Electrorefining: Mn Removal by Simulated Plant Off-Gas

by Masoomeh Askarian, Fariba Mousavi, Roozbeh Mollaabbasi, Elyse Benguerel, Carl Brown, Georges Houlachi and Houshang Alamdari

Metals 2023, 13(10), 1675; https://0-doi-org.brum.beds.ac.uk/10.3390/met13101675 - 30 Sep 2023

Cited by 1 | Viewed by 796

Abstract

Implementing mixed metal oxide (MMO) anodes in zinc electrowinning is highly desired due to the considerable reduction in electrical energy consumption. However, the presence of manganese in the electrolyte is a major obstacle for implementing MMO anodes in the zinc cell houses. In [...] Read more.

Implementing mixed metal oxide (MMO) anodes in zinc electrowinning is highly desired due to the considerable reduction in electrical energy consumption. However, the presence of manganese in the electrolyte is a major obstacle for implementing MMO anodes in the zinc cell houses. In this work, we explore the possibility of using plant off-gas, containing SO₂, to remove manganese. A SO₂/air gas mixture with different SO₂ and O₂ concentrations was therefore used for the oxidative precipitation of manganese. It was shown that the manganese oxidation reaction is highly pH-dependent. Calcium hydroxide was used to control the pH during the process. Different operating parameters, i.e., pH, SO₂/air ratio, reaction time, and effect of cobalt as a reaction catalyst, were investigated. Optimal conditions for manganese removal were reported. Under the optimal conditions, the manganese concentration decreased from 1 g L⁻¹ to less than 1 mg L⁻¹ within 30 min. Precipitates were characterized using EDS, XRF, and XPS techniques and showed coprecipitation of manganese, zinc, gypsum, and cobalt. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy II)

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13 pages, 2789 KiB

Open AccessArticle

Adsorption of Gold from Copper–Tartrate–ThiosulfateSolutions with Ion-Exchange Resins

by Yan Fu, Junnan Chen, Feng Xie, Zhichao Cao and Wei Wang

Metals 2023, 13(8), 1443; https://0-doi-org.brum.beds.ac.uk/10.3390/met13081443 - 11 Aug 2023

Viewed by 720

Abstract

The adsorption behavior of gold from copper–tartrate–thiosulfate solutions with ion-exchange resins was studied in this paper. Experimental parameters include resin dosage, pH, temperature, copper, tartrate, and thiosulfate concentration. A moderate increase in resin dosage, pH, temperature, and tartrate concentration is beneficial for gold [...] Read more.

The adsorption behavior of gold from copper–tartrate–thiosulfate solutions with ion-exchange resins was studied in this paper. Experimental parameters include resin dosage, pH, temperature, copper, tartrate, and thiosulfate concentration. A moderate increase in resin dosage, pH, temperature, and tartrate concentration is beneficial for gold adsorption, but an excessive tartrate concentration or higher temperature depresses the adsorption process. Increasing copper and thiosulfate concentrations may competitively occupy the active sites on the resin surface, leading to a reduction in the gold adsorption capacity. The XPS and FT-IR analyses indicate that copper and gold on the resin after adsorption mainly exist in the form of Cu⁺ and Au⁺, and sulfur mainly exists in the form of SO₄²⁻ and S₂O₃²⁻. This implies that the use of resin for gold recovery from thiosulfate leachate may face critical challenges because there is inevitably a higher content of copper and thiosulfate. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy II)

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14 pages, 6578 KiB

Open AccessArticle

Effects of Ammonium Salts on Rare Earth Leaching Process of Weathered Crust Elution-Deposited Rare Earth Ores

by Zhenyue Zhang, Changyu Zhou, Wendou Chen, Fei Long, Zhuo Chen and Ru’an Chi

Metals 2023, 13(6), 1112; https://0-doi-org.brum.beds.ac.uk/10.3390/met13061112 - 13 Jun 2023

Cited by 3 | Viewed by 1625

Abstract

In order to reveal the influence of ammonium salts on the rare earth leaching process of weathered crust elution-deposited rare earth ores, ammonium acetate, ammonium chloride, and ammonium sulfate were used as leaching agents. The effects of the leaching agent on the rare [...] Read more.

In order to reveal the influence of ammonium salts on the rare earth leaching process of weathered crust elution-deposited rare earth ores, ammonium acetate, ammonium chloride, and ammonium sulfate were used as leaching agents. The effects of the leaching agent on the rare earth leaching efficiency and the expansion, dissolution, and transformation behavior of clay minerals in the rare earth leaching process were studied. The results showed that rare earth leaching efficiency followed the order ammonium acetate > ammonium chloride > ammonium sulfate, with values of 90.60%, 85.96%, and 84.12%, respectively. The swelling ratio of clay mineral followed the order ammonium acetate < ammonium chloride < ammonium sulfate; the clay mineral swelling ratio was 2.09% when ammonium acetate was the leaching agent. Thermogravimetric analysis showed that the interlayer water content was the lowest when ammonium acetate was used as the leaching agent. Under the conditions of different leaching agents, the clay mineral contents changed from illite and halloysite to smectite and kaolinite. When ammonium acetate was used as the leaching agent, the relative conversion of illite was 1.49%, and that of smectite was only 0.17%. SEM analysis showed that the clay minerals expanded and dissolved obviously when ammonium chloride and ammonium sulfate were used as the leaching agents. Meanwhile, the clay mineral layered structure was relatively complete when ammonium acetate was used as the leaching agent. Therefore, when ammonium acetate was used as the leaching agent, it had the least effect on the swelling, dissolution, and transformation of clay minerals. This can provide a theoretical basis for the safe production of weathered crust elution-deposited rare earth ore, and for the screening of green and efficient leaching agents. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy II)

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15 pages, 12124 KiB

Open AccessArticle

Influence of Flow-Gas Composition on Reaction Products of Thermally Treated NMC Battery Black Mass

by Christin Stallmeister and Bernd Friedrich

Metals 2023, 13(5), 923; https://0-doi-org.brum.beds.ac.uk/10.3390/met13050923 - 10 May 2023

Cited by 3 | Viewed by 1786

Abstract

The recycling of lithium-ion batteries (LIBs) is becoming increasingly important regarding the expansion of electromobility and aspects of raw material supply. Pre-treatment and liberation are crucial for a sufficient recovery of all relevant materials from LIBs. Organic removal and phase transformations by thermal [...] Read more.

The recycling of lithium-ion batteries (LIBs) is becoming increasingly important regarding the expansion of electromobility and aspects of raw material supply. Pre-treatment and liberation are crucial for a sufficient recovery of all relevant materials from LIBs. Organic removal and phase transformations by thermal pre-treatment are beneficial in many respects. This study deals with the influence of flow-gas composition on reaction products and water-based lithium recovery after thermal treatment. Therefore, a spent NMC black mass was thermally treated at 610 °C in a moved bed batch reactor under an N₂ atmosphere and mixtures of N₂ with 2.5% and 5% O₂. Since the phase transformation of the lithium content to Li₂CO₃ is targeted for water leaching, a treatment under a CO₂ atmosphere was studied as well. The resulting off-gas was analyzed by FTIR, and the black mass was characterized by XRD. Afterward, water washing of the black mass was carried out for selective lithium recovery. The gained lithium product was analyzed for the purity and phases present. The addition of O₂ resulted in reduced reduction reactions of lithium metal oxides and lower Li-yields in the water leaching compared to the other two atmospheres. In the case of CO₂, the formation of Li₂CO₃ is favored compared to LiF, but the Li-yield of 56% is comparable to N₂ treatment. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy II)

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17 pages, 8378 KiB

Open AccessArticle

Enhanced Precipitation of Gibbsite from Sodium Aluminate Solution by Adding Agglomerated Active Al(OH)₃ Seed

by Andrei Shoppert, Dmitry Valeev, Konstantin Alekseev and Irina Loginova

Metals 2023, 13(2), 193; https://0-doi-org.brum.beds.ac.uk/10.3390/met13020193 - 18 Jan 2023

Cited by 1 | Viewed by 2105

Abstract

The addition of active seed for increasing the precipitation rate leads to the formation of fine Al(OH)₃ particles that complicates separation of solid from the mother liquor. In this study, the enhanced precipitation of coarse Al(OH)₃ from sodium aluminate solution using [...] Read more.

The addition of active seed for increasing the precipitation rate leads to the formation of fine Al(OH)₃ particles that complicates separation of solid from the mother liquor. In this study, the enhanced precipitation of coarse Al(OH)₃ from sodium aluminate solution using active agglomerated seed was investigated. Aluminum salt (Al₂(SO₄)₃) were used for active agglomerated seed precipitation at the initial of the process. About 50% of precipitation rate was obtained when these agglomerates were used as a seed in the amount of 20 g L⁻¹ at 25 °C within 10 h. The agglomerated active seed and precipitate samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). SEM images showed that agglomerates consist of flake-like particles that can be stick together by bayerite (β-Al(OH)₃) acting as a binder. The precipitation temperature above 35 °C and the high concentration of free alkali (α_k = 1.645Na₂O_k/Al₂O₃ > 3) lead to the agglomerates refinement that can be associated with the bayerite dissolution. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy II)

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12 pages, 3519 KiB

Open AccessArticle

Ultra-Fine Centrifugal Concentration of Bastnaesite Ore

by Alex Norgren and Corby Anderson

Metals 2021, 11(10), 1501; https://0-doi-org.brum.beds.ac.uk/10.3390/met11101501 - 23 Sep 2021

Cited by 3 | Viewed by 1734

Abstract

Historically, the ability to effectively separate carbonate gangue from bastnaesite via flotation has frequently proven to be challenging without sacrificing significant rare earth oxide (REO) grade or recovery. However, in light of the fact that the rare earth bearing minerals often exhibit higher [...] Read more.

Historically, the ability to effectively separate carbonate gangue from bastnaesite via flotation has frequently proven to be challenging without sacrificing significant rare earth oxide (REO) grade or recovery. However, in light of the fact that the rare earth bearing minerals often exhibit higher specific gravities than the carbonate gangue, the possibility exists that the use of gravity separation could be used to achieve such a selective separation. This however is complicated by the fact that, in cases such as this study when the liberation size is finer than 50 µm, most traditional gravity separation methods become increasingly challenging. The purposes of this study is to determine the applicability of gravity concentrators to beneficiate bastnaesite from deleterious calcite bearing flotation feed material. Via the use of a UF Falcon, it was possible to achieve rougher gravity REO recoveries approaching the upper 80% range while rejecting on the order of 30% of the total calcium. In terms of purely REO recovery, this represents a significant improvement over results obtained via a traditional Falcon in previously reported studies. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy II)

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15 pages, 3910 KiB

Open AccessArticle

Recovery of Rare Earth Oxides from Flotation Concentrates of Bastnaesite Ore by Ultra-Fine Centrifugal Concentration

by Alex Norgren and Corby Anderson

Metals 2021, 11(9), 1498; https://0-doi-org.brum.beds.ac.uk/10.3390/met11091498 - 21 Sep 2021

Cited by 2 | Viewed by 1682

Abstract

Historically, the ability to effectively separate carbonate gangue from bastnaesite via flotation has frequently proven to be challenging without sacrificing significant rare earth oxide (REO) grade or recovery. However, in light of the fact that the rare earth bearing minerals often exhibit higher [...] Read more.

Historically, the ability to effectively separate carbonate gangue from bastnaesite via flotation has frequently proven to be challenging without sacrificing significant rare earth oxide (REO) grade or recovery. However, in light of the fact that the rare earth bearing minerals often exhibit higher specific gravities than the carbonate gangue, the possibility exists that the use of gravity separation could be used to achieve such a selective separation. This however is complicated by the fact that, in cases such as this study when the liberation size is finer than 50 microns, most traditional gravity separation methods become increasingly challenging. The aim of this study is to determine the applicability of centrifugal concentrators to beneficiate ultra-fine (UF) bastnaesite and calcite bearing flotation concentrates. By using a UF Falcon, it was possible to achieve initial gravity REO recoveries exceeding 90% while rejecting on the order of 25% to 35% of the total calcium from an assortment of rougher and cleaner flotation concentrates. Additionally, when additional stages of cleaner UF Falcon gravity separation were operated in an open circuit configuration, it was possible, from an original fine feed of 35 microns containing 50.5% REO and 5.5% Ca, to upgrade up to approximately 59% REO and 2.0% calcium. While not the goal of this study, these results also support previous limited data to suggest that UF Falcons are potentially capable of treating a wider range of materials than they were originally designed for, including feeds rich in heavy mineral content. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy II)

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