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Minerals
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Rare Metals Extraction and Processing
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Rare Metals Extraction and Processing

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Processing and Extractive Metallurgy".

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 29474

Special Issue Editor

Dr. Shafiq Alam

E-Mail Website
Guest Editor
College of Engineering, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada
Interests: mineral processing; hydrometallurgy; electrometallurgy; separation sciences

Special Issue Information

Dear Colleagues,

This Special Issue will cover extraction and processing of rare metals from primary and secondary sources focusing on primary production as well as secondary production through urban mining and recycling to enable the circular economy. In this issue, rare metals include:

  • Strategic metals that are in increasing demand and subject to supply risks, such as rare earth elements or uranium, which are necessary to maintain manufacturing sectors such as the aerospace, defence and clean technology;
  • Platinum group metals, including platinum, palladium, rhodium, iridium, and others;
  • Battery-related metals, including lithium, cobalt, nickel, and aluminum;
  • Electronics-related materials, including copper and gold;
  • Refractory metals, including titanium, niobium, zirconium, and hafnium;
  • Other critical materials, such as gallium, germanium, indium, and silicon are also included.

This Special Issue will cover various extraction and processing techniques, including but not limited to:

  • Mineral processing using physical separation/concentration techniques, including comminution, flotation;
  • Hydrometallurgy including leaching, solvent extraction, ion exchange, adsorption, precipitation, and crystallization;
  • Electrometallurgy (electrorefining and electrowinning);
  • Pyrometallurgy; and
  • Supercritical fluid extraction.

Papers are welcome to address topics on process development, process control, process modelling, and environmental issues focusing on new innovation, sustainability, and cost-effective or energy efficient processes.

Prof. Dr. Shafiq Alam
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • strategic metals
  • critical metals
  • precious metals
  • rare earth elements (REE)
  • battery-related metals
  • refractory metals
  • mineral processing
  • hydrometallurgy
  • electrometallurgy
  • pyrometallurgy
  • process development
  • process modelling
  • environmental
  • primary production
  • metal recycling
  • circular economy
  • sustainability

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  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
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Further information on MDPI's Special Issue polices can be found here.

Published Papers (6 papers)

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Research

18 pages, 3530 KiB  
Article
Interfacial Structure Change and Selective Dissolution of Columbite–(Fe) Mineral during HF Acid Leaching
by Fanxi Yang, Qiuju Li, Dan Wang, Cang Zhou and Shaobo Zheng
Minerals 2021, 11(2), 146; https://doi.org/10.3390/min11020146 - 31 Jan 2021
Cited by 5 | Viewed by 2478
Abstract
The goal of the paper is to study the charge transfer and reactions at the columbite-(Fe) (FeNb2O6) mineral surface during the HF leaching process. In this paper, X-ray photoelectron spectroscopy (XPS), leaching experiments, and density functional theory (DFT) calculations [...] Read more.
The goal of the paper is to study the charge transfer and reactions at the columbite-(Fe) (FeNb2O6) mineral surface during the HF leaching process. In this paper, X-ray photoelectron spectroscopy (XPS), leaching experiments, and density functional theory (DFT) calculations were used to study the surface element adsorption, charge distribution, chemical state, and energy changes of the mineral surface during the process of leaching columbite–(Fe) with different concentrations of hydrofluoric acid. The results showed that as the concentration of F atoms was increased during the acid leaching process, the Nb–O bond was more likely to be broken than the Fe–O bond; the amount of charge transferred from Nb atom to F atom (0.78 e–0.94 e/atom) was greater than that from Fe atom to the F atom (0.25 e–0.28 e/atom), so it was determined that compared to Fe atoms, it was easier for the Nb atoms to bind to F. The results of XPS analysis showed that the electron binding energies of Nb5+–O, Fe3+–O, and Fe2+–O bonds on the mineral surface increased sequentially, and the M–O bond broke during the acid leaching process, forming more stable M–F bonds. Therefore, the Nb5+–F bonds were easier to form a stable structure. Combined with the ICP results, it was found that in the filtrate after 5M HF and 10M HF acid leaching minerals, c(Nb)/c(Fe) were 2.69 and 2.95, respectively, and the concentration ratio of Nb to Fe element in the mineral was 2 which was lower than 2.69 and 2.95, confirming the result of DFT calculation and illustrating that Nb atoms in columbite-(Fe) mineral were more soluble than Fe atoms. Full article
(This article belongs to the Special Issue Rare Metals Extraction and Processing)
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17 pages, 10710 KiB  
Article
Purification and Phase Evolution Mechanism of Titanium Oxycarbide (TiCxOy) Produced by the Thermal Reduction of Ilmenite
by Chunlin He, Chunhui Zheng, Wei Dai, Toyohisa Fujita, Jian Zhao, Shaojian Ma, Xinsheng Li, Yuezhou Wei, Jinlin Yang and Zongwu Wei
Minerals 2021, 11(2), 104; https://doi.org/10.3390/min11020104 - 21 Jan 2021
Cited by 13 | Viewed by 2594
Abstract
The phase evolution mechanism and purification of titanium oxycarbide (TiCxOy) synthesized via the carbothermal reduction of ilmenite are investigated. The reaction process and products of the performed carbothermal reduction are analyzed by means of X-ray diffraction (XRD), scanning electron [...] Read more.
The phase evolution mechanism and purification of titanium oxycarbide (TiCxOy) synthesized via the carbothermal reduction of ilmenite are investigated. The reaction process and products of the performed carbothermal reduction are analyzed by means of X-ray diffraction (XRD), scanning electron microscopy-energy disperse spectroscopy (SEM-EDS), X-ray photoelectric spectroscopy (XPS) and enthalpy, entropy and heat capacity (HSC) thermodynamic software. According to the shapes of Ti 2p3/2 and Ti 2p1/2 peaks in XPS spectra, together with the XRD analyses, the reduction products of TiO, TiCxOy or TiC can be judged. The phase evolution mechanism involves FeTi2O5, Ti2O3, Fe, TiO, TiCxOy and TiC under enhancing the content of carbon. The phase evolution law can be written as FeTiO3 → FeTi2O5 → Ti2O3 + Fe → TiO + Fe → TiCxOy + Fe. Due to the incomplete reduction state of TiCxOy, the ΔGθ of TiCxOy is detected between TiC and TiO. TiCxOy could be attained under reduction conditions of Ti:C, 1:3–1:4 in argon atmosphere at 1550 °C after 2 h. Grinding, flotation and magnetic separation processes displayed that C, TiCxOy and Fe are not dissociated until the particle size of −38 μm. TiCxOy and Fe can be separated by an iron-bath in a high temperature. 95.56% TiCxOy can be obtained, and resistance of TiCxOy is less than 0.05 Ω. Full article
(This article belongs to the Special Issue Rare Metals Extraction and Processing)
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15 pages, 1057 KiB  
Article
Separation of Aluminum and Iron from Lanthanum—A Comparative Study of Solvent Extraction and Hydrolysis-Precipitation
by Adam Balinski, Norman Kelly, Toni Helbig, Christina Meskers and Markus Andreas Reuter
Minerals 2020, 10(6), 556; https://doi.org/10.3390/min10060556 - 20 Jun 2020
Cited by 12 | Viewed by 5177
Abstract
This study investigates the removal of aluminum and iron from rare earth element (REE) containing solutions by solvent extraction with saponified naphthenic acid and by hydrolysis-precipitation. The results emphasize both, the preferential application as well as limitations of every method. We find that [...] Read more.
This study investigates the removal of aluminum and iron from rare earth element (REE) containing solutions by solvent extraction with saponified naphthenic acid and by hydrolysis-precipitation. The results emphasize both, the preferential application as well as limitations of every method. We find that emulsification occurring during the solvent extraction of aluminum is caused by its slow extraction rate in comparison to the neutralization reaction and by the proximity of the pH value required for aluminum extraction and the pH value at which hydrolysis of aluminum occurs. However, by choosing a long shaking time of at least 4 h, the emulsion recedes. The formation of emulsion can be avoided by strict control of pH value during the extraction. Moreover, the loading capacity of the organic phase with aluminum is limited due to the strong increase in viscosity of the organic phase with increasing aluminum concentration and due to the gel formation. Regarding the extraction of iron, the amount of extracted ions is limited due to the overlap of the pH range required for the extraction with pH range in which sparingly soluble iron oxides/hydroxides are formed. In summary, aluminum and iron can be simultaneously removed from REE-sulfate solution by solvent extraction with saponified naphthenic acid in one extraction stage only from diluted solutions. However, in comparison to the hydrolysis-precipitation method, a higher purity of the solution is achieved. A complete removal of aluminum and iron from concentrated solutions can be achieved in two stages. First, the content of aluminum and iron should be reduced by hydrolysis-precipitation. After that, a high-purity solution can be obtained by subsequent solvent extraction by saponified naphthenic acid. Full article
(This article belongs to the Special Issue Rare Metals Extraction and Processing)
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13 pages, 1045 KiB  
Article
Recovery of Co, Li, and Ni from Spent Li-Ion Batteries by the Inorganic and/or Organic Reducer Assisted Leaching Method
by Weronika Urbańska
Minerals 2020, 10(6), 555; https://doi.org/10.3390/min10060555 - 20 Jun 2020
Cited by 39 | Viewed by 5095
Abstract
The battery powder (anodic and cathodic mass) manually separated from spent Li-ion batteries used in laptops was subjected to acidic reductive leaching to recover the Co, Li, and Ni contained in it. In the laboratory experiments, 1.5 M sulfuric acid was used as [...] Read more.
The battery powder (anodic and cathodic mass) manually separated from spent Li-ion batteries used in laptops was subjected to acidic reductive leaching to recover the Co, Li, and Ni contained in it. In the laboratory experiments, 1.5 M sulfuric acid was used as the leaching agent and the reducing agents were 30% H2O2 solution or/and glutaric acid. Glutaric acid is a potential new reducing agent in the leaching process of spent lithium-ion batteries (LIBs). The influence of the type of the used reducer on obtained recovery degrees of Co, Li, and Ni as well as the synergism of the two tested reducing compounds were analyzed. As a result, it was determined that it is possible to efficiently hydrometallurgically separate Co, Li, and Ni from battery powder into solutions. The highest recovery degrees of the investigated metals (Co: 87.85%; Li: 99.91%; Ni: 91.46%) were obtained for samples where two reducers, perhydrol and glutaric acid, were added, thus confirming the assumed synergic action of H2O2 and C5H8O4 in a given reaction environment. Full article
(This article belongs to the Special Issue Rare Metals Extraction and Processing)
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10 pages, 1624 KiB  
Article
Recovery of Germanium from Sulphate Solutions Containing Indium and Tin Using Cementation with Zinc Powder
by Michał Drzazga, Grzegorz Benke, Mateusz Ciszewski, Magdalena Knapik, Adrian Radoń, Sylwia Kozłowicz, Karolina Goc, Patrycja Kowalik and Katarzyna Leszczyńska-Sejda
Minerals 2020, 10(4), 358; https://doi.org/10.3390/min10040358 - 17 Apr 2020
Cited by 9 | Viewed by 4121
Abstract
Cementation of germanium from sulphate solution obtained after the leaching of GeIn dross using zinc dust was investigated. The composition of the examined solution was 5.15 Ge, 1.52 In, and 5.81 g/dm3 Zn. In order to resemble the solution before detinning, Sn [...] Read more.
Cementation of germanium from sulphate solution obtained after the leaching of GeIn dross using zinc dust was investigated. The composition of the examined solution was 5.15 Ge, 1.52 In, and 5.81 g/dm3 Zn. In order to resemble the solution before detinning, Sn concentration between 2–10 g/dm3 was also investigated. It was found that >99% of germanium may be precipitated from the solution. In order to achieve high selectivity, a detinned solution should be used because the precipitation yields of germanium and tin from the solution containing Sn were similar. For cementation with Zn powder at 75 °C for 2 h with a final pH of 2.0, over 99% of the germanium was removed from the solution, while the indium precipitation yield was 12%. The obtained cementate contained 50% Ge, mainly in elementary form. Full article
(This article belongs to the Special Issue Rare Metals Extraction and Processing)
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13 pages, 2478 KiB  
Article
Extraction of Nickel from Garnierite Laterite Ore Using Roasting and Magnetic Separation with Calcium Chloride and Iron Concentrate
by Junhui Xiao, Wei Ding, Yang Peng, Tao Chen, Kai Zou and Zhen Wang
Minerals 2020, 10(4), 352; https://doi.org/10.3390/min10040352 - 15 Apr 2020
Cited by 20 | Viewed by 9144
Abstract
In this study, segregation roasting and magnetic separation are used to extract nickel from a garnierite laterite ore. The garnierite laterite ore containing 0.72% Ni, 0.029% Co, 8.65% Fe, 29.66% MgO, and 37.86% SiO2 was collected in the Mojiang area of China. [...] Read more.
In this study, segregation roasting and magnetic separation are used to extract nickel from a garnierite laterite ore. The garnierite laterite ore containing 0.72% Ni, 0.029% Co, 8.65% Fe, 29.66% MgO, and 37.86% SiO2 was collected in the Mojiang area of China. Garnierite was the Ni-bearing mineral; the other main minerals were potash feldspar, forsterite, tremolite, halloysite, quartz, and kaolinite in the garnierite laterite ore. The iron phase transformations show that nickel is transformed from (Ni,Mg)O·SiO2·nH2O to a new nickel mineral phase dominated by [Ni]Fe solid solution; and iron changed from Fe2O3 and FeOOH to a new iron mineral phase dominated by metal Fe and Fe3O4 after segregation roasting. Ferronickel concentrate with Ni of 16.16%, Fe of 73.67%, and nickel recovery of 90.33% was obtained under the comprehensive conditions used: A roasting temperature of 1100 °C, a roasting time of 90 min, a calcium chloride dosage of 15%, an iron concentrate dosage of 30%, a coke dosage of 15%, a coke size of −1 + 0.5 mm, a magnetic separation grinding fineness of <45 μm occupying 90%, and a magnetic separation magnetic field intensity of H = 0.10 T. The main minerals in ferronickel concentrate are Fe, [Ni]Fe, Fe3O4, and a small amount of gangue minerals, such as CaO·SiO2 and CaO·Al2O3·SiO2. Full article
(This article belongs to the Special Issue Rare Metals Extraction and Processing)
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