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Minerals
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Advances in Precious and Critical Mineral Beneficiation and Extraction
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Advances in Precious and Critical Mineral Beneficiation and Extraction

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 2025) | Viewed by 45507

Special Issue Editors

Dr. Richmond K. Asamoah

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Guest Editor
Minerals and Resource Engineering, Future Industries Institute, University of South Australia, Mawson Lakes Campus, Adelaide, SA 5095, Australia
Interests: mineral processing and extractive metallurgy; data analytics and machine learning; biohydrometallurgy; surface and interfacial science; environmetal science (ESG)
Special Issues, Collections and Topics in MDPI journals
Dr. Ahmet Deniz Baş

E-Mail Website
Guest Editor
Department of Mining Engineering, Faculty of Engineering, Mugla Sıtkı Kocman University, 48000 Menteşe/Muğla, Turkey
Interests: biohydrometallurgy of base and precious metals; gold leaching; treatment of refractory gold ores; graphite purification; electrochemical methods in leaching applications; mineral electrode; WEEE; quartz bleaching
Special Issues, Collections and Topics in MDPI journals
Dr. George Blankson Abaka-Wood

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Guest Editor
Sustainable Minerals Processing, Future Industries Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia
Interests: battery metals and critical minerals; rare earth elements; extractive metallurgy; mineral processing; process plant design and optimization
Special Issues, Collections and Topics in MDPI journals
Dr. Kali Sanjay

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Guest Editor
CSIR – Institute of Minerals and Materials Technology, Bhubaneswar 751012, Odisha, India
Interests: design and scale-up of hydrometallurgical unit operations; process flow-sheet development to recover non-ferrous metals from low-grade ores/secondaries; solid wastes and effluents processing/electroremediation/electrowashing/salt-splitting
Prof. Dr. Jonas Addai-Mensah

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Guest Editor
Future Industries Institute, University of South Australia, Adelaide, SA 5095, Australia
Interests: hydrometallurgy; physical separation and beneficiation of mineral ores; flotation; colloid and interfacial science and particle interactions; thickening; dewatering and disposal of mineral waste tailings; process water treatment and environmental cleaning
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the increasing demand for valuable metals, advanced techniques are required for processing complex ore bodies and secondary metal sources or wastes (e.g., printed circuit boards). These complex ore bodies and secondary metal sources host precious and critical minerals that will aid the development of high technology equipment and the transition to a clean energy economy. The current Special Issue focusses on novel and advanced beneficiation and extractive metallurgical methods for precious (e.g., gold, silver, and platinum group metals) and critical (e.g., nickel, cobalt, and rare earth elements) metals recovery and/or extraction from primary and secondary sources. The Special Issue is organized into three sections and invites contributions accordingly:

  • Section 1: Advances in physical separation and beneficiation of complex ores and wastes containing precious and critical minerals.
  • Section 2: Developments in hydrometallurgical (including biological) and aqueous extraction of complex ores and wastes containing precious and critical minerals.
  • Section 3: Advances in electrometallurgical processes for precious and critical metal extraction.

Dr. Richmond K. Asamoah
Dr. Ahmet Deniz Baş
Dr. George Blankson Abaka-Wood
Dr. Kali Sanjay
Prof. Dr. Jonas Addai-Mensah
Guest Editors

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 250 words) can be sent to the Editorial Office for assessment.

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

  • precious and critical minerals
  • complex ore bodies
  • physical separation and beneficiation
  • biomining
  • hydrometallurgy
  • electrometallurgy
  • solvent extraction and ion exchange
  • wastes and secondary metal sources
  • recycling

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Published Papers (15 papers)

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28 pages, 6045 KB  
Article
Characterization and Flotation of a Complex Low-Grade Copper Ore: Implications of Collector Chemistry on Gangue Selectivity
by Theophilus Amos-Judge, Giang Nguyen, George Abaka-Wood and Richmond Asamoah
Minerals 2026, 16(5), 472; https://doi.org/10.3390/min16050472 - 30 Apr 2026
Abstract
The flotation performance of a low-grade, polymetallic copper ore, dominated by chalcocite and transitional copper phases, was investigated to assess the interplay between collector chemistry, gangue mineralogy, and entrainment. QEMSCAN analysis identified chalcocite as the main copper host (62%), with minor covellite and [...] Read more.
The flotation performance of a low-grade, polymetallic copper ore, dominated by chalcocite and transitional copper phases, was investigated to assess the interplay between collector chemistry, gangue mineralogy, and entrainment. QEMSCAN analysis identified chalcocite as the main copper host (62%), with minor covellite and bornite, and gangue, predominantly quartz (94%), with variable muscovite (up to 50%). Chalcocite was moderately liberated (100–200 µm), while secondary copper phases showed low exposure and strong gangue association, challenging selective recovery. Baseline flotation with potassium amyl xanthate (PAX) and sodium isobutyl xanthate (SIBX) across pH and dosage ranges showed that PAX yielded higher copper recovery but lower grade, indicating unselective gangue entrainment; SIBX offered lower recovery but higher grade, reflecting superior selectivity. Controlled muscovite doping experiments (10–50 wt.%) were employed to decouple gangue-driven selectivity loss from collector-specific interactions. Results indicate a collector-dependent sensitivity to gangue loading: PAX exhibited a pronounced decline in both copper recovery (82%–67%) and grade under increasing muscovite content, with water recovery rising by approximately 32%, whereas SIBX showed more gradual performance degradation and lower entrainment (15% increase in water recovery), highlighting its resilience in gangue-rich systems. UV-Vis and zeta potential (electrokinetic) measurements confirmed stronger PAX adsorption, consistent with its longer hydrocarbon chain, while flotation trends demonstrated a shift from true flotation-dominated recovery to entrainment-dominated regimes at high muscovite levels, particularly for PAX. This framework links mineralogy, collector chemistry, and gangue entrainment, guiding optimization of circuits for ores like Mt. Gunson while enhancing critical metal recovery, including cobalt. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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18 pages, 2949 KB  
Article
Conceptual Development of a Process to Recover Platinum Group Metals from Base Metal Leach Tailings Using Alkaline Glycine-Based Lixiviants
by Carlos Guillermo Perea Solano, Tony Tang, Chaoran He, Aissa Polenio and Jacques Eksteen
Minerals 2026, 16(5), 464; https://doi.org/10.3390/min16050464 - 29 Apr 2026
Abstract
The increasing demand for platinum group metals (PGMs) and critical base metals (BMs) underscores the critical roles these metals play in renewable energy and advanced technologies, enabling more efficient, environmentally sustainable operations. A hydrometallurgical approach to Au, Pd, and Pt tailings, derived from [...] Read more.
The increasing demand for platinum group metals (PGMs) and critical base metals (BMs) underscores the critical roles these metals play in renewable energy and advanced technologies, enabling more efficient, environmentally sustainable operations. A hydrometallurgical approach to Au, Pd, and Pt tailings, derived from the glycine leaching of low-grade nickel and iron sulfide flotation concentrates, is investigated. The proposed process evaluates two glycine-based systems: glycine combined with KMnO4 and catalyzed by cyanide under starvation conditions. Leaching with glycine in the presence of KMnO4 (72 h, 25% solids, 60 °C, pH 11, dissolved oxygen 10 ppm, 126.7 kg/t glycine, and 7 kg/t KMnO4) achieved extraction efficiencies of up to 66.7% Au, 89.1% Pd, and 95.8% Pt. In comparison, the cyanide-starved glycine system (72 h, 30% solids, 60 °C, pH 11, dissolved oxygen 20 ppm, 98.5 kg/t glycine, and 3.3 kg/t cyanide) resulted in up to 80.8% Au, 78.3% Pd, and 14.3% Pt. Activated carbon and Amberlite resin demonstrated selective adsorption of Au and PGMs. For activated carbon, Au adsorption exhibited a non-linear dependence on carbon dosage, reaching a maximum of 77.61% at 20 g/L, then decreasing to 50.85% at 25 g/L, and finally increasing to 65.04% at 30 g/L, indicating variable adsorption behavior. In contrast, Amberlite resin exhibited more consistent, progressive adsorption with increasing dosage. Au adsorption remained high across all conditions, increasing from 88.06% at 10 g/L to 99.67% at 30 g/L. Similarly, Pd and Pt adsorption improved significantly with resin dosage, reaching maximum values of 81.32% and 83.36% at 25 g/L, respectively, followed by a slight decline at 30 g/L. Implementing a two-stage process using carbon + resin (30 g/L) increased PGM recovery, achieving 99.89% Au, 81.8% Pd, and 92.4% Pt. Elution tests showed that Au (61.97%) and Pd (60.55%) were desorbed efficiently using thiourea (2% w/v) and HCl (0.5 M), whereas Pt elution proved difficult and required alternative strategies. The findings confirm glycine-based technologies as a promising, environmentally friendly alternative to conventional methods and provide a basis for further process development and optimization. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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21 pages, 6127 KB  
Article
A Sensor-Based Magnetite Ore Sorting System Integrating Empirical Mode Decomposition and Convolutional Neural Network
by Yankui Ren, Yan Yang, Jipeng Wang, Chunrong Pan, Fenglian Yuan, Weiqian Chen and Jianzhao Wang
Minerals 2026, 16(2), 210; https://doi.org/10.3390/min16020210 - 19 Feb 2026
Viewed by 399
Abstract
To address the challenge of poor separation performance exhibited by conventional magnetic separation equipment when processing coarse-grained, low-grade magnetite ore, this paper proposes a novel ore recognition method that integrates empirical mode decomposition (EMD) with a convolutional neural network (CNN). First, the original [...] Read more.
To address the challenge of poor separation performance exhibited by conventional magnetic separation equipment when processing coarse-grained, low-grade magnetite ore, this paper proposes a novel ore recognition method that integrates empirical mode decomposition (EMD) with a convolutional neural network (CNN). First, the original signal undergoes standardization to suppress sensor baseline drift. Then, it is decomposed by using EMD to obtain a series of intrinsic mode functions (IMFs). Subsequently, based on scaling exponents and kurtosis values, IMFs containing significant feature information are selected and fused, resulting in a reconstructed signal with substantially reduced noise. To preserve effective features, the absolute values of the reconstructed signal are taken, followed by normalization and dimensional transformation to convert it into a two-dimensional matrix format, thereby constructing training, validation, and test sets. Finally, a CNN is designed and optimized to automatically extract discriminative features from the preprocessed samples, enabling accurate classification of magnetite ore grades. Experimental results demonstrate that the proposed comprehensive identification method achieves effective and stable classification performance across different ore grades. Specifically, the implementation of standardization and EMD-based denoising has been demonstrated to enhance the accuracy of CNNs in recognizing diverse ores. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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14 pages, 1104 KB  
Article
The Influence of a Flotation Solution’s Surface Tension on Pyrochlore Flotation
by Rafael Vaz Dias, José Tadeu Gouvêa Junior and Laurindo de Salles Leal Filho
Minerals 2026, 16(2), 135; https://doi.org/10.3390/min16020135 - 27 Jan 2026
Viewed by 521
Abstract
The low recovery (∼50%) in industrial pyrochlore flotation highlights the need for optimization. This study evaluates the influence of surface tension (γ) of flotation solutions on pyrochlore/gangue separation of samples from Boa Vista mine (Brazil) using gamma flotation. Surface tension was [...] Read more.
The low recovery (∼50%) in industrial pyrochlore flotation highlights the need for optimization. This study evaluates the influence of surface tension (γ) of flotation solutions on pyrochlore/gangue separation of samples from Boa Vista mine (Brazil) using gamma flotation. Surface tension was adjusted using ethanol–water mixtures of reagent-conditioned samples in gamma flotation tests at pH 5.5, with recoveries measured via XRF analysis and separation efficiency calculated using Schulz’s criterion. After reagent conditioning at pH 5.5, the critical surface tension needed for flotability (γc) was determined to be 27 mN/m for pyrochlore and gangue minerals. Recoveries increased steeply from 0% at γ=27 mN/m to plateaus at γ>39 mN/m. The maximum Nb2O5 recovered (99%) occurred at γ=48.9 mN/m. Schulz’s separation efficiency peaked at γ = 48.9 mN/m for pyrochlore/carbonates (68%) and at γ = 39 mN/m for pyrochlore/silicates+oxides. Results suggest operating industrial direct flotation at lower γ values (39 mN/m) than the current method (61 mN/m) for improved selectivity, bridging theory and practice in niobium processing. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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19 pages, 39940 KB  
Article
Key Factors Impacting the Decomposition Rate of REE Silicates During Sulfuric Acid Treatment
by Yves Thibault, Joanne Gamage McEvoy and Dominique Duguay
Minerals 2026, 16(1), 31; https://doi.org/10.3390/min16010031 - 27 Dec 2025
Viewed by 889
Abstract
The decomposition of silicates in sulfuric acid to extract rare earth elements (REE) is typically characterized by the formation of an amorphous silica layer surrounding the receding crystal that may act as a passivation barrier limiting the rate of mineral dissolution. In this [...] Read more.
The decomposition of silicates in sulfuric acid to extract rare earth elements (REE) is typically characterized by the formation of an amorphous silica layer surrounding the receding crystal that may act as a passivation barrier limiting the rate of mineral dissolution. In this context, sulfuric acid treatment experiments coupled with detailed characterization of the evolution of the decomposition reaction were performed on natural allanite (CaREEAl2Fe2+Si3O11O[OH]), as well as synthetic neodymium disilicate (Nd2Si2O7), orthosilicate (Ca2Nd8(SiO4)6O2), and orthophosphate (NdPO4) phases in order to investigate if there are key factors, operating on a wide range of silicates, that negatively impact REE recovery. While, as expected, the acid strength is the driver in promoting the decomposition of the orthophosphate, for the silicates investigated, no matter their crystalline structure and chemical resistance, there is a severe passivation mechanism at play in concentrated H2SO4. However, in all cases, this effect can be minimized by water dilution, which strongly enhances sulfate-forming cation transfer across the produced amorphous silica layer. Taking into consideration this distinct characteristic of the mode of decomposition of silicates in sulfuric acid should help in defining optimal extraction strategies. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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18 pages, 4518 KB  
Article
Nitric Acid Purification of Molybdenite Concentrate: Copper-Iron Removal and Development of a Comprehensive Dissolution Kinetics Model
by Hossein Shalchian, Payam Ghorbanpour, Behzad Nateq, Marco Passadoro, Pietro Romano, Francesco Vegliò and Nicolò Maria Ippolito
Minerals 2025, 15(9), 982; https://doi.org/10.3390/min15090982 - 16 Sep 2025
Cited by 1 | Viewed by 1291
Abstract
The selective removal of impurities from molybdenite concentrates is crucial for producing high-purity molybdenum products. In this study, the purification of molybdenite concentrate was investigated using nitric acid as both a leaching medium and oxidizing agent. Leaching experiments were carried out under various [...] Read more.
The selective removal of impurities from molybdenite concentrates is crucial for producing high-purity molybdenum products. In this study, the purification of molybdenite concentrate was investigated using nitric acid as both a leaching medium and oxidizing agent. Leaching experiments were carried out under various conditions of temperature (22–78 °C) and nitric acid concentration (0.12–0.48 M). The results demonstrated that while molybdenite remained mostly undissolved, copper and iron were effectively leached, with near-complete removal at 78 °C in 0.24 M HNO3 after 6 h. Compared with other acid systems, nitric acid leaching experiments in this study demonstrated higher efficiency and selectivity under relatively moderate conditions of concentration and temperature. Kinetic analyses were performed based on the shrinking core model (SCM) and extended by developing a comprehensive rate equation that incorporates both nitric acid concentration and reactive surface effects. Fitting the developed model to experimental data revealed distinct kinetic regimes below and above 50 °C, suggesting a mechanism shift from surface chemical reaction control to diffusion through an ash layer. The purified molybdenite was characterized by SEM-EDS and ICP-OES, confirming almost complete elimination of Cu and Fe impurities. This work highlights nitric acid as a promising and efficient medium for selective leaching of molybdenite concentrates and provides a comprehensive kinetic model applicable across different leaching conditions. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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19 pages, 3999 KB  
Article
Recovery of Precious Metals from High-MgO-Content Pt-Pd Concentrates Using a Pyrometallurgical Smelting Process
by Chunxi Zhang, Lingsong Wang, Jiachun Zhao, Chao Wang, Yu Zheng and Haigang Dong
Minerals 2025, 15(8), 818; https://doi.org/10.3390/min15080818 - 1 Aug 2025
Cited by 1 | Viewed by 1809
Abstract
The Jinbaoshan Pt-Pd deposit is China’s largest independent PGM deposit. However, the deposit has not been utilized until now because of the low grade of precious metals, the complex mineral composition, and, notably, the presence of precious metals in the microgranular material disseminated [...] Read more.
The Jinbaoshan Pt-Pd deposit is China’s largest independent PGM deposit. However, the deposit has not been utilized until now because of the low grade of precious metals, the complex mineral composition, and, notably, the presence of precious metals in the microgranular material disseminated to other minerals. Its high MgO content, in particular, is regarded as a challenge for efficiently recovering precious metals via mature pyrometallurgical methods. In this research, the feasibility of a smelting process to recover precious metals from Jinbaoshan Pt-Pd concentrates at a conventional smelting temperature (1350 °C) with the addition of iron ore as a metal collector and SiO2 and CaO as fluxes was verified on the basis of thermodynamic slag design and experimental analyses. Under the optimal conditions of 100 g of the Pt-Pd concentrates, 32.5 g of SiO2, 7.5 g of CaO, and 30 g of iron ore at 1350 °C for 1 h, the extraction efficiencies of Au, Pt, and Pd were 94.66%, 96.75%, and 97.28%, respectively. This strategy enables the rapid collection of PGMs from Jinbaoshan Pt-Pd concentrates at the conventional temperature within a short time and minimizes the use of fluxes and collectors, contributing to energy and cost conservation. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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23 pages, 7541 KB  
Article
Assessment of Gold and Mercury Losses in an Artisanal Gold Mining Site in Nigeria and Its Implication on the Local Economy and the Environment
by Nnamdi C. Anene, Bashir M. Dangulbi and Marcello M. Veiga
Minerals 2024, 14(11), 1131; https://doi.org/10.3390/min14111131 - 8 Nov 2024
Cited by 4 | Viewed by 7350
Abstract
The objective of this work was to establish the gold and mercury losses in an artisanal mining deposit (Uke) in Nigeria to convince miners about their inefficiency and suggest changes in their gold extraction practices. Samples of feeds and tailings from five sluice [...] Read more.
The objective of this work was to establish the gold and mercury losses in an artisanal mining deposit (Uke) in Nigeria to convince miners about their inefficiency and suggest changes in their gold extraction practices. Samples of feeds and tailings from five sluice box concentration processes previously ground in hammer mills below 1 mm (P80 = 0.5 mm) were systematically sampled every 15 min. for 4 h and sent for gold analyses by a fire assay and intensive cyanidation. Dry grain size analyses of primary and amalgamation tailings allowed us to find out in which size fraction gold and mercury are lost. Total mercury losses in sixteen operations were obtained by weighing mercury at the beginning and in all steps of the concentrates’ amalgamation. After analyses, the average gold grade in the feed resulted in 3.80 ± 1.52 ppm (two standard deviations). The gold recovery was 29.24 ± 13.24%, which is low due to a lack of liberation of the fine gold particles from the gangue (silicates). Finer grinding would be necessary. The mercury balance revealed that 42% of the mercury added is lost, in which 26% involves tailings and 16% evaporated. The HgLost-to-AuProduced ratio was found to be 3.35 ± 9.46, which is exceedingly high for this type of amalgamation process that should have this ratio around 1. One reason is the excessive amount of mercury in the amalgams, 76.5 ± 38.12%, when the normal is around 40%–50%. Mercury lost by evaporation in open bonfires is clearly contaminating amalgamation operators (usually children), neighbours, and the environment. The Hg-contaminated tailings and primary tailings are sold to local cyanidation plants, and this can form toxic soluble Hg(CN)2 in the process. The results of this research were brought to the attention of the miners and other stakeholders, including the regulatory agencies of the government. The % gold recovery by amalgamation was not established in this study, but if this process recovers 50 to 60% of the liberated gold particles in a concentrate and 30% of gold was recovered in the sluice boxes, then the total gold recovery should be between 15 and 20; i.e., 80 to 85% of gold mined is lost. On average, an operation produces 8.26 g of gold/month, which is split to six miners, representing USD 69/month/miner or USD 2.3/day. It was discussed with miners, authorities, and community members (in particular female miners) how to avoid exposure to mercury, how to improve gold recovery without mercury, and the health and environmental effects of this pollutant. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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17 pages, 7229 KB  
Article
Study of Hydrometallurgical Treatment of Metal-Bearing Material from Environmental Burdens Containing Iron, Chromium, Nickel, and Cobalt
by Martina Laubertová, Oksana Velgosova, Martin Sisol and Tomáš Vindt
Minerals 2024, 14(10), 968; https://doi.org/10.3390/min14100968 - 25 Sep 2024
Cited by 1 | Viewed by 2322
Abstract
In Slovakia, around 200 environmental burdens that contain a significant amount of usable raw materials were created by the extraction of ores or the dumping of industrial waste. In this research, the hydrometallurgical metal recovery method from a metal-bearing environmental landfill in Sereď [...] Read more.
In Slovakia, around 200 environmental burdens that contain a significant amount of usable raw materials were created by the extraction of ores or the dumping of industrial waste. In this research, the hydrometallurgical metal recovery method from a metal-bearing environmental landfill in Sereď was investigated. The analysis of a representative sample of waste obtained from this landfill proved the presence of significant amounts of metals (43.45% Fe; 1.3% Cr; 0.09% Co, and 0.23% Ni). A thermodynamic study of the metals’ (Fe, Cr, Ni, and Co) leaching probability confirmed the possibility of metal extraction in an acidic environment. Subsequently, the effect of the most important factors on the leaching process (stirring intensity, temperature, liquid-to-solid phase ratio, and acid concentration) was experimentally tested. The analysis of the results determined the optimal leaching conditions. The extraction of 90.35% Fe and 59.62% Cr was ensured at a stirring intensity of 400 rpm, a leaching temperature of 80 °C, a liquid-to-solid phase ratio of 40, and a H2SO4 concentration of 3 mol/dm3. Various techniques, including SEM, EDX, XRD, Eh-pH diagrams, and AAS analysis, were used to analyze samples and products after leaching. The possibility of precipitating metals/compounds from the leachate to obtain a marketable product was theoretically proposed and proven. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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17 pages, 2763 KB  
Article
Research on Enhancing Copper-Ammonia-Thiosulfate Eco-Friendly Gold Leaching by Magnetization of Lixiviant Solution and Their Kinetic Mechanism
by Zhengyu Liu, Jue Kou, Lipeng Fan, Weibin Zhang, Jie Tian, Chunbao Sun, Qiang Li, Jiubo Liu, Chengjun Xing and Guanhua Li
Minerals 2024, 14(7), 697; https://doi.org/10.3390/min14070697 - 8 Jul 2024
Cited by 2 | Viewed by 3917
Abstract
In thiosulfate leaching of gold, the copper-ammonia complex serves as an oxidant and catalyst. This study examined the impact of magnetizing the copper-ammonia thiosulphate lixiviant solution on gold leaching from refractory oxidized ores. Magnetization reduced surface tension, improved wettability and infiltration, and enhanced [...] Read more.
In thiosulfate leaching of gold, the copper-ammonia complex serves as an oxidant and catalyst. This study examined the impact of magnetizing the copper-ammonia thiosulphate lixiviant solution on gold leaching from refractory oxidized ores. Magnetization reduced surface tension, improved wettability and infiltration, and enhanced the diffusion of leaching agents. It also increased dissolved oxygen content and boosted the catalytic efficiency of copper-ammonia complexes. These changes led to more efficient gold extraction, with column leaching showing a 4.74% improvement in extraction rates compared to non-magnetized methods and a 3.67% improvement over cyanide processes. These findings suggest that magnetized copper-ammonia thiosulphate lixiviant is a promising, environmentally friendly alternative to cyanide for refractory oxidized gold ores. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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20 pages, 5973 KB  
Article
Development of Process Flow Sheet for Recovering Strategic Mineral Monazite from a Lean-Grade Bramhagiri Coastal Placer Deposit, Odisha, India
by Deependra Singh, Bighnaraj Mishra, Ankit Sharma, Suddhasatwa Basu and Raghupatruni Bhima Rao
Minerals 2024, 14(2), 139; https://doi.org/10.3390/min14020139 - 26 Jan 2024
Cited by 6 | Viewed by 8680
Abstract
The present investigation deals with the development of a process flow sheet for recovering strategic mineral monazite concentrate from a lean-grade offshore placer deposit of the Bramhagiri coast along the southeast coast of Odisha, India.In the present study, both dry and wet processes [...] Read more.
The present investigation deals with the development of a process flow sheet for recovering strategic mineral monazite concentrate from a lean-grade offshore placer deposit of the Bramhagiri coast along the southeast coast of Odisha, India.In the present study, both dry and wet processes are investigated to improve the recovery and purity of monazite. The results of the pre-concentration studies reveal that by using multi-stage spiral concentrators, the Total Heavy Minerals [THM] have been upgraded to 97.8% with a monazite content of 0.33% from a feed sample containing 4.72% total heavy minerals and 0.01% monazite content. The beneficiation studies revealed that the feed was initially subjected to a high-tension separator, and the non-conducting fraction of the high-tension roll was further subjected to magnetic separation. The magnetic product was again subjected to a flotation process followed by cleaning of the flotation product using a magnetic separator. This magnetic product contains 98.89% monazite with 84% recovery and 0.28% yield from a spiral product containing 0.33% monazite and qualifies for extracting rare earths. It is worth recovering monazite mineral from even lean-grade deposits, as it is a source of uranium, thorium, and rare earth elements and is very high in demand for humankind due to technological advancements. In view of this, monazite recovery is not to be considered for the economic profitability of the process but for strategic requirements. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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14 pages, 9117 KB  
Article
Modified Diglycolamide Resin: Characterization and Potential Application for Rare Earth Element Recovery
by Junnile L. Romero, Carlito Baltazar Tabelin, Ilhwan Park, Richard D. Alorro, Joshua B. Zoleta, Leaniel C. Silva, Takahiko Arima, Toshifumi Igarashi, Takunda Mhandu, Mayumi Ito, Steffen Happel, Naoki Hiroyoshi and Vannie Joy T. Resabal
Minerals 2023, 13(10), 1330; https://doi.org/10.3390/min13101330 - 14 Oct 2023
Cited by 6 | Viewed by 4443
Abstract
Rare earth elements (REEs) are crucial for green energy applications due to their unique properties, but their extraction poses sustainability challenges because the global supply of REEs is concentrated in a few countries, particularly China, which produces 70% of the world’s REEs. To [...] Read more.
Rare earth elements (REEs) are crucial for green energy applications due to their unique properties, but their extraction poses sustainability challenges because the global supply of REEs is concentrated in a few countries, particularly China, which produces 70% of the world’s REEs. To address this, the study investigated TK221, a modified extraction chromatographic resin featuring diglycolamide (DGA) and carbamoyl methyl phosphine oxide (CMPO), as a promising adsorbent for REE recovery. The elemental composition and functional groups of DGA and CMPO on the polystyrene-divinylbenzene (PS-DVB) support of TK221 were confirmed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics of neodymium (Nd), yttrium (Y), cerium (Ce), and erbium (Er) followed the pseudo-second-order kinetic model and Langmuir isotherm, indicating monolayer chemisorption. Furthermore, iron (Fe) adsorption reached apparent equilibrium after 360 min, with consistent Fe adsorption observed at both 360 min and 1440 min. The inclusion of Fe in the study is due to its common presence as an impurity in most REE leachate solutions. The Fe adsorption isotherm results are better fitted with the Langmuir isotherm, implying chemisorption. Maximum adsorption capacities (qmax) of the resin were determined as follows: Nd (45.3 mg/g), Ce (43.1 mg/g), Er (35.1 mg/g), Y (15.6 mg/g), and Fe (12.3 mg/g). ATR-FTIR analysis after adsorption suggested that both C=O and P=O bands shifted from 1679 cm−1 to 1618 cm−1 and 1107 cm−1 to 1142 cm−1 for Y, and from 1679 cm−1 to 1607 cm−1 and 1107 cm−1 to 1135 cm−1 for Ce, implying possible coordination with REEs. These results suggest that TK221 has a huge potential as an alternative adsorbent for REE recovery, thus contributing to sustainable REE supply diversification. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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17 pages, 12408 KB  
Article
Composite Collectors for the Flotation of Refractory Alkaline Rock-Type Rare-Earth Ores
by Chunfeng Li, Zhichao Liu, Zhenjiang Liu, Jiajun Liu, Guang Li, Yuhui Tian and Mingliang Zhou
Minerals 2023, 13(8), 1025; https://doi.org/10.3390/min13081025 - 31 Jul 2023
Cited by 4 | Viewed by 2640
Abstract
Alkaline rock-type rare-earth (RE) ores have significant utilisation value. However, the exploitation of such resources faces great challenges owing to the complex mineral and element assemblages. Composite collectors exhibit excellent performances, which may provide solutions to the flotation problem of alkaline rock-type RE [...] Read more.
Alkaline rock-type rare-earth (RE) ores have significant utilisation value. However, the exploitation of such resources faces great challenges owing to the complex mineral and element assemblages. Composite collectors exhibit excellent performances, which may provide solutions to the flotation problem of alkaline rock-type RE ores. Therefore, 16 collectors typically used in RE ores flotation were selected. Flotation tests were performed to identify collectors with high selectivity and collection ability for RE minerals, then nine composite collectors were prepared by combining the satisfactory collectors. The flotation performances of single and composite collectors for RE minerals were examined, and the composite collector FA301 with different carbon chain lengths was identified as the best one. When FA301 was applied in optimal conditions of slurry temperature, grinding size, collector and inhibitor dosage, RE concentrate yield of 6.29%, REO grade of 32.013%, and recovery of 59.02% were achieved. According to the results of the zeta potential, FTIR, and XPS test, the functional groups (dominated by carboxyl groups) in FA301 chemically adsorbed onto the main active sites (La, Ce, Y, etc.) on the surface of RE minerals. The findings can provide scientific basis for the development of efficient collectors to facilitate the exploitation of RE resources. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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Review

Jump to: Research

40 pages, 6177 KB  
Review
Extraction of Nickel and Cobalt from Complex Low-Grade Lateritic Ores: Challenges and Opportunities
by Gertrude Acquah, William Skinner, George Abaka-Wood, Pavel Spiridonov, Jonas Addai-Mensah and Richmond Asamoah
Minerals 2026, 16(3), 287; https://doi.org/10.3390/min16030287 - 9 Mar 2026
Cited by 1 | Viewed by 1128
Abstract
The accelerating transition to low carbon energy systems has intensified the demand for nickel and cobalt from low-grade (<1.5 wt.%) refractory lateritic ores. These low-grade laterites are however not amenable to conventional beneficiation due to their complex mineralogy, eclectic physicochemical properties, and fine [...] Read more.
The accelerating transition to low carbon energy systems has intensified the demand for nickel and cobalt from low-grade (<1.5 wt.%) refractory lateritic ores. These low-grade laterites are however not amenable to conventional beneficiation due to their complex mineralogy, eclectic physicochemical properties, and fine Ni–Co dissemination. This review examines recent advances made in the extraction of nickel and cobalt from complex low-grade lateritic ores, emphasizing the interplay between ore mineralogy, chemistry, beneficiation, pretreatment, and processing route selection. Developments in selective ore comminution–classification have led to the generation of Ni-rich fine fractions (undersize) and Co-rich coarse fractions (oversize), enabling differentiated extraction strategies that improve resource utilization, frugal energy use, and process efficiency. Mechanical activation via stirred media milling, thermal calcination-induced structural disorder, and dehydroxylate goethite products, are shown to significantly enhance Ni–Co leaching kinetics under both atmospheric and heap leaching conditions. A critical comparison of pyrometallurgical (rotary-kiln electric furnace) and hydrometallurgical (HPAL, EPAL, heap, atmospheric, bioleaching) routes demonstrates that ore-specific optimization is essential to balance recovery, acid consumption, and greenhouse gas emissions. The novel resin in moist mix (RIMM) process, which integrates ambient leaching and in situ ion exchange selective recovery, is shown to offer potential for sustainable values extraction from sub-economic resources. Furthermore, the review highlights the key innovation challenges and concomitant opportunities for enhanced critical battery metal recovery from complex laterite ores. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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50 pages, 8453 KB  
Review
Advances in Lithium Extraction from Spodumene: Alternatives to Sulfuric Acid Digestion
by Esmaeil Jorjani, Jessica Sauvageau, Driss Mrabet and Marouan Rejeb
Minerals 2025, 15(6), 574; https://doi.org/10.3390/min15060574 - 28 May 2025
Cited by 4 | Viewed by 6774
Abstract
Conventional lithium extraction from spodumene via sulfuric acid roasting can achieve up to 98% recovery but suffers from high energy use, acidic residues, and purification complexity. This review evaluates alternative methods for both α- and β-spodumene, aiming for improved sustainability. For α-spodumene, Na [...] Read more.
Conventional lithium extraction from spodumene via sulfuric acid roasting can achieve up to 98% recovery but suffers from high energy use, acidic residues, and purification complexity. This review evaluates alternative methods for both α- and β-spodumene, aiming for improved sustainability. For α-spodumene, Na2SO4–CaO salt roasting achieved >95% recovery at 900 °C via water leaching. Sodium carbonate roasting–NaOH leaching and mechanical activation–Na2SO4 roasting reached 95.9% and ~92%, respectively. High-pressure NaOH leaching reached 95.8%, while alkaline decomposition–acid leaching yielded 53.2–84.1%. Microwave-assisted calcination achieved up to 97% recovery, and fluoride-based roasting gave 93–98% but raised environmental concerns. Bioleaching is eco-friendly but slow, with <3.5% recovery. For β-spodumene, high-pressure leaching using sodium carbonate (>94%), sodium sulfate (90.7%–93.3%), sodium chloride (~93%), and nitric acid (~95%) provided high recoveries. Atmospheric leaching with HF and H3PO4 yielded ~90% and ~40%, respectively, while carbonic acid leaching reached 75% after multiple stages. Chlorination roasting achieved near-complete recovery. The Metso-Outotec high-pressure sodium carbonate leaching process is set for industrial-scale implementation at the Keliber project in 2025, confirming its scalability. Overall, these emerging processes have the potential to reduce energy input, reagent demand, and waste generation, offering practical pathways toward more sustainable lithium production from spodumene. Full article
(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)
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