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Minerals
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New Extraction Processes for Critical Metals from Non-Metallurgical Resources
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New Extraction Processes for Critical Metals from Non-Metallurgical Resources

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

Deadline for manuscript submissions: 23 September 2026 | Viewed by 7208

Special Issue Editors

Dr. Rogério C.S. Navarro

E-Mail Website
Guest Editor
Chemical and Materials Engineering Department, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro 22451-900, RJ, Brazil
Interests: thermodynamic modelling; kinetic modelling; heterogeneous catalysis; pyrometallurgy; metals adsorption
Special Issues, Collections and Topics in MDPI journals
Dr. Amilton Barbosa Botelho Junior

E-Mail Website
Guest Editor
Department of Chemical Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
Interests: hydrometallurgy; separation process; electrodialysis; reverse osmosis; ultrafiltration; microfiltration; solvent extraction; recycling processes; circular economy; SDGs; net-zero emission
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Currently, we are witnessing a rapidly increasing number of initiatives contributing to a sustainable energy transition. However, in many cases, there is a limited supply of critical metals to support the future demand for manufacturing devices for electric transport, green energy production, and the ever-increasing consumption of communication and entertainment gadgets. From this perspective, it is imperative to develop new routes to exploit atypical (non-metallurgical) sources of metals, thereby lowering the gap between the future demand and expected supply and avoid hindering energy transition goals. The use of complex raw materials in the metallurgical industry, such as urban residues, low-grade mineral occurrences, and industry wastes and effluents, is not only desirable but also necessary in order to achieve such goals. In this context, processes such as thermodynamic and kinetic modeling, as well as transport phenomena relating to such challenging reaction systems, provide important foundations for the development of efficient extraction routes.

This Special Issue invites submissions of original scientific research associated with new extractive processes, based on the use of complex raw materials as sources for recovering critical metals, which are strongly guided by accurate thermodynamic, kinetic, and/or transport phenomena modeling. This Special Issue focuses on the following topics:

  1. The study of equilibrium conditions to promote the selective recovery of critical metals;
  2. Simulation and optimization of operational conditions based on kinetic modeling;
  3. Transport phenomena simulations to understand the behavior of proposed equipment for metal extraction under different process scales;
  4. Fundamental research based on the application of either density functional theory or molecular dynamics computations.

Yours faithfully,

Dr. Rogério C.S. Navarro
Dr. Amilton Barbosa Botelho Junior
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

  • electronic waste
  • battery metals
  • low-grade resources
  • metallurgical waste
  • pyrometallurgy
  • hydrometallurgy

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Published Papers (5 papers)

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Research

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16 pages, 2913 KB  
Article
Development of an Extraction Process for Niobium Pentoxide from Columbite Using Sodium Carbonate and Boric Acid
by Ramon Silveira, Lucio Rosso Neto, Felipe Fardin Grillo, José Roberto de Oliveira, Matheus Vinicius Gregory Zimmermann, Mateus Milanez, Tiago Elias Allievi Frizon, Jorge Luis Coleti, Agenor De Noni, Jr. and Eduardo Junca
Minerals 2025, 15(12), 1254; https://doi.org/10.3390/min15121254 - 26 Nov 2025
Viewed by 431
Abstract
The aim of this study was to initiate the development of a route for the extraction of niobium oxide from columbite ore using sodium carbonate and boric acid. Initially, the columbite ore was characterized. Eight formulations were prepared to investigate the proportion of [...] Read more.
The aim of this study was to initiate the development of a route for the extraction of niobium oxide from columbite ore using sodium carbonate and boric acid. Initially, the columbite ore was characterized. Eight formulations were prepared to investigate the proportion of sodium carbonate to boric acid. The fusions were carried out at 900 °C for 60 min. Afterwards, magnetic separation was performed to remove the iron present in the formulations. From the non-magnetic fraction, water leaching was conducted to investigate the effects of temperature, time, and solid-to-liquid ratio. Finally, the product obtained from water leaching was calcined to obtain niobium oxide. The results indicated that the addition of boric acid contributed to reducing both viscosity and fusion temperature, favoring the release of niobium. The water leaching step showed an inverse dependence on the solid-to-liquid ratio, meaning that decreasing the solid content and increasing the water content favored the solubilization of niobium-containing phases. Temperature and time did not have a statistically significant effect on the leaching process. At the end of the route, niobium oxide was obtained as the final product, confirmed by X-ray diffraction and scanning electron microscopy. Full article
(This article belongs to the Special Issue New Extraction Processes for Critical Metals from Non-Metallurgical Resources)
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25 pages, 4176 KB  
Article
Aluminothermic Recovery of Strategic Ferroalloys from Ladle Slag: An Integrated Thermodynamic and Experimental Approach
by Filippo Disconzi, Maurizio Bellotto, Riccardo Frazzetto, Katya Brunelli, Matteo Ardit and Gilberto Artioli
Minerals 2025, 15(11), 1121; https://doi.org/10.3390/min15111121 - 27 Oct 2025
Viewed by 848
Abstract
Ladle slag (LF slag) is a by-product of secondary steelmaking that presents unique valorization challenges compared to BOF or EAF slags due to its distinctive chemical composition (high Al2O3 and CaO content) and uncontrolled hydraulic activity. While other steelmaking slags [...] Read more.
Ladle slag (LF slag) is a by-product of secondary steelmaking that presents unique valorization challenges compared to BOF or EAF slags due to its distinctive chemical composition (high Al2O3 and CaO content) and uncontrolled hydraulic activity. While other steelmaking slags can be reused as supplementary cementitious materials or aggregates, LF slag is predominantly landfilled, with over 2 million tons discarded annually in Europe alone. This study introduces a novel pyrometallurgical valorization strategy that, unlike conventional approaches focused solely on mineral recovery, simultaneously recovers both metallic and mineral value through aluminothermic reduction. This process utilizes end-of-waste aluminum scrap rather than virgin materials to reduce Fe and Si oxides, creating a circular economy solution that addresses two waste streams simultaneously. The process generates two valuable products with low liquidus temperatures: a ferrosilicon alloy (FeSi15-50 grade) and a residual oxide rich in calcium and magnesium aluminates suitable for cementitious or ceramic applications. Through the integration of FactSage thermodynamic simulations with experimental validation, it is possible to predict and control phase evolution during equilibrium cooling, an approach not previously applied to LF slag valorization. Experimental validation using industrial slags confirms the theoretical predictions and demonstrates the process operates in a near-energy-neutral, self-sustaining mode by recovering both chemical and sensible thermal energy (50–100 kWh per ton of slag). This represents approximately 90% lower energy consumption compared to conventional ferrosilicon production. The work provides a comprehensive and scalable approach to transform a problematic waste material into valuable products, supporting circular economy principles and low-carbon metallurgy objectives. Full article
(This article belongs to the Special Issue New Extraction Processes for Critical Metals from Non-Metallurgical Resources)
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16 pages, 2562 KB  
Article
Metal Recovery from Discarded Lithium-Ion Batteries by Bioleaching Coupled with Minimal Mechanical Pre-Treatment
by Lidia Garcia, Joan Morell, Conxita Lao, Montserrat Solé-Sardans and Antonio D. Dorado
Minerals 2025, 15(6), 566; https://doi.org/10.3390/min15060566 - 26 May 2025
Cited by 3 | Viewed by 4655
Abstract
The rising demand for lithium-ion batteries (LIBs), driven by the growing consumption of electronic devices and the expansion of electric vehicles, is leading to a concerning depletion of primary metal resources and a significant accumulation of electronic waste. This urgent challenge highlights the [...] Read more.
The rising demand for lithium-ion batteries (LIBs), driven by the growing consumption of electronic devices and the expansion of electric vehicles, is leading to a concerning depletion of primary metal resources and a significant accumulation of electronic waste. This urgent challenge highlights the need for sustainable recovery methods to extract valuable metals from spent LIBs, aligning with circular economy principles. In this study, the preparation of spent batteries for the bioleaching process was achieved with minimal manipulation. This included a preliminary discharge to ensure safety in subsequent processes and a brief crushing to facilitate the access of leaching agents to valuable metals. Unlike most studies that grind batteries to obtain powders between 70 and 200 microns, our approach works with particles sized around 5 mm. Additionally, our preparation process avoids any thermal or chemical treatments. This straightforward pre-treatment process marks a significant advancement by reducing the complexity and cost of processing. A systematic study was conducted on various fractions of the large particle sizes, using Fe (III) produced through bio-oxidation by A. ferrooxidans and biogenically obtained H2SO4 from A. thiooxidans. The highest metal extraction rates were achieved using the unsorted fraction, directly obtained from the black mass after the grinding process, without additional particle separation. When treated with bio-oxidized Fe (III), this fraction achieved a 95% recovery of Cu, Ni, and Al within 20 min, and over 90% recovery of Co, Mn, and Li within approximately 30 min. These recovery rates are attributed to the combined reducing power of Al and Cu already present in the black mass and the Fe (II) generated during the oxidation reactions of metallic Cu and Al. These elements actively facilitate the reduction of transition metal oxides into their more soluble, lower-valence states, enhancing the overall metal solubilization process. The extraction was carried out at room temperature in an acidic medium with a pH no lower than 1.5. These results demonstrate significant potential for efficient metal recovery from spent batteries with minimal pre-treatment, minimizing environmental impact. Additionally, the simplified residue preparation process can be easily integrated into existing waste management facilities without the need for additional equipment. Full article
(This article belongs to the Special Issue New Extraction Processes for Critical Metals from Non-Metallurgical Resources)
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Review

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30 pages, 1856 KB  
Review
Unveiling the Potential of Microalgae for Efficient Metal Recovery from E-Waste Leachates
by Houda Ennaceri, Mohneesh Kalwani, Rexley Charles, Tasneema Ishika, Ashiwin Vadiveloo and Navid Reza Moheimani
Minerals 2026, 16(3), 243; https://doi.org/10.3390/min16030243 - 26 Feb 2026
Viewed by 246
Abstract
Electronic waste (e-waste) has emerged as one of the most critical environmental challenges of the twenty-first century. It encompasses a wide range of discarded electrical and electronic equipment, including information and communication technologies, household appliances, entertainment systems, and related components. While e-waste contains [...] Read more.
Electronic waste (e-waste) has emerged as one of the most critical environmental challenges of the twenty-first century. It encompasses a wide range of discarded electrical and electronic equipment, including information and communication technologies, household appliances, entertainment systems, and related components. While e-waste contains valuable recoverable materials, it also harbours hazardous substances such as toxic heavy metals, flame retardants, and persistent organic pollutants. Inadequate disposal practices, particularly open dumping and landfilling, result in the generation of toxic leachates that contaminate soil as well as surface and groundwater, posing severe threats to environmental integrity and public health. Evidence indicates that landfill leachates can infiltrate groundwater at considerable depths, exceeding permissible limits of heavy metals and metalloids and contributing to serious health disorders. Consequently, the implementation of effective e-waste management strategies and environmentally sound disposal practices is imperative to minimize its detrimental environmental and human health impacts. Microalgae systems can achieve up to 98% removal efficiency and up to five cycles reusability. In this paper, the drawbacks of the traditional methods for metal recovery from e-waste and the potential of microalgae were discussed. The downstream processing and metal extraction from microalgal biomass is critically discussed as well as strategies to support the circular economy. Full article
(This article belongs to the Special Issue New Extraction Processes for Critical Metals from Non-Metallurgical Resources)
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22 pages, 1198 KB  
Review
Biogenic Production of Iron Oxide Nanoparticles from Mining Tailings: A Sustainable Approach to Magnetic Materials
by Gloria Amo-Duodu, Emmanuel Kweinor Tetteh, Parisa Arabzadeh Bahri, Navid Reza Moheimani and Houda Ennaceri
Minerals 2026, 16(3), 241; https://doi.org/10.3390/min16030241 - 26 Feb 2026
Viewed by 290
Abstract
Mining tailings are considered a significant environmental challenge due to their large quantities and high residual metal content, particularly iron. Recent developments in biogenic technologies offer a sustainable approach to recovering valuable materials from these waste streams. We consider a biogenic iron oxide [...] Read more.
Mining tailings are considered a significant environmental challenge due to their large quantities and high residual metal content, particularly iron. Recent developments in biogenic technologies offer a sustainable approach to recovering valuable materials from these waste streams. We consider a biogenic iron oxide nanoparticles production process from mining tailings as an environmentally friendly route to magnetic materials. Microorganisms, including iron-oxidizing and iron-reducing bacteria, microalgae, and fungi, can convert soluble and mineral-bound iron into iron oxide nanoparticles (NPs) phases such as magnetite, maghemite, and hematite. These biogenic iron oxide NPs often exhibit specific physicochemical properties, including controlled particle size, high surface area, and engineered magnetic properties, which make them potentially important for applications in environmental remediation, catalysis, and agriculture. The processes behind microbial iron conversion, the parameters governing mineral phase formation, and the approaches for optimizing the process are presented. This strategy supports the circular economy concept by combining biogenic synthesis with various forms of mining waste, thereby reducing environmental threats associated with tailings confinement and providing an environmentally friendly mechanism for the production of value-added magnetic materials. Full article
(This article belongs to the Special Issue New Extraction Processes for Critical Metals from Non-Metallurgical Resources)
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