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Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals

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A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Extractive Metallurgy".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 25836

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Special Issue Editor

Dr. Stefano Ubaldini

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Consiglio Nazionale delle Ricerche (CNR)—Istituto di Geologia Ambientale e Geoingegneria (IGAG), Area della Ricerca di Roma RM 1, Montelibretti, Via Salaria Km 29,300—C.P. 10, 00015 Monterotondo Stazione, Roma, Italy
Interests: primary and secondary raw materials; low-grade georesources; metals recovery; precious metals; heavy metals; leaching; hydrometallurgy; bio-hydrometallurgy; bioprecipitation; electrowinning; remediation processes; environmental innovative technologies; industrial wastes; exhausted batteries; WEEE; minerals; wastewater; acid mine drainage
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Special Issue Information

Dear Colleagues,

The study of innovative and sustainable technologies for the recovery and reuse of raw materials (RMs) from primary and secondary resources is fundamental for economic and industrial development, in compliance with environmental protection, in the context of the circular economy.

Bio/hydrometallurgical processes are new solutions and represent environmentally sustainable practices, not only in the mining and in the environmental sectors for the extraction of base, precious, and toxic metals and rare earth elements (REE), but also for secondary resource valorization with a high content of critical raw materials (CRMs), fundamental in modern technological applications.

Bio/hydrometallurgy consists of leaching and recovery unit operations. Leaching is the solubilization of metals from a solid phase using chemicals or biological agents, whereas recovery is the extraction of metals from polymetallic leachate using physicochemical processes, electrowinning, or biological processes.

The economic value of the processes, which is closely linked to the choice and optimization of the experimental parameters, is of great importance.

For publication in this Special Issue, those articles that contribute to the improvement of innovative bio- and/or hydrometallurgical processes applied for the recovery and recycling of valuable and critical metals will be considered.

I hope you accept this invitation, and help us to create a high-impact and high-quality Special Issue on "Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals".

Dr. Stefano Ubaldini
Guest Editor

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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. Metals 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 2600 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

Primary and secondary raw materials
Low-grade georesources
Precious metals
Heavy metals
Hydrometallurgy
Bio-hydrometallurgy
Electrowinning
Environmental innovative technologies
Industrial wastes
WEEE

Published Papers (14 papers)

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Editorial

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4 pages, 191 KiB

Open AccessEditorial

Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals

by Stefano Ubaldini

Metals 2023, 13(6), 1105; https://doi.org/10.3390/met13061105 - 12 Jun 2023

Viewed by 1054

Abstract

Studying innovative and sustainable technologies for the recovery and reuse of raw materials (RMs) from primary and secondary resources is fundamental for economic and industrial development in compliance with environmental protection and in the context of a circular economy [...] Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

Research

Jump to: Editorial, Other

19 pages, 5984 KiB

Open AccessArticle

Study of Metal Leaching from Printed Circuit Boards by Improved Electrochemical Hydrochlorination Technique Using Alternating Current

by Vera Serga, Aleksej Zarkov, Andrei Shishkin, Edgars Elsts, Maksims Melnichuks, Mikhail Maiorov, Ervins Blumbergs and Vladimir Pankratov

Metals 2023, 13(4), 662; https://doi.org/10.3390/met13040662 - 27 Mar 2023

Cited by 3 | Viewed by 1616

Abstract

This paper presents the results of the leaching of metals from computer PCBs by electrochemical hydrochlorination using alternating current (AC) with an industrial frequency (50 Hz). Leaching was carried out with a disintegrator-crushed computer motherboard with a particle size (d) of <90 μm. In the course of the research, the leaching efficiency of metals including Fe, Sn, Mn, Al, Cu, Zn, Pb, Ni, Ti, Sb, Cr, Co and V was evaluated depending on process parameters, such as AC density, experiment duration, hydrochloric acid concentration in the electrolyte solution, solid/liquid ratio, electrolyte temperature, and the loading option of raw material (loading option 1 involving loading into the electrolyte solution, and loading option 2 involving loading into the filter containers attached to electrodes). The research results showed that AC superimposition significantly intensifies the leaching of metals. It was established that the complete leaching of metals including Al, Mn, Sn, Ti and Zn, under experimental conditions (loading option 2, C_HCl = 6 mol·L⁻¹, i = 0.80 A·cm⁻², S/L = 8.6 g·L⁻¹), is reached after 1.5 h, and that of Cu and Ni is reached after 2 h from the beginning of the experiment. At the same time, the degree of leaching of other metals after 2 h is Co-78.8%, Cr-84.4%, Sb-91.7%, Fe-98.9%, V-98.1% and Pb-5.1%. The paper also reports the results on the leaching of all abovementioned metals, as well as Ag and Pd, with disintegrator-crushed mixed computer PCBs with d < 90 μm and loading option 1. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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15 pages, 1139 KiB

Open AccessArticle

Economic and Environmental Sustainability of an Innovative Cryo-Mechano-Hydrometallurgical Process Validated at Pilot Scale for the Recycling of Li Batteries

by Francesca Pagnanelli, Pier Giorgio Schiavi, Pietro Altimari, Francesca Beolchini, Alessia Amato, Jacopo Coletta, Flavia Forte, Emanuela Moscardini and Luigi Toro

Metals 2023, 13(3), 497; https://doi.org/10.3390/met13030497 - 1 Mar 2023

Cited by 2 | Viewed by 1584

Abstract

An innovative cryo-mechano-hydrometallurgical process (named LIBAT) was demonstrated at pilot scale for the treatment of EOL lithium primary batteries with chemistry Li(0)-MnO₂. The process allowed the recycling of steel scraps from external cases after cryomechanical dismantling, and the recovery of Mn and Li products after hydrometallurgical processing. During demonstration activities, about nine tons of batteries were treated in the cryomechanical section, and one ton of black mass was treated in the hydrometallurgical section for the recovery of Mn hydroxides and Li₂CO₃. The environmental impacts of the process were evaluated in comparison with an innovative pyrometallurgical approach allowing Li recovery, confirming the benefits of the proposed process due to a reduction in energy consumption. Process simulations were performed considering different mixture feeds (only Li primary, or mixture with Li-ion batteries) and process options (only the cryomechanical section of the integral process) to assess the lower limits of potentiality that would ensure economic sustainability. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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14 pages, 2254 KiB

Open AccessArticle

Extraction and Recovery of Metals from Spent HDS Catalysts: Lab- and Pilot-Scale Results of the Overall Process

by Nertil Xhaferaj and Francesco Ferella

Metals 2022, 12(12), 2162; https://doi.org/10.3390/met12122162 - 15 Dec 2022

Cited by 4 | Viewed by 2695 | Correction

Abstract

The present study proposes an overall recycling process for spent hydrodesulfurization (HDS) catalysts. The process put together stages already known in the technical literature, tested again with samples coming from the roasting stage in a pilot kiln, which is the most limiting stage of metal recovery from spent catalysts. These catalysts contain valuable metals like cobalt (Co), molybdenum (Mo), nickel (Ni), and vanadium (V). In particular, one Co-Mo catalyst was treated in order to optimize the roasting step (time, soda ash, and temperature) at a pilot scale and thus maximize the extraction yield of molybdenum (Mo) and vanadium (V). In particular, a dry Co-Mo catalyst was used. After roasting at 700 °C for 2.5 h, the best conditions, the catalysts underwent water leaching, separating Mo and V from Co and the alumina carrier, which remained in the solid residue. The pregnant solution was treated to remove arsenic (As) and phosphorus (P), representing the main impurities for producing steel alloys. V was precipitated as NH₄Cl, and further calcined to obtain commercial-grade V₂O₅, whereas Mo was recovered as molybdic acid by further precipitation at a pH of around one. Thus, molybdic acid was calcined and converted into commercial-grade MoO₃ by calcination. The hydrometallurgical section was tested on a lab scale. The total recovery yield was nearly 61% for Mo and 68% for V, respectively, compared with their initial concentration in the spent Co-Mo catalysts. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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17 pages, 11147 KiB

Open AccessArticle

Bio-Assisted Leaching of Non-Ferrous Metals from Waste Printed Circuit Boards—Importance of Process Parameters

by Arevik Vardanyan, Narine Vardanyan, Mohamed Aâtach, Pierre Malavasi and Stoyan Gaydardzhiev

Metals 2022, 12(12), 2092; https://doi.org/10.3390/met12122092 - 6 Dec 2022

Cited by 5 | Viewed by 1765

Abstract

The effect of varying process parameters during bio-catalyzed leaching of metals from end-of-life printed circuit boards (PCBs) was investigated. Fragmented PCBs (under 2 mm) were subjected to an indirect bioleaching in a stirred tank reactor while pulp density, pH and initial ferric iron content were varied. An iron oxidizing Acidithiobacillus ferrooxidans 61 microbial strain was used to generate the lixiviant through oxidizing Fe(II) to Fe(III). Chemically generated Fe(III) was tested as lixiviant under the same conditions as the biological one for comparative purposes. Cell enumeration during leaching and microscopic observations of the input and leached PCBs were conducted in parallel to shed light on the observed phenomena. The degree of bringing metals in solution was found to depend mainly on ferric iron concentration and pH. For the entire duration being always kept as 24 h, substantial portion of Cu (~87%) was extracted respectively at 1% pulp density (PD), 15.5 g/L Fe³⁺ and pH 1. For Zn and Ni, nearly 100% recovery was observed at 5% PD, 18 g/L Fe³⁺ and pH 1.1. The achieved results offer possibilities for further studies at higher pulp density, to ultimately render the bioleaching approach as enabling economical and environmentally friendly technology for urban mining of non-ferrous metals. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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17 pages, 4090 KiB

Open AccessArticle

Leaching of Gold and Copper from Printed Circuit Boards under the Alternating Current Action in Hydrochloric Acid Electrolytes

by Vera Serga, Aleksej Zarkov, Ervins Blumbergs, Andrei Shishkin, Janis Baronins, Edgars Elsts and Vladimir Pankratov

Metals 2022, 12(11), 1953; https://doi.org/10.3390/met12111953 - 15 Nov 2022

Cited by 6 | Viewed by 2253

Abstract

Modern technologies for recycling electronic waste (e-waste) have high economic efficiency and environmental safety requirements. Among the existing technologies, hydrometallurgy is considered to be the most promising technology for e-waste recycling. Increasing attention paid to the chlorination method is associated with the complex recycling of low-grade ores containing noble metals and the raw materials of secondary polymetallic. In this paper, we propose a new scheme for leaching metals from computer printed circuit boards (PCBs) pre-crushed in a disintegrator: The processes of chlorine production and hydrochlorination are implemented in one reactor under the action of an alternating current (AC) of industrial frequency (50 Hz). Three fine fractions of raw material powders with particle size d < 90 µm, d = 90–180 µm, and d = 180–350 µm were used as research objects and the finest fraction of the raw material (d < 90 µm) was studied in more detail. It was found that complete leaching of gold is achieved from fractions of raw materials with a particle size d = 90–180 µm and d = 180–350 µm, containing 277 ppm and 67 ppm of the gold, respectively, at an experiment duration (t_ex) of 2 h, a current density (i) of 0.66 A·cm⁻², and a solid/liquid (S/L) ratio of 8.6 g·L⁻¹. Under the same conditions of the electrochemical leaching process from the fraction of raw materials with a particle size of d < 90 µm and a gold content of 824 ppm, the degree of metal leaching is 80.5%. At the same time, with an increase in particle size in the raw material fractions from d < 90 µm to d = 180–350 µm and a copper content in the raw material from 1.40% to 6.13%, an increase in the degree of its leaching from 81.6% to 95.2%, respectively, is observed. In the framework of the preliminary study presented in this work, for the finest raw material fraction with d < 90 μm the highest gold leaching degree (86.3%) was achieved under the following experimental conditions: t_ex= 4 h, C_HCl = 6 M, i = 0.88 A·cm^–2, S/L ratio—8.6 g·L^–1 and the highest copper leaching degree (94.2%) was achieved under the following experimental conditions: t_ex = 2 h, C_HCl = 6 M, i = 0.64 A·cm^–2, and S/L ratio—2.9 g·L^–1. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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12 pages, 4203 KiB

Open AccessArticle

The Role of Mycorrhizal-Assisted Phytomining in the Recovery of Raw Materials from Mine Wastes

by Adalgisa Scotti, Vanesa Analía Silvani, Natalia Andrea Juarez, Alicia Margarita Godeas and Stefano Ubaldini

Metals 2022, 12(11), 1828; https://doi.org/10.3390/met12111828 - 27 Oct 2022

Cited by 4 | Viewed by 1382

Abstract

In recent years, critical and secondary raw materials (CRMs and SRMs, respectively) have received great interest within the circular economy model. In this work, the mycorrhizal-assisted phytomining (MAP) system, composed of Helianthus annuus–arbuscular mycorrhizal fungus Rhizophagus intraradices–Zn-volcanic ashes, was applied in bioreactors for the recovery of CRMs (Sr, P) and SRMs (Cr, Zn, Cu, Mn, Rb, Ni) from mining wastes of the Los Cóndores mine (Argentina). Our results showed high bioaccumulation of Sr, P, Mn, and Zn in the aerial tissues, and a high root-to-shoot translocation for Mn (4.02) > Sr > P > Rb > Zn (0.84). Mycorrhization treatment increased the root-to-leaf translocation for Cr and P and prevented translocation towards flower tissues in most elements. The estimated bioextracting potential of the MAP system (290 plants) in a vegetable depuration module (VDM) ranged from 158 mg/m³ P > Zn > Mn > 15.1 mg/m³ Sr. We demonstrated a promising and cost-effective biotechnology applicable in agronomical practices, given the exclusion of toxic elements in flower parts, as well as for the recovery of CRMs and SRMs by hydrometallurgy from plant biomass. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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17 pages, 1557 KiB

Open AccessArticle

Biosorption and Bioaccumulation Capacity of Arthrospira platensis toward Yttrium Ions

by Nikita Yushin, Inga Zinicovscaia, Liliana Cepoi, Tatiana Chiriac, Ludmila Rudi and Dmitrii Grozdov

Metals 2022, 12(9), 1465; https://doi.org/10.3390/met12091465 - 31 Aug 2022

Cited by 8 | Viewed by 1775

Abstract

Yttrium is an element of critical importance for industry and technology. Cyanobacteria Arthrospira platensis was employed for Y(III) recovery from contaminated wastewater through biosorption and bioaccumulation processes. The effect of pH of a solution, contact time, temperature, and initial Y(III) concentration on the adsorption behaviour of Arthrospira platensis were studied. The maximum adsorption capacity of 719.8 mg/g was attained at a pH of 3, temperature of 20 °C, and adsorption time of 3 min. The Langmuir and Freundlich isotherm models were suitable to describe the equilibrium of the biosorption, while kinetic of the process followed the pseudo-first-order model. Thermodynamic parameters showed that the biosorption process was spontaneous and exothermic in nature. In bioaccumulation experiments, Arthrospira platensis was able to remove up to 70% of Y(III) from the solution. Beside biomass uptake capacity, the toxic effect of Y(III) on the biomass productivity and biochemical composition was assessed. Thus, Y(III) in concentration of 10–30 mg/L led to a decrease in the content of proteins, carbohydrates, and phycobiliproteins in the biomass and had no significant negative impact on productivity and photosynthetic pigments content. Experiments performed using Arthrospira platensis showed that biological objects have a great potential to be applied for the recovery of rare earth elements from wastewater. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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14 pages, 4280 KiB

Open AccessArticle

Effect of Temperature on Biobeneficiation of Bulk Copper-Nickel Concentrate with Thermoacidophilic Microbial Communities

by Anna Panyushkina, Natalya Fomchenko, Vladislav Babenko and Maxim Muravyov

Metals 2021, 11(12), 1969; https://doi.org/10.3390/met11121969 - 7 Dec 2021

Cited by 6 | Viewed by 2164

Abstract

Bioleaching of the bulk copper–nickel sulfide concentrate was proposed as a method to remove nickel from it and to obtain a concentrate containing copper as chalcopyrite. This approach is based on the different refractoriness of sulfide minerals in ferric sulfate solutions and oxidation by acidophilic microorganisms. The bulk concentrate contained 10.8% copper in the form of chalcopyrite (CuFeS₂) and 7.2% nickel that occurred in pentlandite ((Ni,Fe)₉S₈) and violarite (FeNi₂S₄). Three microbial communities grown at 35, 40, and 50 °C were used for bioleaching. The microbial community at 40 °C was the most diverse in the genus and species composition. At all temperatures of the process, the key roles in bioleaching belonged to mixotrophic and heterotrophic acidophiles. The highest levels of nickel leaching of 97.2 and 96.3% were observed in the case of communities growing at 40 and 50 °C, respectively. At the same time, the bioleach residue, which could be characterized as a marketable high-grade copper (chalcopyrite) concentrate, was obtained only at 40 °C. This solid contained 15.6% copper and 0.54% nickel. Thus, the biobeneficiation of bulk sulfide concentrates can be a promising field of biohydrometallurgy. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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17 pages, 2291 KiB

Open AccessFeature PaperArticle

Leaching of Zinc for Subsequent Recovery by Hydrometallurgical Techniques from Electric Arc Furnace Dusts and Utilisation of the Leaching Process Residues for Ceramic Materials for Construction Purposes

by Juan María Terrones-Saeta, Jorge Suárez-Macías, Evaristo Rafael Moreno-López and Francisco Antonio Corpas-Iglesias

Metals 2021, 11(10), 1603; https://doi.org/10.3390/met11101603 - 9 Oct 2021

Cited by 7 | Viewed by 1547

Abstract

Steel is one of the most widely used materials in the past and today. Various techniques are used to recycle this material, including the electric arc furnace. This process has several advantages, but it also has a major disadvantage, namely, the generation of waste such as electric arc furnace dusts. Electric arc furnace dusts are classified as hazardous waste due to their high percentage of heavy metals, including zinc. Consequently, in the present research, the leaching of zinc for recovery with sulfuric acid solutions at ambient temperature and atmospheric pressure is evaluated, as well as the reuse of the leaching process residue as a raw material for ceramic materials. The sulfuric acid solutions were 0.125, 0.25, 0.5, and 1 molar, using clay for ceramic conforming and percentages of the leaching residue from 0–50%. The results showed that the optimum solution was 1 molar sulfuric acid, recovering all the zinc in the sample in 36 h. Furthermore, it was found that the clay-conformed ceramics with less than 40% leaching residue showed acceptable physical and mechanical properties according to standards. Therefore, this research develops a new environmental hydrometallurgy in which metallic elements of interest are valorized and the production of waste is avoided, reducing the deposition of hazardous waste in landfills and the extraction of raw materials for the manufacture of construction materials. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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24 pages, 3983 KiB

Open AccessArticle

Evaluation of Copper Leaching for Subsequent Recovery from the Waste Dumps of the Linares Mining District and Their Use for Construction Materials

by Juan María Terrones-Saeta, Jorge Suárez-Macías, Ana María Castañón and Francisco Antonio Corpas-Iglesias

Metals 2021, 11(8), 1328; https://doi.org/10.3390/met11081328 - 23 Aug 2021

Cited by 3 | Viewed by 2105

Abstract

The development of the population’s well-being involves the use of different raw materials. However, metallic elements such as copper are currently scarce due to their intensive use in different sectors. Therefore, new sources of raw materials that provide these elements, are of lower cost, and use waste for their extraction must be sought. For this reason, in this research, different waste dumps of the mining district of Linares (Spain) are studied to evaluate the existence of recoverable copper by hydrometallurgical techniques. The material from the waste dump selected as potentially viable is leached with different sulfuric acid solutions (0.25, 0.5, 1, and 2 mol) and at different times, obtaining copper concentrations usable for subsequent hydrometallurgical processes. In addition, in order to develop an environmental hydrometallurgy, the leach waste is characterized, and bituminous mixtures are made with it. The results of the present investigation showed that it was possible to recover 80% of the copper in the waste dumps of the Linares mining district with 1 and 2 mol solutions of sulfuric acid. At the same time, the waste from the leaching process was found to be suitable for use as an aggregate in bituminous mixtures. Therefore, bituminous mixtures were conformed, and it was obtained that the optimum percentage of bituminous emulsion was 6.95% for the proposed granulometry. This emulsion percentage, which corresponds to a residual bitumen percentage of 4.17%, showed particle loss test results of 14% and 18% after immersion. In addition, the stability test values for the Marshall test with the above-mentioned bitumen emulsion percentage and leaching waste showed a stability of 8.99 KN. This fact demonstrates the quality of the bituminous mixture made with the leaching waste for use in bituminous mixtures. Consequently, it can be affirmed that in the present investigation, a significant percentage of copper has been extracted from the waste dumps of the mining district of Linares (Spain) and that the waste after processing can be used in bituminous mixtures, there being a closed cycle of materials in which no waste is produced. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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17 pages, 30399 KiB

Open AccessArticle

Sustainable Recovery of Secondary and Critical Raw Materials from Classified Mining Residues Using Mycorrhizal-Assisted Phytoextraction

by Adalgisa Scotti, Stefano Milia, Vanesa Silvani, Giovanna Cappai, Daniela Guglietta, Francesca Trapasso, Emanuela Tempesta, Daniele Passeri, Alicia Godeas, Martín Gómez and Stefano Ubaldini

Metals 2021, 11(8), 1163; https://doi.org/10.3390/met11081163 - 22 Jul 2021

Cited by 8 | Viewed by 2101

Abstract

In this work, mycorrhizal-assisted phytoextraction (MAP, Helianthus annuus–arbuscular mycorrhizal fungus Rhizophagus intraradices–Zn-volcanic ashes) was applied for the recovery of secondary and critical raw materials (SRMs and CRMs, respectively) from Joda West (Odisha, India) mine residues, within a novel multidisciplinary management strategy. Mine residues were preliminarily characterized by using advanced analytical techniques, and subsequently mapped, classified and selected using multispectral satellite Sentinel-2A images and cluster analysis. Selected mine residues were treated by MAP at laboratory scale, and the fate of several SRMs (e.g., Zn, Cr, As, Ni, Cu, Ca, Al, K, S, Rb, Fe, Mn) and CRMs (such as Ga, Ti, P, Ba and Sr) was investigated. Bioconcentration factors in shoots (BC_S) and roots (BC_R) and translocation factors (TF) were: 5.34(P) > BCS > 0.00(Al); 15.0(S) > BCR > 0.038(Ba); 9.28(Rb) > TF > 0.02(Ti). Results were used to predict MAP performance at larger scale, simulating a Vegetable Depuration Module (VDM) containing mine residues (1 m³). Estimated bio-extracting potential (BP) was in the range 2417 g/m³ (K) > BP> 0.14 g/m³ (As), suggesting the eventual subsequent recovery of SRMs and CRMs by hydrometallurgical techniques, with final purification by selective electrodeposition, as a viable and cost-effective option. The results are promising for MAP application at larger scale, within a circular economy-based approach. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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14 pages, 4461 KiB

Open AccessArticle

Pressure Oxidation of Arsenic (III) Ions in the H₃AsO₃-Fe²⁺-Cu²⁺-H₂SO₄ System

by Kirill Karimov, Denis Rogozhnikov, Oleg Dizer, Maksim Tretiak, Sergey Mamyachenkov and Stanislav Naboichenko

Metals 2021, 11(6), 975; https://doi.org/10.3390/met11060975 - 17 Jun 2021

Cited by 1 | Viewed by 1783

Abstract

The processing of low-grade polymetallic materials, such as copper–zinc, copper–lead–zinc, and poor arsenic-containing copper concentrates using hydrometallurgical methods is becoming increasingly important due to the depletion of rich and easily extracted mineral resources, as well as due to the need to reduce harmful emissions from metallurgy, especially given the high content of arsenic in ores. Ferric arsenates obtained through hydrothermal precipitation are the least soluble and most stable form of arsenic, which is essential for its disposal. This paper describes the investigation of the oxidation kinetics of As (III) ions to As (V) which is required for efficient purification of the resulting solutions and precipitation of low-solubility ferric arsenates. The effect of temperature (160–200 °C), the initial concentration of Fe (II) (3.6–89.5 mmol/dm³), Cu (II) (6.3–62.9 of mmol/dm³) and the oxygen pressure (0.2–0.5 MPa) on the oxidation efficiency of As (III) to As (V) was studied. As (III) oxidation in H₃AsO-Fe²⁺-Cu²⁺-H₂SO₄ and H₃AsO-Fe²⁺-H₂SO₄ systems was controlled by a chemical reaction with the apparent activation energy (Ea (≈84.3–86.3 kJ/mol)). The increase in the concentration of Fe (II) ions and addition of an external catalyst (Cu (II) ions) both have a positive effect on the process. When Cu (II) ions are introduced into the solution, their catalytic effect is confirmed by a decrease in the partial orders, Fe (II) ions concentration from 0.43 to 0.20, and the oxygen pressure from 0.95 to 0.69. The revealed catalytic effect is associated with a positive effect of Cu (II) ions on the oxidation of Fe (II) to Fe (III) ions, which further participate in As (III) oxidation. The semi-empirical equations describing the reaction rate under the studied conditions are written. Full article

(This article belongs to the Special Issue Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals)

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