Special Issue "Hydrometallurgical Recycling of Critical Metals from End-of-Life Devices"

A special issue of Recycling (ISSN 2313-4321).

Deadline for manuscript submissions: 15 May 2022.

Special Issue Editor

Dr. Ana Paula Paiva
E-Mail Website
Guest Editor
Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa Campo Grande, C8 1749-016 Lisboa, Portugal
Interests: liquid–liquid (solvent) extraction in hydrometallurgy; synthesis and characterization of organic extractants; extraction of platinum-group metals (platinum, palladium, rhodium and ruthenium), silver and iron from chloride media; hydrometallurgical recycling of end-of-life materials, e.g., spent catalysts
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Special Issue Information

Dear Colleagues,

The long list of technological devices used in our day-to-day life and in modern industrial plants and diverse facilities relies extensively on the use of several metals. When those devices are no longer useful, they should be processed to recycle the involved materials since most of them are scarce, harmful to the environment, and valuable. This overall situation has led European Union to prepare lists of “critical raw materials” every 3 years since 2011. The latest one from 2017 identified 27 “critical raw materials,” 17 of which are metals. Recycling of metals from spent devices should therefore be considered as a top priority.

Several recycling plants worldwide are primarily based on pyrometallurgical techniques, but hydrometallurgy arises as a possible alternative; as lower temperatures are involved, it exhibits potential for extraction of any valuable co-metals, it can be adapted to both small- and large-scale operations, and liquid effluents are usually easier to handle than the volatile combustion emissions from the pyro-based recycling sites.

This Special Issue welcomes review, original research, and case studies articles, focusing on innovative and challenging hydrometallurgical techniques particularly developed to recycle end-of life devices containing critical metals, e.g., spent industrial catalysts and catalytic converters (SCC), waste electrical and electronic equipment (WEEE), spent batteries of different kinds, end-of-life fluorescent lamps, NdFeB magnets and similar devices, waste liquid crystal displays (LCD).

Dr. Ana Paula Paiva
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 papers will be 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. Recycling is an international peer-reviewed open access quarterly 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 1400 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

  • Recycling of spent devices
  • SCC, WEEE, LCD
  • Hydrometallurgy
  • Leaching/digestion
  • Bioleaching
  • Separation and purification methods
  • solvent extraction
  • Ion exchange
  • Ionic liquids
  • Critical metals

Published Papers (5 papers)

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Research

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Article
Recovery of Ag, Au, and Pt from Printed Circuit Boards by Pressure Leaching
Recycling 2021, 6(4), 67; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6040067 - 13 Oct 2021
Viewed by 417
Abstract
Reclamation of printed circuit boards (PCBs) to recover metals is gaining growing attention due to minerals being non-renewable resources. Currently, metals extraction from PCBs through an efficient and green method is still under investigation. The present investigation concerns the recycling of printed circuit [...] Read more.
Reclamation of printed circuit boards (PCBs) to recover metals is gaining growing attention due to minerals being non-renewable resources. Currently, metals extraction from PCBs through an efficient and green method is still under investigation. The present investigation concerns the recycling of printed circuit boards using hydrometallurgical processes. First, the basic metals (Cu, Ni, Zn and Fe) were separated using a sulfuric acid solution at moderate temperatures. The remaining solids were characterized by SEM-EDS, whereby a high content of precious metals (Au, Ag and Pt) was observed. In the second stage, solids were leached with a solution of HCl and NaClO in a 1-L titanium reactor with varied oxygen pressure (0.2, 0.34 and 0.55 MPa), temperature (40, 50 and 80 °C) and concentration of HCl (2 and 4 M), obtaining extractions above 95% at [HCl] = 4 M, P = 0.34 MPa and T = 40 °C. The extraction increased depending on the concentration of HCl. Eh–pH diagrams for Ag–Cl–H2O, Au–Cl–H2O and Pt–Cl–H2O were constructed to know the possible species in the solution. Full article
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Article
Recovery of Platinum from a Spent Automotive Catalyst through Chloride Leaching and Solvent Extraction
Recycling 2021, 6(2), 27; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020027 - 17 Apr 2021
Viewed by 1173
Abstract
Considering economics and environmental sustainability, recycling of critical metals from end-of-life devices should be a priority. In this work the hydrometallurgical treatment of a spent automotive catalytic converter (SACC) using HCl with CaCl2 as a leaching medium, and solvent extraction (SX) with [...] Read more.
Considering economics and environmental sustainability, recycling of critical metals from end-of-life devices should be a priority. In this work the hydrometallurgical treatment of a spent automotive catalytic converter (SACC) using HCl with CaCl2 as a leaching medium, and solvent extraction (SX) with a thiodiglycolamide derivative, is reported. The aim was to develop a leaching scheme allowing high Pt recoveries and minimizing Al dissolution, facilitating the application of SX. The replacement of part of HCl by CaCl2 in the leaching step is viable, without compromising Pt recovery (in the range 75–85%), as found for the mixture 2 M CaCl2 + 8 M HCl when compared to 11.6 M HCl. All leaching media showed good potential to recover Ce, particularly for higher reaction times and temperatures. Regarding SX, results achieved with a model solution were promising, but SX for Pt separation from the real SACC solution did not work as expected. For the adopted experimental conditions, the tested thiodiglycolamide derivative in toluene revealed a very good loading performance for both Pt and Fe, but Fe removal and Pt stripping from the organic phases after contact with the SACC solution were not successfully accomplished. Hence, the reutilization of the organic solvent needs improvement. Full article
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Article
Determination of Metals’ Content in Components Mounted on Printed Circuit Boards from End-of-Life Mobile Phones
Recycling 2020, 5(3), 20; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling5030020 - 09 Sep 2020
Cited by 2 | Viewed by 1921
Abstract
The electronic components mounted on the printed circuit boards (PCBs) of mobile phones represent a resource that is rich in metals, and after separation from the boards, these components could be considered secondary raw materials. The concentrations of the valuable metals are insignificant [...] Read more.
The electronic components mounted on the printed circuit boards (PCBs) of mobile phones represent a resource that is rich in metals, and after separation from the boards, these components could be considered secondary raw materials. The concentrations of the valuable metals are insignificant when compared with those of complete PCBs; however, they could be significantly higher in a fraction formed from the separated components. This study focused on the analysis of Ag, Au, Cu, Nd, Nb, Ni, Pb, Pd, Sn, and Ta in fractions produced by the separation of all the components mounted on PCBs from several types of mobile phones. Atomic absorption spectrometry, atomic emission spectrometry, and mass spectrometry techniques were utilized, and a comparison of five older models of “brick” phones and five modern smartphones was conducted. Additionally, 50 kg of PCBs from the current recycling market were analyzed in the same way to create a summary of the current recycling stream. Full article
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Review

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Review
Electrochemical Approaches for the Recovery of Metals from Electronic Waste: A Critical Review
Recycling 2021, 6(3), 53; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6030053 - 09 Aug 2021
Cited by 2 | Viewed by 1355
Abstract
Electronic waste (e-waste) management and recycling are gaining significant attention due to the presence of precious, critical, or strategic metals combined with the associated environmental burden of recovering metals from natural mines. Metal recovery from e-waste is being prioritized in metallurgical extraction owing [...] Read more.
Electronic waste (e-waste) management and recycling are gaining significant attention due to the presence of precious, critical, or strategic metals combined with the associated environmental burden of recovering metals from natural mines. Metal recovery from e-waste is being prioritized in metallurgical extraction owing to the fast depletion of natural mineral ores and the limited geographical availability of critical and/or strategic metals. Following collection, sorting, and physical pre-treatment of e-waste, electrochemical processes-based metal recovery involves leaching metals in an ionic form in a suitable electrolyte. Electrochemical metal recovery from e-waste uses much less solvent (minimal reagent) and shows convenient and precise control, reduced energy consumption, and low environmental impact. This critical review article covers recent progress in such electrochemical metal recovery from e-waste, emphasizing the comparative significance of electrochemical methods over other methods in the context of an industrial perspective. Full article
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Review
Extraction of Valuable Elements from Red Mud with a Focus on Using Liquid Media—A Review
Recycling 2021, 6(2), 38; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020038 - 10 Jun 2021
Cited by 4 | Viewed by 1213
Abstract
Bauxite residue, known as red mud, is a by-product of alumina production using the Bayer process. Currently, its total global storage amounts to over 4.6 billion tons, including about 600 million tons in Russia. The total global storage of red mud occupies large [...] Read more.
Bauxite residue, known as red mud, is a by-product of alumina production using the Bayer process. Currently, its total global storage amounts to over 4.6 billion tons, including about 600 million tons in Russia. The total global storage of red mud occupies large areas, leading to environmental damage and increasing environmental risks. Moreover, it contains a significant amount of sodium, which is easily soluble in subsoil water; therefore, a sustainable approach for comprehensive recycling of red mud is necessary. The bauxite residue contains valuable elements, such as aluminum, titanium, and scandium, which can be recovered using liquid media. In recent years, many methods of recovery of these elements from this waste have been proposed. This paper provides a critical review of hydrometallurgical, solvometallurgical, and complex methods for the recovery of valuable components from red mud, namely, aluminum, titanium, sodium, and rare and rare-earth elements. These methods include leaching using alkaline or acid solutions, ionic liquids, and biological organisms, in addition to red mud leaching solutions by extraction and sorption methods. Advantages and disadvantages of these processes in terms of their environmental impact are discussed. Full article
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