Special Issue "Separation and Leaching for Metals Recovery"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 30 April 2020.

Special Issue Editor

Prof. Jaeryeong Lee
E-Mail Website
Guest Editor
Department of Energy and Resources Engineering (ENRE), Kangwon National University, Chuncheon 24341, South Korea
Interests: urban mine; recycling technology; dismantling; grinding; physical separation; hydrometallurgy; purification; rare metals

Special Issue Information

Dear Colleagues,

In recent decades, the interest in urban mines has been gradually increasing. As a result, the industrial scale and case for commercialization have also been increasing dramatically. Raw materials in the urban mining industry can be divided mainly into industrial waste (including scrap) and municipal waste (including end-of-life products). Unfortunately, the current recycling research and metal recovery rates for municipal waste are much lower compared to industrial waste. This may be the result of a shortage of economic feasibility, the variety in compositions (such as non-metal and organic materials), and the lower content of metals in the municipal wastes. Municipal waste having these characteristics is not directly processed for metal recovery, and first requires separation and concentration using a separation pretreatment.

Therefore, further research is needed on the recovery and recycling of metal components from municipal wastes using a leaching process, as well as separation processes such as unit separation, dismantling/detaching, thermal decomposition, and physical separation (also referred to as mineral processing). This research could form the basis for the development of commercialization processes for municipal wastes and in addition to realization of a sustainable society through the continuous growth of the urban mining industry.

This Special Issue aims to address the latest research on not only leaching processes but also separation processes for waste with low-content metals (including end-life products), in order to achieve economic feasibility. Moreover, research articles will focus on the development of integrated environmentally friendly and cost-effective separation and leaching processes for the recovery of valuable metals.

Prof. Jaeryeong Lee
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. 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 1500 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

  • urban mine
  • municipal waste
  • recycling
  • end-life product
  • separation process
  • leaching process
  • hydrometallurgical processes
  • unit separation
  • dismantling/detaching
  • thermal decomposition
  • mineral processing
  • low content of metals
  • environmentally friendly
  • cost-effective

Published Papers (3 papers)

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Research

Open AccessArticle
Investigation on the Effect of Roasting and Leaching Parameters on Recovery of Gallium from Solid Waste Coal Fly Ash
Metals 2019, 9(12), 1251; https://doi.org/10.3390/met9121251 - 22 Nov 2019
Abstract
Coal fly ash (CFA) provides important resources of gallium, which is regarded as an irreplaceable material in many technologies. A prospective roasting reagent assisted acid leaching process was proposed for the purpose of extracting gallium. The extraction efficiency of gallium by NaF (sodium [...] Read more.
Coal fly ash (CFA) provides important resources of gallium, which is regarded as an irreplaceable material in many technologies. A prospective roasting reagent assisted acid leaching process was proposed for the purpose of extracting gallium. The extraction efficiency of gallium by NaF (sodium fluoride) roasting followed by HNO3 (nitric acid) leaching process was demonstrated. The effect of roasting temperature, roasting time, the NaF-CFA mass ratio, acid leaching temperature, acid leaching time, and acid concentration were investigated. The results revealed that under optimal conditions (roasting temperature of 800 °C, roasting time of 10 min, acid leaching in 2 mol/L HNO3 for 1 h, and the NaF-CFA mass ratio of 0.75:1), 94% of gallium was extracted. Compared to previous studies, the process is a cost-effective method which can greatly shorten reaction time. It can reduce environmental pollution as it requires fewer acid reagents with low concentration and additives. It is expected to provide a method for the extraction of gallium from CFA. Full article
(This article belongs to the Special Issue Separation and Leaching for Metals Recovery)
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Open AccessArticle
Effects of Solid Content and Substrate Concentration on Bioleaching of Heavy Metals from Sewage Sludge Using Aspergillus niger
Metals 2019, 9(9), 994; https://doi.org/10.3390/met9090994 - 09 Sep 2019
Abstract
The presence of heavy metals in sewage sludge not only affects the performance of sludge anaerobic digestion process but also restricts the land application of treated sewage sludge. Therefore, a fungi-mediated bioleaching process for simultaneous metal leaching and sludge digestion by Aspergillus niger [...] Read more.
The presence of heavy metals in sewage sludge not only affects the performance of sludge anaerobic digestion process but also restricts the land application of treated sewage sludge. Therefore, a fungi-mediated bioleaching process for simultaneous metal leaching and sludge digestion by Aspergillus niger was developed to treat the sewage sludge containing heavy metals in this study. The effects of two important parameters, sludge solid content and substrate (sucrose) concentration, on the performance of fungal bioleaching were investigated in this study. The results showed that the rate of pH reduction increased with increasing sludge solid contents and sucrose concentrations. In this study, the efficiency of metal removal decreases in the order of Mn > Zn > Ni > Pb. The efficiencies of metal leaching and solid degradation (SS and VSS) were found to be decreased with an increase of sludge solid content and a decrease of sucrose concentration. At 2 days of reaction time, the maximum efficiency of metal solubilization was 95, 56, 21 and 13% for Mn, Zn, Ni and Pb, respectively. Full article
(This article belongs to the Special Issue Separation and Leaching for Metals Recovery)
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Open AccessArticle
Destruction of Cyanide and Removal of Copper from Waste Printed Circuit Boards Leach Solution Using Electro-Generated Hypochlorite Followed by Magnetite Adsorption
Metals 2019, 9(9), 963; https://doi.org/10.3390/met9090963 - 02 Sep 2019
Abstract
The removal of the cyanide and copper (Cu) from the waste printed circuit boards (WPCBs) cyanide leach solution through the alkaline chlorination using electro-generated hypochlorite (NaOCl) followed by magnetite (Fe3O4) adsorption is investigated. The efficiency of the destruction of [...] Read more.
The removal of the cyanide and copper (Cu) from the waste printed circuit boards (WPCBs) cyanide leach solution through the alkaline chlorination using electro-generated hypochlorite (NaOCl) followed by magnetite (Fe3O4) adsorption is investigated. The efficiency of the destruction of cyanide and precipitation of Cu was increased with increasing the concentration of free available chlorine in NaOCl. More than 99% of free cyanide and 76% of Cu were removed under the following conditions: concentration of chlorine in electro-generated NaOCl, 5.2 g/L; volume ratio of NaOCl/leach solution, 1; pH, ~9.8; ambient temperature for 12 h. Then, magnetite adsorption for selective removal of remaining Cu (50.5 mg/L) was selected and more than 99% of copper ion was successfully removed with dosage 10g/100mL, shaking speed 150 rpm within 30 min. The results revealed that the alkaline chlorination using electro-generated NaOCl followed by magnetite adsorption could completely remove the cyanide and Cu, remaining Au in the final solution. Full article
(This article belongs to the Special Issue Separation and Leaching for Metals Recovery)
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