Special Issue "Sustainable Use of Metals - Reprocessing, Recovery and Recycling"

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

Deadline for manuscript submissions: 30 June 2018

Special Issue Editor

Guest Editor
Prof. Dr. Bernd Friedrich

IME Process Metallurgy and Metal Recycling Department, RWTH Aachen University, Germany
Website | E-Mail
Interests: process technology; metals; recycling; purification; alloying; WEEE; spent batteries; critical materials; circular economy

Special Issue Information

Dear Colleagues,

The high demand on advanced metallic materials raises the need for an extensive recycling of metals and a more sustainable use of raw materials. Advanced materials are crucial for technological applications, coexisting with an increasing scarcity of natural resources. This Special Issue, "Sustainable Use of Metals—Reprocessing, Recovery and Recycling", is dedicated to the latest scientific achievements in efficient production of metals, purposing a sustainable resource use.

The idea of a circular economy is the point of origin for contributions, aiming on the recirculation of metal-rich waste streams—such as Waste Electric and Electronic Equipment (WEEE), multi-metal alloys and composite materials—back into metal production. This topic goes along with pursuing the holistic use of input materials, resulting in the avoidance of waste by-products. In order to minimize material losses and energy consumption, this issue explores concepts for the optimization concerning the interface between mechanical and thermal pre-treatment and metallurgical processes.

Furthermore, the direct re-use of complex alloys and composite materials without splitting them up into their single constituents is taken into account.

Papers in this issue are also engaged with the question, how the properties of indispensable advanced materials and alloys can be preserved by a more responsible input or even avoidance of particular constituents. In this regard, new approaches in material design, structural engineering and substitution are provided.

Considering both principal aspects—circular economy and material design—the recovery and the use of minor metals play an essential role, since their importance for technological applications often goes along with a lack of supply on the world market. Additionally, their ignoble character, as well as their low concentration in recycling materials cause a low recycling rate of these metals, awarding them the status of “critical metals”.

Prof. Dr. Bernd Friedrich
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 1000 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.


  • recycling
  • circular economy
  • zero waste
  • material design and substitution
  • critical metals

Published Papers (1 paper)

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Open AccessArticle Concentration and Separation of Scandium from Ni Laterite Ore Processing Streams
Metals 2017, 7(12), 557; doi:10.3390/met7120557
Received: 7 November 2017 / Revised: 8 December 2017 / Accepted: 8 December 2017 / Published: 12 December 2017
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The presence of a considerable amount of scandium in lateritic nickel-cobalt ores necessitates the investigation of possible processing alternatives to recover scandium as a byproduct during nickel and cobalt production. Therefore, in this study, rather than interfering with the main nickel-cobalt production circuit,
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The presence of a considerable amount of scandium in lateritic nickel-cobalt ores necessitates the investigation of possible processing alternatives to recover scandium as a byproduct during nickel and cobalt production. Therefore, in this study, rather than interfering with the main nickel-cobalt production circuit, the precipitation-separation behavior of scandium during a pH-controlled precipitation process from a synthetically prepared solution was investigated to adopt the Sc recovery circuit into an already existing hydrometallurgical nickel-cobalt hydroxide processing plant. The composition of the synthetic solution was determined according to the hydrometallurgical nickel laterite ore processing streams obtained from a HPAL (high-pressure sulphuric acid leaching) process. In order to selectively precipitate and concentrate scandium with minimum nickel and cobalt co-precipitation, the pH of the solution was adjusted by CaCO3, MgO, Na2CO3, and NaOH. It was found that precipitation with MgO or Na2CO3 is more advantageous to obtain a precipitate containing higher amounts of scandium with minimum mass when compared to the CaCO3 route, which makes further processing more viable. As a result of this study, it is proposed that by a simple pH-controlled precipitation process, scandium can be separated from the nickel and cobalt containing process solutions as a byproduct without affecting the conventional nickel-cobalt hydroxide production. By further processing this scandium-enriched residue by means of leaching, SX (solvent extraction), and precipitation, an intermediate (NH4)2NaScF6 product can be obtained. Full article
(This article belongs to the Special Issue Sustainable Use of Metals - Reprocessing, Recovery and Recycling)

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