Recovery and Recycling of Valuable Metals

1. Introduction and Scope

Metals have always played a significant role in human life; contemporary global growth and prosperity are directly dependent on these materials. With the rapidly growing global demand for metals, their extraction from natural minerals (as their primary sources) has been enhanced. This has caused significant reductions in the grade and quality of the ores in ore deposits. In this context, huge amounts of waste can be generated through mining and metallurgical activities which need management. Although these huge quantities of waste generated through all steps of metal production are known to be a source of environmental pollution, their valorization can create value via recycling metals or even through use in the production of other valuable materials. Such waste valorization is also in line with the United Nations’ Sustainable Development Goals (SDGs), as well as implementation of the Paris Agreement. On this matter, the recycling of end-user products in order to reproduce valuable metals can also create significant values and reduce mining activities, and accordingly, their harmful consequences all around the world. Therefore, research and development into state-of-the-art technologies for the recovery and recycling of metals are absolutely necessary [1,2,3,4]. In this regard, more novel ideas focusing on the development of advanced metal recovery technologies from primary and secondary sources can lead the mining and metal sectors towards increased sustainability in the future.

In this Special Issue, the endeavor was to collect a range of articles covering different aspects of valuable metal recovery and recycling from primary and secondary sources. The objective was to decipher all new methods, processes, and knowledge in the production of valuable metals from various sources. We hope that this open access Special Issue will represent a great opportunity to demonstrate the prestigious work of active researchers in the field, contributing towards advancements in the mining and metal sectors.

2. Contributions

Seventeen articles have been published in this Special Issue of Metals, encompassing the fields of mineral processing and extractive metallurgy [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]. These articles cover a wide range of topics in the field and provide some ideas for active researchers who are working on the production of valuable metals from primary and secondary resources. Similarly, researchers from different disciplines can contribute to the enrichment of this Special Issue, through sharing multidisciplinary views on the outputs of each article.

3. Conclusions and Outlook

Different interesting research subjects focusing on metal production process development and identification are published in the present Special Issue of Metals, with endeavors of demonstrating new insights towards future advancement of the field. Although most articles focused on hydrometallurgical operational units and processes, mineral processing procedures were also taken into account by some of them. The articles had specific views regarding waste recycling and valorization, indicating the importance of such topics between decision makers in the mining and metal sectors from economic and environmental point of views.

As Guest Editor of this Special Issue, I am so proud of the outcome, and I have high confidence that such effort can help to make future advancement of the field. I deeply appreciate all the authors for their great efforts and contributions to this Special Issue, especially during the difficult situation caused by the COVID-19 pandemic. Their commitment and fantastic results have resulted in the publication of this Special Issue with great success. Likewise, I would like to take this opportunity to warmly thank the many anonymous reviewers who assisted me in the reviewing process. Without their help, this Special Issue could not have been finalized. Sincere thanks also goes to the Editors of Metals for their continuous help, and to the Metals Editorial Assistants for their valuable support during the preparation of this Special Issue. In particular, my sincere thanks goes to Mr. Toliver Guo for his great help and support from the beginning until the end of the project.