**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 [1–4]. 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.
