Resource recovery and water reclamation from acid mine drainage: Market analysis, industry trends, and future research directions

Acid mine drainage (AMD) is a highly recalcitrant wastewater that is typically generated from coal and metal mining activities and contains elevated levels of (heavy) metals and sulphates, along with rare earth elements (REEs) and radionuclides in some instances. This review seeks to elucidate AMD’s physicochemical characteristics and resource recovery avenues that can underpin circularity and introduce the waste-to-resource paradigm. Opportunities for major metals (e.g., iron (Fe) aluminum (Al), and manganese (Mn)) and critical minerals, such as v cobalt (Co), nickel (Ni), and notably rare earth elements (REEs), recovery, along with other minor constituents such as radionuclides were explored. Other valorization avenues such as sulfates transformation to sulfuric acid and recovery and water reclamation were further explored. The techniques for resource recovery from AMD, such as precipitation, adsorption, solvent extraction and ion exchange, were discussed, as well as possible industrial uses of the recovered materials (e.g., coagulants, adsorbents, pigments and catalysts). AMD beneficiation and valorization can minimize the ecological footprint of AMD and reduce virgin resource extraction, such as REEs, while water reclamation can provide water security in water-scarce countries. The recovered resources can provide an important revenue stream, via offsetting treatment costs and even making the process self-sustainable due to the high value of certain products. For example, the REEs global market in 2023 was USD$5.9 billion and is expected to reach USD$14.2 billion by 2033, with a compound annual growth rate (CAGR) of 12%, thus denoting that recovering REEs from AMD could be profitable, while it also reduces mining requirements and associated environmental impacts. Finally, knowledge gaps in terms of recoverability, along with their challenges and prospects and avenues for further research, were also distilled.