Recovery of critital raw materials from mining wastes: challenges, opportunities and barriers.

Abstract

Mining is a critical activity aimed at providing commodities for economic developing. However, the generation of wastes in the vicinity of the mines may lead to severe environmental problems and human health risks. Therefore, mining companies have to face huge investments in remediation options. This situation is especially challenging in historical mine sites, which accumulate large amounts of metal-rich wastes without any environmental regulation [1]. However, these wastes could be a source of critical raw materials due to the high concentrations observed for some elements. This is especially important in those countries with absence of primary deposits, which suffer from a strong external dependence for supply. The recovery of these critical raw materials could constitute a great opportunity to satisfy the internal demand and at the same time help to offset expensive waste treatment costs. However, the effective recovery of these valuable elements requires a vast amount of previous work such as site-by-site studies to determine the potential metal grade in wastes and deep investigation of mineralogical siting of valuable metals in these wastes or selective recovery methods. In this sense, there are some social, economic and technological barriers that must be overcome to achieve the final recovery. In this sense, the use of waste materials has commonly met resistance in the industrial sector and only being accepted after proved experience is achieved. On the other hand, the application of technologies may face technical and economic barriers such as the non-selectivity of extraction and recovery methods developed and the high initial costs which put in risk the return on investment and the cost efficiency of the recovery scheme [2]. Therefore, deep case-by-case investigation is required to achieve cost-effective secondary source of critical raw materials from wastes. [1] Cánovas, C.R., Macías, F., Basallote, M.D., Olías, M., Nieto, J.M., Pérez-López, R., 2021. Metal(loid) release from sulfide-rich wastes to the environment: the case of the Iberian Pyrite Belt (SW Spain). Current Opinion in Environmental Science & Health 20, 100240. https://doi.org/10.1016/j.coesh.2021.100240.   [2] Cánovas, C.R., Macías, F., Pérez-López, R., Basallote, M.D., Millán-Becerro, R., 2018. Valorization of wastes from the fertilizer industry: Current status and future trends. J. Clean. Prod. 174, 678e690. https://doi.org/10.1016/j.jclepro.2017.10.293.