CHEMICAL AND MINERALOGICAL CHARACTERIZATION OF MINING TAILINGS TO ASSESS THEIR VALORIZATION POTENTIAL (Invited Presentation)

Nowadays, the mining industry is conditioned by several factors, such as increased demand for raw materials to cover society's needs, low-grade deposits, and as a consequence, a greater volume of waste generated. Environmental site remediation of affected areas by mining is crucial and must be contemplated from exploration to mine closure. Among these activities, resource maximization through waste valorization can be a promising option for residue treatment and mine site restoration. The Buenavista del Cobre mine (Cananea) located in Sonora State in northwestern Mexico, is the most important copper mine in the country. BVC produces the largest amount of copper in the Mexican territory, generating a high volume of waste, such as waste rock from the heap leach pad process, lixiviates, and tailings; therefore, valorization of current and old waste can be a big step in the way to rehabilitation. The objective of this study is to chemically and mineralogically characterize the mine wastes to provide a possible guide for future valorization as part of environmental remediation plans. Accordingly, a total of 56 tailings samples were collected in excavation pits of 250 cm depth. The sampling sites were selected according to the heterogeneity of tailings considering color, texture, degree of concretion, and pH measured in the field. Tailings samples were analyzed by Instrumental Neutron Activation Analysis and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP/OES), after total digestion, at the ACTLABS laboratories in Ontario, Canada. All samples were analyzed as bulk samples by X-ray diffraction (XRD) using a SIEMENS D5000 diffractometer (Cu Ka radiation, k = 1.5406 A˚). Geochemical analyses revealed enrichment in Cu, Zn, As, Mo, Ag, In, Sn, Sb, W, Pb, Bi, Au, Cd, S, Re, and Se; and according to the cut-off grades of different deposits, Cu, Ga, Mo, and Re can be prospects to be valorized. In contrast, mineralogical results show the need for detailed characterization studies to determine the availability of these elements in the mineral phases. Giving value to mine tailings is in line with two of the 17 sustainable development goals of the United Nations: Goal 11 Sustainable cities and communities and Goal 12 Responsible consumption and production. It is essential to highlight the importance of geoscientists, their projects, and research on this path towards a conscious future in pursuit of the common good. Therefore, this study is an advance toward responsible valuation and management of the impact of extractive activities.