Desulfurization of aged gold-bearing mine tailings

Desulfurization is a novel approach for the reclamation of abandoned mine sites that can have environmental and economic benefits, particularly when combined with the recovery of valuable elements. Desulfurization by flotation produces sulfide-lean tailings, which can be used as cover materials, and sulfide-rich concentrates, which may contain valuable sulfide-associated metals such as gold. Because unreclaimed, aged tailings are often at advanced stages of the weathering process the surfaces of sulfide minerals are usually encapsulated by oxidation products. This surface oxidation reduces sulfide hydrophobicity and, thus, flotation efficiency. Therefore, the main goal of this study was to evaluate how effectively various mechanical pretreatment processes enhance the flotation process for aged tailings. After initial characterization of an aged tailings sample, various parameters were adjusted to optimize the desulfurization process. Subsequently, several mechanical pretreatments (i.e., agitation, attrition, regrinding) were tested. Results show the possibility to produce a concentrate rich in sulfides and gold.