Gold Recovery from Sulfide Concentrates Produced by Environmental Desulfurization of Mine Tailings

Abstract

Environmental desulfurization is gaining attention as an efficient approach to manage sulfidic mine tailings by separating sulfide minerals from tailings. While extensive research has been done to reuse desulfurized tailings in mine site reclamation, the responsible management or potential of valorization of desulfurization concentrates did not receive as much attention. The objective of this study was to evaluate the potential to recover Au from desulfurization concentrates originating from active gold mine sites. Desulfurization concentrates were produced by froth flotation of tailings and characterized. Cyanidation tests and gravity separation experiments were performed on the concentrates. Desulfurization concentrates, mostly composed of fine particles, contained high amounts of S (between 23.0 and 34.5% S) and variable contents of Au (between 0.7 and 1.9 g/t). Mineralogical characterization by SEM showed that 99% of Au-bearing particles were locked, mainly in pyrite (94%). Cyanidation allowed the recovery of 13 to 78% of Au, depending on the desulfurization concentrate. Low Au-bearing particles liberation, and possibly the presence of Cu, were identified as parameters negatively affecting the Au recovery. Gravity separation was poorly efficient (<50%) in recovering Au, which is quite consistent with physical (small particle size) and mineralogical characterizations. A desulfurization concentrate reprocessing flowsheet is proposed.