DOI: 10.36347/sjet.2017.v05i11.005

Pages: 629-638

The mining industry generates enormous volumes of mining wastes. Among these mine discharges, tailings are the most problematic given their very fine particle sizes and the chemicals used to process the ore. Moreover, if they contain iron and sulphides, their exposure to atmospheric agents, causes their oxidation and the production of acid mine drainage (AMD). Acid mine drainage is a concern for mining companies people and policy makers. It poses a threat to the environment and human health. The objective of this paper is to propose a technically and economically cost-effective method for recovering otherwise precious metals from tailings. To do this, various tests in flasks were carried out in the laboratory. The organic acids were used individually or as a mixture of the acids in pairs or a mixture of three acids. Selective sequential extraction (SSE) was performed to assess the geochemical distribution of metals. A statistical analysis was carried out through analysis of the variance (ANOVA) one-factor (type of acid, type of mixture, concentration or time) from the Tukey test. Citric acid (5.10-2 g/L) provides the highest solubilization percentages. The solubilization sequence of the metals is: Cu > Zn > Pb > Ni ~ Cd > Fe. All the metals in the exchangeable, carbonate, oxide/hydroxide geochemical fractions were solubilized (100%). In the case of commercial organic acids, the results confirm that the solubilization of metals contained in the tailings is not linked to extracellular enzymes but to the acidification of the medium. They show that leaching by commercial organic acids offers the possibility of recovering at attractive concentrations heavy metals retained in the large quantities of tailings released by the mining industry.