Catalytic efficiency of Acidithiobacillus ferrooxidans for bioleaching copper from chalcocite containing sulfide ore from Reko Diq deposits

Abstract

Bioleaching of low-grade secondary copper sulphide ores using different microbial strains is an ecologically safe technology for the recovery of metals in the mineral and mining industry. The purpose of the present study was to analyze the mineral contents of Reko Diq deposits and to assess the dissolution of copper from sulfide ore by an indigenously isolated strain of acidophilic iron-and sulfur-oxidizing bacterium (BSTFe-2) in shake flask experiments. X-ray diffraction (XRD) analysis of the ore sample suggested that it contained 0.81% Cu on dry matter basis and contained chalcocite (Cu2 S) and covellite (CuS) as main copper minerals. Pyrite (FeS2) was also present as a sulfide mineral. The other minerals detected in the ore matrix were muscovite (a di-octahedral mica mineral), quartz, feldspar (anorthite) and calcite. Quartz (SiO2) was the main silicate mineral present in the sample. Calcite (CaCO3) was found as the main acid-consuming gangue mineral. We observed that about 80-90% of the total Cu content present in the ore matrix was solubilized during 30 days of the leaching process mediated by Acidithiobacillus ferrooxidans at 30ºC. Copper dissolution from ore was found to be directly related to the reaction pH (1.5-1.9). The leaching data obtained from the pulp densities (5, 10 and 20% wt/vol) at 30ºC are comparable. The results of the present study concluded that the bioleaching can be a suitable alternative for conventional hydrominerological processing of low-grade copper ores.