Microbiological Processing of a Porphyry Copper Ore and Mineralogical Analysis of Solid Residues

The treatment of porphyry copper ores which are considered an important source of non-ferrous and precious metals requires the development of high-efficient technologies for metal extraction ensuring a low impact on the environment. The goal of the present work was to study the feasibility of a biohydrometallurgical approach for the processing of Kajaran porphyry copper-molybdenum ore as no attempt was done previously for microbiological processing of the mentioned ore. Sulfide and oxide ore samples used for bioleaching tests contained 0.63 and 0.77% copper, 1.81 and 1.55% iron, and 0.14 and 0.023% molybdenum, respectively. The experiments were carried out in 250 ml flasks under shaking conditions. Indigenous and adapted bacterial consortia 'Kashen' and 'Kavart' were used for bioleaching of ore samples. The objectives of the study were to investigate the influence of particle size (PS), pulp density (PD), and adaptation of the bacterial cultures to the process of copper extraction. The composition of feed material and leaching residues from bioleaching experiments were characterized by geochemical, mineralogical, and particle analyses. As a result, nearly complete bioleaching of the sulfide and oxide ores could be achieved after the optimization of the experiments. The particle analyses showed an enhanced liberation of chalcopyrite particles out of the intergrown ore under bioleaching conditions compared to the abiotic controls and hence an improved Cu solubilization under bioleaching conditions.