Investigation into the Biological Leaching of Copper from Chalcopyrite Concentrates Using Moderate Thermophilic Bacteria

Biological leaching is a process in which metals are dissolved from sulfide ores into aqueous solutions using bacteria as catalysts. bioloqical leaching is currently gaining acceptance as a viablealternative to pyrometallurgical smelting, due to decreasing ore grades and legislated limits on sulfur dioxide gas emission into the environment. in this research,the feasibility of copper bioleaching fromchalcopyrite concentrates by three chemotropic strains was investigated. the strains, coded ms1, ms2 and tsb, were moderate thermophilic bacteria. ms1 and ms2 were indigenous to the site of the mine but tsb had been isolated elsewhere from an acidic hot spring. the bioleaching experiments were done on two types of chalcopyrite concentrate with different compositions. the strains had similar performances.the copper recovery increased from about 15% to about 30% when they were grown on a concentrate with a total initial copper content of 30.16%. when grown on a concentrate with an initial copper content of43.35%, the copper recovery increased from about 5% to about 35%. the time period for all experiments was 22 days. the effect of ph on the strain performance was also investigated. all the strains performedbetter when the ph was kept constant at 1.5 compared to 2.2.