Role of jarosite precipitation on copper bioleaching

Bacterial leaching )Bioleaching) is the extraction of metals from their ores by means of iron and sulfur oxidizing microorganisms to catalyze the dissolution of base metals such as copper , zinc and etc. The metal-solubilization process is due to a combination of chemistry and microbiology: chemistry, due to the consideration of being mainly as result of chemical oxidation chalcopyrite by ferric iron and/or acid on the mineral, and microbiology, due to biological oxidation of ferrous iron to ferric iron and all these reactions followed by direct or indirect mechanisms.Copper solubilization is influenced by some parameters such as initial concentration of ferric ion, pulp density, method of leaching, jarosite precipitation, temperature, pH and etc . In this study the effect of initial concentration and jarosite precipitation is investigated and for this purpose two experiments was performed .one of them was chemical and bacterial leaching of chalcopyrite in 500ml erlenmeyers with ferric concentration of two times more than stoichiometric amount and resulted that the efficiency of biological extraction was 46.36 since the recovery of chemical leaching was 19.77 which confirms that bioleaching is more effective than chemical leaching. To study the effect of jarosite percipitation, the experiments was performed with the ratio of Fe3+ to chalcopyrite with 1/10,1/20,1/30,1/40,1/50 of stochiometric amount. It was resulted that lowering the concentration enhances the biological extraction of copper up to 65.7% which was 2.43 times larger than bioleaching with high concentration of Fe3+ at the same day.

Keywords:

Bioleaching , chalcopyrite , jarosite