At the end, these sulfur compounds are completely oxidized to sulfate in the solution, the schematic diagram is showed as followed (Fig. 3) The related equations are listed as the followed: equation(4) FeS2+6Fe3++3H2O+7Fe2++S2O32−+6H+ equation(5) S2O32−2+8Fe3++5H2O→8Fe2++2SO42−+10H+ Balci et al. proposed that the dominant bacterial role is
likely to oxidize the ferrous ions to ferric ions which catalyzes the followed Reaction (6) because ferric is still the main oxidizing agent  and . equation(6) Fe2++14O2+H+→bacterial oxidationFe3++12H2O The leaching rate of chalcopyrite (CuFeS2) is known to be quite slow and tends to be depressed with time  and , that is the main Ku-0059436 resistance and obstruction to the commerical application. The metal–sulfur bonds can be cleaved by the assault or attack of the protons, which analyze its acid-solubility and quite different
from the pyrite. It has been widely studied that the sulfur moiety of these metal sulfides is oxidized mostly into elemental sulfur at low pH condition . Carneiro et al. detected elemental sulfur on the surface of the chalcopyrite in the solution of ferric sulfate (FeSO4) or ferric chloride (FeCl3) under the conditions of low-temperature  and , which is considered to Astemizole be related with the obstinate character selleck kinase inhibitor on dissolution. There are a battery of chemical and biochemical reactions that explain the formation of elemental sulfur through the polysulfide pathway on the surface of acid-soluble metal sulfide minerals. The metal-deficient sulfides (Cu1−xFe1−yS2−z) are intermediate product phases of chalcopyrite dissolution in acidic and oxidizing solution, at the condition of low temperatures , ,  and  or at high temperatures . Warren et al. presented the formation of bornite, which is considered as a passive intermediate product phase in acidic sulfate solutions based on the thermodynamic analysis .
The equations are listed as followed: equation(7) CuFeS2→Cu1−xFe1−yS2−z+xCu2++yFe2++zS+2(x+y)eCuFeS2→Cu1−xFe1−yS2−z+xCu2++yFe2++zS+2(x+y)e equation(8) Cu1−xFe1−yS2−z→(2−z)CuS+(−1−x+z)Cu2++(1−y)Fe2++2(−x−y+z)eCu1−xFe1−yS2−z→(2−z)CuS+(−1−x+z)Cu2++(1−y)Fe2++2(−x−y+z)e equation(9) CuS→Cu2++S+2eCuS→Cu2++S+2e equation(10) Cu1−xFe1−yS2−z→(1−x)Cu2++(1−y)Fe2++(2−z)S+2(2−x−y)e The leaching chemical mechanism of solubilization of chalcopyrite has been shown as followed equations. The bioleaching and biooxidation of the minerals are functioned by the microbes or archaea that responsible for producing ferric iron and sulfuric acid used for the leaching of copper .