Influence factors of pyrite promotion on the bioleaching of chalcopyrite

Chalcopyrite-pyrite bioleaching tests were performed with shaking flasks by Acidithiobacillus ferrooxidans.The research focused on the effects of basic salt mediums,pyrite-to-chalcopyrite mass ratio and mineral size distribution.It is found that chalcopyrite bioleaching can be promoted by pyrite.The leaching rate of copper in the iron-free 9K medium in pyrite-chalcopyrite bioleaching is 1.68 times as large as that in the 9K medium.The leaching of copper is better using a wide size range of minerals and the leaching rate of copper is related to the mass ratio of pyrite to chalcopyrite.When the mass ratio is 2∶2,the highest leaching rate of copper is obtained to be 45.58%.The content of pyrite is of the essence in affecting the leaching rate level of copper.At a mass ratio of pyrite to chalcopyrite no more than 5∶2 the oxidation of Acidithiobacillus ferrooxidans plays an important role in the bioleaching,but when the mass ratio is 10∶2 the galvanic effect between the two sulphide minerals mainly influences the bioleaching.X-ray diffraction analyses of leaching residues indicate that the generation of jarosite in the iron-free 9K medium is less than that in the 9K medium,FeSO4 in the 9K medium can be replaced by pyrite,the galvanic effect forms with chalcopyrite,and therefore the bioleaching efficiency of copper is increased.