SEVERAL APPROACHES TO ENHANCE THE BIOLEACHING OF ENARGITE

摘要

Some approaches were investigated to enhance the recovery of Cu from enargite by bioleaching withAcidithiobacillus ferrooxidans using the galvanic interaction with pyrite and activated carbon, andwith thermophilic bacteria, Acidianus brierleyi. Addition of pyrite initially enhanced Cu leachingby the Galvanic effect, but after that the formation of secondary minerals passivated the surface ofenargite in inoculated batches. Activated carbon improved Cu recovery from enargite much betterthan pyrite, when it is contacted with enargite. Recovery of Cu from enargite has been recorded toat largest 2.4 per cent within 30 days in the presence of activated carbon when mesophilic bacteriawere inoculated at 25℃. The recovery of Cu from enargite was drastically enhanced by inoculationof thermophilic bacteria, Acidianus brierleyi, up to 60 per cent within 40 days at 70℃ and still notleveled off after 40 days unless the formation of Fe(III) precipitates occurred. After 40 days dissolvedmolar ratio of Cu/As is around 5.2, suggesting that metal-deficient sulfides and/or ferric arsenatemight be formed on the surface of enargite.