Biohydrometallurgical extraction of Indian copper ores by thermoacidophiles

Studies on mesophilic vs, thermophilic leaching of copper ores have reveale d a better. extraction by the latter than the former, Although several repo rts are available on leaching of Indian copper ores by mesophilic Thiobacil lus ferrooxidans strains, these could not be applied for successful leachin g of recalcitrant chalcopyrite ore deposits. In the present study the leach ing ui two chalcopyrite ore samples and a concentrate from Indian mines was carried out. when leaching experiments were carried our at 65 degrees C un der rotating condition, the results indicated efficient leaching of ores an d the concentrate by Acidianus brierlevi, but nor much with Sulfolobus meta llicus. Scanning electron microscopy of biologically leached chalcopyrite c hips revealed dissolution of ore: to occur through formation of pits and fr actures on the surface in the case of A. brierleyi. but Metallosphaera sedu la strain leached the ore mostly through surface etching. Acidic ferric sul phate solution also leached the ore chip through formation of pits and crac ks both in presence and in absence of silver catalyst. Heavy colonisation o f the A. breirleyi strain occurred on chalcopyrite chips whereas the M. Sed ula strain did not colonise on the ore. It is interpreted that thermoacidop hiles can leach recalcitrant chalcopyrite ores and concentrates thereof, an d may be explored for commercial exploitation.