Pyrite Bioleaching and Slag Neutralisation - Two Treatments in a Single Process for Recovering Valuable Metals from Both Materials Very often the production of copper sulfide concentrate yields pyrite concentrate as a by-product. This is the case at the Kre mine in northern Turkey. This kind of concentrate may contain low grades of valuable non-ferrous metals. Bioleaching of such pyrite concentrates is a processing technique to solubilise metals like copper, zinc or cobalt in a sulfuric acid pregnant solution._x000D_
The pyrometallurgical processing of copper sulfide concentrate produces slag that still contains valuable metals in varying concentrations._x000D_
Slag is used in many ways: as aggregates, ballast, pavement material, in cement production and glass making. Due to its relatively alkaline nature, it can also be used to neutralise acidic solutions._x000D_
A preliminary study of the bioleaching of the pyrite concentrate (Co 0.28 per cent, Cu 0.56 per cent and sulfur as sulfide 42.6 per cent) produced at Kre has been undertaken with the assessment of the neutralisation of the acidic bioleach solution by using old slag (Co 0.29 per cent, Cu 1.70 per cent and sulfur as sulfide 0.89 per cent) stockpiled on the site._x000D_
The main conclusions of the study were as follows: Kre pyrite was amenable to bioleaching at 40C._x000D_
Cobalt solubilisation directly related to pyrite degradation reached a maximum yield above 90per cent._x000D_
Final copper recovery was limited to approximately 66 per cent not directly related to bacterial growth and pyrite oxidation._x000D_
Slag could be used as a substitute for limestone as a neutralising agent in the bioleaching tanks._x000D_
Cobalt and copper could be recovered from pyrite concentrate and slag simultaneously from both materials._x000D_
A pre-feasibility study is underway to carry out a preliminary cost estimate of an installation for cobalt and copper production from these two materials processed in a single operation.