Chalcopyrite concentrate leaching with b

Biological ferric iron production was combined with ferric sulphate leaching of chalcopyrite concentrate and the effects of pH, Fe3+, temperature, and solids concentration on the leaching were studied. The copper leaching rates were found to be similar at pH levels between 1.0 and 1.8, even in the presence of varying concentrations of Fe3+, which showed significant iron precipitation at higher concentrations. Increasing the leaching temperature from 50 °C to 86 °C, along with a rise in solids concentration from 1% to 10%, led to an increased copper leaching rate. However, higher solids concentrations resulted in decreased copper yields, dropping from 80% to 40%. The stepwise addition of ferric iron did not enhance copper yields, and electrochemical potentials indicated a passivating layer formation that comprised jarosite and sulphur precipitates, contributing to reduced leaching rates. This study underlines the complexities in optimizing bioleaching processes and the crucial role of operational parameters in achieving efficient copper recovery from chalcopyrite concentrates.