Journal of Pure and Applied MicrobiologyVol. 8 No. 2

Silver-catalyzed Bioleaching of a Low Grade Complex Nickel-copper Concentrate: Optimization of Process Variables by Response Surface Methodology

Rong Cheng*, Rongbo Shu, Xiangwen Liao, Houming Liu and Changliang Wang

Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Chengdu - 610 041, China.

Received on 21 June 2013 and accepted on 12 August 2013

 

ABSTRACT

This study was prompted by the phenomenon of the optimal conditions for nickel and copper extractions were quite different in the bioleaching of a low grade complex nickel-copper concentrate. Response surface methodology (RSM) was firstly utilized to promote chalcopyrite oxidation under optimal condition of nickel recovery. The experiment results showed that a satisfactory second-order polynomial regression equation was achieved with a high coefficient of determination (R2=0.9522) which demonstrated that the model could be effectively applied for optimization of silver-catalyzed bioleaching process. Based on the model, the term of silver-bearing species and the interaction term of adding time and Ag+ concentration exhibited high contribution to copper extraction. The different effect of silver-bearing species on bioleaching was revealed by RSM. Besides, the addition time of silver was quite significant in silver-catalyzed bioleaching process, which has never been reported. The high copper extraction reached 0.814 under the optimal conditions of Ag2SO4 as silver-bearing species, adding catalyst after 7 d of bioleaching and Ag+ concentration 1.1 g Ag/kg of ore. Moreover, validation tests were performed and the results were very close to the predicted values.

Keywords : Bioleaching, Nickel-copper concentrate, Box-Behnken design, Silver catalysis, Chalcopyrite.