A model GM(grey model)(1,1) for forecasting the rate of copper extraction during the bioleaching of primary sulphide ore was established on the basis of the mathematical theory and the modeling process of grey system theory. It was used for forecasting the rate of copper extraction from the primary sulfide ore during a laboratory microbial column leaching experiment. The precision of the forecasted results were examined and modified via "posterior variance examination". The results show that the forecasted values coincide with the experimental values. GM(1,1) model has high forecast accuracy;and it is suitable for simulation control and prediction analysis of the original data series of the processes that have grey characteristics,such as mining,metallurgical and mineral processing,etc. The leaching rate of such copper sulphide ore is low. The grey forecasting result indicates that the rate of copper extraction is approximately 20% even after leaching for six months.
As thiourea and sulfur-containing mixed additives contaminate cathodic copper,inhibition behavior of some new mixed additives such as gelatin+hexadecylpyridinium bromide (HDPBr),gelatin+polyethylene glycol(PEG),gelatin+polyacryl amide (PAM),gelatin+PEG+cetyl-tri-methyl ammonium bromide (CTABr) and gelatin+PAM+CTABr was investigated by cyclic voltammetry as well as cathodic polarization in order to improve the quality of cathodic copper in bio-metallurgical process.The results indicate that the inhibition performances of these additives are dependent on complex and adsorption behaviors as well as the deposit potential.For a solution of acidic copper sulpate containing 40 g/L Cu2+ and 180 g/L H2SO4,the additive (gelatin+HDPBr) is the most efficient among the investigated additives because HDPBr with a large organic cation and π electron can adsorb on the cathodic surface to block the active sites and Br-ion can precipitate Cu2+ to form Cu2Br2.The additive (gelatin+PAM) also has a better inhibition performance,while the additives (gelatin+PEG),(gelatin+PEG+CTABr) and (gelatin+PAM+CTABr) are comparatively lower inhibition performance compared with the additive (gelatin+thiourea) which has been frequently used so far.
