Inhibition behavior of some new mixed additives upon copper electrowinning

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.