Production of copper powder from wastewater containing CuSO4 and alcoholic additives in a modified stirred tank reactor by cementation

The kinetics of cementation of copper from copper sulphate solutions in a stirred tank reactor fitted with a rotating perforated basket of novel geometry packed with zinc Raschig rings were studied. The effect of different parameters such as initial copper sulphate concentration, basket rotational speed, temperature and the effect of presence of some alcohols, such as methanol, ethanol and butanol were studied. The rate of cementation was found to increase with increasing initial copper sulphate concentration, basket rotational speed, and temperature, while a decrease in the rate of copper cementation was observed in the presence of alcohols according to the following order: butanol > ethanol > methanol. The thermodynamic activation parameters ∆H≠, ∆G≠ and ∆S≠ were calculated within the range of temperature studied. The activation energy was found to be 6 J/mol K which confirms the diffusion controlled nature of the reaction. Mass transfer study of the process has revealed that the present data can be correlated by the equation: Sh = 0.00 13 Sc 0.33 Re 0.943 for the conditions: 2056 < Sc < 2202 and 6700 < Re < 28,300. A comparison between the present modified stirred tank reactor with the rotating cylinder reactor and the rotating disc reactor has shown that a higher rate of cementation was obtained in the present reactor.