A kinetic study of copper cementation with zinc in aqueous solutions

Cementation of copper from zinc containing copper solutions using metallic zinc was studied in this work. The effect of copper, zinc and ammonium chloride concentration, stirring speed, pH and temperature on the cementation of copper was determined. Cementation rate increased with initial copper concentration, stirring speed and temperature. pH variation from 1 to 4 increased the cementation rate but at higher pH, the rate was not significantly effected. The cementation rate of copper increased with Zn2+ ion concentration. However, the rate of this rise was slightly less compared to the rise that occurred in the Zn2+ ions free copper solution.The cementation reaction followed first order kinetics. It was observed that the reaction progressed with consecutive surface reaction and diffusion controlling steps. The activation energy and pre exponential factors for each step were calculated and a model describing the process was proposed.