EFFECTS OF TEMPERATURE AND POWDER MORPHOLOGIES ON THE CEMENTATION RATE OF COPPER IN ALKALINE ZINC SOLUTION

Computer-generated simulation, previously described by the authors, wa s used to explain the effects of temperature and powder morphologies o n the cementation rate of copper in alkaline zinc solution (300 g/lite r NaOH, 60 g/liter Zn, and 0.2 g/liter Cu). It reveals good reliabilit y on predicting the cementation behavior. Results of laboratory-scale experiments fit the computer simulation for a temperature range of 35 to 75-degrees-C. A rise in temperature increases the cementation rate, and the activation energy was equal to 5.5 kcal/mol as predicted by c omputer. Zinc powders were obtained by alkaline electrolysis at variou s current densities (from 1000 to 9000 A/m2) and their reactivity were compared to the industrial atomized powder. Results show a higher rea ctivity of the electrolytic powder in comparison to the atomized powde r. Also, the cementation rate increases with a powder obtained at high er current densities. Since the powders obtained from electrolysis do not have a spherical shape, predictions made by simulation did not fit the results of laboratory scale cementation. To remedy these differen ces, a mathematical correlation between the simulation and the laborat ory scale experiments was developed to predict the effect of powder mo rphologies on the cementation rate.