EFFECTS OF ULTRASOUND ON THE CEMENTATION OF COBALT ON ZINC

Studies on the effects of ultrasound on the reaction of zinc powder in aqueous cobaltous sulphate solution showed that ultrasound was effective in increasing both the rate and the degree of completion of the removal of cobalt ions from solution at temperatures greater than 50-degrees-C. At lower temperatures ultrasound had negligible effects and under some conditions it was actually unfavourable to the reaction. This is likely to be due to the acceleration of other reactions by ultrasound, in particular the formation of zinc hydroxide. The formation of a hydroxide precipitate is readily noted when ultrasound is applied to zinc powder in water, even at room temperature. The effects of the variation of particle size and of some additives were also studied and provided some counter-intuitive results.