Dissolution kinetics of malachite in sulphuric acid

A kinetic study of the sulphuric acid leaching of oxidised copper ore, primarily malachite, was carried out. The effects of leaching time, stirring speed, acid concentration, solid to liquid ratio, reaction temperature, and particle size of the ore were investigated. Using the best conditions, the copper recovery was nearly 94% at 25 °C and 99% at 80 °C after 180 min leaching. Dissolution of malachite during the leaching was described by a logarithmic function, y=a ln(x)+b. The data obtained for the leaching kinetics indicated that the initial dissolution of malachite is a diffusion controlled reaction.