Dissolution kinetics of an oxidized copper ore in ammonium chloride solution

The dissolution kinetics of malachite ore in ammonium chloride solutions has been investigated with respect to the effects of ammonium chloride concentration, particle size, solid/liquid ratio, stirring speed, and reaction temperature. It was determined that the dissolution rate increased with increasing ammonium chloride concentration, stirring speed, and reaction temperature. However, increasing particle diameter and solid to liquid ratio decreased the dissolution rate. Examination of data by heterogeneous model suggested that the dissolution rate is controlled by mixture kinetics. The following mathematical model was proposed to represent the reaction kinetics. 1 - 2(1 - x)(1/3) + (1 - x)(2/3) = 1 . 10(-5) (c)(2.10) . (d(p))(-1.96) . (rho(S/L))(-0.64) . (n)(1.78) . e((-8500/T) . t) The activation energy for the dissolution reaction was calculated as 71 kJ mol(-1). Where x is the reacted fraction of the solid, c is the ammonium chloride concentration, d(p) is the particle diameter, rho(S/L) is the solid to liquid ratio, n is the stirring speed, E is the activation energy, T is the reaction temperature and t is the reaction time.