The kinetics of the dissolution of chalcocite in alkaline cyanide solution

A kinetic study of the dissolution of chalcocite in an alkaline cyanide solution indicates that the reaction is first order with respect to surface area and free cyanide ion concentration, and inversely proportional to the sulfide ion concentration to approximately the 0.1 power. The experimental rate constant is approximately 7.5 × 10⁻⁵ (mole Cu¹⁺/ min) ([S⁻²]^0.1/[CN¹⁻]/cm²/l at 25°C. The activation energy of 2.5 kcal/mole indicates rate control by diffusion through a limiting boundary layer. The concentrations of the important ions in the cyanide solutions are obtained by solving the ionic equilibria and mass balance equations for the system.