DISSOLUTION OF CADMIUM-SULFIDE AT PH = 2 IN AQUEOUS-SOLUTIONS OF SULFURIC-ACID AND SULFURIC-ACID CONTAINING CADMIUM SULFATE

Dissolution of particulate CdS suspended in aqueous solution of H2SO4 (pH = 2) containing 0.00, 0.05 and 0.10 mol m-3 CdSO4 respectively was followed by measuring cadmium concentration in suspension filtrates. It takes about 150 days for cadmium concentration in solution to become constant. An exponential type relation correlating cadmium concentration with system parameters (initial cadmium concentration in solution, mass transfer coefficient, weight and specific surface area of CdS, solution volume) and the time. All systems aligned with a single, experimentally determined (mean) mass transfer coefficient value of (8.0 +/- +/- 1.4) X 10-(11) ms-1. Dissolution of CdS was not solute diffusion but probably a surface chemical reaction controlled process.