The dissolution of chalcocite in oxygenated sulfuric acid solution

Abstract

In the oxidative dissolution of chalcocite (Cu 2 S) in oxygenated sulfuric acid solution under ambient conditions, the only reaction found in the dissolution process is Cu2S + 1/2 02 + 2H+ = CuS + Cu2 + H20 where CuS is a stable reaction product. The rate law governing the reaction is R = k ( PO2 ) ( H+ ) ( SO4 -2 ) -1.18 The rate of reaction in the presence of NO3 - and C104 - ions is higher relative to the rate in SO4 -2 solutions. The presence of Cl - and Br - ions causes a 100-fold increase in rate relative to the rate in SO 4 -2 solutions. Reaction rate is a function of stirring speed up to 700 rpm. Surface area has a first-order effect on the reaction rate. A proposed reaction mechanism consistent with the experimental results includes both physical and chemical processes, but the rate-controlling step is thought to be chemical.