Dissolution of iron sulfide (troilite) in aqueous sulfuric acid

Abstract

The dissolution of iron sulfide (troilite) was studied in dilute sulfuric acid, sodium hydroxide, and H2S saturated solutions of different pH. The dissolution kinetics of the reaction FeS + 2H+ ⇄ Fe2+ + H2S (g) was studied by following the depletion of H+ from the bulk solution in which disks holding FeS pellets were rotated. These studies showed that the rate of reaction is not controlled by transport of the reactants or the products. The activation energy for the dissolution of FeS is 60 ± 7 kJ mol-1. The forward reaction is directly proportional to the acid concentration and the reverse reaction is one-half order with respect to both the concentration of Fe2+ and H2S pressure. Thermodynamic quantities for the dissolution reaction are reported.