Kinetics of indium dissolution from sphalerite concentrate in pressure acid leaching

The mineralogical analysis of a sphalerite concentrate by electron-microprobe shows that the main indium-bearing minerals are pyrite, zinckenite, galena, cassiterite, jamesonite. The kinetics of indium dissolution from sphalerite concentrate in the sulphuric acid–oxygen system indicated that the particle size, temperature and sulphuric acid concentration significantly influenced the leaching efficiencies of indium. The experimental data indicated that under the conditions employed up to 92% indium extraction were achieved. The empirical kinetic model, − ln(1 − x) = kt was used to describe the dissolution kinetics of indium in sulphuric acid solutions, and the results showed that indium dissolution process was controlled by chemical reaction with the activation energies calculated to be 47 kJ/mol and the reaction order with respect to sulphuric acid concentration closed to 1.