Kinetics of indium dissolution from sphalerite concentrate in pressure acid leaching.

Experiments were carried out on a sphalerite concentrate in which the main In-bearing minerals were determined to be pyrite, zinckenite, galena, cassiterite and jamesonite. The kinetics of In dissolution from the concentrate in a sulphuric acid-oxygen system were studied. The results showed that reducing the particle size enhanced In dissolution but that the effect was minor at particle sizes below 58 micrometres. Increasing the temperature from 120 to 150 degrees C and the acid concentration from 1 to 2.5 mol/l both improved the leaching rate. Under optimum conditions, up to 92% In extraction was achieved. An empirical first-order kinetic model used to describe the dissolution kinetics showed that the process was controlled by chemical reaction with a calculated activation energy of 47 kJ/mol and a reaction order with respect to H2SO4 concentration close to 1.
Experiments were carried out on a sphalerite concentrate in which the main In-bearing minerals were determined to be pyrite, zinckenite, galena, cassiterite and jamesonite. The kinetics of In dissolution from the concentrate in a sulphuric acid-oxygen system were studied. The results showed that reducing the particle size enhanced In dissolution but that the effect was minor at particle sizes below 58 micrometres. Increasing the temperature from 120 to 150 degrees C and the acid concentration from 1 to 2.5 mol/l both improved the leaching rate. Under optimum conditions, up to 92% In extraction was achieved. An empirical first-order kinetic model used to describe the dissolution kinetics showed that the process was controlled by chemical reaction with a calculated activation energy of 47 kJ/mol and a reaction order with respect to H2SO4 concentration close to 1.