Leaching Kinetics of Stibnite in Sodium Hydroxide

Spherical pellets of antimony sulphide were dissolved in 1 molar sodium hydroxide solutions at different temperatures. It was found that the shrinking core with ash layer model could satisfactorily explain the dissolution process. Using this model it was found that initially the rate controlling step is a chemical reaction with activation energy of 10.2 kJ/mol. As the ash layer builds up, diffusion through the ash layer becomes the rate controlling step. The activation energy for this process is 33.4 kJ/mol.