DISSOLUTION KINETICS OF CALCINED COLEMANITE IN AMMONIUM-CHLORIDE SOLUTION

The leaching kinetics of calcined colemanite in ammonium chloride solu tions were studied. The effects of calcination temperature, solution c oncentration, reaction temperature and pre-hydration were evaluated. T he rate of dissolution increased with increasing calcination temperatu re, solution concentration and reaction temperature, while it was not affected by pre-hydration. It was found that the dissolution rate, bas ed on the homogeneous reaction model, can be expressed as: (1-x)-1-1=k [NH4Cl]3/4t. The activation energy for the dissolution of the colemani te sample calcined at 400-degrees-C was found to be 89 kJ mol-1.