DISSOLUTION KINETICS OF ULEXITE IN AMMONIUM-CHLORIDE SOLUTION

The leaching kinetics of ulexite in ammonium chloride solutions were s tudied. The effects of particle size, calcination temperature; solutio n concentration, and reaction temperature were evaluated. The rate of dissolution increases with decrease in particle size, with increase in ammonium chloride concentration, and with temperature. The ulexite sa mple calcined at 140 degrees C has the highest dissolution rate. A kin etic model for ammonium chloride leaching of ulexite can be given by [ (1 - X)(-1) - 1] = k(T)[NH4Cl]R-3/4 t The activation energy for the di ssolution is found to be 80 kJ mol(-1). (C) 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.