Dissolution Kinetics of Phosphate Ore in SO2-Saturated Water

Abstract

SO[sub 2] gas produced with the roasting of sulfur minerals has substantially caused air pollution. SO[sub 2] has been used only for the production of H[sub 2]SO[sub 4] for a long time in the past. However, at present, this side product is being used for the extraction of ores and the production of some chemicals. In this study, the dissolution of phosphate ore from Mazidagi-Mardin, Turkey, the products formed, and the dissolution kinetics were investigated in SO[sub 2]-saturated water. In experiments, particle size, stirring speed, solid/liquid ratio, and temperature were chosen as parameters. It was determined by X-ray diffractometer that the final solid product contains CaHPO[sub 4][center dot]2H[sub 2]O, Ca[sub 3](SO[sub 3])[sub 2][center dot]SO[sub 4][center dot]12H[sub 2]O, and CaSO[sub 4][center dot]2H[sub 2]O. It was observed that the dissolution rate increased with the increase in stirring speed and reaction temperature, and with the decrease in particle size and solid/liquid ratio. A semiempirical mathematical model in the following form, including the effect of the parameters was established to express the dissolution kinetics of phosphate ore: [minus]ln(1 [minus] X) = 35.874D[sup [minus]0.512]w[sup 0.380][center dot](S/L)[sup [minus]0.825]e[sup [minus]2575/Tt0.781], where X is the conversion fraction of the ore, w is stirring speed, D is particle size,more » and S/L is the solid/liquid ratio in weight. The activation energy for the process was found to be 21,408.55 J/mol.« less