Kinetics of conversion of celestite to strontium carbonate in solutions containing carbonate, bicarbonate and ammonium ions, and dissolved ammonia

Celestite concentrate (SrSO4) was converted to SrCO3 in solutions containing CO32-, HCO3- and NH4+ and dissolved ammonia. The effects of stirring speed, CO32- concentration; temperature and particle size of SrSO4 on the reaction rate were investigated. It was found that the conversion of SrSO4 was increased by increasing the temperature and decreasing the particle size, while the reaction rate was decreased with increasing the CO32- concentration. However, the stirring speed had no effect on the reaction rate. The conversion reaction was under chemical reaction control and the shrinking core model was suitable to explain the reaction kinetics. The apparent activation energy for the conversion reaction was found to be 41.9 kJ mol(-1). The amounts of the elements in the reaction solution were determined quantitatively by inductively coupled plasma-optical emission spectrometry. The characterization of the solid reactant and product was made using the scanning electron microscopy-energy dispersive spectrometry and X-ray powder diffraction analytical techniques.