Preparation of strontium carbonate via celestite leaching in NaHCO3 using two interconnected reactors

Two interconnected reactors were used to produce high quality SrCO 3 by leaching celestite in NaHCO 3 solution at elevated temperature of 363.15 K. This new method avoids undesirable polluting by-products generated in the widely used black ash process. The precipitation kinetics of celestite (SrSO 4 ) leaching in NaHCO 3 at various temperatures was investigated with a view to industrial application. It was found that high temperature significantly enhanced the leaching conversion while initially concentrated Na 2 SO 4 in leaching solution has limited influence on the leaching reaction. The new process overcomes the key disadvantage of high energy consumption during sodium sulfate recovery that is inherent in the soda ash process. Having studied the effects of NaHCO 3 concentration and temperature on the leaching reaction, a shrinking core model was established with an apparent activation energy of E a  = 86.6 kJ/Mol. The rate-determining step was the diffusion of ions through the product layer. Saleable Na 2 SO 4 products were successfully obtained via evaporative cooling crystallisation