Carbonation reaction in phosphogypsum waste conversion to calcium acetate: experiment and kinetic model study

Abstract The high cost of utilizing phosphogypsum resources and the low added value of the resulting product represent significant challenges that have limited the large-scale use of phosphogypsum. This work proposes an approach for the valorization of phosphogypsum by converting it into high-value calcium acetate. To enhance the reaction rate and control the overall cost, the carbonation reaction – an essential step influencing product quality in the production of calcium acetate from phosphogypsum – was systematically investigated from a kinetic perspective. The results show that the carbonation reaction follows the shrinking-core model. A kinetic equation was developed within the temperature range of 25–40 °C and sodium carbonate concentration range of 200–350 mol m −3 , and the temperature dependence of the reaction rate constant was established. The experimental results indicate that the carbonation process exhibits a low activation energy. A calcium carbonate purity exceeding 90 % was achieved by reacting phosphogypsum in 0.25 M sodium carbonate solution at room temperature for 10 min. In addition, the removal of impurities originating from phosphogypsum during the reaction process was also discussed, and the final calcium acetate product was characterized to confirm its high purity and structural integrity. The proposed method holds significant potential for reducing production costs and promoting the large-scale, value-added utilization of phosphogypsum.