Modified mineral carbonation of phosphogypsum for CO2 sequestration

A modified phosphogypsum carbonation was systematically investigated, and ammonium acetate was used to separate Ca2+ and concentrate impurity ions from PG. The effect of technological conditions on salt-leaching and carbonation results were discussed. The calcium leaching rate was 98.1%, and the only crystal phase of salt-leaching product was quartz with granular morphology and some pores in the surface. The carbonation ratio (eta) was 98.32%, and 1000 kg of phosphogypsum produced 510 kg of high-purity CaCO3 and sequestered 224 kg of CO2 under the optimized conditions. The spherical vaterite carbonation product met the recommended Chinese standard (HG/T 2226-2010). The carbonation filtrate can be reused for salt-leaching experiments. Various polymorph and morphology of CaCO3 were achieved by adjusting the carbonation temperature and ammonia dosage. The mechanism of phosphogpysum carbonation was studied by using thermodynamics research. All of this indicated that the whole procedure setup of phosphogypsum carbonation showed potential application for phosphogypsum utilization and CO2 sequestration.