Based on the process of pressurized carbonation with phosphogypsum

the effect of raw material types on carbonation conversion was experimentally studied. In addition

the influence of some operation parameters on the conversion had been analyzed by Aspen plus process simulation software. The results showed that the carbonation reaction can reach equilibrium within 5 minutes under pressured conditions

and it was much more easily for pure anhydrous calcium sulfate to convert completely. However

because of containing crystal water or other impurities

it was difficult for both pure dihydrate calcium sulfate and phosphogypsum to convert completely. Besides

it was found that increasing the initial ammonia concentration

the mole ratio of added ammonia to SO3 in the raw materials

and properly increasing the reaction temperature and system pressure can effectively improve the equilibrium carbonation conversion. Most importantly

the formed ammonium carbonate from the reaction between ammonia and CO2 under high temperature and pressure condition is unstable when pressure decreased. Thus combing the flash operation after pressured carbonation

the formed ammonium carbonate can decompose to release ammonia and CO2

which can further be absorbed and returned to the pressurized carbonation process. This could effectively improve the ammonia utilization rate and reduce the production cost of ammonium sulfate as well.