Phosphogypsum (PG) is a solid waste produced in the phosphate fertilizer industry and is environmentally harmful. The decomposition of PG to recycle calcium and sulfur is a proper way to reutilize PG. Current work aims at enriching the basic theory of coal decomposition process of PG. The emphasis was laid on the exploration of impact of main impurities on the process. On the other hand

according to Reaction Module

Equilib Module

and Phase Diagram Module of FactSage

the simulation computation was done on the systems of pure gypsum mixed with coal

with or without impurities for avoiding other impurities interference. Later

possible reactions in the process were deduced. Additionally

experiments were conducted in a TG-DTA integrated thermal gravimetric analyzer and a tube furnace. The products from the experiments were characterized and analyzed to verify the accuracy of theoretical calculations. The results showed that these impurities can change the decomposition process of PG. For example

aluminum oxide was transformed to calcium sulfoaluminate

while iron oxide was transformed to dicalcium ferrite. Furthermore

the results help to further improve the basic theory of phosphogypsum decomposition.