Abstract: Taking the phosphogypsum,a by-product in the phosphorus fertilizer industry as main raw material,coal powder as reducer,calcium sulfide was prepared through deoxidizing,roasting,and decomposing phosphogypsum.Influences of the reactant ratio,time,temperature,and ambience of the reaction on the preparation of calcium sulfide were studied.The optimum conditions of deoxidation and decomposition were found through single factor experiments,and then orthogonal experiments were made to find out the optimum process parameters,which were as follows:coal powder exceeded 25%,temperature was 870 ℃,and the reaction time was 2 h.The content of calcium sulfide was analysized by iodometric method,and the conversion rate of phosphogypsum through calculation was above 98% under those conditions.

Key words: phosphogypsum, calcium sulfide, orthogonal experiment