Comparison of the Determination Methods for the Calcium Sulfate Content in Phosphogypsum

Phosphogypsum is a kind of by-product of the phosphate fertilizer production process, mostly in the form of CaSO₄·2H₂O, the analytical determination of the content of the main component is the basis for the comprehensive utilization of phosphogypsum. This paper introduces three analytic procedure to determinate the content of crystal water, SO₄^2-, Ca²⁺ to calculate the CaSO₄ content of phosphogypsum, through a comparison between the results of three methods, we can conclude that granularity of phosphogypsum has the smallest influence on the crystal water determination method, but only applicable to determination of gypsum containing crystal water in single phase. However, the measure of SO₄^2-, Ca²⁺ is not restricted by the phosphogypsum phase, but influenced by the particle size. SO₄^2- determination operation is relatively simple and easy to control, reversely, Ca²⁺ determination operation is complex and hard to control.