Effect of aging on physicochemical properties of phosphogypsum
X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FT-IR),field emission scanning electron microscopy(SEM),and chemical analysis were employed to investigate the variation of impurity content,microstructure,and crystal characteris-tics of raw and aged phosphogypsum from a chemical factory at different particle sizes.The results showed that the total phospho-rus content gradually increased from 1.07%to 1.46%with decreasing particle size,the soluble fluorine content decreased from 0.58%to 0.10%with decreasing particle size;the iron content increased from 0.35%to 0.72%,the organic matter content decreased by nearly 17.6%,short-term aging did not change the pH of phosphogypsum,in addition,the aging process affected the mass distri-bution of the phosphogypsum in each particle size and increased the average particle size of phosphogypsum.The impurity content in phosphogypsum with larger particle sizes was higher than that in phosphogypsum with smaller particle sizes.Phosphogypsum ag-ing under part of the physical phase CaSO4·2H2O in the aging process will lose the binding water converted to CaSO4·0.5H2O,part of the crystalline form from rhombic to short rod.
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