A new basic burning raw material for simultaneous stabilization/solidification of PO 4 3- -P and F - in phosphogypsum.

Phosphogypsum (PG) contains a lot of soluble phosphate (PO-P) and fluorine ion (F), which seriously has hindered the sustainable development of the phosphorous chemical industry. In this study, a new burning raw material (BRM) as an intermediate product in the cement production process was used for PO-P and F stabilize in PG. The stabilizing mechanism of PO-P and F were investigated by Fourier Transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), Scanning Electron Microscopy (SEM), X-ray fluorescence (XRF) and X-ray spectroscopy system (XPS). The effect of PG and BRM weight ratio, solid-to-liquid ratio, reaction time, and reaction temperature on the concentrations of PO-P and F were studied. The results showed that the concentration of F in the PG leaching solution was 8.65 mg/L and the stabilizing efficiency of PO-P was 99.78%, as well as the pH of the PG leaching solution was 8.12 when the weight ratio of PG and BRM was 100:2, and the solid to liquid ratio was 4:1, reacting for 24 h at the temperature of 30 ℃. PO-P and F were mostly solidified as Ca(PO)F, CaPO(OH), Ca(PO)(OH), CaPO·2HO, CaSOPO(OH)·4HO, CaF, and CaFPO·2HO. Leaching test results indicated that the concentrations of PO-P, F and heavy metals were less than the integrated wastewater discharge standard (GB8978-1996). This study provides a new harmless treatment method for PG.