A Low Cost of Burning Raw Material For PO43−-P And F− Solidification/Stabilization In Phosphogypsum

Abstract Phosphogypsum (PG) contains a lot of soluble phosphate (PO4 3−-P) and fluorine ion (F−), which seriously has hindered the sustainable development of phosphorous chemical industry. In this study, a new burning raw material (BRM) was used for the stabilize of PO43−-P and F− in PG. The characteristics of PG and BRM, stabilize mechanism of PO43−-P and F−, leaching test and economic evaluation were investigated. The effect of PG and BRM weight ratio, solid to liquid ratio, reaction time and reaction temperature on the concentrations of PO43−-P and F− were studied. The results showed that the concentration of F− in PG leaching solution was 8.65 mg/L and the removal efficiency of PO43−-P was 99.78 %, as well as the pH of 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 ℃. PO43−-P and F− were mostly solidified as Ca5(PO4)3F, CaPO3(OH), Ca5(PO4)3(OH), Ca2P2O7·2H2O, CaSO4PO3(OH)·4H2O, CaF2, and CaFPO3·2H2O. Leaching test results indicated that the concentrations of PO4 3−-P, F− and heavy metals were less than the integrated wastewater discharge standard (GB8978-1996). Economic evaluation revealed that the cost of PG treatment was $ 0.88/ton. This study provides a new low cost and harmless treatment method for PG.