An innovative method for simultaneous stabilization/solidification of PO43− and F− from phosphogypsum using phosphorus ore flotation tailings

Abstract Phosphogypsum (PG) contains plenty of PO43− and F− and some heavy metals. Phosphorus ore flotation tailing (POFT) mainly consists of dolomite (CaMg(CO3)2) and calcium fluophosphate (Ca5(PO4)3F). Traditional methods of POFT and PG storage could seriously damage the ecological environment. In this study, an innovative method for simultaneous stabilization/solidification (S/S) of PG and POFT was studied. The effects of PG and POFT mass ratio, S/S pH, solid-liquid ratio and temperature on the concentrations of PO43− and F− in the leaching solution as well as the characteristics of POFT and PG were studied. Meanwhile, the simultaneous S/S mechanisms of PG and POFT and leaching test were investigated. The results showed that the concentrations of F− and PO43− in the leaching solution were 6.0 mg/L and 4.0 mg/L, respectively, when the mass ratio of PG and POFT was 1:1 and the initial pH was 8.0 after being solidified for 30 days. F− and PO43− were mainly stabilized as (Ca, Mg, Zn)F2 and (Ca, Mg, Zn)3(PO4)2, respectively. Leaching test results showed that PO43− was reduced from 508.0 mg/L to 4.0 mg/L, and the concentrations of all the measured heavy metals and F− were within the permitted level for the GB8978-1996 after 30 days S/S.