Simultaneous removal of SO2 and NO by phosphate tailings-derived composite slurry: A study of phosphorus element migration and transformation

Abstract

In this study, we developed a composite slurry using industrial hazardous solid waste phosphate tailings and yellow phosphorus for the simultaneous removal of SO2 and NO. Additionally, the migration and transformation of the P element within the slurry were thoroughly investigated. The experimental results revealed that this composite slurry exhibited efficient removal of both SO2 and NO. Further investigations indicated that Ca5(PO4)3F and CaMg(CO3)2 within the composite slurry acted as the primary active phases during the SO2 removal process. On the other hand, the yellow phosphorus (P4) components facilitated the conversion of O2 to O3, which subsequently oxidized NO to nitrate. Throughout the course of the reactions, significant amounts of the P element in the solid phase (Ca5(PO4)3F and yellow phosphorus (P4) were leached out as PO43−, accumulating in the liquid phase. The resulting solution containing NO3− and PO43− could potentially serve as a valuable raw material for the production of nitrogen-phosphorus composite fertilizers. Additionally, a small portion of the P element within the composite slurry was oxidized to P2O5 and released into the gas phase, resulting in a partial loss of the P element.