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

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 PO₄^3-, accumulating in the liquid phase. The resulting solution containing NO₃^- and PO₄^3- 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.