Efficient Removal of Phosphides from Yellow Phosphorus Tail Gas Using Phosphate Rock Powder as a Dephosphorization Agent

Abstract

Yellow phosphorus tail gas, containing over 90% CO gas, serves as a high-quality fuel resource. Nevertheless, the phosphoric acid produced by the combustion of PH3 can corrode the gas-fired boilers. Herein, we propose an in situ dephosphorization strategy using fluidized phosphate rock powder as an absorbent during tail gas combustion. In an industrial fluidized bed boiler, PH3 is oxidized to P4O10 and H3PO4, which are captured by the powder. The system achieved over 99.8% dephosphorization efficiency, and the phosphorus content at the outlet was less than 5 mg/m3. Meanwhile, the phosphorus content of phosphate rock powder increases by 5.25%, enabling its reuse as a yellow phosphorus production feedstock. Characterization and reactivity tests reveal that dephosphorization active components are CaMg(CO3)2, KAl2(Si3AlO10)(OH)2, Ca5(PO4)3F, and SiO2, with reactivity decreasing in that order. In addition, the phosphate products formed after dephosphorization were identified. This work provides certain theoretical guidance for the efficient dephosphorization of the phosphate rock powder.