Leaching behavior and microstructure of phosphorus in converter slag

Converter slag is a by-product of the steelmaking process and contains a large amount of Ca, Fe, P and other elements. If the phosphorus in the converter slag can be effectively extracted, the resulting phosphorus can be used as a phosphate fertilizer. Phosphorus in converter slag is mainly enriched in 2CaO·SiO2–3CaO·P2O5 (C2S–C3P) solid solution and is easily dissolved in water. Therefore, acid leaching method was used to dissolve the solid solution to extract phosphorus in converter slag, so as to realize the recycling of phosphorus resources in converter slag. The leaching behavior of three actual converter slags from different steel mills in acid leaching solutions composed of citric acid, sodium hydroxide, hydrochloric acid and deionized water was studied by X-ray diffraction, scanning electron microscopy combined with energy dispersive spectrometry, Fourier transform infrared spectroscopy and Raman spectroscopy to reveal the change in object image structure as well as SiO4 and PO4 tetrahedron before and after acid leaching. The results show that only a small amount of phosphorus in converter slag with too low basicity is enriched in C2S–C3P solid solution, resulting in poor leaching effect. When the converter slag has a high basicity, the removal effect of phosphorus is 70.64