2010 Volume 51 Issue 6 Pages 1094-1101
In order to clarify the dissolution behavior of solid P2O5 rich phase in slag, the solid phosphate compound silicocarnotite 5CaO·SiO2·P2O5 being the representative of P2O5 rich phase was dipped into the molten CaO-SiO2-FeOx slag at 1573 and 1673 K. Since the initial slag was free of P2O5, the increase of P2O5 content in the slag is the indication of the dissolution behavior of solid 5CaO·SiO2·P2O5. Therefore, the concentration profile of P2O5 across the interface between solid 5CaO·SiO2·P2O5 and slag was analyzed to evaluate the dissolution behavior.
The results show that the dissolution of solid 5CaO·SiO2·P2O5 into slag can be divided into the following stages: interaction of solid phase with slag, disintegration of solid phase, reaction between disintegrated solid phase and surrounding slag, and diffusion of CaO and P2O5 from solid sample to slag. The diffusivity of P2O5 in the liquid slag was calculated. It was found that higher temperature is favored for the diffusion in some cases, whereas larger CaO/SiO2 ratio of the slag restrains the diffusion.