Thermodynamic behavior of phosphorus in CaO-CaF2-SiO2 and CaO-Na2O-SiO2 systems
Tóm tắt
In order to understand the thermodynamic behavior of phosphorus, such as the polymerization of phosphate ions in slag melts, the influence of phosphorus content of slag melts on the partition of phosphorus between slags and carbon-saturated iron or silver was investigated for the CaO-CaF2-SiO2 and CaO-Na2O-SiO2 systems at 1573 and 1473 K, respectively. The predominant species changes from PO
4
3
to P2O7
4-approximately at 2 mass pct of phosphorus in slag melts, which is defined as the critical phosphorus content, for the CaO-CaF2-SiO2 system which is doubly saturated with CaO and 3CaO · SiO2. The critical phosphorus content was found to be about 1 mass pct for the CaO-CaF2-SiO2 melts saturated with 2CaO · SiO2. On the other hand, in the case of the 20CaO-35Na2O-45SiO2 system, PO4/3- is the predominant species until the slag becomes saturated with Ca3(PO4)2. No effect of sulfur on the phosphorus partition ratio was observed for the CaO-CaF2-SiO2 system.
Tài liệu tham khảo
E.T. Turkdogan:Physical Chemistry of High Temperature Technology, Academic Press, New York, NY, 1980, p. 8.
A. Tagaya, Y. Nabika, T. Hashimoto, F. Tsukihashi, and N. Sano:Trans. 1SS, 1991, July, in press.
R. Selin:Proc. 3rd Int. Conf. on Molten Slags and Fluxes, The Institute of Metals, London, 1989, pp. 317–22.
M. Uo, E. Sakurai, F. Tsukihashi, and N. Sano:Steel Res., 1989, vol. 60, pp. 496–502.