Phase Relations in the CaO-P2O5-FeO-Fe2O3-H2O System at High Temperatures.

The liquidus temperatures and primary-phase boundaries of the CaO-P//2O//5-(iron oxide) system in equilibrium with gas atmospheres, such as CO//2/Co equals 8, with and without water vapor were determined at temperatures other than 1600C. P//2O//5 concentrations were below 50%. It was found that water in the system causes an increase of the stability of phases with apatite structure and has a significant effect on the boundaries of the basic phosphate phases on the liquidus plane. The results made it possible to determine the most favorable compositions of phosphate slags for refining steel melts, and also the conditions under which these slags give the most easily soluble fertilizers, because of low apatite structure constituents.