Abstract
The effect of temperature (1250°-1450°C), and silicon and manganese in carbon-saturated iron (0.1%P, 0.05%S) on the dephosphorization was studied by using the flux of the CaSO4-CaCO3 system. It was found that CaSO4, although it is in solid state, has strong dephosphorization power. The following dephosphorization reaction was derived from the results of EPMA of the products of dephosphorization reaction: 7/2CaSO4(s)+2P=3CaO•P2O5(s)+1/2CaS(s)+3SO2
The above reaction was found to proceed with increasing temperature. No effect of the oxidation of silicon on the degree of dephosphorization and no reversion of phosphorus and sulfur were observed, but marked sulfur pick-up in metal took place as a result of the reactions of CaSO4 with carbon, phosphorus and silicon. To use this flux for the dephosphorization of hot metal, all efforts were made to prevent such a sulfur pick-up by the additions of CaF2, Na2CO3 and CaG2 to the flux.
