Removal of FeO during Foaming of CaO-Al2O3-SiO2-FeO Slags by Low Carbon-Iron Melts

Removal of FeO from CaO-SiO2-Al2O3-FeO slags by low carbon-iron melts has been investigated experimentally at 1723 K. The rates of FeO removal were estimated using experimentally measured rate of pressure rise in the reactor due to evolution of CO (g). Several flash X-ray images were obtained during the course of these experiments. The experiments were conducted by dropping a small amount (10-90g) of slag over an Fe-C melt weighing 400g. Based on the rates of reduction of FeO dissolved in CaO-SiO2-Al2O3 slags by two types of Fe-C (1.3 and 2.2%) melts, it was determined that the reactions were independent of carbon concentration and followed first order rate kinetics with respect to FeO concentration. The reactions did not stop until metal and slag phases reached thermodynamic equilibrium with respect to the iron oxide in the slag. The calculated value for the rate constant was 7.34×10-4m/s and it was independent of slag weight or foam volume. Therefore, it was concluded that the presence of foam on the matal bath did not influence the mechanism of FeO removal from slag by Fe-C melts. Maximum height, hf, of the foam generated was established to be a linear function of slag weight, ws, present on the Fe-C melt surface and the relationship was given by hf=11.69+1.993ws