Mathematical modelling of magnesia carbon refractories reactions with steel

The production of super clean steel has put in clear evidence the importance of the refractory in influencing the degree on internal cleanliness of steel. In fact chemical species transfer from the refractory to the steel bath. To reduce the steel contamination caused by the refractory it is necessary to know the interaction between the refractory and the steel. A mathematical model of the modifications of the refractory surface in contact with the steel has been developed. The work is focused on magnesia-carbon refractory (taking into account the presence of reducing agents too, as Al, Si and Mg) and carbon steel. The model calculates the new phases formed when liquid steel and refractory are in contact. The model is based on the following mechanism of reactions: (i) Magnesia reacts with graphite forming gaseous CO and Mg. (ii) The other oxides present in the refractory (mainly CaO and SiO 2 which constitutes a glassy phase) pass into the steel, giving dissolved elements and dispersed oxides. (iii) Gaseous Mg reacts at the interface refractory/steel with oxygen dissolved in the steel forming solid MgO. (iv) The MgO generated and the oxides originating from the glassy phase form the new oxide system. The newly formed phase can potentially be transferred to the bath through the steel flow against the refractory walls. The results of the model simulations have been validated by experimental tests.