| Corrosion and erosion of refractory bricks used for lining the slag-line of secondary steelmaking vessels are an important problem. Refractories are a major cost factor in steel shops and their loss needs to be minimized. Corrosion of MgO-C refractories occurs through the loss of carbon bond phase and by reaction with corrosive slags. A laboratory slag corrosion testing method was developed and successfully used to obtain a mathematical model to describe the corrosion process and its dependence on time, temperature, slag basicity and atmosphere. Response surface plots as a function of time, temperature, slag basicity were graphically plotted, and a polynomial equation was developed to predict the amount of corrosion in the range of factors studied. The correlation coefficient of the model developed was 0.95. Other experimental methods have long suffered from lack of reliable and reproducable quantitative data mainly due to the lack of adequate control of important factors that influence the corrosion rate. The tests used were performed in isothermal conditions in a controlled atmosphere in a vertical tube furnace while the refractory specimens were immersed into the melt for prescribed amounts of time. Activation energy for slag viscosity was estimated from high temperature viscosity measurements. The mathematical model developed can be used by steelmakers followed by a limited number of more refined tests using their industrial materials. |
