ESTIMATION OF CARBON CONCENTRATION IN THE METAL BATH BY MEANS OF ON-LINE MEASUREMENT OF THE CONCENTRATION OF THE OFF-GAS IN THE EAF

Over the past 60 years the steel making process has developed valuable technology for the scrap melting operation inside EAF. Traditionally, operators rely on the calculation of static charge models that are able to predict chemical composition and temperature of the bath at tapping. These models, however, have a limited ability to predict the tapping time carefully because they do not take into account the dynamics of the process and the variability of the initial conditions. Currently, a great number of steel shops are equipped with a system that allows the calculation of the temperature and the carbon concentration in the metal bath through off-gas analysis. The aim of the present work is to correlate the off gas composition with the values of temperature and carbon concentration at the end of melting and refining process. For the calculation of the temperature, the thermal regime was estimated within the EAF and thereafter the temperature inside the metal bath as a function of the concentration of carbon present. The carbon concentration was calculated using coefficients of activity, mass balances and estimation of the rate of decarburization law by the chemical composition of the fumes, in order to calculate the carbon concentration inside the metal bath at the end of the blowing.