Carbon/slag interactions between coke/rubber blends and EAF slag at 1550°C

Abstract

Using the sessile drop approach, interfacial reactions taking place in the slag/carbon region were investigated at 1 550°C in a horizontal tube furnace under inert atmosphere (1 L/min Ar). In this study, waste rubber tyres were blended with metallurgical coke, already used as injectant in electric arc furnace (EAF) steelmaking, in different proportions. Off gas analyses and physicochemical properties of the slag have been evaluated and correlated with the carbon/slag interactions. The gaseous emissions from metallurgical coke showed lower concentrations in comparison to the emissions from the coke-rubber blends. With an increase of rubber in the blend, gaseous emissions were enhanced. Significant carbon/slag interactions occurred when coke/rubber blends were used, with associated iron oxide reductions within the slag phase. Higher gas entrapment in the slag was also observed when the rubber partially replaced the coke. High levels of gas generation leads to increased likelihood of convective transport of reactants and products from the carbonaceous material surface due to evolution of gases as a result of slag/carbon interactions. The oxides present in the ash partially dissolve the molten slag, modifying the slag composition. The results have been discussed and correlated with the hydrogen, ash and sulphur contents of the carbonaceous residues as well as with the dynamic changes in slag composition. This study highlights significant differences in the carbon/slag interactions of coke/rubber blends with EAF slag, compared to interaction of coke with the same slag. © 2009 ISIJ.