Investigation of in-situ chemical reactions of Al2O 3-SiC-SiO2-C refractory and its interactions with slag

Abstract

Experiments were carried out to investigate in-situ reactions of refractory and its interactions with slag (composition: 45.4%SiO2+36.6%CaO+15. 9%AI2O3) using a horizontal furnace by detecting CO and CO2 contents in off gas with an infrared (IR) analyzer. The composition of refractory is 69.4%Al2O3+7.3%SiO 2+10.6%SiC+12.7%C. Temperature was from 1 773 to 1 873 K. The samples after high temperature experiments were analyzed using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) - Energy Dispersive Spectrometer (EDS). Mullite was detected after refractory samples were maintained at high temperatures. The refractory/slag reaction was evaluated by calculating the carbon removed. Carbon removal process was a two-step reaction, in the beginning the carbon was removed very quickly (fast reaction stage) and both CO and CO2 gases were detected by IR analyzer. Then after around 2 000s the reaction slowed down and no CO2 gas could be detected (slow reaction stage). The main in-situ reaction product was SiC rather than SiO. Slag showed good wetting with the refractory and penetrated into it through pores. Low melting point compounds, anorthite (CaAl2Si2O8) and gehlenite (Ca2Al2SiO7) were detected after heating refractory for 7 200 s while remaining in contact with slag.