Synthetic Coal Slag Infiltration into Varying Refractory Materials

摘要

The infiltrations of synthetic coal slag into 99%A1_2O_3, 85% Al_2O_3-15%SiO_2, and 90%Cr_2O_3-10%Al_2O_3 refractories with a temperature gradient induced along the penetration direction were compared to one another. The infiltrating slag was synthesized with a composition that is representative of an average of the ash contents from U S coal feedstock. Experiments were conducted with a hot-face temperature of 1450℃ in a CO/ CO_2 atmosphere. Minimal penetration was observed in the 90%Cr_2O_3-10%Al_2O_3 material because interactions between the refractory and the slag produced a protective layer of FeCr_2O_4, which impeded slag flow into the bulk of the refractory. After 5 h, the 99%A1_2O_3 sample exhibited an average penetration of 12.7 mm whereas the 85%Al_2O_3-15%SiO_2 sample showed 3.8 mm. Slag infiltrated into the 99%A1_2O_3 and 85%Al_2O_3-15%SiO_2 refractory systems by dissolving the respective refractories' matrix materials, which consist of fine A1_2O_3 particles and an amorphous alumino-silicate phase. Due to enrichment in SiO_2, a network-former, infiltration into the 85%Al_2O_3-15%SiO_2 system yielded a higher viscosity slag and hence, a shallower penetration depth. The results suggest that slag infiltration can be limited by interactions with the refractory through the formation of either a solid layer that physically impedes fluid flow or a more viscous slag that retards infiltration.