Degradation mechanisms of magnesia-chromite refractory bricks used in oxygen side-blown reducing furnace

摘要

Oxygen side-blown reducing smelling is an efficient and environment-friendly technology to directly process the liquid high-lead slag, but it shows high refractory wear during industrial practice. To understand the specific degradation mechanisms, a post-mortem analysis of magnesia-chromite refractory bricks (fused-grain rebonded type) taken from the tuyeres of the furnace was performed by SEM and phase diagram. According to the results, typical reaction zone and infiltrated zone were formed between the hot face and the original refractory. The fast and deep infiltration of PbO-containing fayalite slag under turbulent conditions was responsible for the significant dissolution of periclase grains, which caused the development of a continuous and thick forsterite layer. Meanwhile, the components of FeO and ZnO in the slag were mainly absorbed by the chromite grains. Then the increased CaO/SiO2 of the slag resulted in the large formation of monticellite in the infiltrated zone. Based on these results, the key reasons for the high wear of refractory lining were revealed and several possible solutions were also proposed.