关键词: 废旧耐火材料, 高铝砖, LF精炼渣, 溶解, 反应机制

Abstract: The Al₂O₃ in LF slag usually originates from bauxite,and LF slag has similar composition with waste high-alumina bricks.Hence,it is possible to substitute for bauxite with waste high-alumina bricks.Waste high-alumina bricks were cut into cylindrical specimens (17.3 mm×12.0 mm) and put into the refining slag of 1 600 ℃ for different durations (5,10,15,and 25 min).The dissolution rate and microstructure of the waste high-alumina specimens as well as the composition of the refining slag after reaction were analyzed,and the dissolution mechanism of waste high-alumina bricks in the refining slag was explored.The results show that after dissolution,there is an obvious boundary layer between the high-alumina specimen and the refining slag,and MgO in the refining slag preferentially diffuses to the boundary layer to form Al₂O₃-MgO solid solution with the dissolved Al₂O₃ in the specimen;with the increasing reaction time,the Al₂O₃-MgO solid solution gradually increases,forming an Al₂O₃-MgO solid solution layer on the specimen surface at the later stage of reaction,which prevents the diffusion of dissolved calcium aluminate into the refining slag;after 25 min of reaction,the dissolution rate of the specimen reaches 35%;by comparing the slag reacted for 25 min with that reacted for 5 min,the Al₂O₃ content increases to 30.9 mass% from 27.1 mass%.

Key words: waste refractory materials, high-alumina brick, LF refining slag, dissolution, reaction mechanism