Synthesis And Properties Of Light-weight Mullite Refractory By Coal Gangue

Coal gangue is a solid wastes resulting from the process of coal mining and washing,accounting for10~20%of the original coal production. Accumulated coal gangue not onlyinvaded land and but also caused other environment pollution. Therefore, fabrication oflight-weight mullite refractory by coal gangue and its performances were studied in this article.The main contents in this paper include two parts. Firstly, influence of sintering temperature,content of coal gangue, content of pore-forming and its particle size as well as content of kyaniteon the properties and microstructure of light-weight bricks were investigated when light-weightmullite brick was prepared by coal gangue as main materials. Properties comparison betweenlight-weight mullite bricks prepared by coal gangue and light-weight mullite bricks at home andabroad were subsequently assessed. Secondly, influence of sintering temperature and coalgangue content on the properties and microstructures of both M70and M55light-weightaggregates were studied when light-weight mullite aggregates were fabricated by coal gangue asmain materials. In addition, M75, M55and common M65light-weight aggregates in marketwere prepared light-weight castables. The detailed results were listed as follows:(1)To light-weight mullite bricks: The light-weight mullite bricks with bulk density ofabout0.83g/cm~3,cold comprehensive strength up to2.5MPa,linear change ratio on reheatingachieved0.24%at1450℃×3h, thermal conductivity of about0.217W/(m·K)（300℃）ismanufactured when coal gangue content is added to60wt%, content and particle size ofpore-forming is50wt%and165um respectively, and kyanite is10wt%. The physical propertiesof prepared light-weight mullite bricks are compared with the bricks at home and abroad. Itsthermal conductivity is lower.(2)To light-weight mullite aggregates: The M70light-weight mullite aggregates with bulkdensity of about1.21g/cm~3, water absorbing ratio up to53.7%, packing density of about0.71g/cm~3and cold comprehensive strength achieved5.24MPa was fabricated at1450℃when coalgangue is added to50wt%; The M55light-weight mullite aggregates with bulk density of about1.32g/cm~3, water absorbing ratio of about42.09%, packing density of about0.97g/cm~3and coldcomprehensive strength of about4.28MPa was fabricated at1300℃when coal gangue is addedto50wt%. The physical properties of light-weight castables manufactured by M70and M55arecorresponding to castables prepared by M65in market and its thermal conductivity is lower，providing an effective way of utilization of coal gangue.