Synthesis And Properties Of Light-Weight Mullite Refractory By Kyanite Containing Zirconium

Kyanite containing zirconium,a kind of tailings generated from beneficiation of some zirconite mineral.Its main composition is kyanite but can't equal to normal kyanite because of the residual zirconite.The amount of its accumulation is large and the related researches are not seen reported in detail.To solve this problem,this subject carried out the research about synthesis of light-weight mullite refractory by kyanite containing zirconium as the main raw material,which provides a new way and theoretical guidance for the comprehensive utilization of kyanite containing zirconium.This study discussed the impacts of raw materials amounts,firing temperature and other process parameters on linear change ratio after firing,cold compressive strength,thermal conductivity and other properties of light-weight mullite refractory;compared different kyanites and analyzed their impacts on the synthesis of materials and the occurrence of zirconium in the materials;analyzed the relationship between the phase composition /microstructure of properties in the materials by XRD,SEM,EDS and other testing means.The detailed results were listed as follows:(1)When the content of clay is 30 wt.%,the content of microsilica is 3 wt.%,the content of sawdust is 25 wt.%,the sintering temperature is 1450 oC,the light-weight mullite refractories from kyanite containing zirconium,get the better comprehensive properties: linear change ratio after firing 0.11%,cold compressive strength(CCS)5.86 MPa,bulk density 0.96g/cm3,thermal conductivity 0.229 W/(m·K)at the testing temperature 400 oC.(2)In the process of synthesis of light-weight mullite refractories,it can be found that the grain and aggregation morphology of mullite which generated from the decomposition of kyanite are obviously different from which generated from the reaction of clay and other materials.The former grains are short and thick,cross together as a whole closely,with tight grain spacing.The latter grains are long and thin,intertwined like a mesh,with loose grain spacing.(3)Compared with other kyanite,kyanite containing zirconium brought a small total content of zirconium as raw material,has little effect on the overall performance of the light-weight mullite refractories.In the light-weight mullite refractories,the zirconiumshowed no change and dispersed in granular form,and some connected together with mullite grains.