Synthesis Of MA-CA₂/CA₆and Its Reaction With Cement Clinker

Magnesia-spinel bricks have excellent thermal shock resistance and alkali, chlorine,sulfur, resistance, etc, which are the development trend of chrome-free basic refractoriesin cement rotary kiln burning zone, but the magnesia-alumina spinel (MA) of magnesiaspinel brick components easily by the erosion and dissolution of cement clinker evenlead to spalling of magnesia spinel bricks and can not form a stable kiln skin structure.In this paper the refractory materials of the cement rotary kiln with chrome free andmodification of magnesia spinel brick are reviewed, in addition, effect of sinteringproperties and micro-structure of CA2/CA6content to MA-CA2/CA6composite materialare researched and the poor corrosion resistance of MA to cement clinker and thecharacteristics of low melting point compound formed in reaction with cement clinkerare improved, finally, improving the bond strength of magnesia spinel brick with cementclinker after high temperature reaction. The following conclusions were obtained.(1)Dolomite, magnesite and industrial alumina as raw materials for the preparation ofMA-CA2/CA6composite materials, In the sample group with CA2addition, the densityof samples gradually fall, the bulk density of the specimen which the content of CA2is10wt%is highest to3.39g/cm3and the apparent porosity of it is lowest to5.2%. In theother side, in the sample group with CA6addition, the density of samples graduallyincrease, the bulk density of the specimen which the content of CA6is30wt%is highestto3.03g/cm3.(2)MA and CA6and CA2were enriched in the partition region in MA-CA2/CA6composite materials, and then the contents of CA2and CA6are different influence forthe development of MA crystal size which CA2can promote the growth of MA grainsize while CA6inhibits the growth of that.(3)Compared with78MA, CA2/CA6can prevent erosion of composite materialsresistance of CaO erosion infiltration from cement clinker. When the content of CA2is40wt%, the increase quantity of CaO is drop lowest to0.78mol%. The MA-CA2/CA6composite materials and cement clinker reaction are CA, C3S and CS, which havehigher melting point advantaged to improve the cement clinker viscosity and bondingstrength of reaction sintering layer, further depressing the erosion of cement clinker andsecondary permeability.(4)The specimen which is adding15wt%composite MA contained30wt%CA6tomagnesia is the best of the corrosion and permeability of cement clinker and it reacted with cement clinker to form CA, C2S and other high melting point phase which candepressing the erosion of cement clinker and secondary permeability.(5)Substituting MA-CA2/CA6for78MA to prepared magnesia spinel brick willimprove the shear bond strength of magnesia spinel brick and cement clinker fired athigh temperature reaction and protect the MA in the reaction, is expected to improve themagnesia spinel brick kiln skin performance.