Study On The Preparation And Properties Of Lightweight Microporous Bauxite Clinker

Lightweight of refractory is one of the important effective measures to achieveenergy saving for high temperature industrial furnace, the lightweight aggregateaccounts for60%among refractory material, which has a major impact on the overallperformance of the lightweight refractories. So the study of microporous aggregate isthe key to realize the preparation of high performance lightweight refractory material.This paper focused on the preparation of lightweight microporous bauxite clinker byusing method of wet milling casting in situ decomposition, as well as investigationabout the effect of starch, Al(OH)3, additives and different bauxite sources on propertiesof lightweight microporous bauxite clinker.Furthermore,the content of solid and liquidphase were calculated by using FactSage software, through which analyzed its effect onthe sintered properties about lightweight microporous bauxite clinker.The main conclusions are as follows:(1)The bauxite slurry had good fluidity and stability and was suitable formoulding by slurry injection when the amount of water was about45wt%; The openpores in the sample can be transformed into the closed pores, which made the samplehad a high closed porosity and simultaneously low apparent porosity as well as bulkdensity when the sintering temperature is1650℃.(2)The increased amount of starch would lead to the porosity and total porosity ofsample increased at first and then decrease, but the closed porosity and bulk densityshown opposite change correspondingly.A large number of pores were uniformlydistributed in the grain boundary, and small amount of pores were distributed withinthe grains, the pore size distribution was unimodal and the average pore diameterincreased gradually.(3)It is conducive to the formation of closed pore and reduction of the porosity of samples by adding a small amount of Al(OH)3, resulting in the transition of pore sizedistribution from single peak to multi peak,and the pore size was increased anddistributed dispersedly.(4)Part of closed pores were transformed into open pores by adding some BO2orsintered magnesia, the distribution of pore size was changed into multi peakdistribution at the same time. The open pores in the sample could be partlytransformed into a closed pore and the pore size decreased after adding some fusedmagnesia. The pores in samples were almost wrapped by the grain boundary and wereevenly distributed, the size of which concentrated on4~6μm and the distribution ofwhich was single peak. The best performance of the sample was obtained when adding1%fused magnesia and the ratio of Al2O3/SiO2was above23, the best performanceswere as follows: porosity7.5%, bulk density2.95g/cm3, water absorption2.59%,closed porosity15.6%, and the average pore size0.82μm, the ratio of the solid phaseand liquid phase in the sample was about9.67.(5)Use different bauxite which contain different amounts of Al2O3、Fe2O3andR2O to synthetize lightweight microporous bauxite clinker, the porosity was lowerthan11.4%, the closed porosity was higher than13%, the bulk density was lower than3.00g/cm3, the water absorption was lower than3.9%, and the average pore sizedistributed uniformly whose size of the pores was smaller than5.11μm.(6)After converting the complex multiple system into a ternary system andquaternary system by Richter rule, the contents of the solid phase and liquid phase inthe sample was calculated and a Kingery and LSW model was established. The resultsindicated that, we can get the lightweight microporous bauxite clinker with lowapparent porosity, high closed pore rate, low bulk density, and reasonable pore sizedistribution when the ratio of the solid phase and liquid phase was about10.