Preparation And Research On Red Mud Thermal Insulation Ceramic Bricks

Red mud is a solid waste generated during aluminum production from bauxite. With the increasing of alumina output,red mud causes a number of environment problems and its disposal becomes more and more important.In order to utilize this industrial solid waste,the high performances thermal insulation bricks based red mud have been made from red mud,poor clay shale and some additives as raw materials in this paper.Especially,two kinds of making techniques semi-dry pressing and extrusion were used in this study.And the pre-production has been performed.The results indicated that the sinter red mud and bayer red mud are not suit for bricks preparation individually because of its composition.But their mixture can be prepared simple bricks.By the test of performances and microstructure of the insulation thermal ceramic brick samples,the reaction mechanism and the insulation thermal mechanism were investigated.The performances of the samples were measured by TG-DTA,SEM,XRD and EPMA.The results showed that the samples could be prepared with high performances when the addition of red mud is more than 50%,and showed that the insulation thermal ceramic bricks with the best performances and microstructure (water absorption(Wa)of A-4 is 24.18%,porosity absorption(Pa)is 42.68%, density(D)is 1.77g/cm³,the bending strength is 19.78MPa and the compression strength is 45.76MPa,freeze-thaw resistance is 36.74MPa,thermal conductivity(α)is 0.88W·cm^-1·K^-1)could be prepared when the content of the sinter red mud is 30%and the content of the bayer red mud is 30%.Its main crystals composition are quartz(SiO₂),ferric oxide(Fe₂O₃),andradite(Ca₃Fe₂Si₃O₁₂),gehlenite(Ca₂Al₂SiO₇), diopside(CaMgSi₂O₆).The extrusion technique is another making method of the ceramic manufacturing processes.In this thesis,it has also used the technique to make the insulation thermal ceramic bricks.In the part,four factors were investigated,such as the research on the body plasticity,the research on body drying and firing system and the factors affecting the heat-insulating property of the insulation thermal ceramic bricks.It was found that the plasticity of the body were the best when the ageing times was 2 days, the plasticity could be markedly increased by adding the lignosulphonate incorporation.With the increasing of red mud,the plasticity has become worse.It also showed that the insulation thermal bricks with the best performances and microstructure(Wa of J-1 is 25.36%,Pa is 41.89%,D is 1.68g/cm³,and the compression strength is 23.87MPa,freeze-thaw resistance is 21.70MPa,thermal conductivity(α)is 0.58W·cm^-1·K^-1)could be prepared when the content of the sinter red mud is 20%and the content of the bayer red mud is 30%.The pre-production of the insulation thermal ceramic brick has been performed, and some problems which were found in the pre-production were solved.