Sintered Series Bauxite-based Study Of All Material

Based on the our rich bauxite resources, preparation of a series bauxite-based homogenized grogs(60-90wt.%Al₂O₃) have been investigated in the paper by homogenization process and sintering method using bauxite as starting material incorporated with appropriate amount of coal gangue and addition of a small quantity of Al₂O₃ to accommodate tinily compositions.The series of homogenized grogs with consistent components and structure and properties using different grades of bauxite as starting material have been prepared. The sintering temperatures of corundum homogenized grogs both are 1550℃, apparent porosity are <2.5%, bulk density are 3.44g/cm³ and 3.29g/cm³ respectively. The sintering temperatures of homogenized mullite grogs with 70wt.% and 60wt.% Al₂O₃ are 1700℃ and 1600℃, apparent porosity are <2.5% and their bulk density are 2.75g/cm³ and 2.64 g/cm³ respectively. The properties of corundum homogenized grogs with about 90wt.%Al₂O₃ content reach international level, the properties of mullite homogenized grogs reach national level. The sintering temperatures and Refracteriness-under-Load of mullite grogs are higher than that of corundum grogs respectively. This is mainly because the former is more mullitization and its microstructure is characterised by continuous interlocking network structure of well-developed prisimatic mullite crystals.Preparation of homogenized mullite grogs with 68-72wt.%Al₂O₃, Al₂O₃/SiO₂ ratio of 2.68-3.18 and with 68-72wt.%Al₂O₃ based grade II of bauxite as raw material in corporated with appropriate amount of coal gangue partialy addition of slight amounts of active alumina to improve purity have been investigated. It is found that sintering temperatures of the grogs both are 1700℃(68-72wt. % Al₂O₃) and 1650℃(58-62wt.%Al₂O₃), apparent porosity are <2.5%, bulk density are 2.66-2.75g/cm³, and their Refracteriness-under-Load(T_0.6) are 1605℃ and 1550℃ respectively, and their properties reach the international level. Based on our investigations, it can be concluded that bauxited-based homogenized grogs can be prepared if only the control of chemical compositions of specimens(such as content of Al₂O₃, ratio of Al₂O₃/SiO₂ and impurity content of specimens) and adoption of homogenization technology and high temperature sintering method. Homogenized grogs with 68-72wt.%Al₂O₃ and 58-62wt.%Al₂O₃ can be prepared by specimens with Al₂O₃≥72wt.%, TiO₂≤3.5wt.%, Fe₂O₃≤2.5wt.% and Al₂O₃≥62wt.%, TiO2≤3.0wt.%, Fe₂O₃≤2.0wt.% respectively. Thus consequently quality, premium and price of bauxite grogs are upgraded as well as increased utilization ratio of gradeII bauxite and abandon bauxite ores. The results of industry production practice(5000kg) of preparation of bauxite-based homogenized mullite grogs with 68-72wt.%Al₂O₃ by wet vacuum crush molding method demonstrate the industry feasibility of the technology, sintering temperature of the grogs is 1600℃, apparent porosity is <1.0%, bulk density is ≥2.81g/cm³, Refracteriness-under-Load is 1610℃, and its properties is constant.In order to decrease sintering temperature, cost and energy consumption, the effects of CeO₂ and MgO sintering aids on the sintering properties of bauxite-based homogenized mullite grogs have been investigated. It is found that simultaneous addition of CeO₂ and MgO is more effective than addition of CeO₂or MgO alone in promoting sintering. With 0.75wt.% simultaneous addition of CeO₂ and MgO and...