The production process of magnesium aluminum series is quite similar to that of magnesia series. The only difference is that ingredients in the series contains a certain proportion of industrial alumina or super alumina clinker. The series is also be produced by pressure moulding and sintering within high temperature. The impurity content of industrial alumina is lower than that of high bauxite clinker. Adding natural bauxite clinker into ingredients is able to improve plasticity of the clay. In the same condition, volume density of raw bricks will be higher.
The amount added of industrial alumina is commonly 5% ~ 10%. It is usually fine grinded together with magnesia by a certain proportion. With adding those fine powder, it is conducive to form an uniform distribution of new phases of magnesium aluminum spinel series in products substrate. In addition, another producing method is pre-synthesizing magnesium aluminum spinel and then batching to produce as blocks. In the process of batching, large critical particle size is conducive to improve thermal shock resistance of the product. However, it goes against product density and strength. Therefore, the size is usually adopted to 3 mm.
The particle size is generally 3 ~ 1mm and 1 ~ 0.088mm, and the proportion of 3 ~ 2mm coarse particles and fine powder less than 0.088mm should be controlled to improve thermal shock resistance of the series. The combustion temperature of magnesium aluminum product should be determined on the basis of purity of raw materials. More specifically, the temperature should be generally 30 ~ 50ºC higher than that of magnesium product. And combustion temperature of high-purity magnesium aluminum product is 1750 ~ 1800ºC.
The product is widely used in top space structure of glass furnace and the lining of calcined lime and cement rotary furnace.
The series has advantages of good erosion resistance, peeling resistance, high temperature resistance, low product pollution, etc.
Physical and Chemical Indicators