Basic Method of Synthesis and Preparation of Magnesium Aluminum Spinel

At present, spinel can be used as refractory material only by synthetic method. The synthetic method is mainly sintering and electromelting. The raw materials are high purity alumina and chemical grade magnesium oxide. The advantage of sintering is that the process is a continuous ceramic process, which can control the feeding rate and keep the temperature distribution in the kiln uniform, so the product is very homogeneous, the grain size is between 30 and 80μm, the porosity is also low (< 3°%); Fused law belongs to the intermittent operation process, before the operation have to be sorting homogenization of raw materials in advance, because if too much raw material block requires longer cooling time, at this time in the process of cooling of non-uniform microstructure would happen, and if too fast cooling causes a spinel crystal is smaller than in the inside, and outside the center gathered a large number of low melting point impurity set. 

Magnesia alumina spinel has high slag erosion resistance, thermal shock resistance and high temperature compressive strength. High quality pre-synthetic spinel provides new raw materials for the production of amorphous and amorphous high purity refractories, so it has been widely used.

Magnesium-alumina spinel refractory castable is composed of corundum, magnesia, high bauxite and synthetic magnesium-alumina spinel aggregate and powder. Due to the presence and generation of spinel, there will be expansion and micro-cracks, so that the thermal stress generated in the material is buffered, so the slag erosion resistance and thermal shock resistance is good, at the same time, the spinel phase can wrap magnesite and improve hydration resistance.  Therefore, adding spinel into magnesium castable can greatly improve the properties of the material and expand its application field.