Can silicon-magnesia red bricks be used as the inner lining of lithium ash kilns?

Silicon-magnesia red bricks are high-grade composite refractory bricks made by adding silicon carbide, andalusite and mullite to traditional high alumina bricks. They belong to weakly acidic refractory materials. Some of their properties match the requirements of lithium ash kilns, so they should be selected and used with caution. Due to its characteristics, silicon-magnesia red bricks are mostly used in the pre-transition zone of cement rotary kilns. As the product is sintered in a reducing atmosphere, if it is used in an oxidizing atmosphere area, especially in an alkaline atmosphere area, severe erosion, structural spalling and rapid damage will occur. If the lithium ash kiln contains limestone components, it is best not to use silicon-magnesia red bricks in the firing zone. Phosphate bricks, aluminum-magnesia spinel bricks, and directly bonded magnesia-chrome bricks all have superior alkali resistance than silicon-magnesia red bricks. Silicon-magnesia red bricks are not absolutely forbidden to use. They can be used in the transition zone. However, they are not recommended for use in the firing zone because in areas with high concentrations of alkali vapor, their lifespan will be shortened, leading to frequent kiln shutdowns, which would be counterproductive. If used in the low-temperature zone, the cost increases. Its service life is similar to that of phosphate bricks, but it is more expensive. Phosphate bricks are not as good as those used in the low-temperature zone. If the initial production cost is not high, special phosphate bricks can be chosen as the inner lining of the firing zone. If magnesia-alumina spinel bricks are selected as the inner lining of the firing zone, although the cost is high, the service life is long. Overall, the cost has actually decreased. Some lithium ash kiln manufacturers in the market choose silicon-magnesia red bricks for the firing zone and require a three-year service life. In this case, if silicon-magnesia red bricks must be used, the production process needs to be modified to adapt to the firing zone of the lithium ash kiln lining. While adding andalusite in the process, different binders should be used for bonding, and the raw material matrix should also be improved to enhance the oxidation resistance of the andalusite bricks. Otherwise, it is best not to choose silicon-magnesia red bricks for use in the lithium ash kiln firing zone.