Silica Mullite Brick

Silica mullite brick is made of sintered bauxite and high dense SiC silicon carbide by process of pressing and firing at high temperature .

Silica-mullite bricks are characterized by good performance of thermal shock resistance, better wear-resistance and spalling resistance.

It's a good choice for cement kiln and applied in transition zone, cooling zone and outlet.

Silica brick
This brick is made mainly of natural minerals such as quartzite, siliceous gravel, and non-cavitating stone, bonded by the addition of 3–3.5% cao, which forms a small amount of glass when fired. The equilibrium of the quartzite raw material is converted into tridymite and cristobalite. This brick is characterized by a very high coefficient of thermal expansion between room temperature and 500°c, so it must be heated and cooled very slowly through this temperature range. Silica brick has excellent load-bearing capacity at high temperatures. It is available in three types: Super silica brick, which has very low alumina and alkali content; ordinary or conventional silica brick; and coke oven quality. More recently, silica compositions made from molten or glassy forms have been used for hot repair and other applications, such as shrouds that are subject to great thermal shock. The coefficient of expansion of glassy silica is much lower than that of crystalline silica.

Semi-silica brick
Silica brick is made from siliceous clay and consists mainly of cristobalite and glassy phases. It usually contains 18–25% alumina and 72–80% silica. This brick has excellent load-bearing capacity at temperatures up to 1300°c, but like ordinary silica bricks, it has relatively high thermal expansion at temperatures from room temperature to 500°c.

Clay bricks
This brick is made from natural refractory clay, whose alumina content is usually between 25% and 45%. Its refractoriness increases with increasing alumina content and decreases with decreasing content of impurities such as alkali metals and iron oxide. The refractoriness of this type of brick is usually measured by the high temperature cone equivalent (see section 5), which shows the effect of temperature and time on refractory materials.

Dolomite bricks
Dolomite bricks are made from a highly calcined natural mineral with a composition of caco 3 .Mgco 3. Unfired bricks made from dolomite particles are usually bonded with tar or bitumen because the lime component is easily hydrated; fired dolomite bricks are usually impregnated with tar or bitumen to extend their service life.

Magnesia bricks
This brick consists primarily of the mineral periclase (mgo) and is available in chemically bound, bituminous bound, fired or calcined, and fired and bituminous impregnated types. Historically, calcined natural magnesite (mgco 3 ) was the raw material for this brick, but with increasing requirements for higher temperatures and reduction of process impurities, high purity magnesium oxide from seawater or underground brine is increasingly being used. In the seawater and brine processes, magnesium oxide is obtained by calcining precipitated mg(oh) 2, which provides mgo with purity up to 98%. Seawater or brine plants are found in the united states, mexico, the united kingdom, italy, japan, and the soviet union. Refractory grade natural magnesite deposits are found in austria, greece, china, brazil, and the united states (washington and nevada). Natural magnesite generally contains more impurities, but calcined magnesite from chinese deposits has been reported to contain no less than 95% mgo.