Introduction to silica brick

Silica brick is an acidic refractory material, with good resistance to acid slag erosion. The softening temperature under load is as high as 1640~1670℃, and the volume is relatively stable under high temperature for long-term use.

Silica bricks are mainly composed of tridymite, cristobalite and a small amount of residual quartz and glass phases composed of acidic refractory materials.

The silica content is above 94%. The true density is 2.35g/cm3. It has resistance to acid slag erosion. Higher high temperature strength. The starting temperature of load softening is 1620~1670℃. It will not deform after long-term use at high temperature. Low thermal shock stability (1~4 times of heat exchange in water) Natural silica is used as the raw material, and an appropriate amount of mineralizer is added to promote the conversion of quartz in the body to tridymite. Slowly fired at 1350~1430℃ in a reducing atmosphere. When heated to 1450℃, there will be about 1.5~2.2% of the total volume expansion. This residual expansion will make the cut joints close and ensure good air tightness and structural strength of the masonry.

Composition and raw materials of silica brick

The mineral phase composition of silica bricks is mainly tridymite and cristobalite, with a small amount of quartz and vitreous. Tridymite, cristobalite, and residual quartz have large changes in volume due to changes in crystal form at low temperatures, so the thermal stability of silica bricks at low temperatures is very poor. During use, slowly heating and cooling below 800°C to avoid cracks. Therefore, it is not suitable for use on kilns with sudden temperature changes below 800°C.

The raw material for making silica bricks is silica. The higher the SiO2 content of the silica raw material, the higher the refractoriness. The most harmful impurities are Al2O3, K2O, Na2O, etc., which seriously reduce the refractoriness of refractory products. Silica bricks use silica with SiO2 content not less than 96% as raw material, add mineralizers (such as iron scales, lime milk) and binders (such as molasses, sulfite pulp waste liquid), and then mix, shape, dry, and burn Manufactured by other processes.

Application of silica brick

It is mainly used for the partition wall of the coking chamber and combustion chamber of the coke oven, the regenerator and the slag chamber of the steel open furnace, the soaking furnace, the refractory material of the glass melting furnace and the firing kiln of ceramics, etc. Load-bearing parts. It is also used for high temperature load-bearing parts of hot blast stoves and acid open hearth furnace roof.