What is silica brick?
Silica refractory brick, with a content of more than 93%, is a kind of quartzite as raw material, a small amount of mineralizer is added, and it is fired at high temperature. It is a complex structure composed of tridymite, cristobalite, a small amount of residual quartz, high temperature vitreous and other minerals. Silica brick is an acidic refractory material, which has strong corrosion resistance to acid slag, but is strongly corroded by alkaline slag, and is easily damaged by oxides such as Al2O3, K2O, Na2O, etc. It has good resistance to oxides such as alumina, alumina, and alumina. antioxidant properties.
Its mineral phase composition is mainly scaly quartz and cristobalite, with a small amount of quartz and vitreous quartz. Due to the change of crystal type, the volume of flake quartz, cristobalite and residual quartz changes greatly at low temperature, and the thermal stability of silica brick is very poor at low temperature. When in use, slowly heat or cool below 800°C to avoid cracks. Therefore, it is not suitable to be used in variable temperature kiln below 800℃.
What are the characteristics of silica brick?
The softening temperature under load is high; the coke oven silica brick can withstand the dynamic load of the top coal charging truck at high temperature, and it will not deform after long-term use;
(2) High thermal conductivity. In the carbonization chamber, coke transfers heat to the furnace wall through the furnace wall, and then transfers heat to the furnace wall through the furnace wall, so the silica bricks used to build the furnace wall should have high thermal conductivity. Compared with clay bricks and high alumina bricks, silica bricks have better thermal conductivity in the temperature range of the coke oven combustion chamber. Compared with ordinary coke oven silica bricks, the thermal conductivity of dense coke oven silica bricks is increased by 10%~20%;
(3) Strong heat resistance at high temperature. Due to the periodic coking and coal loading of the furnace, the temperature of the silica brick combustion chamber on both sides of the furnace changes drastically. Because the coke oven silica brick has good thermal shock resistance under the high temperature condition above 600℃, in the normal working temperature range, the silica brick will not have serious cracks or fall off; (4) the high temperature body is stable. The crystal transformation in the silica brick is good, and the residual quartz is not more than 1%. When the coke oven is in normal operation, the furnace temperature cannot drop below 600 ℃, and the furnace body cannot have a large change, so that the masonry can be stable and strong for a long time.
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