Technical conditions of lightweight silica insulating firebrick for glass kilns

Lightweight silica insulating firebrick is a heat-insulating refractory product with SiO2 content of not less than 91% made of silica as the main raw material. The bulk density of the lightweight silica insulation firebrick is 0.9~1.1g/cm3, the thermal conductivity is only half of that of the ordinary silica brick, and the thermal shock resistance is good. hot brick. Therefore, the maximum service temperature of siliceous thermal insulation bricks can reach 1550 ℃. It does not shrink at high temperatures and even slightly expands.

Lightweight silica insulating firebrick generally uses crystalline quartzite as raw material, and flammable substances, such as coke, anthracite sawdust, etc., are added to the ingredients, or a porous structure is formed by gas foaming. Similar to the production industry of ordinary silica bricks, some mineralizers (CaO, Fe2O3) are added to the ingredients to promote the conversion of quartz, and pulp waste liquid is used as a binder to make the bricks have a certain strength. When coke or anthracite is used as combustible material, since ash will be brought into Fe2O3 and Al2O3, there is no need to add iron and phosphorus to the ingredients. When the lightweight silica brick is fired, a strong oxidizing flame should be maintained before 1200 °C, so that the additions are completely burned out.

The mineral composition of lightweight silica insulating firebrick is phosphor quartz 78%~86%, cristobalite 78%~86%, and quartz 78%~86%. Generally, the compressive strength of lightweight silica bricks is 2.0~9.5MPa, and the thermal conductivity is 0.35~0.42W/(m·K). Lightweight silica insulating firebrick has excellent refractory properties. The softening temperature under load is close to that of dense silica bricks, reaching above 1620°C, with only a small amount of residual expansion, and its thermal stability is better than that of dense silica bricks. Therefore, lightweight silica bricks can be used for a long time at 1500~1550℃ under high-temperature conditions without contact with slag.