The molding and production rules of silica bricks
2021-12-25
Silica brick is an acidic refractory material with good resistance to acid slag erosion. Its softening temperature under load is as high as 1640~1670℃, and its volume is relatively stable under high temperature for long-term use. 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 load softening start temperature 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 a proper amount of mineralizer is added to promote the conversion of quartz in the body to tridymite. Slowly fired at 1350~1430℃ under 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 that the masonry has good air tightness and structural strength.
The water content of the mud used to make silica bricks is generally 5-9%, the water content of the hand-molded mud is 7-9%, and the water of the mechanical molding mud is 5 to 6%.
Nowadays, silica bricks are mainly used for the partition walls of the coking chamber and combustion chamber of coke ovens, the regenerator and slag chamber of steel open-hearth furnaces, soaking furnaces, refractory materials of glass melting furnaces, and firing kilns of ceramics. The vault and other load-bearing parts. It is also used for high temperature load-bearing parts of hot blast stoves and acid open hearth furnace tops
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 severely reduce the refractoriness of refractory products. Silica fire 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), and then mix, shape, dry, and burn Manufactured by other processes. When preparing silica brick mortar, a certain amount of waste silica brick is usually added to the ingredients, the purpose of which is to reduce the expansion and stress generated during the firing of the product, reduce the occurrence of cracks, and increase the yield. The amount added is related to the shape and weight of the brick. For special-shaped bricks weighing less than 25Kg: 20% can be added; for special-shaped bricks above 25Kg, 30% can be added; for special-shaped bricks, 30% can be added. Pay attention to this problem when adding waste silica bricks. Excessive addition will reduce the refractoriness and mechanical strength of the product and increase the porosity. Therefore, the amount of waste bricks should not be too much.How to prepare slurry for silica brick
When preparing silica brick slurry, you should operate according to a certain feeding sequence. First, add various silica powder and waste silica brick powder into the wet mill in a certain proportion, dry mix for 2~3 minutes, and then add the sulfite pulp waste liquid and lime. The mixed liquid of milk and iron oxide powder, according to the requirements of the molding method, mix for another 8~17min. The length of the mud mixing time depends on the weight of the roller, the number of rotations of the roller, the amount of raw materials added, the hardness of the raw materials, the particle composition of the mud, and the molding method. Special-shaped bricks and mud used for manual molding require a longer mixing time than mud used for mechanical molding. The mixing time of different mud materials should be determined by experiment. The binders used in the manufacture of silica bricks are sulfite pulp waste liquid and lime milk. When lime milk is used as a binder, it acts as a plasticizer. The lime milk increases the strength of the brick during the drying process, and is called a mineralizer during firing, which promotes the conversion of quartz.The water content of the mud used to make silica bricks is generally 5-9%, the water content of the hand-molded mud is 7-9%, and the water of the mechanical molding mud is 5 to 6%.
Nowadays, silica bricks are mainly used for the partition walls of the coking chamber and combustion chamber of coke ovens, the regenerator and slag chamber of steel open-hearth furnaces, soaking furnaces, refractory materials of glass melting furnaces, and firing kilns of ceramics. The vault and other load-bearing parts. It is also used for high temperature load-bearing parts of hot blast stoves and acid open hearth furnace tops
Relevant information
-
Silicate fire brick
Silicon thermal insulation refractory brick refers to the thermal insulation refractory products made of silica as the main raw material, with a SiO2 content of no less than 91%. In addition to the heat insulation perfor··· -
silica bricks manufacturing process
1.1 Determination of raw material ratio and particle compositionThe raw materials for making silica bricks are silica and waste bricks containing more than 96% SiO2, in addition to lime, mineralizers and organic binders.··· -
Alumina hollow ball bricks
Alumina hollow ball bricks are made of alumina hollow balls and alumina powder as the main raw materials, combined with other binders, and fired at a high temperature of 1750 degrees. It belongs to a kind of ultra-high t··· -
Anti-stripping high alumina brick for cement kiln
Anti-stripping high alumina bricks are made of high alumina bauxite clinker, mullite, kyanite, zircon sand, and binder first through granulation and powdering processes, mixed in a certain proportion, then pressed into s···