Molding and production rules of silicon brick
Silica content above 94%. True density 2.35g/cm3. It is resistant to acid slag erosion. High temperature strength. Load softening starting temperature 1620 ~ 1670℃. Long-term use at high temperature without deformation. Low thermal shock stability (heat exchange in water is 1 to 4 times) Natural silica is used as raw material, and an appropriate amount of mineralizing agent is added to promote the conversion of quartz in the billet into quartz. It is slowly fired at 1350 ~ 1430℃ in a reducing atmosphere. When heated to 1450℃, there is a total volume expansion of about 1.5~2.2%, and this residual expansion will make the cut joints close to ensure that the masonry has good air tightness and structural strength.
The raw material for making silicon bricks is silica. The higher the SiO2 content of silica raw materials, the higher the refractoriness. The most harmful impurities are Al2O3, K2O, Na2O, etc., which seriously reduce the refractoriness of refractory products. Silica brick with SiO2 content of not less than 96% silica as raw materials, adding mineralizing agents (such as iron scale, lime milk) and bonding agents (such as molasses, sulfite pulp waste liquid), through mixing, molding, drying, burning and other processes to produce. When preparing silicon brick mud, a certain amount of waste silicon brick is usually added to the mix, which aims to reduce the expansion and stress generated during the firing of the product, reduce the generation of cracks, and improve 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: more than 25Kg special-shaped bricks can be added 30% : for special special-shaped bricks, 30% can be added. When adding waste silicon bricks, attention should be paid to such problems, adding too much will reduce the refractoriness and mechanical strength of the product, and increase the porosity. Therefore, the amount of waste brick should not be too much.
When preparing silica brick mud, all kinds of silica powder and waste silica brick powder should be added to the wet mill according to a certain feeding sequence, dry mixing for 2~3min, and then add the mixture of sulfite pulp waste liquid, lime milk and iron oxide powder, and then mix for 8~17min according to the requirements of the molding method. The length of mixing time depends on the weight of the roller, the number of rotation of the roller, the amount of raw material added, the hardness of the raw material, the particle composition of the mud and the forming method. Special-shaped bricks and mud for hand molding require a longer mixing time than mud for mechanical molding. The mixing time of different mud materials should be determined by experiment. The bonding agents used to make silicon bricks are sulfite pulp waste liquid and lime milk. When lime milk is used as a bond, it acts as a plasticizer. The lime milk increases the strength of the brick during the drying process, and is called a mineralizer when fired, promoting the conversion of quartz.
