The status of silica bricks for glass kilns
Different types, sizes, and configurations of furnaces for producing glass have different requirements for the performance and use of refractory materials. Glass industry, especially for float glass kiln, is mainly composed of fused cast refractories, silica bricks and magnesia refractories. Silica bricks are traditional products of refractory materials for glass kiln, and refer to refractory products with SiO2 content ≥93%. Silica bricks are based on silica with SiO2 content ≥96%, adding mineralizers and binders, and obtained by mixing, forming, drying and calcining processes. The higher the SiO2 content in the silica raw material, the higher the refractoriness of the product. Silicon bricks are acidic refractory materials and have strong resistance to acid attack. Silica bricks have higher load softening temperatures, lower density, and lower prices. Widely used in coke oven carbonization chamber, combustion chamber and partition wall, glass tank kiln and kiln roof, pool wall, hot blast furnace high temperature bearing parts, carbon baking furnace and other thermal equipment. Silica bricks used in glass tank kiln are mainly used for furnace kiln and partial flame space. The quality of silica bricks is related to the normal operation and life of the kiln. Silicon bricks have experienced three generations of development since their inception. The first generation of silica bricks is a conventional ordinary silicon brick, and the second generation is an advanced silicon brick. Compared with common silicon bricks, it has the characteristics of “three highs and three lows”. “Three highs” refers to high purity (SiO2 content >96%), high loading softening temperature (>1685°C), and high silica and cristobalite (quartz and cristobalite content >90%); "three lows" It refers to low impurity content (Al2O3 + 2R2O ≤ 0.5%), low true density (≤ 2.34g/cm3), low residual quartz (≤ 3%). The third generation is an improved brick of the second generation of bricks. The content of CaO is reduced from 2% to 3% to 1% or less, the content of alkali metal oxide is further reduced by 0.5%, FeO content is below 0.2%, and the pores The rate dropped from 20% to 22% in the second generation to 16% to 18%. China's silicon brick production technology is relatively mature, but the product quality is not the same. With the development and promotion of glass furnace oxy-fuel combustion technology, the use of silica bricks tends to require lower apparent porosity, lower melt index, and at the same time reduce the glass The rat holes produced in the furnace are required to have less structural defects and dense cemented joints between the expansion joints.