Silica brickAcid refractory, with good resistance to acid slag erosion,LoadThe softening temperature is as high as 1640~1670 ℃, and the volume is relatively stable for long-term use under high temperature.
Chinese name
Silica brick
Foreign name
silica brick
Materials
Acid refractory
Features
Good acid resistance to slag erosion
Load softening temperature
1640～1670℃
Service conditions
Stable volume for long-term use under high temperature
The mineral phase composition of silica brick is mainly tridymite and cristobalite, with a small amount of quartz and glassy.The volume of tridymite, cristobalite and residual quartz changes greatly due to the change of crystal form at low temperature, so the thermal stability of silica brick at low temperature is poor.During use, heat and cool slowly below 800 ℃ to avoid cracks.Therefore, it is not suitable for use in kilns with rapid temperature changes below 800 ℃.
Transformation relationship of silica variants
The properties and process of silica brick are closely related to the crystal transformation of SiO2, so the true specific gravity is an important quality index of silica brick.The general requirement is below 2.38, and the high-quality silica brick should be below 2.35.The true specific gravity is small, reflecting that there is a large amount of tridymite and cristobalite in the brick, and the amount of residual quartz is small, so the residual quartzlinear expansionSmall, and less strength drop in use.Silica has seven crystalline variants and one amorphous variant.These variants can be divided into two categories: the first is quartz, tridymite and cristobalite, whose crystal structure is very different, and their transformation between each other is very slow;The second type of variant is the subspecies of the above variants -αβ and γ, their structures are similar, and they can transform each other quickly.In theory, their mutual transformation relationship is shown in the figure Transformation Relationship of Silicon Dioxide Variants.
The raw material for manufacturing silica brick is silica.The higher the SiO2 content of silica raw material, the higher the refractoriness.The most harmful impurities are Al2O3, K2O, Na2O, etc., which seriously reduce the refractoriness of refractory products.Silica brick takes silica with SiO2 content not less than 96% as raw material, and mineralizer (such asIron scale、Lime milk）And binders (e.gmolasses、SulfitePulp waste liquid), after mixing, forming, dryingFiringAnd other processes.
The United States launched an anti-dumping investigation against Chinese silica bricks
December 6, 2012, United StatesMinistry of CommerceAnnounced the initiation of anti-dumping investigation on silica brick products imported from China.
The US Department of Commerce said that the investigation was initiated at the request of the Utah Refractory Company.The latter claimed that such products imported from China to the United States were dumped, ranging from 118.47% to 290.12%.The products involved in the investigation are silica brick products with silica content of more than 90%.
According to the US procedure,United States International Trade CommissionThe preliminary determination of the investigation is scheduled to be made around December 31. If the agency determines that such products imported from China have caused material damage or threat to relevant industries in the United States, the U.S. Department of Commerce will continue to implement anti-dumping investigations and make a preliminary determination in April 2013.
Silicon brick isAcid refractoryIt is mainly used for coke oven, iron making hot blast furnace and glass melting furnace.According to the data of the US Department of Commerce, the total value of silica brick products imported by the US from China in 2011 was about 43.2 million US dollars.
