Abstract: The impurities in silica brick have a certain effect on it s refractoriness and refractoriness under load，a certain amount of impurities can promote the crystal transformation of quartz，which is beneficial to reduce the true density and thermal expansion coefficient of silica brick. The effects of various impurities on different properties of the product should be fully considered in the production，and the contents of impurities such as Na2O，K2O and Al2O3 should be scientifically controlled so as to improve the comprehensive properties of the product.

Key words: Silicon brick, Impurity, Refractoriness, Refractoriness under load, True density, Thermal expansion coefficient, High temperature properties