Sillimanite is a kind of high-temperature metamorphic mineral, commonly found in the contact zone between igneous rocks and argillaceous rocks, the crystal is needle or columnar, the aggregate is radial or fibrous, belongs to the rhombotic crystal system, the color is generally grayish green, light green, grayish yellow, light yellow, brown, light brown, white or colorless, ductile. The melting point of sillimanite is 1850ºC, the density is 3.2~3.27g/em, the hardness is 6.5~7.5, the coefficient of thermal expansion is low, the chemical composition is relatively pure, the impurity content is very small, the chemical properties are very stable, insoluble in water and acid, and the corrosion resistance of metal and glass melt slag is good. It has good thermal shock resistance, slag erosion resistance, mechanical strength, wear resistance, chemical corrosion resistance and high fire resistance.
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