Brown Fused Alumina is made of natural bauxite as a raw material, carbon (mainly coke) as a reducing agent, and iron filings are added as a settling agent (clarifier) to form a ferrosilicon at the bottom of the electric furnace.
Brown Fused Alumina is tan, generally with Al2O3 ≥ 94.5%, SiO2 ≤ 3.5%, TiO2 ≤ 0.5%, and Fe2O3 ≤ 1% mineral. The composition is mainly composed of α-Al 2 O 3 , and the center of the crystal shape is diamond-shaped, thick plate-shaped, and cracked particles. There are more silicon oxide and calcium oxide melt crystals in the periphery, showing a long plate shape, and the coarsest grains are braided. Platelets. Since the impurities have not been completely removed, brown fused alumina also contains secondary phases such as calcium hexaaluminate, calcium plagioclase, spinel, and rutile, as well as glass phases, ferroalloys, and solid solutions. The color of brown corundum depends to a large extent on the titanium oxide remaining in the product.
Brown fused alumina is mainly used as abrasive. In recent years, it has been used as the aggregate for large and medium-sized blast furnace cast iron ditch castables and iron-out gun-nosed mud, as well as for the production of common corundum bricks (including high-alumina silicon carbide bricks).
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