GB139195A - Improved manufacture of aluminium nitride - Google Patents

Abstract

Aluminium nitride is obtained by passing nitrogen into pure molten alumina in presence of a reducing agent such as carbon or a reducing gas or vapour while electric energy is supplied to maintain the temperature. Coal dust and a nitrogenous gas, with or without a reducing gas, may be blown into or sucked through molten alumina, or the liquid alumina in an atmosphere of nitrogen, may be caused to flow across carbon having a large surface, the operation in either case being effected in an open or closed are or resistance furnace. The alumina may be prepared by melting in an electric furnace a mixture of aluminous material and carbon or aluminous material, carbon and iron or ferric oxide. Alkalies if present are volatilized, and silica &c. is reduced and combines with the iron forming compounds such as ferro silicon, which separate from the fused alumina. The following raw materials are mentioned: impure alumina, corundum, bauxite, burnt alunite, aluminium silicates such as feldspar and mica, and red bauxite. In the last case, pig iron may be obtained as a by-product. The production of the alumina is preferably not effected in the furnace in which the nitride is produced.ALSO:Aluminium nitride is obtained by passing nitrogen into pure molten alumina in presence of a reducing agent such as carbon or a reducing gas or vapour while electric energy is supplied to maintain the temperature. Coal dust and a nitrogenous gas, with or without a reducing gas, may be blown into or sucked through molten alumina, or the liquid alumina, in an atmosphere of nitrogen, may be caused to flow across carbon having a large surface, the operation in either case being effected in an open or closed arc or resistance furnace. The alumina may be prepared by melting in an electric furnace a mixture of aluminous material and carbon or aluminous material, carbon, and iron or ferric oxide. Alkalies if present are volatilized, and silica &c. is reduced and combines with the iron, forming compounds such as ferro silicon, which separate from the fused alumina. The following raw materials are mentioned: impure alumina, corundum, bauxite, burnt alunite, aluminium silicates such as feldspar and mica, and red bauxite. In the last case, pig iron may be obtained as a by-product. The production of the alumina is preferably not effected in the furnace in which the nitride is produced.