Patent GB-418859-A (GB)
Title: A process for obtaining products containing spinels
IPC: C04B35/12
Filed: 1933-09-14
Abstract: Products containing spinels and it may be also periclase crystals are obtained by melting materials containing magnesium oxide and either or both aluminium oxide and chromic oxide, together with silica and calcium oxide in such proportions that the molecular proportion of calcium oxide is at least equal to that of the silica, and subjecting the product after cooling to dressing and/or treatment with solvents to remove the silicates. In producing the spinels up to 10 per cent of the magnesium oxide may be replaced by ferrous oxide.  The solidified mass preferably contains at least 20 per cent of calcium silicates, and by having present more than 2 mols. of calcium oxide per mol. of silica, products which break down on cooling to lumps and powder are obtained.  Wet or dry mechanical treatments including grinding or magnetic separation may be used singly or in combination for removing the silicates, and as solvents aqueous sulphur dioxide, hydrochloric acid, aluminium chloride, or sulphuric acid may be used. When using solvents silica remaining in the mass may be separated mechanically or be left admixed with the spinels.  The production of spinels may be combined with the production of chromium or chromium alloys, in which case spinels containing chromium may be readily obtained.  Alternatively a charge comprising dolomite and bauxite, with or without chromite may be used, and when an excess of magnesium oxide is present, periclase crystals are also obtained.  The products may be used as grinding materials, for refractory coatings or linings or for the production of refractory articles.  Those with a high percentage of chromium oxide may be used for the production of chromium or its alloys.  They may be mixed with corundum, magnesite, periclase, or chromium ore, and may be used as main component or as filling material in the production of shaped bodies by moulding under pressure and heating say to 1700 DEG  C.  In this connection binding media which may be used include sulphite liquor, clay, kaolin, aluminium silicates, silicic acid, quartz, bauxite, ferrous oxide, sillimanite, and ferric oxide.ALSO:In the production of ferrochromium from a charge comprising chromium ore, bauxite, and lime, the charge constituents are used in such proportions that the slag on cooling yields spinels and contains at least one and preferably more than two mols. of calcium oxide per mol. of silica.  An example is given.ALSO:Products containing spinels and it may be also periclase crystals are obtained by melting materials containing magnesium oxide and either or both aluminium oxide and chromic oxide, together with silica and calcium oxide in such proportions that the molecular proportions of calcium oxide is at least equal to that of silica, and subjecting the product after cooling to dressing and/or treatment with solvents to remove the silicates. In producing the spinels, up to 10 per cent of the magnesium oxide may be replaced by ferrous oxide.  The solidified mass preferably contains at least 20 per cent of calcium silicates, and by having present more than 2 mols. of calcium oxide per mol of silica, products which break down on cooling to lumps and powder are obtained.  Wet or dry mechanical treatments, including grinding, or magnetic separation may be used singly or in combination for removing the silicates, and as solvents aqueous sulphur dioxide, hydrochloric acid, aluminium chloride, or sulphuric acid may be used.  When using solvents silica remaining in the mass may be separated mechanically or be left admixed with the spinels. The production of spinels may be combined with the production of chromium or chromium alloys, in which case spinels containing chromium oxide may be readily obtained.  Alternatively a charge comprising dolomite and bauxite, with or without chromite or magnesite may be used, and when an excess of magnesium oxide is present, periclase crystals are also obtained.  The products may be used for refractory coatings or linings or for the production of refractory articles.  They may be mixed with corundum, magnesite, periclase, or chromium ore, and may be used as main component or as filling material in the production of shaped bodies by moulding under pressure and heating say to 1700 DEG  C.  In this connection binding media which may be used include sulphite liquor, clay, kaolin, aluminium silicates, silicic acid, quartz, bauxite, ferrous oxide, sillimanite, and ferric oxide.