| 摘要 |
Silicon containing not more than 0.2 per cent by weight of aluminium and less than 0.1 per cent of calcium is obtained by treating impure silicon in the molten state with magnesium silicate or with a mixture of magnesium or a magnesium compound and silica or a silicate and removing the slag. The silicon starting material may be that obtained by reduction of quartz or sand or may be an alloy, e.g. ferro-silicon, and copper may be added thereto (for the preparation of organo-halosilanes, see Group IV (a)). The Specification also describes the preparation of less pure silicon by including magnesium oxide in quartz reduction mixtures. Specifications 575,667, 575,668, 575,669, 575,673 and 575,674 are referred to.ALSO:Organo-halosilanes containing increased yields of dihalosilanes are prepared by reacting a halogenated hydrocarbon with silicon which has been purified by treating in the molten state with magnesium silicate or with a mixture of magnesium or a magnesium compound and silica or a silicate and removing the slag containing calcium and aluminium impurities, so that the silicon contains not more than 0.2 per cent by weight of aluminium and less than 0.1 per cent of calcium. The silicon preferably contains copper in proportions of 3 to 20 per cent by weight, and iron may also be present in proportions up to 25 per cent. An activator such as cuprous chloride, iron chloride or other metal salt is preferably employed. The examples describe the preparation of methyl, ethyl and phenyl chlorosilanes containing up to 65 per cent of the dichlorosilane. Specifications 575,667, 575,668, 575,669, [Group III], 575,673 and 575,674 are referred to. |
