Reaction medium comprising solution of calcium carbide in a molten halide of lithium or an alkaline-earth metal or a mixture of such halides

摘要

Calcium carbide is dissolved in an anhydrous or substantially anhydrous molten halide of lithium, calcium, strontium or barium or a mixture of such halides. The calcium carbide which may be in lump, pellet, finely-divided or other suitable form is introduced together with the halide mixture into a reaction vessel lined with stainless-steel, the vessel is heated electrically and a homogeneous solution is formed. The dissolution should be effected in an inert atmosphere, e.g. of argon. Fluxing agents, e.g. sodium and potassium halides, for instance the chlorides, may be added to the molten halide mixture. At atmospheric pressure, the temperatures used for the dissolution can be varied from the melting point of the solvent halide or mixture thereof with a fluxing agent to the point at which the mixture or solvent halide alone volatilizes, e.g. 350 DEG to 2200 DEG C. Higher temperatures can be used by employing super-atmospheric pressure. In preparing the solution either the molten halide solvent is first prepared and the carbide added to it, or the solid carbide and halide are first mixed and the mixture then heated to melt the halide and dissolve the carbide in the molten mass. In the examples, the molten halides used are (a) lithium chloride, (b) calcium chloride, (c) lithium bromide, (d) a mixture of lithium chloride and potassium chloride, (e) barium chloride, (f) lithium fluoride and (g) a eutectic mixture of lithium chloride and lithium fluoride.ALSO:Metallic lead is prepared by adding anhydrous lead chloride to a molten solution of calcium carbide in lithium chloride at 820 DEG C., the yield of lead being about 50% of the theoretical.