GB505112A - Improvements in or relating to the manufacture of alkali metals - Google Patents

Abstract

505,112. Extracting alkali metals. DU PONT DE NEMOURS & CO., E. I. Nov. 4, 1937, No. 30299. Convention date, Nov. 4, 1936. [Class 82 (i)] Alkali-metals, e.g. sodium, are produced by electrolyzing an aqueous solution of an alkalimetal salt, e.g. sodium carbonate or halide, with a mercury cathode, distilling the resulting amalgam to produce an alkali-metal containing a small amount of mercury as impurity, subjecting the impure alkali-metal at a temperature above its melting point to the action of an alkaline-earth metal (including magnesium) and separating, e.g. by filtering, settling, or centrifuging, solid mercury-containing material from the melt. The electrolysis may be carried out as described in Specification 491,879, [Group III], the treatment with alkaline earth metal may take place in the presence of alkali-metal and the distillation may be carried out under reduced pressure and in two stages, the first of which is such as to yield as residue a solid amalgam. The alkaline earth metal should be in finely-divided form, such as that produced by cooling to 100-120‹ C. a solution of the metal in alkali-metal made at 500-700‹ C. the precipitated metal being used either after filtering or in the form of a mixture with the alkali-metal. The alkaline earth metal should be agitated for 1-10 minutes with the dilute amalgam at 200-300‹ C. and in amount equal to 3-5 times the amount of mercury present, and, if desired, in the presence of alkali metal in such proportions that the mixture contains 50-75 per cent of alkali metal, the mixture being then cooled to 100-200‹ C. and the alkali-metal obtained as filtrate. The precipitate will consist of a mixture of alkaline-earth metal, mercury and alkali-metal, which after distillation of the mercury, may be used for the. treatment of further quantities of alkalimetal amalgams. Specification 505,097 also is referred to.