NOVEL ZINC COMPOSITION

1,130,934. Dispersions of Na-Zn alloys; zinc and sodium hydrosulphites. NATIONAL DISTILLERS & CHEMICAL CORP. 10 Oct., 1966 [8 Oct., 1965], No. 45225/66. Heading C1A. [Also in Division C7] A sodium-zinc alloy, containing 0.5 to 4% sodium and having a particle size of 1 to 50 microns is mixed with a liquid hydrocarbon in the form of a paste, suspension or stable gel. The gel may be formed by shaking the mixture of hydrocarbon and alloy with 1 to 8% by weight, based on the hydrocarbon, of a surfaceactive agent such as a stearate of aluminium, zinc or sodium. Suitable liquid hydrocarbons have boiling points of 160-250‹ C., 6-16 carbon atoms per molecule, are exemplified by kerosene, naphtha, ligroin, mineral spirits, tetralin, decalin, high flash-point gasoline and mixtures thereof, and are generally used in volume ratios of 0À5 : 1 to 8 : 1 based on the zinc. The alloy may be prepared by melting together appropriate amounts of sodium and zinc and casting into ingots and can be comminuted in a steel ball mill containing the liquid hydrocarbon. Zinc hydrosulphite solutions may be prepared by reacting sulphur dioxide in aqueous solution with the above sodium-zinc alloy/liquid hydrocarbon compositions at 5‹ to 60‹ C. and at a pH of 3 to 8. The reaction may be carried out in static beds, agitated beds or rotating drums. The zinc hydrosulphite may be converted to sodium hydrosulphite by reaction with sodium hydroxide or carbonate at 0‹ to 65‹ C. In an exemplified process, the sodium-zinc alloy/hydrocarbon composition is circulated in water, together with liquid sulphur dioxide, through a tubular cooler at 35‹ C. After filtration the zinc hydrosulphite solution is converted to sodium hydrosulphite with 25% caustic soda. Na 2 S 2 O 4 .2H 2 O is salted out with sodium chloride and alcohol, filtered, washed with alcohol and dried under vacuum at 60-80‹ C.