GB646916A - Improvements in or relating to sulphur - Google Patents

Abstract

<PICT:0646916/III/1> Insoluble sulphur is produced by quenching a stream of vapour with a non-aqueous inert liquid, e.g. carbon bisulphide, benzene, toluene, xylene, pentane, butane, or petroleum hydrocarbon fractions such as petroleum naphtha or kerosene, in sufficient quantity to vaporize the liquid and condense the sulphur, and recovering the insoluble sulphur. In Fig. 1, after the system has been purged with inert gas, e.g. carbon dioxide or cold combustion gases, sulphur vapour enters baffled tower 7 mounted on tank 6 containing carbon bisulphide, to form a slurry of insoluble sulphur maintained in suspension by agitator 30. The slurry is washed with fresh carbon bisulphide in washer 29, and is sprayed through jets 54 on to rotating drum drier 56 whence the sulphur is removed by conveyer 57. The carbon bisulphide containing soluble sulphur passes from washer 29 through vessel 36 to fractionating column 41 whence molten sulphur is withdrawn at 42 and returned to melter 44 for mixing with crude sulphur for recycle. Carbon bisulphide vapour from column 41 and tower 7 passes to condenser 22 and storage tank 25 whence it is returned, together, if desired, with carbon bisulphide containing soluble sulphur from vessel 36, to tower 7 through sprays A, B, to washer 29, or to column 41 as reflux. Carbon bisulphide vapour from drier 56 is condensed at 59 and returned from vessel 60 to washer 29. Water seals are placed above the carbon bisulphide in all vessels to p exclude air. To stabilize the insoluble sulphur, the slurry may be retained between 30 DEG and 80 DEG C. for 1-24 hours in tank 6 or a separate vessel, or the dried product may be so retained. The product may be treated with solvents such as carbon bisulphide, benzene, toluene, or xylene, to extract any soluble sulphur. Alternative apparatuses are described where: (1) anhydrous conditions are obtained by substituting inert gas for water seals; (2) mixtures of soluble and insoluble sulphur are produced; (3) sulphur vapour is quenched by complete vaporization of an injected liquid; (4) the vaporization temperature is reduced by introducing liquid into the molten sulphur before quenching. Insoluble sulphur may be converted to the soluble form by adding alkali such as ammonia or ammonium carbonate, or water containing a wetting agent. Insoluble sulphur is further stabilized by treatment, before, during, or after quenching, e.g. with the quenching liquid containing 1 per cent for 1 hour at 90-100 DEG F., with a halogen such as iodine, bromine, or chlorine; a sulphur halide such as sulphur monochloride or bromide; an inorganic halide such as titanium tetrachloride, thionyl chloride, phosphorus oxychloride, tri- or penta-chloride of phosphorus, silicon tetrachloride; or organic halides such as allyl chloride or bromide. The halogen may be washed out after treatment, and a second washer may be included for this treatment.