GB1329622A - Treatment of a sulphite-containing solution to produce elemental sulphur - Google Patents

Abstract

1329622 Production of sulphur from sulphite solutions UNIVERSAL OIL PRODUCTS CO 19 April 1971 [22 Jan 1970] 20121/71 Heading C1A A sulphite-containing aqueous solution is treated to produce elemental sulphur while minimizing sulphate by-products by a method which comprises the steps of (a) Contacting the sulphite solution with a reducing agent selected from finely divided sulphur, polysulphide compounds, water soluble sulphide compounds and mixtures of two or more thereof, at thiosulphate production conditions to form a thiosulphate-containing effluent stream; (b) Reacting the effluent stream from step (a) with a water-soluble sulphide compound at reduction conditions selected to result in an effluent stream containing a polysulphide compound ; and (c) Subjecting at least a portion of the effluent stream from step (b) to polysulphide decomposition conditions effective to form elemental sulphur, a sulphide compound and a treated aqueous stream. The reducing agent used in step (a) may be at least a portion of the elemental sulphur recovered in step (c) or a portion of the polysulphide compound produced in step (b) and the water soluble sulphide compound used in step (b) is preferably at least a portion of the sulphide compound produced in step (c). Preferably the sulphite is ammonium sulphite and the water soluble sulphide compound in step (b) is either hydrogen sulphide or ammonium hydrosulphide. The thiosulphate production conditions utilized in step (a) are a temperature of from 20‹ to 150‹ C., a pressure sufficient to maintain the sulphite solution in the liquid phase and a contact time of 0À05 to 1 hour; the reduction conditions utilized in step (b) are a temperature of about 100‹ to 370‹ C. and generally a pressure of from about 7À8 to 341 atm. and a contact time of 0À01 to 1 hour. The preferred polysulphide decomposition procedure involves a temperature of about 100‹ to 200‹ C. and a pressure of about atmospheric to 6À1 atm. Generally the polysulphide decomposition reaction can be conducted in a distillation zone wherein H 2 S is stripped from the polysulphide solution with the aid of a suitable gas stream such as steam, carbon dioxide or nitrogen.