GB949952A - Process for the recovery of carbon disulphide and sulphur from exhaust gas - Google Patents

Abstract

A process for the recovery of carbon disulphide and sulphur from exhaust gas containing air, carbon disulphide and hydrogen sulphide, comprises contacting the exhaust gas with activated carbon on which the carbon disulphide and sulphur, formed from the hydrogen sulphide by oxidation with air, are simultaneously adsorbed, the carbon disulphide being subsequently extracted from the carbon by steam, and the sulphur being extracted with liquid carbon disulphide, e.g. that obtained during a previous steam treatment of the activated carbon. The activated carbon used is preferably freed from iron or other transition metals or, alternatively, the oxidation effect of such metals is inhibited by treatment with a complexing agent, e.g. hydrocyanic acid, hydrofluoric acid, or sodium fluoride. Any sulphuric acid formed in the activated carbon may be neutralized by a gaseous base, e.g. ammonia, and the resulting sulphate removed by washing with water. In operation, exhaust gas, e.g. from a spinning mill, is passed into the carbon until CS2 begins to escape, and the carbon is then washed with inert gas and the CS2 recovered by steam treatment. The carbon is then dried with warm air, cooled and recharged. The adsorption and desorption of CS2 is continued until H2S begins to break through, at which point the sulphur is extracted from the carbon by immersion in liquid CS2, the resulting solution being distilled to recover pure CS2 and sulphur. In an example 42,000 cubic metres of exhaust gas per hour were passed through activated carbon, said gas containing 12 g. of CS2 and 2 g. of H2S per cubic metre, 15 tons of CS2 and 2.5 tons of sulphur per day being recovered. Specification 829,650 is referred to.ALSO:Exhaust gas comprising air, carbon disulphide and hydrogen sulphide, e.g. that from a spinning mill is deodorized by or contacting with activated carbon whereby the H2S is converted to sulphur by air oxidation and the resulting sulphur is simultaneously adsorbed with the CS2 on the carbon. The activated carbon used is preferably either freed from iron or other transition metals or treated with a complexing agent, e.g. hydrocyanic acid, hydrofluoric acid or sodium fluoride, to inhibit the oxidation effect of such metals. Any sulphuric acid formed in the activated carbon may be neutralized by a gaseous base, e.g. ammonia, and the resulting sulphate removed by washing with water. Specification 829,650 is referred to.ALSO:Carbon disulphide is recovered from exhaust gas containing air, carbon disulphide and hydrogen sulphide by contacting the gas with activated carbon on which carbon disulphide and sulphur are adsorbed simultaneously, the sulphur being formed by air oxidation of the hydrogen sulphide, and the carbon disulphide and sulphur are subsequently removed from the carbon by steam treatment and CS2 extraction respectively. The CS2 used for extracting the sulphur may be that previously obtained by steam-heating the carbon. The activated carbon used is preferably freed from iron or other transition metals or, alternatively, the oxidation effect of such metals is inhibited by treatment with a complexing agent, e.g. hydrocyanic acid, hydrofluoric acid, or sodium fluoride. Any sulphuric acid formed in the activated carbon may be neutralized by a gaseous base, e.g. ammonia, and the resulting sulphate removed by washing with water. In operation, exhaust gas, e.g. from a spinning mill, is passed into the carbon until CS2 begins to escape, and the carbon is then washed with inert gas and the CS2 recovered by steam treatment. The carbon is then dried with warm air, cooled and recharged. The adsorption and desorption of CS2 is continued until H2S begins to break through, at which point the sulphur is extracted from the carbon by immersion in CS2, the ressulting solution being distilled to recover pure CS2 and sulphur. In an example 42.000 cubic metres of exhaust gas per hour were passed through activated carbon, said gas containing 12 g. of CS2 and 2 g. of H2S per cubic metre, 15 tons of CS2 and 2,5 tons of sulphur per day being recovered. Specification 829,650 is referred to.