Recovery of sulphur

摘要

In the recovery of sulphur from sulphide ores, such as those containing sulphides of iron, nickel and copper, the ore is subjected to the action of gaseous hydrogen chloride in the presence of water vapour and oxygen to produce hydrogen sulphide and sulphur dioxide which are caused to react to produce sulphur. The ferrous chloride formed is treated with chlorine, or with a gaseous mixture containing chlorine, to form ferric chloride from which hydrogen chloride is obtained, this being in part converted to chlorine. Temperatures of 550-800 DEG C., preferably 550-600 DEG C., may be employed for the main reaction. The water vapour may be provided by introducing the ore in a damp condition and the oxygen supplied as air. Preferably the amounts of air and water vapour are controlled so as to produce two molecules of hydrogen sulphide for each molecule of sulphur dioxide by the use of two sets of apparatus one of which is so controlled that, when mixed, the products of the two apparatus give gases of the desired proportions. The reaction is exothermic so that no source of extraneous heat is necessary. The ore-charging end of the reaction chamber is maintained at 550-600 DEG C. and the other where the hydrogen chloride, water vapour, and air are introduced is kept at 300-400 DEG C. Sulphur dioxide, hydrogen sulphide, ferrous, copper, and nickel chlorides are formed, the solid materials being continuously discharged and the gases cooled to condense any sulphur vapour therein. Reaction between sulphur dioxide and hydrogen sulphide is effected by passing the gases through packed towers through which water containing hydrochloric acid passes in countercurrent. The hot residue of metallic chlorides is acted on by chlorine or chlorine containing gases to form and vaporize ferric chloride, the reaction being conducted at a temperature exceeding 300 DEG C., preferably 350-400 DEG C., and the gases cooled to condense the ferric chloride, which is re-vaporized and hydrolysed with steam at 350 DEG C. to produce hydrogen chloride and ferric oxide. The hydrogen chloride is dried by passage through a condenser and a sulphuric acid tower and treated to produce chlorine by passage with preheated air through a catalytic tower impregnated with nickel or copper sulphate or chloride; the reaction, which is exothermic, may be so controlled as to maintain a temperature of 370-400 DEG C. The reaction is not complete and the issuing gases, consisting of chlorine, hydrogen chloride, water vapour, oxygen and nitrogen, are used first for treatment of ferrous chloride and then of original ore. Specification 374,098 as open to inspection under Sect. 91 (3) (a) is referred to.