RECOVERY OF SULPHUR VALUES FROM SULPHURIC-ACID-CONTAINING AQUEOUS LIQUID

摘要

1524233 Recovering sulphur values from aqueous effluents INSTITUT FRANCAIS DU PETROLE 11 Aug 1975 [14 Aug 1974 6 March 1975] 33396/75 Headings C1A and C1C Sulphur values are recovered from an aqueous effluent containing sulphuric acid and, optionally, heavy metal ions by: (a) reacting the effluent with an aqueous solution containing ammonium sulphite and/or ammonium bisulphite, separating from the solution the sulphur dioxide formed and, then optionally, treating the solution with hydrogen sulphide and/or ammonia to precipitate a sulphide and/or a hydroxide of the heavy metal which is separated; (b) reacting calcium oxide with the solution contained in step (a) to precipitate the sulphate ions thereof in the form of calcium sulphate and to form an aqueous ammoniacontaining solution; (c) vaporizing ammonia from the aqueous solution formed in step (b); (d) reducing the calcium sulphate formed in step (b) with carbon or hydrocarbon so as to form calcium oxide and a sulphur dioxide-containing gas; (e) contacting the ammonia from step (c) with the sulphur-containing gas from step (d) and with water, to form an aqueous solution containing ammonium sulphite and/or ammonium bisulphite; (f) recycling to step (a) at least a portion of the aqueous solution formed in step (e); and (g) recycling to step (b) at least a portion of the calcium oxide formed in step (d). The sulphur dioxide obtained in the process may be converted to sulphur trioxide or elemental sulphur.