Patent GB-191113383-A (GB)
Title: Improvements relating to the Recovery of Sulphur from the Refining Materials Employed in the Manufacture of Gas or from other Industrial Residues.
IPC: C01B17/033
Filed: 1911-06-03
Granted: 1912-05-09
Abstract: 13,383. Soc. H. GouthiÞre et Cie, and Ducancel, P. June 7, 1910, [Convention date]. Sulphur is extracted from certain industrial residues, such as spent gas-purifier material, residues from the manufacture of Chardonnet silk &c. by the application of one of two set cycles of operations. The sulphur is extracted by means of ammonium sulphide or sulphydrate, forming a soluble polysulphide; the polysulphide is decomposed so as to reform the sulphide or sulphydrate, and yield the sulphur in a commercial form. According to the first cycle of operations, the spent materials, substantially free from cyanogen, and composed chiefly of sulphur, iron oxide, calcium sulphate and carbonate, and wood saw-dust, with traces of ferrocyanides &c. are treated with ammonium sulphydrate, giving a solution of polysulphide, while the iron oxide in the residue is converted into sulphide. By oxidation in the air the sulphide is converted into iron oxide and sulphur. The solution of polysulphide is distilled, giving a distillate of ammonium sulphide which is treated with hydrogen sulphide obtained from another part of the process so giving sulphydrate for re - use. The remaining liquor is filtered giving precipitated sulphur, which is purified yielding commercial sulphur, and a filtrate from which is extracted traces of ferrocyanides. The solid residue, after the air oxidation referred to above, is treated with a wash of lime, forming calcium sulphides, which are then decomposed by carbon dioxide, obtained from the lime kiln, giving off hydrogen sulphide to be used as above. The final residue consists of renewed purifying-material, which may be used afresh for the refining of illuminating-gas. According to the second cycle, the spent materials treated contain cyanogen and consist, principally, of sulphur, iron sulphide, calcium sulphate and carbonate, wood saw-dust, Prussian blue, ferrocyanides, sulphocyanides, &c. Treatment with an ammoniacal solution of ammonium sulphide gives a solution of polysulphide and an insoluble residue consisting chiefly of iron sulphide, sawdust, calcium carbonate and sulphate, with traces of ferrocyanide and Prussian blue. Air oxidation converts the iron sulphide into oxide, giving renewed purifying material. Distillation of the polysulphide solution gives a distillate of ammonium sulphide for re-use, while on filtration a precipitate of sulphur is obtained as before, and a filtrate from which can be extracted ferrocyanides and ammonia which is re-used with the ammonium sulphide. The Specification as open to inspection under Section 91 (3) (a) comprises also the following: -(1) Extracting sulphur from certain natural products poor therein, for example " sulphurs of " Apt." (2) The general method of obtaining sulphur by (a) extraction with an alkali or alkaline-earth sulphide, or by forming a soluble polysulphide, and (b) decomposition of the polysulphide obtained by a suitable treatment, reforming the sulphide and obtaining the sulphur in a commercial form. (3) A scheme for the treatment with sodium sulphide resembling generally the first cycle described above. This subject-matter does not appear in the Specification as accepted.