The formation of silicon sulphide in the desulphurisation of iron

W. Fielding
1909 Transactions of the Faraday Society  
A Pafcr rend Bcforc tlrc Foscnla. Socicty, Tiicstlo.y, Juitc 15, 1909, Dr. N. T. M. WILSMORIC in flic Clrciir.) Thc objcct of thc work was to iiivestigatc thc conditions under which ferrosilicon can react with fcrrous sulphidc and liberatc a sulphide of silicon. In the refining of stccl in tlic electric furnace a vcry complete desulphurisation of thc mctal can bc cffcctcd. This action is, in practice, found to be considerably facilitated by thc addition of a charge of fcrrosilicon. Several
more » ... licon. Several explanations have been put forward to account for this influence on the removal of ~~l p h~i r . Some have ascribed it to the high temperature produced during the reduction of thc ferrous oxide present by the ferrosilicon. Professor Osann (Sfnhl z i t i d Eiseia, July 15, 190s) believes that this removal of the iron oxidc prevcnts the bacl~ action between it and calcium sulphide ; at tlic same tiinc a higher tcnipcraturc is produced by thc deoxidation, which assists the rcmoval of sulphur as calcium sulphide. At the end of his paper he suggests the possibility of tlic formation of a gaseous compound, silicon sulphide. Max Haff (Elccfipoc?tciia. nttd ilf cfall. I d . , March, 1908, p. 96) had previously declarcd that silicon sulphidc was produced by heating together sulphides and silicides at a high tcnipcraturc, but no details wcrc givcn of his experiments. Silicon sulphidc (SiS,) is clcscribcd (Hcmpcl and v. Haasy) as a solid at ordinary tempcratures, which at a red heat sublimes under 60 mm. pressure. In the present work the rcaction bettvccn fcrrosilicon and fcrrous sulphide was investigated by heating iiitimatc mixtures of these compounds in a vacuum at known tcmpcraturcs. The reacting substances were placed in a crucible in the form of a liolio~v grxpliitc rod, which could bc evenly heated by the passage of an electric 'current. Electrical connection was made with the rod by fitting it in graphite plugs, which in turn were soldered into water-coolcd brass tubes to which cables could be attached (compare Pring and Hutton, Tmits. Cltctit. SOC. (1o00) 89, p. 1593, and H. C. Greenwood, Trans. Clzmt. SOC. (1908) 93, p. 1485). The rod was surro_unded by a watcr-jacketed Jcna glass tube, for experiments in tvhich thc rod was heated below 1,500~ ; above this temperature a silica tubc was etnploycd. The apparatus was made air-tight by luting tlic ends of tlic tube with soft wax. Temperature readings were made by means of thc Wanner optical pyrometer in those cases in which a glass tubc was cmployed, and changes in pressures were indicated by a mcrcury gauge coiinccted with tlic tubc (see Fig.) . In experiments in which thc comnicrcial variety of iron sulphide was used the mass fused at a tcnipcraturc of about 930° C., and a vigorous reaction set in with rise of tcmperaturc. In later cxperiincnts, using pure iron sulphide (free from oxide) 110 rcactioii was obscrvcd up to about 1,30o0C., hence the reaction noted in tlic first case was probably due to reduction of I10
doi:10.1039/tf9090500110 fatcat:2yfwpknyy5hj3fqr3zuiwqbihm