Patent GB-209350-A (GB)
Title: Improvements in and in connection with the treatment of arsenious sulphide sludges for the separation of the sulphide from the associated liquid
IPC: C01G28/00
Filed: 1923-04-10
Abstract: Arsenious sulphide is separated from arsenious sulphide mud for instance the mud obtained in the treatment of sulphuric acid with sulphuretted hydrogen (the sulphuric acid being recovered also), by mixing it with a small quantity of an organic substance such as benzene, petrol, mineral oil such as paraffin oil, toluene, cresols, tar oils, turpentine, chloroform and carbon disulphide. Other compounds such as amyl acetate nitrobenzene, sulphonated oils, sperm oil, soap solution, fatty acids, linseed oil and paraffin wax may be used alone or in admixture or in solution in the lighter solvent oils but are not usually so advantageous, and certain other organic compounds such as aniline or pyridine are suitable when the liquid associated with the arsenious sulphide is not acid but are not suitable when it is acid.  The separation may be facilitated by warming or agitation, and the sulphide is then separated by ordinary means such as filtration centrifugal action or settling.  The sulphide thus obtained is associated with the organic substance employed but may be washed practically free of the liquid originally associated with it.  The organic substance may be recovered by the use of a vacuum drier or by dissolving the sulphide in a solvent such as sodium hydrate, sulphide or polysulphide to obtain sodium or calcium thioarsenate; or the organic substance may be left to facilitate the burning of the sulphide when it is desired to make arsenious acid and sulphur dioxide, the latter being used for the production of sulphuric acid.ALSO:Arsenious sulphide is separated from arsenious sulphide mud, for instance, the mud obtained in the treatment of sulphuric acid with sulphuretted hydrogen, the sulphuric acid being recovered also, by mixing it with a small quantity of an organic substance such as benzene, petrol, mineral oil such as paraffin oil, toluene, cresols, tar oils, turpentine, chloroform, and carbon disulphide.  Other compounds such as amyl acetate, nitrobenzene, sulphonated oils, sperm oil, soap solution, fatty acids, linseed oil and paraffin wax may be used alone or in admixture or in solution in the lighter solvent oils but are not usually so advantageous, and certain other organic compounds such as aniline or pyridine are suitable when the liquid associated with the arsenious sulphide is not acid but are not suitable when it is acid.  The separation may be facilitated by warming or agitation, and the sulphide is then separated by ordinary means such as filtration, centrifugal action or settling.  The sulphide thus obtained is associated with the organic substance employed but may be washed practically free of the liquid originally associated with it.  The organic substance may be recovered by the use of a vacuum drier or by dissolving the sulphide in a solvent such as sodium hydrate, sulphide or polysulphide to obtain sodium or calcium thioarsenate; or the organic substance may be left to facilitate the burning of the sulphide when it is desired to make arsenious acid and sulphur dioxide, the latter being then used for the production of sulphuric acid.