GB309307A - Improvements in the metallurgy of ores or materials containing tin - Google Patents

Abstract

309,307. Ashcroft, E. A. April 5, 1928. Stannous and other chlorides, oxides, and sulphides; carbonates.-Tin-bearing materials, for instance ores, concentrates, slags, residues, alloys &c. are uniformly heated with ammonium chloride. In the case of materials containing, in addition to oxidic compounds of tin other than cassiterite oxidic compounds of other metals such as iron, on heating to 350-400‹ C., all the metals form chlorides which may be lixiviated from the product. Alternatively, by raising the temperature to 620-700‹ C. stannous chloride may be volatilized and collected. As cassiterite, when present, is not directly chlorinated at 350-400‹ C., materials containing it may be first reduced; or when the material contains metallic constituents, the cassiterite be reduced by the hydrogen evolved in the formation of their chlorides; or iron be added to the charge to form a mixture of iron and iron chloride which will reduce and chlorinate the tin when the temperature is raised to 600-700‹ C. When material containing metals, for instance metal powders, alloys of nickel and tin, or of nickel, tin, and iron are treated, all the metals present including tin may be chlorinated, and by admixing cassiterite with such materials the tin therein is first reduced by the hydrogen liberated during the chlorination of the other metals present and then converted to chloride. When treating sulphidiferous materials, such as complex Bolivian ores containing zinc and lead as sulphides and tin both as cassiterite and sulphostannate, iron or other metal is added to the charge, and chlorides of all the metals present, including tin, are formed. The ammoniacal sulphur compounds or free ammonia evolved in the reactions, with or without carbon dioxide, may be used to precipitate from their solutions the chlorides, including tin chloride, formed with regeneration of ammonium chloride for further use in the process. Examples relate to the treatment with ammonium chloride alone of compounds such as slags, residues, or complex ores containing oxidic tin materials such as silicates or stannates, iron being assumed to be present; with ammonium chloride alone of metallic materials containing tin or of such materials admixed. with cassiterite; with ammonium chloride and iron of a complex sulphide ore containing cassiterite, sulphostannate of lead, and lead, zinc, and some iron as sulphides, with or without previous roasting of the ore: and with ammonium chloride alone of the residues obtained bv purifying lead bullion with caustic soda, which contains sodium stannate, antimonate, and arsenate, free caustic soda and sodium carbonate. From a solution of the chlorides formed metals other than sodium present may be precipitated by ammonia with or without carbon dioxide and the sodium then be recovered as bicarbonate by the ammoniasoda process with regeneration of ammonium chloride. Specifications 295,805 and 297,784, [both in Class 82 (i), Metals, Extracting &c.], and 302,851 are referred to.