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The decomposition of pyrite and other sulphide minerals by sulphur chloride

University of British Columbia

The reactions of pyrite (FeS₂) and other sulphide minerals with liquid sulphur chloride (S₂Cl₂) have been investigated in an attempt to develop a process for the extraction of metals such as Fe, Pb, Cu, Mo, etc. from sulphide minerals using S₂Cl₂ (with or without dissolved sulphur) as both the solvent and reactant. For this purpose, flotation concentrates and synthetic mineral powders of various particle sizes were reacted at temperatures in the range 40-150°C with S₂Cl₂ containing 0-40 weight percent dissolved sulphur. Pyrite, chalcopyrite (CuFeS₂) and galena (PbS) reacted with excess S₂Cl₂ to form solid metal chlorides (FeCl₃, CuCl₂, PbCl₂) and dissolved sulphur. Pyrite " 2 <- reacts completely with S₂Cl₂ containing 25-40 wt % dissolved sulphur, but only partially with S₂Cl₂ or S₂Cl₂ containing 10 wt % or less of dissolved sulphur. Chalcopyrite was found to react completely with S₂Cl₂ solutions containing 40 wt % S. Galena (PbS) reacts completely with distilled S₂Cl₂ or S₂Cl₂ containing 10 wt % S, and this reaction was found to be catalyzed by the natural impurities silver, antimony, and bismuth. Pyrrhotite (FeS) and a marmatitic zinc concentrate were only partially decomposed by S₂Cl₂. A series of Investigations with sphalerite (ZnS) and molybdenite (MoS₂) indicated that these minerals could not be significantly attacked by S₂Cl₂. In all cases, sulphur produced in these reactions can be crystallized in stoichiometric yield by cooling the s olvent. A geometric model for the reactions of pyrite, galena, and chalcopyrite with sulphur chloride has been used to interpret the reaction data and to calculate specific rates and activation energies for the reactions concerned. On the basis of this investigation, potential processes for the treatment of pyrite, galena and molybdenite are proposed.

Text

2011-03-23

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http://hdl.handle.net/2429/32794

Materials Engineering

University of British Columbia

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