GB805922A - Improvements in or relating to decomposition of sulfide minerals - Google Patents

Abstract

Sulphur and metal chlorides are prepared by treating metal sulphides with a chlorinating agent at 100 DEG to 440 DEG C. in the presence of 2 to 1 parts by weight for each part of metal sulphide, of a liquid which is a solvent for the chlorinating agent. Whilst sulphur is the preferred solvent, other liquids which dissolve the chlorination agent used or the chlorine liberated therefrom, may be employed. The chlorinating agent may be free chlorine, sulphur chlorides or ferric chloride and the operation may be effected at atmospheric or super-atmospheric pressures. As shown in the drawing, dried finely-ground sulphide is introduced into a reactor 4 through line 1 and is intimately mixed therein with liquid sulphur from line 3 and chlorine from line 2, the latter preferably being in less than the <PICT:0805922/III/1> stoichiometric proportion. The products leave the reactor through line 5 as a suspension of metal chloride, unreacted sulphide and sulphur and pass to a settler 6 where a portion of liquid sulphur corresponding to that formed in reactor 4 is separated and withdrawn through line 7. The bottoms from the separator 6, consisting of metal chlorides, unreacted sulphide and sulphur, pass through line 8 to a second reactor 9 where they are contacted with chlorine from line 10 to complete the decomposition of the sulphide. The reaction products pass to a settler 12 where the ferrous chloride is withdrawn from the bottom and the excess sulphur containing sulphur chlorides is recycled through lines 13 and 3 to the first or second stage reactors 4 and 9. The ferrous chloride may be converted to ferric chloride by known means or may be heated with air or oxygen to convert it to ferric oxide, thereby liberating chlorine which is recycled to the reactor 9. Alternatively the mixture of ferrous chloride and sulphur which is removed from the reactor 9 by line 11 is reacted with ferric chloride, thereby producing ferrous chloride and releasing sulphur chloride which may be recycled as a chlorinating agent. The ferrous chloride after separation of the excess sulphur may be oxidized by air or oxygen to form ferric chloride, which is used to decompose further ferrous chloride, and iron oxide in an amount corresponding to the iron content of the ferrous chloride contained in the original ferrous chloride-sulphur mixture. According to an example, finely-ground pyrites was suspended in molten sulphur and at 349 DEG C. chlorine was passed therethrough. 98 per cent of the metal sulphide was decomposed in about 2 hours whilst the temperature rose to 390 DEG C. A further example relates to the use of sulphur dichloride as the chlorinating agent, the liquid sulphur solvent reacting with such dichloride to produce free chlorine.