GB760624A - Improved method for the treatment of mineral sulphide ores - Google Patents

Abstract

760,624. Treating ores. CHEMICAL CONSTRUCTION CORPORATION. May 6. 1954 [May 9, 1953; Oct. 22, 1953], No. 13294/54. Class 82(1) [Also in Group III] Sulphur is produced by reacting pyrrhotitic mineral sulphide particles dispersed in a returned aqueous acidified sulphate solution or in water containing a small amount of sulphuric acid at a temperature 100-290‹F., preferably 200-290‹F., with a free oxygen-bearing gas under a partial pressure of free oxygen of above 25 p.s.i., say up to 100 p.s.i.. continuing the reaction to oxidize sulphide sulphur to elemental sulphur agglomerating- the sulphur to liquid sulphur globules, cooling below the melting temperature of sulphur and recovering sulphur pellets from the mixture. Oxygen, air or oxygen enriched air may be used, the sulphide may be 35-325 mesh Tyler, and 25-45 per cent solids may be in the dispersion. Where the oxidation is carried out at below the melting point of sulphur, the dispersion is heated to above the melting point after oxidation, to agglomerate the liquid sulphur globules which are solidified by cooling, e.g. by dilution. If the oxidation is carried out at below the melting point of sulphur non-ferrous metal values present in the mineral are mainly found in the solution as sulphates, while if oxidation is effected at above the sulphur melting point, the non-ferrous metals are mainly occluded in the liquid sulphur pellets as sulphides. Pyrrhotitic minerals are those containing no labile sulphur or from which labile sulphur has been removed, and includes sulphide material resulting from heating pyrites minerals in an atmosphere free of oxygen, or containing less than half the stoichiometric amount to convert all sulphur to sulphur dioxide. A number of minerals containing iron, arsenic, copper, cobalt, nickel, and antimony are named as suitable, and other non-ferrous metals referfed to as being recoverable are zinc, gold, silver and cadmium. The minerals may be flotation concentrates. The cooled pellets may be filtered to remove large sulphur pellets and a residue containing ferric oxide, while ferric sulphate is present in the solution. The sulphur pellets may be melted and separated from non- ferrous metal sulphides by filtration. Alternatively, the sulphur slurry may be subjected to conventional oil type flotation at pH 2-3.5 with stove oil, kerosene, or fuel oil, or to sulphide flotation with a xanthate sulphide collector and pine oil frother at pH 7-8.5, after neutralization with lime or soda ash to separate pure sulphur and non-ferrous metal sulphides. The sulphates in solution may be recovered by crystallization, or they may be reduced to sulphide by action of carbon monoxide or hydrogen at elevated temperature and pressure, or by neutralization with lime and treatment with hydrogen or calcium sulphides or by action of iron sulphide at 300-400‹F. with consequent formatior of ferrous sulphate. Sulphur may be mixed with the pyrrhotitic mineral before oxidation or part of the sulphur produced may be returned for this purpose and the solution may be recycled after separatior of solids and acidified'with sulphuric acid