Patent GB-321911-A (GB)
Title: A process for recovering sulphur and iron oxide from ironcontaining sulphide ores or the like
IPC: C22B1/08
Filed: 1928-05-17
Abstract: 321,911. Elkington, H. D., (Comstock & Westcott, Inc.). May 17, 1928. Grant of Patent opposed. Sulphur.-Materials containing iron sulphide, such as ores, concentrates, or mattes, are treated with a dilute chlorinating agent so that sulphur is displaced with the formation of ferrous chloride, and the dilute sulphur vapours are separated therefrom at temperatures sufficient to keep all the sulphur in the vapour form, but insufficient to volatilize the ferrous chloride appreciably, the degree of dilution of the chlorinating agent being such that a substantial range of temperatures exists within which these conditions can be satisfied. The separation of sulphur from ferrous chloride may take place at temperatures of from 325‹C. to 400‹C., the degree of dilution of the chlorinating agent being such that initial condensation of the sulphur would occur below about 325‹C. The dilute sulphur vapours may be contacted with water-cooled condensing elements., in which the water is at a temperature corresponding to a steam pressure of from 2 to just under 6 atmospheres, so that substantially pure sulphur condenses in a freely liquid condition, and may be delivered through steamjacketed pipes to suitable containers. The condenser may be an ordinary fire tube boiler provided with means for ensuring tortuous passage of the vapours and good contact between vapour and metal. The ferrous chloride remaining behind after the sulphur has been expelled may be further chlorinated to ferric chloride, which is then volatilized and burnt with air to form ferric oxide and dilute chlorine. The process may be made cyclic by utilizing this dilute chlorine for treating fresh ore. In burning the ferric chloride, the air may be preheated by the dilute chlorine leaving the burner. In order to produce coarse-grained ferric oxide the air may be mixed with a small proportion of producer gas, which is preferably delivered under pressure to the air-supply pipe, so as to secure a balancing of pressures in the heat exchanging system. In an example, finely granulated pyrites is caused to move with agitation in countercurrent to dilute chlorine coming from a burner for ferric chloride. At one end of the apparatus, at which the ore enters and dilute sulphur vapours are withdrawn, the temperature is maintained between 320‹C. and 400‹C. At the point where dilute chlorine enters and chlorinated. ore leaves, the temperature is kept low enough to permit ferric chloride to exist in the solid state, the heating of the chlorinated ore to volatilize the ferric chloride being a separate operation. When using batch operation with stationary ore, chlorination is facilitated by sizing the finely ground ore, and using the various sizes separately, either as superimposed layers or as different charges. When complex ores. such as pyrrhotite, chalcopyrite, or pentlandite are used, metals such as silver, copper, zinc, and lead are converted to anhydrous chlorides, while gold and platinum, if present, may be partially chlorinated. These chlorides and metals remain with the gangue and may be worked up therefrom by known methods. Specifications 255,639 and 306,107 are referred to.