GB240424A - An improved process and apparatus for the production of pigments from sulphide ores - Google Patents

Abstract

240,424. Kendall, S. W. Sept. 24, 1924, [Convention date]. Pigments. - In the manufacture of pigments comprising sulphates from sulphide ores, particularly lead ores, by heating the ores to vaporize the sulphides without oxidizing them, as for instance in a reducing atmosphere, and oxidizing the sulphides to sulphates, the oxidized fume is chilled by liquid atomized thereinto in limited quantity such that it becomes practically completely vaporized, after which the precipitated sulphates are filtered from the products of combustion in a substantially dry state. Jakna or other sulphide ores are fed by the elevator 2 and worm conveyer 3, Fig. 1, to a rotating sprinkler 4 and distributed over a coke-bed 9 in a furnace 10. The sulphide vapours pass into the oxidizing chamber 12 where they are mingled with cold air entering through adjustable openings 13, whence the oxidized vapours immediately pass to the cooling chamber 14 to cool them below their dissociation temperature. The vapours are chilled by water &c. sprayed by atomizers 15, and pass between water cooled cheeks 16. The sulphate which condenses is removed by doors 24, and a worm conveyer 21, any low grade material being returned to the furnace for retreatment. The fume, comprising fine divided sulphate and combustion gases passes through a conduit 25, Fig. 3, into a space 27a, and thence upwards into the flannel &c. filter bags 28, where the solid material is filtered out, the gases passing into a conduit 28a. The current of gas &c. is maintained throughout the apparatus by a suction fan 29. The bags 28 may be shaken by a handle 34 operating a suspension bar 33, the solid material being removed by scraper conveyers 35 and a worm conveyer 36. The filter chamber may be divided into sections as shown in Fig. 2, each provided with a valve 31. The characteristics of the product. may be varied by the injection of reagents through atomizers 15. Thus, sulphuric acid vapour may be injected to obtain a practically neutral lead sulphate instead of the basic one normally produced from lead sulphide ores. Colours such as a water suspension of ultramarine may be injected to form a product analogous to a lake on a lead base. Separate, atomizers may be used for the reagents if required, and they may be introduced into the combustion or oxidizing chambers. Steam may be injected by nozzles 40, Fig. 1, to prevent formation of sulphites. A particularly suitable pigmentary product which may be obtained has the formula (PbSO4)14 PbO.