Improvements in or relating to the separation of metallic halides

摘要

Iron chloride is removed in dry form from the gases resulting from the chlorination of titaniferous material by passing the gases successively through a primary cooling chamber where they are cooled by admission of a quantity of atomized titanium chloride suspension such as will vaporize completely, a settling chamber, where dry solid ferric chloride is removed, and a washing tower irrigated with a recirculated countercurrent stream of titanium chloride suspension. The suspension of iron chloride in liquid titanium chloride from the washing tower is recycled to the chlorinator and to the primary cooling chamber, thereby effectively depositing all the iron chloride in the primary cooling chamber and the settling chamber in dry solid form. In the drawing, the titaniferous material, e.g. rutile or ilmenite, is chlorinated in the chlorinator 11, which may operate as a fluidized bed. The gases pass to the primary cooling chamber 13, entering at a temperature of about 900 DEG C. and are cooled to about 165 DEG C. (30 DEG to 70 DEG C. above the dew-point of the titanium chloride constituent) by a finely-divided spray of titanium chloride suspension admitted through 14 and the spray device 15, e.g. an atomizing wheel, the added TiCl4 vaporizing. The gases now pass to the settling chamber 17, e.g. a cyclone, and then to the bottom of the washing tower 19, where they flow in countercurrent to liquid titanium chloride suspension at a temperature of 75 DEG to 130 DEG C., preferably 90 DEG to 110 DEG C., which is admitted through 23, thereby removing residual iron chloride. The gases leave the tower via 20 to a condenser 21, where they are cooled to between 0 DEG and - 20 DEG C., preferably - 15 DEG C. Any uncondensed gases leave via 22, where, after further purification, they are discharged to the air. The titanium chloride collects in 31 and is then passed to storage container 32. This titanium chloride may be recirculated in part to the chlorinator via 36, to control the chlorinator temperature, or be withdrawn via 35. The suspension of iron chloride in liquid titanium chloride from the washing tower collects in the tank 24, the level of which may be adjusted by the admission of extra titanium chloride from 31 via 33. This titanium chloride suspension is circulated by means of pump 25, in part to the washing tower 19 via the water-jacketed conduit 26 and branch 23, and in part to the chlorinator and primary cooling chamber via 27 and valves 28 and 30. By controlling the amount of titanium chloride suspension admitted to the washing tower the condensation of titanium chloride may be limited to such an extent that the quantity of suspension recycled to the chlorinator and cooling chamber is not greater than the total required to control the chlorinator temperature and to cool the hot chlorination gases in such a way that practically the whole of the liquid constituent is evaporated. It is desirable that the titanium chloride suspension contains between 1 and 30 per cent of iron chloride. This iron chloride will contain small quantities of other volatile chlorides which condense to solids under the conditions of the process, e.g. zirconium chloride, aluminium chloride.