Process for the treatment of zinc ore

摘要

The production of zinc oxide from zinc ores is effected by introducing into a continuous electrically heated shaft furnace a granular free-flowing charge, preferably preheated, comprising granular sintered zinc ore and granular carbonaceous material and heating the charge by utilizing its resistance to the passage of an electric current to a temperature sufficient to distil the zinc but insufficient to fuse or slag the residue and preferably below the distillation point of the sulphide in the ore, e.g. about 1100 DEG C. The sintering of the ore may be carried out in conjunction with a desulphurizing process. The furnace used may comprise a series of independently supported sections A .. D, forming the reducing chamber, a preheater section F and a discharge section E. The sections are supported from columns 18 by means of brackets 19 and adjustable insulated depending rods 20 carrying skew-rings 25 which support annular rings 26 of brickwork on which brick columns 27 and annular rings 28 rest. A shell or casing 29 is provided in sections B, C, D and F, the space between the shell 29 and the brickwork 27 being packed with powdered chrome ore. In the annular space between the rings 28, 26 are luted either condensers 34x, Fig. 8, if metal is required, or, if oxide is required, tuyeres 32, Fig. 4, leading the zinc vapour to conduits 33 into which air is introduced to oxidize the vapour. Three electrodes G, H, I, Fig. 9, preferably rectangular or square in cross section, spaced about 120 DEG apart, extend through the section A of the furnace and corresponding electrodes displaced through 180 DEG , G<1>, H<1>, I<1>, extend through the section D, the current passing diagonally through the charge from each upper electrode to the corresponding lower electrode. Either alternating or direct current may be used. The preheater section F comprises a tube 10 heated by combustion products from a burner which pass upward in a tortuous path through a flue 11 with baffles 12. The discharge section E, which may be cylindrical or tapered, is provided beneath its lower end with a rotating table 36 for removal of the residue and to render the furnace readily accessible a lift 34, mounted on a circular track extending round the furnace, is provided.