GB576906A - Improvements relating to the production of zinc - Google Patents

Abstract

576,906. Extracting zinc. NATIONAL SMELTING CO., Ltd., MORGAN, S. W. K., WOODS, S. E., and DERHAM, L. J. March 13, 1943, No. 4130. [Class 82 (i)] In order to produce high-grade zinc dust from a gas containing only a small proportion of zinc vapour and also a similar proportion of carbon dioxide, such as results when zinc is reduced from a sintered ore in a blast furnace, a stream of the gas is shock-chilled to a temperature below the solidification point of zinc and the zinc dust so produced is prevented from remaining in contact with the hot gases of the stream. The gas, while being shock-chilled, may be caused to flow so rapidly that the zinc dust is substantially all carried forwards by the cooled. gas. The gas, which may be produced in at blast furnace 1, Fig. 1, and passed to the outlet 21 through a bed 10 of heated coke, may be shock-chilled by passage through cooled iron tubes 22 at a speed of not less than 20 ft. per second, the zinc dust, instead of settling in the tubes 22, being carried with the cooled gas up through a tube 24, where further cooling occurs, into bag filters 25. The bags are rapped at frequent intervals by shaking- gear 26 to knock off zinc dust, which is collected in hoppers 27 below. Zinc dust which separates from the gas in passing through the tubes 22 falls into a hopper 23, out of direct contact with the main stream of hot gas. The dust is removed from this hopper at intervals. In another arrangement, the gas passes down through a bank of vertical water-cooled iron pipes 29, Fig. 2, and then-up through another bank 30. Some zinc dust separates out in the space 31 in which the gas changes direction, this dust falling on to a conveyer 32 which removes it from contact with the hot gas. Specification 572,960 is referred to.