Improvements in the manufacture of zinc white and apparatus therefor

摘要

In the production of zinc white from ores or residues containing the zinc as oxide, carbonate, or silicate, the vapours and gases leaving the customary conversion furnace A which may be of the Wetherill type are passed through a second furnace B to bring their temperature up to at least 1000 DEG C., and then passed into an expansion chamber for treatment with preheated air before passing to cooling and condensing chambers. In the second furnace fine particles of fuel entrained with the gases are completely burnt, and in the expansion chamber complete oxidation of the zinc is effected and solid impurities deposited. The furnace A comprises paired hearths 1-1a, 2-2a with air-supply passages 3-3a, 4-4a. The gases and vapours, mixed with secondary air supplied at 6, pass through the flue 5, down the passage 9 and over the hearth 7 of the furnace B without appreciable change of speed, and thence through passage 10 into the expansion chamber.