| 摘要 |
1,239,053. Distilling metals. GRILLOWERKE A.G. July 22, 1968 [July 20, 1967], No.34762/68. Heading C7D. A metal is purified from one or more less volatile metals in a distillation process in which fused crude metal is fed from above to a packed fractionation column so that the metal flows as a coherent stream down at least part of the length of the column, the outer region of the column being heated to a temperature greater than that of the coherent stream to set up a temperature gradient across the column from the stream to the outer region. Vapour of the metal passes upwardly in countercurrent to the stream and purified metal is drawn off as vapour at the head of the column. In the drawing a retort 7 is filled with packing'17 such as small pieces of coke which is fed to the retort through a hopper 5 and can be removed at the lower end through outlet 10 for cleaning and reintroduction. A feed pipe 2, preferably centrally placed, for crude metal dips into the packed section for a distance which may be varied up to two thirds of the length of the column. The column is heated externally by burners 11, 12, 13 to provide a lower evaporation zone, an intermediate rectification zone and, corresponding to the length of the feed pipe, a purification zone primarily for filtering of impurity-containing liquid droplets from the metal vapour. The temperature of the packing layer in the purification zone may be the same as that of the vapour leaving the rectification zone, or it may be above or below that of the vapour. A horizontal temperature gradient in the purification zone is ensured by the external heating and by the relatively cold liquid flowing through the feed pipe 2. To avoid vapourisation of metal in the feed pipe, this may be provided with an insulating layer 4. Vapour is condensed in condenser 16 and the sump product containing the less volatile impurities is removed, continuously or batchwise via 8, 9. Reference is made to the production of pure zinc from its alloys with lead, iron, aluminium and/or copper.
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