| 摘要 |
1292297 Cooling molten metal COMPAGNIE PECHINEY 5 Dec 1969 [6 Dec 1968] 59481/69 Heading C7D In the purification of metals a volume of liquid metal maintained near its melting point is progressively solidified by plunging a cooled body into the metal, the small crystals which form near the cooled body are collected near the bottom of the container where they are sintered to form large crystals by tamping, with expulsion of impure sinterstitial liquid, and the purified fraction of large crystals is separated from the fraction enriched in impurities. The cooled body may be a hollow graphite plunger internally cooled by a flow of fluid such as air and the speed of solidification may be regulated by adjustment of the rate of flow of such fluid, the heat input to the crucible containing the melt and the thermal insulation of the crucible. Preferably the crystals are repeatedly removed from the body as they form by movement of a surrounding graphite scraper ring and fall by gravity to the lower deposition zone. Reference is made to the purification of aluminium from such impurities as iron, silicon, copper and zinc, and to the purification of lead and zinc. |
