IMPROVED METAL PURIFICATION PROCEDURE BY FRACTIONAL CRYSTALLIZATION.

摘要

The invention relates to a process for the purification of metals and in particular aluminium by fractional distillation. The process which comprises: (a) causing progressive solidification within a volume of liquid metal which is maintained in the vicinity of its melting point in an externally heated container by immersing therein an internally cooled body; (b) collecting at the bottom of the container all of the small crystals which are formed, (c) by compacting causing sintering of the small crystals to produce large crystals; and (d) separating the purified fraction consisting of large crystals from the liquid fraction which is enriched in respect of impurities, by tilting the container; is characterized in that, to increase the purification action, the container is maintained in its tilted position to drain off the purified fraction. The invention is used in particular in the purification of aluminium where it makes it possible for example directly to reduce the amount of iron from 800 to 1 ppm.