The invention relates to a process for fractional crystallization of metals at the surface of a rotary drum. It is characterized in that the distance between the drum (1) and the bottom of the trough (4) containing the metal in the liquid state is regulated and said trough is divided, in the direction of rotation of the drum (3), into an upstream zone (6) and a downstream zone (7) between which the circulation of liquid is restricted, said distance being regulated in such a way as possibly to permit the crystals to be compressed in the upstream zone, and that the crystals are re-melted in the downstream zone, in order to collect the purified metal in the liquid state. The invention is used in the continuous purification of metals such as in particular aluminum.
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