Abstract: The device according to the present invention comprises a furnace (10) provided with heating means allowing said material to be crystallised to be rendered liquid, then to be cooled until it progressively solidifies. The device also comprises reception means (20) of the material (21) disposed in the furnace, fixed relative to the furnace and situated such that the material is in the intermediary zone. The heating means (11, 12, 13) supply three heating zones: a hot zone (16), an intermediary zone (15) and a cold zone (14). Thermally conductive means (17) are disposed between the reception means (20) and the heating means (11, 12, 13) and extend from the cold zone as far as the hot zone.