The installation concerns in particular the production of millimeter balls of Al O intended for the manufacture of synthetic sapphire. It comprises a tubular crucible (1) made of a refractory metal housed in a tube (3) of insulating ceramic, a heater (4) of this crucible (1) by induction, the bottom of the crucible (1). is provided with at least one capillary outlet with an internal diameter of 0.5 to 2 mm. The aforementioned assembly (1,3,4) is under a controlled atmosphere in a quartz tube (5) with a neutral gas circulation longer than that of the crucible (1) so that the drops of molten alumina formed at the lower end of the capillary outlet of the crucible (1) fall into the quartz tube (5) in free fall and cool by temperature radiation. The lower part of the quartz tube (5) is provided with a grid (6) with millimeter mesh allowing, if necessary, to break up large drops of alumina, and then an accelerated pre-cooling device (7, 8). allows the millimeter balls to be cooled before being discharged to a container (9).
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