Verfahren zum kontinuierlichen Zonenschmelzen

The ingredients of a material containing at least two ingredients at least one of which has a segregation coefficient other than unity, are redistributed by passing a series of molten zones 6 and 7 (Fig. 1A) from left to right through the material 5 in a container 1, removing material at ports 2 and 3 each time the material adjacent the ports 2 and 3 is molten, and adding material at an inlet 4 at a higher elevation than the ports 2 and 3 so that the upper surface of the material 5 is inclined from the inlet 4 to the ports 2 and 3. When the minor ingredient of a two-ingredient mixture has a distribution coefficient less than one, material removed at port 2 contains less of the minor ingredient and material removed at port 3 contains more than in the original material. Optionally, the bottom of the container may have inclines parallel to the surfaces of the material, and there may be vertical partitions extending a short distance below the surface of the material to prevent overflow from the molten zones. When the material contains two minor ingredients, one having a distribution coefficient k less than one and the other k greater than one, it is treated in apparatus as above but having a vertical baffle 63 as shown in plan in Fig. 5A. The material is introduced at 61 and the surfaces are inclined towards ends 66 and 67. Molten zones such as 64 and 65 are passed from left to right and material withdrawn at 66 is enriched in the minor ingredient having k greater than one, and material withdrawn at 67 is enriched in the minor ingredient having k less than one. Material not withdrawn at 66 and 67 flows round the ends of baffle 63 towards a port 68 lower than the ports at 66 and 67 as the molten zones pass from left to right, and material reduced in both minor ingredients is removed at 68. This process may be repeated using apparatus in cascade as shown in Fig. 8. In a further modification material containing two minor ingredients is treated as above in apparatus shown in plan in Fig. 10A having a baffle 120, the material entering at F and being removed at 123, 124 and 125 as molten zones are passed from left to right. This may be repeated using apparatus in cascade as shown in Fig. 11A. Specifications 769,673, 786,170 and 786,171 are referred to.