Procédé pour séparer l'un des ingrédients d'une matière fusible contenant au moins deux ingrédients ou pour modifier la répartition de cet ingrédient

摘要

A process for treating fusible material comprising at least two ingredients in a column includes the steps of producing a molten region in the column by means of a movable heater, moving the heater so that the molten region traverses the column in one direction, moving the heater the same distance in a reverse direction at such a rate that the state of the material does not substantially change during the reverse travel and repeating the series of steps at least once. A number of heaters may be used to produce alternately spaced molten and solid regions in the material the heaters being moved in one direction from one end of the column to the other for a distance equal to a digital number of solid region lengths and then moved the same distance in the reverse direction. The invention is particularly applicable to processes for redistributing ingredients in solvent-solute systems, e.g. semi-conductor materials such as silicon containing conductivity-determining impurities and the term "column" includes any chamber having openings at either end. Figures 1A and 1B show a column for treating a material by the process of Specification 786,170, and comprising an enriching section 18 having a product outlet 20, a stripping section 19 having a waste outlet 21 and a feed tank 122. Heaters 22 are mounted on heater plates 23, 24 behind the sections 18, 19 respectively and the heater plates are connected by a belt 25 which passes over pulleys 26 and is driven by a motor 27 via a pulley 28. In operation, the heaters for section 18 are moved slowly upwards and their heaters for section 19 are moved slowly downwards by rotation the pulley 28 until the heaters have advanced a digital number of cold region lengths when an arm 29 attached to the heater plate 23 actuates a switch 30 and de-energizes a magnetic clutch 31 between the motor and the motor pulley. A weight 32 then causes a rapid reversal of travel of the heaters until the arm 29 actuates a switch 33 causing re-energization of the clutch. In modifications of the apparatus, the lengths of the heaters or the cross-sectional area of the sections may be varied to alter the volumes of the molten regions as they travel through the length of the sections.