Method and apparatus for evaporating components of multiple substance mixtures and multiple substance systems

For the evaporation of given components from initial multiple-substance mixtures and systems at subatmospheric pressure, individual portions (P 1 , P 2 , P 3 , P 4 , P 5 ) of the multiple-substance mixture and systems are placed in ring crucibles ( 17 ) stacked at several levels. Vapors of the lower-boiling component are drawn off through a vapor exhaust opening in each crucible, while the top ring crucible ( 17 ) is closed except for its vapor exhaust opening. In order to obtain products of high purity through short diffusion path lengths and great uniformity of temperature distribution, a) ring crucibles ( 17 ) are used which act as susceptors towards alternating electromagnetic fields, b) heat bodies ( 16, 21 ) are arranged under and over the crucible stack, and likewise act as susceptors towards alternating electromagnetic fields, c) the ring crucibles ( 17 ) and the heat bodies ( 16, 21 ) are heated by inductive coupling, doing so d) with such timing that at least one of the given components of the multiple-substance mixture or system is obtained in the greatest possible purity.