PROCESS AND APPARATUS FOR CONTINUOUS PURIFICATION OF A SOLID MIXTURE BY FRACTIONAL SUBLIMATION/DESUBLIMATION

A process is proposed for continuously purifying a solid mixture comprising a sublimable product of value and components with lower and higher sublimation temperatures by fractional sublimation/desublimation in a hot wall tubular oven (1) with supply of the solid mixture together with an inert gas stream, into which the solid mixture is dispersed by means of a dispersing unit (2), at one end of the hot wall tubular oven (1), heating the dispersed solid mixture in the hot wall tubular oven (1) at a temperature at which the product of value sublimes to obtain a gas mixture comprising components with a higher sublimation temperature than the product of value as solid particles, passing the gas mixture comprising components with a higher sublimation temperature than the product of value as solid particles through a hot gas filter (3) with a suitable pore size in order to retain the solid particles with a higher sublimation temperature than the product of value, cooling the gas mixture from which the components with a higher sublimation temperature than the product of value have been removed to a temperature at which the product of value desublimes, and at which the components with a lower sublimation temperature than the product of value are yet to desublime, to obtain a gas mixture comprising the particulate product of value and separating the purified particulate product of value from the cooled gas mixture.