Fractionation of a mixture of substances

Abstract

A method for dry fractionation of a mixture of meltable, higher molecular weight organic substances, including: melting a mixture of organic substances which is meltable and which has a higher molecular weight by heating the mixture to a temperature effective to provide a melt, the melt having an interior temperature; pre-cooling the melt with a cooling means including a coolant to one of (1) cool the melt without nucleation of crystallization and (2) cool the melt and nucleate crystallization at a nucleation temperature; and growing crystals under conditions effective to one of (1) nucleate crystallization at the nucleation temperature and ripen the crystals, and (2) ripen crystals nucleated in step (b), wherein pre-cooling, nucleating and crystal ripening each include a thermal treatment, wherein, during precooling, temperature reduction is effected at any desired rate but under the conditions that the coolant has a temperature which is not more than 10.degree. C. below the nucleation temperature, wherein, during nucleation, specific heat flow from the mixture into the coolant does not exceed 20 W/kg of the mixture and the temperature of the coolant is not more than 20.degree. C. below the interior temperature of the melt, and wherein, during crystal ripening, specific heat flow from the melt into the coolant does not exceed 10 W/kg of the mixture and the temperature of the coolant is not more than 25.degree. C. below that of the melt.