SEPARATION OF ORGANICS BY MELT CRYSTALLIZATION WITH DIRECT-CONTACT COOLING

The application of direct contact cooling to melt crystallization for the separation of organics was examined. Three types of immiscible coo lants for gas, liquid, and liquefied gas were investigated. The crysta ls produced by this direct contact cooling techniques were of good qua lity, significantly larger than those by scraped-surface crystallizers . The content of the impurity included in the crystals was correlated with mass ratio of suspended crystals, For upgrading the crystals, thr ee kinds of methods were studied, Direct contact melting using warm co olants was found to be the most efficient, From comparison between eff ective distribution coefficients obtained before and after washing, th e inner side of crystals was found to be very pure and any impurity wa s concentrated in the outer layer of crystals. Crystals were found to be contaminated by adhering residual melt in this melt crystallizer wi th direct contact cooling. Performance for separation of organics was more efficient than that of film crystallization in terms of purity of crystal and production.