Crystallization of Benzene from Benzene-Cyclohexane Mixtures by Layer Melt Crystallization - Phenomena of Impurity Inclusion in Crystal -

경막형 용융결정화에 의한 벤젠-사이클로헥산 혼합물로부터 벤젠의 결정화-결정의 불순물 내포현상-

  • Kim, Kwang-Joo (Chemical Process & Engineering Center, Korea Research Institute of Chemical Technology) ;
  • Lee, Jung-Min (Chemical Process & Engineering Center, Korea Research Institute of Chemical Technology) ;
  • Ryu, Seung-Kon (Department of Chemical Engineering, Chungnam National University)
  • 김광주 (한국화학연구소 화학공정연구센타) ;
  • 이정민 (한국화학연구소 화학공정연구센타) ;
  • 유승곤 (충남대학교 공과대학 화학공학과)
  • Received : 1997.01.03
  • Accepted : 1997.04.04
  • Published : 1997.06.10

Abstract

The distribution of impurity included in benzene layer crystal was explored in layer crystallization of cyclohexane and benzene mixtures. The influence of crystal growth rate on crystal purity was investigated. All experimental results for bezene-cyclohexane system obtained in layer crystallizer have been evaluated with the criterion of Wintermantel. The purity of crystal decreases with increasing degree of subcooling, decreasing feed concentration and increasing crystal growth rate. The crystal growth rate was a key parameter to determine the inclusion of impurity in crystals. The results obtained from runs performed at increasing crystallization time(i.e. crystal thickness) have clearly shown that migration of inclusions within crystal layer to the melt, leading to the removal of impurity occurs. The diffusion of impurity which takes place during the crystallization from the beginning, enhances a further purification of the crystal layer if that underwent a thermal gradient after growth of the layer crystal stops.

Keywords

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