| 초록 |
Suspension melt crystallization is known for its potential to separate close boiling organic isomers and also to treat waste effluents. The ease of separation of residual melt from the crystals through filtration or washing is very much depended on the crystal properties such as the size, shape and CSD. Ostwald ripening is the most extensive way to improve crystal properties. This process generally occurs at very low supersaturation and in practically isothermal systems. However the process is slow. In this paper, the method has been exploited in a new way; in the course of ice ripening, fixed amounts of superheated melt is continuously added to the crystal suspension thus causing a melting of fines below the critical size and recrystallization of un-melted ice. Through this process, ice slurry produced from 10000mg/l cod redwater had ice crystal size improved from 200㎛to 700㎛ in 7hrs of holding time. The study further highlights the effect of solid fraction, degree of added melt superheat and rate of addition of melt on the rate of the ripening process. After crystal growth, the purity of the crystals was found as functions of growth rate, Crystal size, and initial impurity concentration. |
