EFFECT OF MIXING ON PRIMARY NUCLEATION

Batch cooling crystallization was carried out in temperature range 96- 25 degrees C. Metastable zone width was measured at various cooling ra te with constant stirring speed and then rpm of the stirrer was change d as a running parameter. The particle size distribution of the final product was determined by MALVERN laser diffraction method. Kinetic ch aracteristics n and k(N) were determined and nucleation rate N-N was c alculated [1]. In our case the nucleation rate is low until Re number 1000 and then it increases significantly up to Re number 4000 and its order of magnitude remains constant in the region 4000 less than or eq ual to Re less than or equal to 8500. Also the criteria of the needed power input to keep particles moving was determined and the critical R e-number belonging to it were calculated [2, 6]. This is closely the s ame with the experimental Re-number 4000 where the nucleation rate bec omes independent of the mixing (Re-crit = 4308). This critical mixing level is in accordance with the visual experience.