Collect. Czech. Chem. Commun. 1986, 51, 2502-2508

Mathematical modelling of salt purification by recrystallization. Estimation of the recrystallization factor for countercurrent arrangement

Benitto Mayrhofera, Jana Mayrhoferováb and Lubomír Neužila

a Department of Chemical Engineering, Prague Institute of Chemical Technology, 166 28 Prague 6
b Institute of Physics, Czechoslovak Academy of Sciences, 180 40 Prague 8


In a previous paper a simple model was developed for salt purification by countercurrent recrystallization. Analysis of mass balances for a microcomponent provided a relation for the composition (purity) of the product as a function of the number of recrystallization stages and of recrystallization conditions reduced to a single parameter called the recrystallization factor. The problem can be readily solved if the dependence of the product purity on the number of recrystallization stages is to be established for a given recrystallization factor. Some difficulties arise when the product purity and maximum number of stages are fixed. For this variant, relations are derived from which the upper and lower limits for the recrystallization factor can be estimated. For recrystallization factors K > 2, this method is more accurate than the use of diagrams published previously. An example is given to illustrate the proposed method.