Collect. Czech. Chem. Commun. 1986, 51, 2489-2501

Mathematical modelling of salt purification by recrystallization. A cross-current flow model and its comparison with the countercurrent arrangement

Benitto Mayrhofera, Jana Mayrhoferováb, Lubomír Neužila and Jaroslav Nývltc

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
c Institute of Inorganic Chemistry, Czechoslovak Academy of Sciences, 160 00 Prague 6


A model is derived for a multi-stage crystallization with cross-current flows of the solution and the crystals being purified. The purity of the product is compared with that achieved in the countercurrent arrangement. A suitable function has been set up which allows the cross-current and countercurrent flow models to be compared and reduces substantially the labour of computation for the countercurrent arrangement. Using the recrystallization of KAl(SO4)2.12 H2O as an example, it is shown that, when the cross-current and countercurrent processes are operated at the same output, the countercurrent arrangement is more advantageous because its solvent consumption is lower.