Collect. Czech. Chem. Commun. 1987, 52, 1198-1203

Salt purification by recrystallization. Application of the homogeneous distribution law

Benitto Mayrhofera and Jaroslav Nývltb

a Department of Chemical Engineering, Prague Institute of Chemical Technology, 166 28 Prague 6
b Institute of Inorganic Chemistry, Czechoslovak Academy of Sciences, 160 00 Prague 6


In a recently published series of papers on mathematical modelling of salt purification by recrystallization, the microcomponent distribution was assumed to follow the homogeneous distribution law Y = kHX, where X and Y are the mean masses of the microcomponent per unit mass of the macrocomponent in the liquid and solid phases, respectively, and kH is the analytically determined distribution coefficient of the microcomponent. From the physical point of view, it is more rigorous to assume the validity of an equation of the form Y = kH*X, where Y and X are the masses of the microcomponent per unit mass of the macrocomponent at the surface of the solid phase and in the solution, respectively, and kH* is the homogeneous distribution coefficient relating to the equilibrium between the microcomponent and macrocomponent in the solution and at the crystal surface (whereas the analytically determined kH relates to the equilibrium with respect to the bulk of the crystals). This paper presents a simple relationship between the empirical coefficients of the two equations, permitting the recrystallization process to be described by means of the original simple equation using analytically determined component concentrations.