EFFECT OF TEMPERATURE ON THE SOLUBILITY OF CARNALLITE TYPE DOUBLE SALTS

A method based an Pitzer's model has been used for calculation of the solubilities of carnallite type double salts crystallizing in the syst ems MeX - MgX(2) - H2O (Me = Li, NH4, K, Rb, Cs; X = Cl, Br). The solu bility of congruently soluble double salts was also determined experim entally at 25 - 75 degrees C. The results from studies of the solubili ty diagrams of ternary carnallite type water-salt systems over a wide temperature range are summarized It is found that the width of the cry stallization region for each of the salts can be explained by the rela tive differences in the solubilities of the ternary solution component s (MeX, MgX(2) . 6H(2)O and MeX . MgX(2) . 6H(2)O) and by a change of temperature, and by the effect of temperature on the solubility. A met hod is proposed for calculating Pitzer's ternary parameters of interio nic interaction (theta(MN) and Psi(MNX)) on the basis of experimental data for the solubility in water of the double salts crystallizing in the corresponding ternary water-salt systems.