Abstract
For the purpose of obtaining the fundamental data for the graphical calculations of the concentration process for the ion exchange membrane brines and the treatment of their bitterns, the solubility equilibria for the system NaCl-KCl-MgCl2-CaCl2-H2O at 100°C were determined by isothermal method. As a result, four quaternary systems, KCl-MgCl2-CaCl2-H2O, NaCl-MgCl2-CaCl2-H2O, NaCl-KCl-CaCl2-H2O and NaCl-KCl-MgCl2-H2O, and one quinary system NaCl-KCl-MgCl2-CaCl2-H2O at 100°C were shown by five tables and four diagrams on the triangular coordinates, and by one diagram on the ordinary tetrahedron coordinates. For the quinary system, a diagram on triangular coordinate of Janecke type was also shown by assuming the saturation with sodium chloride, to facilitate practical calculations.
The diagram of this system at 100°C had eight crystallization regions, of which four were double salts,i.e., carnallite (KCl·MgCl2·6H2O), tachhydrite (CaCl2·2MgCl2·12H2O), baeumlerite (CaCl2·KCl), and 2CaCl2·MgCl2·6H2O. In the tetrahedron diagram, the total fields of sodium chloride and potassium chloride occupied almost all the volume of the tetrahedron, while those of the other crystals were very small and located close to the surface of the quaternary system KCl-MgCl2-CaCl2-H2O on the tetrahedron.
