ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Phase diagrams of some systems important in electrolytic production of magnesium. II. Three-component system MgCl₂-CaCl₂-NaCl

K. Matiašovský

Slovak Academy of Sciences, Bratislava

Abstract: A phase diagram of 3-component system MgCl₂-CaCl₂-NaCl was constructed. By TA and DA 20 polythermal cuts were composed in this system and proved by the law of min. nos. of phase-boundary-surfaces. The phase diagram is characterized by 3 nonvariant points with 2 peritectics and 1 eutectic, by 5 lines of eutectic crystn., and by 2 lines on which the peritectic reactions occur. These lines sep. 5 areas of primary crystn. of CaCl₂, NaCl, MgCl₂, Na₂MgCl₄, and NaMgCl₃. The size of areas is decreased in the order: NaCl-CaCl₂-MgCl₂-Na₂MgCl₄-NaMgCl₃. The concn. triangle is divided by characteristic lines into 22 elementary crystn. areas that differ in the order of processes occurring during cooling and into 18 elementary structural areas that differ in the structural compn. of the solid mixt. In view of the phase compn. of the solid mixts. and completion of the peritectic reactions, the concn. triangle can be divided by lines CU and CV into 3 areas: in NCU are crystals of NaCl, CaCl₂ and Na₂MgCl₄, in UCV Na₂MgCl₄, CaCl₂, and NaMgCl₃, and in VCM MgCl₂, CaCl₂, and NaMgCl₃. It was proved by the phase analyses that, owing to incomplete peritectic reactions in NCU area, NaMgCl₃ crystals are present and in VCM area Na₂MgCl₄ crystals. In the triangle UCV the NaCl crystals in the alloy are in the same area where there is primary or secondary NaCl crystn. This is true for MgCl₂ also. N, C, M, U, and V represent pure NaCl, CaCl₂, MgCl₂, Na₂MgCl₄, and NaMgCl₃, resp., on the triangular phase diagram.

Full paper in Portable Document Format: 132a78.pdf (in Slovak)

Chemical Papers 13 (2) 78–97 (1959)