Murmansk State Technical University, Murmansk, Russia

Yu. A. Bezymyanova, Senior Lecturer of the Chemistry Chair

I. V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials (Kola Scientific Center of Russian Academy of Sciences), Apatity, Russia

G. S. Skiba, Head of the Laboratory of Chemical and Optical Methods of Analysis, e-mail: skiba@chemy.kolasc.net.ru

Examined the solubility in NaCl – ZrOCl₂ – HCl – H₂O system in three cross-sections of HCl concentrations (18, 28 and 33% (mas.)) at temperatures of 25, 50 and 75 ^oС. The method, used in these solubility studies, is based on the assumption that the concentration figure of a system of any dimension (when the composition is normalized to unity) can be located in the rectangular coordinate system so that equations of analytic and differential geometry can be applied to it. The compositions of equilibrium liquid phases in this case are calculated by the equations of lines passing either through two initial compounds located in certain cross-sections, or through one initial compound and the compounds of the solid phase crystallizing in this area, if the concentration of at least one component in the equilibrium liquid phase is known. The compositions of liquid and solid phases are provided. The solubility isotherms (either lines or surfaces) can be represented not only as tabulated data but as polynomial equations as well. In a four-component system, the surface expressing the composition of solutions saturated with an x salt, is approximated by a quadratic equation of the following type Ax₁² + Bx₂² + Cx₃² + Dx₁x₂ + Ex₁x₃ + Fx₂x₃ + Gx₁ + Hx₂ + Ix₃ + 1 = 0, where x₁, x₂, x₃ are concentrations of the three components in mass fractions. Using these data, approximated the isothermal and polythermal solubility surfaces by polynomial equations. Findings can be used to determine the location of any initial composition in the phase diagram, calculate the quantities of equilibrium phases and optimize the process of crystallization separation of sodium and zirconium chlorides in solutions with different HCl concentrations (18–33% (mas.)) in the temperature range of 25–75 ^oС.

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4. Voskoboynikov N. B., Skiba G. S. Matematicheskoe modelirovanie fazovykh ravnovesiy v vodno-solevykh sistemakh (Mathematic modeling of phase equilibriums in water-salt systems). Apatity : Kola Scientific Center of Russian Academy of Sciences, 1994. 260 p.

5. Bezymyanova Yu. A., Skiba G. S. Sistema NaCl – ZrOCl₂ – HCl – H₂O (razrez 33 %) pri 25 i 50 ^оC (NaCl – ZrOCl₂ – HCl – H₂O system (section: 33 %) with the temperature of 25 and 50 ^оC). Tezisy dokladov vserossiyskoy nauchnoy konferentsii s mezhdunarodnym uchastiem “Nauchnye osnovy khimii i tekhnologii pererabotki kompleksnogo syrya i sinteza na ego osnove funktsionalnykh materialov. Nauchno-tekhnicheskie problemy v oblasti khimii i khimicheskikh tekhnologiy”. 8–11 aprelya 2008 goda (Thesises of reports of All-Russian scientific conference with international participation “Scientific basis of chemistry and technology of processing of complex raw materials and synthesis of functional materials on its basis. Scientific and engineering problems in the area of chemistry and chemical technologies”. April 8–11, 2008). Apatity : Kola Scientific Center of Russian Academy of Sciences, 2008. pp. 11–15.
6. Bezymyanova Yu. A., Skiba G. S. Zhurnal neorganicheskoy khimii — Russian Journal of Inorganic Chemistry. 2010. Vol. 55, No. 8. pp. 1379–1382.