Selection of ternary fused chlorides for the electrowinning of aluminum based on calculated thermodynamic properties

Abstract

. Can. J. Chem. 60, 1664 (1982). Phase diagrams and total vapour pressures in the reciprocal ternary systems LiCI-NaCI-LiAIC1,-NaAICl,, LiC1-KCILiAIC1,-KAICI,, and NaCI-KCI-NaAlC1,-KAICI, have been calculated by means of computerized optimization and interpolation techniques based on an analysis of the constituent binary systems.The system LiC1-NaCI-LiAlC1,-NaAlCl, exhibits an extensive composition region of one-phase liquid solution whereas the LiCI-KCI-LiAIC1,-KAICI, system has a miscibility gap which covers 50% of the composition region. Comparison of the calculated phase diagram with measured data for NaCI-KCI-NaAIC1,-KAICI, was made and the agreement between the two was found to be satisfactory.Temperatures and compositions of chloride electrolytes suitable for the electrowinning of aluminum have been proposed from the isothermal sections of the phase diagrams and total vapourpressure curves. In all of the systems, the total vapour pressure is greater than the minimum for non-volatilization.

Thermodynamic evaluation and optimization of the (NaCl+KCl+AlCl3) system

“…The liquids exhibit strong negative deviations from ideality at the equimolar composition (due to short-range ordering) and the binary liquid phases exhibit a region of (liquid + liquid) immiscibility at high AlCl 3 content. A thermodynamic optimization of the basic region (x AlCl 3 6 0:5) of the ternary system (NaCl + KCl + AlCl 3 ) was reported previously [3,4]. In the present study, the entire composition range (0 6 x AlCl 3 6 1) was considered for the first time.…”

An Amorphous Phase of Zinc and Silicon at Composition Zn2Si5(:H, OH)

“…In any case, the proton transfer to the precursor implies the oxidation of the silicon atoms and, finally, the expulsion of the Li cations from the solid. The formally resulting LiAlCl 4 has a low melting point, and should be easily miscible in liquid state with tetrachloroaluminate salts, and dissolve in the excessive IL at the preparation conditions. After protonation, the thermolabile Si–H can release H 2 either directly or in consecutive reactions with the protic DTA + .…”

“…[37] In any case, the proton transfer to the precursor implies the oxidation of the silicon atoms and, finally, the expulsion of the Li cations from the solid. The formally resulting LiAlCl 4 has a low melting point [38,39] and should be easily miscible in li-Z. Anorg.…”

Simultaneous optimization of binary phase equilibrium and thermodynamic data for organic systems

“…The proposed procedure is similar to a method used elsewhere (Bale and Pelton, 1983d) for the treatment of metallurgical systems. The strategy has been applied with considerable success to alloys (Ashtakala et al, 1981a-c;Bale and Pelton, 1983a-c), oxides (Blander and Pelton, 1983; Pelton and Blander, 1984), molten salts (Bale and Pelton, 1982;Gabriel et al, 1985;Gabriel and Pelton, 1985;Hatem et al, 1982;Pelton et al, 1982;Sangster and Pelton, 1984), and other inorganic systems where there may be several phases. The objective is to provide one set of coefficients which enables the calculation of the various excess properties of mixing over the entire range of experimental conditions and permits reasonable extrapolations outside this region.…”