Thermodynamics of the Ca-CaO-CaF2 system

Abstract

A static method was used to measure the partial vapor pressure of calcium over the Ca-CaO, CaCaF 2 , and Ca-CaO-CaF 2 liquid solutions in the temperature range from 1165 to 1812 K. Simultaneously, the solubility of solid CaO or CaF 2 in the melts was determined. All solutions are characterized by positive deviations from Raoult's law. The thermodynamic properties of the Ca-CaF 2 melt were approximated by a subregular-solutions model with the ideal entropy term and those of Ca-CaO by a model that takes into account some ordering in molecular arrangement. The thermodynamic description of the ternary liquid solution was attained under the assumptions that interparticle interactions do not change in going from the binary constituent systems to the ternary one and that there is no triple interaction. The models were applied for the computation of phase diagrams of the studied systems.

CO2 gas decomposition to carbon by electro-reduction in molten salts

“…This relation is the same when metallic Li is used as reductant as shown in Eqs. (10,(15)(16)(17). Especially in case that the molten CaCl 2 -CaO is used, CO gas tends to be produced by Boudouard reaction as shown in Eq.…”

“…The reduction mechanism was reported in the previous papers [2][3][4][5][6][7], and it is briefly written as below in case of reduction of titanium dioxide. CaCl 2 can dissolve 20mol% CaO and 2-4mol% metallic Ca at 1173K in equilibrium [8][9][10]. CaO is ionized in the molten salt as presented in Eq.…”

Reduction of CaTiO₃ in Molten CaCl₂ - as Basic Understanding of Electrolysis

“…(3) dissolves in the CaCl 2 melt, because the solubility of Ca is reported as about 4 mol%Ca [13][14][15][16][17][18] . The droplets of Ca may be found as the metal fog near the cathode 19,20) , when Ca dissolution rate is delayed.…”

Calciothermic reduction of NiO by molten salt electrolysis of CaO in CaCl2 melt

“…This implies that the rate of reduction was faster at the higher CaO concentration, probably because the larger amount of CaO in the melt was consumed for electrolysis and the larger amount of Ca for reduction is being generated in a short period. Slight decrease in the rate of current decline at 5.0 mol% CaO may be due to the possible precipitation of liquid Ca metal because molten CaCl 2 can only dissolved up to 4 mol% Ca [23][24][25][26][27][28] and this value decreased with small addition of CaO in the bath [31]. The microscopic oxygen distribution was tried to be measured by SEM equipped with energy dispersive X-ray (EDX) detector, but the precise profiles were not detected because of light nature of oxygen.…”