Phase studies of the KClCaCl2ZnCl2 system

Thermodynamic evaluation and optimization of the (NaCl + KCl + MgCl2+ CaCl2+ ZnCl2) system

“…As emphasized by Perry et al [16], variations in the melting temperature in the range 523 K to 638 K are reported in the literature. These variations are due to the possible presence of impurities, the extent of dehydration, the tendency of liquid ZnCl 2 to supercool [16] as well as the relatively high viscosity of pure liquid ZnCl 2 (688 mPa Á s at T = 638 K according to [17]). A temperature of fusion of 591 K was finally selected, in agreement with the recommendations of Kubaschewski et al [13] and Binnewies and Milke [18].…”

“…The phase diagram has been measured by the method of cooling curves [16,59]. No solid solubility was reported and the measured limiting slope of the CaCl 2 liquidus curve agrees with equation (2).…”

“…Note that the calculated eutectic temperature of 588 K is significantly higher than the eutectic temperature of 572 K reported by these authors. From the eutectic composition x ZnCl 2 % 0:98 reported by Perry et al [16], our selected temperature of fusion of ZnCl 2 of 591 K (in agreement with the recommendations of Kubaschewski et al [13] and Binnewies and Milke [18]: see Section 2) and the lowest acceptable value for the enthalpy of fusion of ZnCl 2 (16,100 J Á mol À1 according to Kubaschewski et al [13]: see Section 2), and using the well-known limiting liquidus slope equation (van't Hoff equation) and assuming Raoultian liquid behaviour of ZnCl 2 (l) in the limit, one calculates a minimum eutectic temperature of 587 K which agrees closely with our calculated value of 588 K (see figure 18b). …”

“…The measurements of Perry et al [16] were favoured. Note that the calculated eutectic temperature of 588 K is significantly higher than the eutectic temperature of 572 K reported by these authors.…”

“…(NaCl + ZnCl 2 ), (KCl + ZnCl 2 ), (MgCl 2 + ZnCl 2 ), and (CaCl 2 + ZnCl 2 )}, both the entropy of mixing DS TOT m (including the configurational and non-configurational entropies of mixing) and the configurational entropy of mixing DS CONFIG m were calculated at T = 1080 K using the optimized model parameters (see equations (16), (19), (20), (21) in Section 4). The calculated curves are displayed in figures 4 and 5, respectively.…”