Phase relations in the system NaCl-KCl-H sub 2 O: IV. Differential thermal analysis of the sylvite liquidus in the KCl-H sub 2 O binary, the liquidus in the NaCl-KCl-H sub 2 O ternary, and the solidus in the NaCl-KCl binary to 2 kb pressure, and a summary of experimental data for thermodynamic-PTX analysis of solid-liquid equilibria at elevated P-T conditions

The sylvite liquidus in the binary system KCl-H{sub 2}O and the liquidus in the ternary system NaCl-KCl-H{sub 2}O were determined by using isobaric differential thermal analysis (DTA) cooling scans at pressures up to 2 kbars. Sylvite solubilities along the three-phase curve in the binary system KCl-H{sub 2}O were obtained by the intersection of sylvite-liquidus isopleths with the three-phase curve in a P-T plot. These solubility data can be represented by the equation Wt.% KCl ({plus minus}0.2) = 12.19 + 0.1557T {minus} 5.4071 {times} 10{sup {minus}5}T{sup 2}, where 400 {le} T {le} 770C. These data are consistent with previous experimental observations. The solidus in the binary system NaCl-KCl was determined by using isobaric DTA heating scans at pressures up to 2 kbars. Using these liquidus and solidus data and other published information, a thermodynamic-PTX analysis of solid-liquid equilibria at high pressures and temperatures for the ternary system has been performed and is presented in an accompanying paper (Part 5 of this series). However, all experimental liquidus, solidus, and solvus data used in this analysis are summarized in this report (Part 4) and they are compared with the calculated values based on the analysis.