Phase relations in the system NaCl-KCl-H2O. Part I: Differential thermal analysis of the NaCl-KCl liquidas at 1 atmosphere and 500, 1000, 1500, and 2000 bars

I.-Ming Chou

doi:10.1016/0016-7037(82)90133-8

Phase relations in the system NaCl-KCl-H2O. Part I: Differential thermal analysis of the NaCl-KCl liquidas at 1 atmosphere and 500, 1000, 1500, and 2000 bars

Geochimica et Cosmochimica Acta

By: I.-Ming Chou

https://doi.org/10.1016/0016-7037(82)90133-8

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Abstract

A simple differential thermal analysis (DTA) technique has been developed to study phase relations of various chemical systems at elevated pressures and temperatures. The DTA system has been calibrated against known melting temperatures in the system NaCl-KCl. Isobaric sections of the liquidus in the system NaCl-KCl have been determined at pressures of 1 atmosphere and 500, 1000, 1500, and 2000 bars. Using the least-squares method, the following equation was used to fit the experimental data: $T(°C)= ∑ i=0 6 a_{i} X^{i}_{KCl}$

where T is the liquidus temperature, X_KCl is mole fraction of KCl, and a_i (listed below) are the derived empirical constants.

P (bars)	$a_{o}$	$a_{1}$	$a_{2}$	$a_{3}$	$a_{4}$	$a_{5}$	$a_{6}$
1 atm.	800.1	−334.2	781.6	−6490.3	17553.1	−17638.4	6098.3
500	813.5	−354.9	743.3	−6011.7	16406.4	−16516.3	5702.8
1000	824.5	−406.7	1446.8	−8818.4	21253.5	−20343.7	6839.4
1500	838.6	−418.7	1434.7	−8819.0	21557.9	−20908.4	7123.1
2000	848.5	−381.5	1246.9	−8605.0	21785.8	−21449.1	7375.8

The liquidus temperatures estimated from these equations are within ±3°C of experimental values. The measured liquidus temperatures at 1 atmosphere agree with the best available data to within 5°C. The melting temperatures for pure end members at higher pressures agree with the values calculated from the Simon equation (Clark, 1959) to within 3°C. No previous melting data are available for the intermediate compositions at elevated pressures. Using the data in both heating and cooling scans, the minimum melting temperature at 1 atmosphere in the system was located at 658° ± 3°C where the sample has an equimolar composition.

Additional publication details
Publication type	Article
Publication Subtype	Journal Article
Title	Phase relations in the system NaCl-KCl-H2O. Part I: Differential thermal analysis of the NaCl-KCl liquidas at 1 atmosphere and 500, 1000, 1500, and 2000 bars
Series title	Geochimica et Cosmochimica Acta
DOI	10.1016/0016-7037(82)90133-8
Volume	46
Issue	10
Year Published	1982
Language	English
Publisher	Elsevier
Description	6 p.
First page	1957
Last page	1962
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