Phase relations in the system NaCl-KCl-H2O II: Differential thermal analysis of the halite liquidus in the NaCl-H2O binary above 450°c
Phase relations in the system NaCl-KCl-H2O II: Differential thermal analysis of the halite liquidus in the NaCl-H2O binary above 450°c
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DOI：
10.1016/0016-7037(83)90152-7
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发表时间：
1983-05
影响因子：
5
通讯作者：
W.D Gunter;I. Chou;Sven Girsperger
中科院分区：
文献类型：
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作者：
W.D Gunter;I. Chou;Sven Girsperger
在 0.3 至 4.1 kb 之间的压力和高于 450°C 的温度下，对 NaCl-H 2 O 系统中的岩盐液相线进行了热分析，其中 NaCl 摩尔分数 (X NaCl) 大于 0.25（即 > 50 wt.% NaCl）。液相线的位置仅通过冷却扫描的差热分析 (DTA) 来定位，因为加热扫描不会产生明确的 DTA 峰。液相线的 dP/dT 斜率在高压下为正且陡峭，但在高 X NaCl 和低于 0.5 kb 的压力下，它似乎反转斜率并以浅角度与三相曲线（液体-石盐-蒸气）相交。然而，由于 P<-0.5 kb 时 DTA 信号的复杂性，对于在这些低压下进行的实验中到底记录了什么事件存在很大的疑问。岩盐的溶解度可以表示为液相 (L) 中 NaCl 的摩尔分数活性、温度 (T,° K) 和压力 (P, bar) 的函数 In α NaCl (LTP)=− 19.884− 0.001275 T− 1388 T+ 3.2305 In (T)− 0.07574 PT 我们的液相线数据（基于 10 种成分）将这些盐水的 500 以上的棒与该方程结合起来，生成 NaCl 的活度系数，该系数在其实验不确定性范围内适合以下一个参数 Margules 方程 In γ NaCl (LTP)=(0.7268− 695.7 T− 0.1217 PT)(1− X NaCl) 2. NaCl 浓溶液显示出与理想值的负偏差，随着 X NaCl 的减小，其幅度迅速增加。
Thermal analysis of the halite liquidus in the system NaCl-H 2 O has been conducted for NaCl mole fractions (X NaCl) greater than 0.25 (ie,> 50 wt.% NaCl) at pressures between 0.3 and 4.1 kb and temperatures greater than 450° C. The position of the liquidus was located by differential thermal analysis (DTA) of cooling scans only, as heating scans did not produce definitive DTA peaks. The dP/dT slope of the liquidus is positive and steep at high pressures, but at high X NaCl, and pressures below 0.5 kb it appears to reverse slope and intersects the three-phase curve (liquid-halite-vapour) at a shallow angle. However, due to the complex nature of the DTA signal when P<-0.5 kb, there is considerable doubt about exactly what event has been recorded in the experiments conducted at these low pressures. The solubility of halite can be expressed as a function of the mole-fractional-based activity of NaCl in the liquid phase (L) in temperature (T,° K) and pressure (P, bars) In α NaCl (LTP)=− 19.884− 0.001275 T− 1388 T+ 3.2305 In (T)− 0.07574 PT Our liquidus data (based on 10 compositions) above 500 bars for these brines were combined with this equation to generate activity coefficients of NaCl which were fit within their experimental uncertainties to the following one parameter Margules equation In γ NaCl (LTP)=(0.7268− 695.7 T− 0.1217 PT)(1− X NaCl) 2. Concentrated solutions of NaCl show negative deviations from ideality which rapidly increase in magnitude with decreasing X NaCl.