The prediction of mineral solubilities in natural waters: A chemical equilibrium model for the NaKCaMgClSO4H2O system at temperatures below 25°C
The prediction of mineral solubilities in natural waters: A chemical equilibrium model for the NaKCaMgClSO4H2O system at temperatures below 25°C
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DOI：
10.1016/0016-7037(90)90354-n
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发表时间：
1990-03
影响因子：
5
通讯作者：
R. Spencer;N. Møller;J. Weare
中科院分区：
文献类型：
--
作者：
R. Spencer;N. Møller;J. Weare
提出了Na <$K <$Ca <$Mg <$Cl <$SO 4 <$H 2 O体系的低温热化学模型。水的物种和固溶反应的标准化学势的建模从公布的数据为二元和三元溶液。强调了低于25°C的温度范围（至接近−60°C），尽管模型参数在25 ° C至100°C之间与更高温度模型的参数平滑融合。二元和三元特定离子相互作用项随温度独立变化，并使用凝固点下降和矿物溶解度测量建模。冰水反应的标准化学势独立于模型拟合（来自蒸汽压和自由能数据）。固溶反应的剩余标准化学势与特定离子相互作用项沿着拟合。模型预测与已发表的矿物形成数据和通过将海水冷却至低共熔（约-54 °C）获得的盐水成分进行了测试。该模型预测了从冷却海水中观察到的沉淀物的固相序列（云母-芒硝-水卤石-钾盐-MgCl 2·12 H2O镁橄榄石）。除芒硝外，所有模型的温度都在测量温度的不确定性范围内。该模型预测的卤水组成也与观测的卤水组成密切相关，可以准确预测体系中简单和复杂溶液的凝固点。低温相平衡和矿物溶解度也可以预测。该模型可用于根据低温相平衡确定多组分体系中流体包裹体中卤水的组成。
A low temperature thermochemical model for the system NaKCaMgClSO4H2O is presented. Aqueous species and standard chemical potentials of solid-solution reactions are modeled from published data for binary and ternary solutions. The temperature range below 25°C (to near −60°C) is emphasized, although the model parameters are fitted to merge smoothly with those of higher temperature models at temperatures between 25 and 100°C. Binary and ternary specific ion interaction terms vary independently with temperature and are modeled using freezing point depression and mineral solubility measurements. The standard chemical potential of the ice-water reaction is fitted independent of the model (from vapor pressure and free energy data). Remaining standard chemical potentials of solidsolution reactions are fitted along with the specific ion interaction terms.Model predictions are tested against published data for minerals formed and brine compositions obtained by chilling seawater to the eutectic (about −54°C). The model predicts the sequence of solid phases observed to precipitate from chilled seawater (mice-mirabilite-hydrohalite-sylvite-MgCl2· 12H2Oantarcticite). For all but mirabilite model temperatures are within the uncertainty of the measured temperature. The compositions of brines predicted by the model also closely follow the observed compositions.The model allows accurate predictions of the freezing points of simple and complex solutions in the system. Low temperature phase equilibria and mineral solubilities may also be predicted. The model may be used to determine the composition of brines in fluid inclusions in the multicomponent system based on low temperature phase equilibria.