THE PREDICTION OF MINERAL SOLUBILITIES IN NATURAL-WATERS - THE NA-K-MG-CA-CL-SO4-H2O SYSTEM FROM ZERO TO HIGH-CONCENTRATION AT 25-DEGREES-C
THE PREDICTION OF MINERAL SOLUBILITIES IN NATURAL-WATERS - THE NA-K-MG-CA-CL-SO4-H2O SYSTEM FROM ZERO TO HIGH-CONCENTRATION AT 25-DEGREES-C
复制标题
DOI：
10.1016/0016-7037(80)90287-2
复制
发表时间：
1980-01-01
影响因子：
5
通讯作者：
WEARE, JH
中科院分区：
文献类型：
--
作者：
HARVIE, CE;WEARE, JH
本文提出了一个海水体系的化学模型Na <$K <$Mg <$Ca <$Cl <$SO 4 <$H2 O，用于预测矿物在零到高离子强度范围内的溶解度。从石膏饱和度（I< 0.06m）到水氯镁石饱和度（I > 20 m），计算的溶解度与实验数据一致。该模型利用Pitzer及其同事最近开发的活度系数表达式和快速识别共存相及其平衡组成的算法。活度系数表达式参数化使用二元和三元系统的溶解度和渗透数据。结果表明，由二元和三元体系数据定义的自由能模型可以准确地预测更复杂体系的溶解度。简要讨论了一般化学平衡问题的求解算法。该方法可以用来模拟系统的任意数量的可能的非理想的解决方案阶段。迭代过程是保证收敛，并已被发现是有效的，易于实现。计算的相图与海水系统的实验数据进行了比较。我们的计算是在实验的准确性，而其他海水模型的预测是在很大程度上不一致的数据，即使在低浓度。还简要讨论了蒸发序列的计算，并与现场数据进行了定性比较。与相图法（Braitsch，1971年）预测的序列相比，用这种方法预测的矿物组合与岩心样品的一致性更好，相图法不明确包括Ca组分。
A chemical model of the seawater system, NaKMgCaClSO4H2O, is developed for predicting mineral solubilities in brines from zero to high ionic strengths. The calculated solubilities are shown to be in agreement with the experimental data from gypsum saturation (I< 0.06m) to bischofite saturation (I > 20 m). The model utilizes activity coefficient expressions recently developed by Pitzer and co-workers and an algorithm for rapidly identifying the coexisting phases and their composition at equilibrium. The activity coefficient expressions are parameterized using binary and ternary system solubility and osmotic data. The results indicate that a free energy model defined by binary and ternary system data will accurately predict solubilities in more complex systems. The algorithm for solving the general chemical equilibrium problem is briefly discussed. The method can be used to model systems with an arbitrary number of possible non-ideal solution phases. The iterative procedure is guaranteed to converge and has been found to be efficient and easy to implement.Calculated phase diagrams associated with the seawater system are compared to experimental data. Our calculations are within experimental accuracy whereas the prediction of other seawater models are in substantial disagreement with the data even at low concentration. The calculation of evaporation sequences is also briefly discussed and qualitatively compared to field data. The mineral assemblages predicted by this method are in substantially better agreement with core samples than the sequences predicted by phase diagram methods (Braitsch, 1971), which do not explicitly include the Ca component.