察尔汗盐湖铷铯元素在钾肥生产过程中的分布规律研究

There are abundant rubidium and cesium resources in Qinghai Chaerhan salt lake brine in our country. However, these resources were dispersed and wasted in the potash production process. Up to now, we have no idea about where did the rubidium and cesium elements have gone, and what is the reason of the dispersion. Therefore, we carry out this preliminary basic research for the application of Chaerhan salt lake rubidium and cesium resources. The Research objectives are: through the phase diagram studies by experimental determination and Pitzer model calculation, of series salt lake brine systems related to these elements at 298.15 K, the distribution and crystallization of the rubidium and cesium elements of Chaerhan salt lake in the solar pond (halite solar-pond, sylvite solar-pond, carnallite solar-pond) stage of the potash production process can be revealed, the direction where did the rubidium and cesium elements have gone can be found, the scientific basis for the development and extract chaerhan salt lake rubidium and cesium resources can be provided. The specific research contents include: the determination of the systems' solubility data at 298.15 K; the isopiestic determination of the systems' component activity at 298.15 K; the correlation of component activity and solubility data at 298.15 K by the thermodynamic model; the establishment of model that can present and calculate the thermodynamic properties and diagrams of the systems. Studying the systems' diagrams mainly by thermodynamic model and combined with the experimental determination is the innovation point of this research.

我国青海察尔汗盐湖原卤水中含有丰富的铷铯资源。然而，这些资源却在钾肥生产过程中分散流失。目前，对察尔汗盐湖铷铯元素在钾肥生产过程中的走向、导致其流失的原因尚不清楚。因此，本项目开展察尔汗盐湖铷铯资源利用的前期应用基础研究，目标是：通过对与铷铯相关的一系列盐湖卤水体系298.15 K时相图的实验测定、pitzer模型计算研究，揭示察尔汗盐湖铷铯元素在钾肥生产过程中盐田摊晒（钠盐池、钾石盐池、光卤石池）阶段的分布和析出规律，找出铷铯元素的走向，为开发提取察尔汗盐湖铷铯资源提供科学依据。具体研究内容包括：体系298.15 K时的溶解度的实验测定；体系298.15 K时的热力学组分活度的等压测定；组分活度和溶解度数据的热力学模型关联；能够准确表达和计算体系298.15 K时的热力学性质和相图的Pitzer模型的建立。以热力学模型计算为主，与实验测定相结合的方法研究体系相图是本课题的创新之处。

本项目针对青海察尔汗盐湖卤水中的铷铯元素在加肥生产过程中的流失的问题，通过对与铷铯相关盐湖水盐体系的相图的实验测定及其热力学模型模拟计算，从固液转化及相平衡的角度提出了铷铯元素在加肥生产过程中的流失的机理及分布规律，为察尔汗盐湖高附加值的铷铯资源的综合开发利用提供了理论支撑。获得的研究成果如下：（1）建立了快速准确测定含干扰离子的盐湖水盐体系溶解度测定的连续浊点法；建立了铷、铯离子的分析方法；（2）建立了固溶体-水溶液（Solid solution-Aqueous solution，SS-AS）体系相平衡模型计算理论，提出了固体溶液中组分与水溶液中相应组分化学势相等作为模型计算的判据。（3）获得了铷铯相关水盐体系298.15 K时的热力学性质和溶解度数据，填补了国内空白；（4）构建了与铷铯相关水盐体系298.5 K 时的热力学Pitzer模型，为察尔汗盐湖铷铯资源提取提供了数据支撑和科学依据。共发表论文4篇，SCI收录3篇。