Potassium resources are abundant in the brine of chloride-type salt lakes. The main challenge in the efficient separation and extraction of potassium from salt lakes lies in the insufficient understanding of the structure and crystallization behavior of brine solutions and their correlation. In the present work, X-ray scattering (XRS) and computational simulation methods were used to study the microstructure of KCl and MgCl₂ mixed solutions, including the hydration and association structures of ions in the solutions. Furthermore, infrared (IR) spectroscopy was used to further study the crystallization behavior of solution droplets. The results indicate that the hydrogen bond network structure is disrupted as the mass fraction of MgCl₂ increases. The addition of MgCl₂ causes Mg²⁺ to compete with K⁺ for Cl⁻ in solutions, hindering K⁺–Cl⁻ association and forming contact K⁺–Cl⁻–Mg²⁺ clusters, which results in a slower precipitation and crystallization rate of mixed solutions compared with that of aqueous KCl solutions. This study is expected to provide theoretical guidance for the efficient separation and extraction process of potassium resources in salt lake brine.

中文翻译：

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KCl–MgCl2 水溶液的结构和结晶行为


氯化物型盐湖的盐水中钾资源丰富。从盐湖中高效分离和提取钾的主要挑战在于对盐水溶液的结构和结晶行为及其相关性了解不足。在本工作中，采用 X 射线散射 （XRS） 和计算模拟方法研究了 KCl 和 MgCl₂ 混合溶液的微观结构，包括溶液中离子的水合和缔合结构。此外，红外 （IR） 光谱用于进一步研究溶液液滴的结晶行为。结果表明，随着 MgCl₂ 质量分数的增加，氢键网络结构被破坏。MgCl₂ 的添加导致 Mg²⁺ 与 K⁺ 竞争溶液中的 Cl⁻，阻碍 K⁺–Cl⁻ 缔合并形成接触 K⁺–Cl⁻–Mg²⁺ 团簇，这导致混合溶液的沉淀和结晶速率比 KCl 水溶液慢。本研究有望为盐湖卤水中钾资源的高效分离提取工艺提供理论指导。