Structure and crystallization behavior of aqueous KCl-MgCl₂ solutions.

Area of Science:

• Geochemistry
• Materials Science
• Solution Chemistry

Background:

• Salt lake brines are rich in potassium resources.
• Efficient potassium extraction is hindered by poor understanding of brine microstructure and crystallization.
• Chloride-type salt lakes present unique challenges for resource recovery.

Purpose of the Study:

• To investigate the microstructure of potassium chloride (KCl) and magnesium chloride (MgCl2) mixed solutions.
• To understand the hydration and association structures of ions within these brines.
• To correlate solution microstructure with crystallization behavior for improved potassium extraction.

Main Methods:

• X-ray scattering (XRS) to probe solution microstructure.
• Computational simulations to model ion interactions and structures.
• Infrared (IR) spectroscopy to analyze crystallization dynamics of solution droplets.

Main Results:

• Increased MgCl2 concentration disrupts the hydrogen bond network in the brine.
• Mg2+ ions compete with K+ for Cl- ions, forming K+-Cl--Mg2+ clusters.
• The presence of MgCl2 significantly slows the precipitation and crystallization rate of KCl.

Conclusions:

• The study elucidates the ion interaction mechanisms affecting potassium crystallization in mixed salt solutions.
• Findings provide theoretical insights into hindering K+ association by Mg2+ competition.
• This research offers guidance for optimizing potassium extraction from salt lake brines.