Inline Monitoring of Lithium Brines with Low-Field NMR

The importance of and demand for lithium are high and are expected to further increase. Therefore, efficient lithium exploitation processes are essential, for example, Li extraction from brines. Powerful analytical methods are needed, especially with an inline capability. Nuclear Magnetic Resonance is a widely used analytical tool with extensive possibilities. Low-field NMR is particularly suitable for inline quality control thanks to its customizable applications. This study investigates the possibilities of measuring the lithium content in aqueous solutions and brines using 1H and 7Li NMR based on transverse relaxation measurements, using two different low-field NMR instruments. Both static and measurements under flow are presented. The influence of other parameters, such as sample temperature and sodium content of the brine, has also been investigated. The results demonstrate the proof of concept of quantifying lithium content by low-field NMR and provide detailed insights, whilst showing the prerequisites for future industrial applications for inline quality control in lithium extraction processes.