Lithium enrichment from mine waters using CO2 hydrate-based desalination

Lithium (Li) recovery from secondary resources, such as mine waters, is essential to meet the increasing global demand. However, lithium in mine waters typically occurs at low concentrations, necessitating efficient and environmentally sustainable methods for enrichment. Hydrate-based desalination (HBD) is a novel and energy-efficient approach that can simultaneously concentrate lithium and produce clean water. In this study, CO2 HBD was applied to upgrade lithium in real mine waters. The effects of stirring rate and reaction time were evaluated, showing that operation at 600 rpm for 1 h achieved a lithium enrichment factor of 1.57 ± 0.09 and a water recovery of 53 ± 4%. A multi-stage configuration further improved performance, with Li enrichment in the brine stream reaching 2.75. This increased the concentration of lithium from 180 mg/L to about 500 mg/L, a level considered feasible for further treatment towards lithium recovery. The desalting efficiency in the hydrate phase also increased from 40 to 81%. A key finding was that naturally occurring fine particles (silicate/aluminosilicate particles) in the mine water acted as effective in situ kinetic promoters, eliminating the need for external additives. This not only simplifies the process design but also helps to avoid additional separation steps and costs. Overall, these results highlight CO2 HBD as a promising technology for lithium enrichment from dilute aqueous resources and water reuse in mining operations, with potential to contribute to more sustainable resource management.