Salt lake extraction tech harvests both lithium and magnesium

Claimed to be a world-first, the method uses ethylenediaminetetraacetic acid (EDTA) as a selective chelating agent to separate lithium from other minerals commonly found in salt lake brines. Testing on brines from China’s Dongtai Lake and the Longmu Co Lake in Tibet saw the two-stage filtration process recover lithium at a rate close to 90 per cent. Magnesium ‘waste’ was converted to useful magnesium hydroxide and 99 per cent of the EDTA was regenerated.

According to the researchers, the new technique could make lithium extraction in challenging environments cheaper and more sustainable. The work is described in Nature Sustainability.

“High-altitude salt brine flats in countries like China (Tibet and Qinghai) and Bolivia are examples of areas with tougher brine conditions that have traditionally been ignored,” said Dr Zhikao Li, from Monash University’s Department of Chemical and Biological Engineering.

“In remote desert areas, the vast amounts of water, chemicals and infrastructure required for conventional extraction just aren’t available either, underscoring the need for innovative technologies.”

Unlike conventional methods that deplete water resources in arid regions, the nanofiltration method actually produces freshwater as a by-product. According to Dr Li, the technology could quickly be scaled up to industrial levels, sustainably tapping lithium resources that were previously thought uneconomic.  

“This breakthrough is crucial for avoiding a future lithium shortage, making it possible to access lithium from hard-to-reach sources and helping power the shift to clean energy,” he said.

“These [salt lakes] can now be commercially viable sources of lithium and valuable contributors to the global supply chain. Our technology achieves 90 per cent lithium recovery, nearly double the performance of traditional methods, while dramatically reducing the time required for extraction from years to mere weeks.”

The research was co-led by Dr Li along with Professor Xiwang Zhang from the University of Queensland.