Researchers achieve brine concentration using waste heat or sunlight

Scientists at the Australian National University (ANU) have developed a simple and cost-effective method that could make the process of extracting valuable resources from brine deposits more environmentally friendly.

Brine mining is important for lithium extraction, with a significant portion of global lithium production coming from continental brine deposits. In 2024, ANU researchers developed a thermal desalination method, where water remains in the liquid phase throughout the entire process. They have now successfully applied this method to brine concentration.

The power-saving method is triggered not by electricity, but by moderate heat generated directly from sunlight, or waste heat from machines such as air conditioners or industrial processes.

Lead Chief Investigator Associate Professor Juan Felipe Torres, a mechanical and environmental engineer who first proposed the concept of thermodiffusion desalination, said the new research shows the potential of thermodiffusion for concentrating brine with higher salinity.

“Existing technologies for desalination and brine concentration are well-established, but our thermodiffusion technology offers a promising alternative,” he said. “Current desalination technologies — where salt is filtered through a membrane — require large amounts of electric power and expensive materials that need to be serviced and maintained.

“Our thermodiffusive method has been successfully used for water desalination, while reducing energy costs and corrosion issues.”

According to the ANU researchers, all-liquid thermodiffusive brine concentration offers new solutions for materials extraction in several industries, including brine mining.

“More recently, we have been able to apply the same method to manipulate the salinity of brine concentration solution without evaporating it, which also means that precious water isn’t wasted in the process,” Torres said. “Our goal is to replace traditional evaporation ponds — a technology that is thousands of years old — and instead of using vast amounts of land area and water resources, we can do the job with a much-reduced environmental footprint.

“So, for example, lithium is used for batteries, and lithium extraction can occur from brine, and our method could be used in the future to enhance this process.”

Dr Shuqi Xu, an ANU research fellow and study co-author, said the advantages of the technology include material-free and efficient separation of water from ions.

“Our research shows how our method is able to manipulate brine concentration for salt production without evaporation,” she said. “Future improvements could increase the flow rate and energy efficiency by at least 40 times.”

The ANU researchers have partnered with US-based company Wacomet Water Co to commercialise this technology in Australia and overseas. Torres and colleagues have also co-founded Soret Technologies, a spin-off from ANU.

“Our vision with Soret Technologies is to revolutionise brine concentration and desalination processes, making them more cost-effective through innovative thermodiffusion technology,” Torres said.

Image caption: Brine mining. Image credit: iStock.com/chokmoso