How brine 'mining' could reduce water desalination costs in Chile

Desalination plants are not only a way to secure water supply but also an opportunity to recover basic elements from waste brine, experts say. 

The value of these resources could help reduce desalinated water costs in Chile.

In addition to requiring large investments, desalination plants are complex, and obtaining permits is one of the principal challenges, Claudia Valdez, principal infrastructure officer at IDB Invest, told a desalination conference held by Vostock in Santiago.

Fernando Cubillos, a private sector business manager at Latin American development bank CAF, told the event about the challenges for projects involving long pipelines from the coast to transport water in terms of obtaining socio-environmental permits.

Chilean mines are located on average at about 3,000m above sea level, so pumping water to the facilities requires high energy consumption.

While the cost of transforming seawater into freshwater, with reverse osmosis, is about US$0.5/m3, transporting the water can double or triple the cost of desalination, reaching values of US$1.5/m3 or US$2/m3, Claudio Sáez, water researcher at the Universidad Playa Ancha, told local media.  

However, there is a way to obtain byproducts from brine that could contribute to economic feasibility.

Brine 'mining'

Using technologies, it is possible to recover elements from the desalination process from waste brine, such as sodium chloride, potassium chloride, magnesium sulfate, sodium sulfate, sodium bromide, calcium, boron, strontium and lithium, according to scientific papers.

"Desalination plants around the world take in about 86,000Mm3 of seawater annually and discharge a staggering amount of super-salty waste brine back into the ocean, which contains materials with an aggregate value of US$2.2tn, including 15.8mn kilograms of lithium," the Brine Miners team at Oregon State University research center says in an article.

The high concentration of salts and minerals in brine can generate environmental benefits by incorporating the circular economy and increasing project sustainability, as well as economic benefits by generating profitability from byproducts that can reduce infrastructure, energy and production costs.

This could be key for Chile's mining industry, which represents almost 80% of the country's desalination capacity and plans to continue growing in this area due to the scarcity of continental water resources.

"It will be necessary to use seawater in all mining operations," Alejandro Hepp, sales manager at ABB Motion's mining and EPC segment told BNamericas.

That is why miners are looking for innovative initiatives to improve water efficiency, such as the "treatment of recovered tailings, a process that allows fo reuse, while reducing the environmental impact related with mining waste, and the recovery or reuse of treatment water from leaching," Hepp added.