High up in the Andes mountains of northwestern Argentina, a new industry has gained a foothold in a mammoth emerging market. What didn’t exist a decade ago is now bringing a more efficient and safer way to mine lithium, essential for today’s electronics and electric vehicles, among a host of other applications. It’s made possible with the help of non-contacting radar and other wireless monitoring technology with which industry insiders are quite familiar.
At Emerson Exchange 2025 in San Antonio, Texas, Gabriel Carrizo, electronics engineer, Rio Tinto; Leonel Brunet, senior instrumentation engineer, Servicios San Jose; and Sebastian Kasses, mining leader, Emerson Argentina; guided a full room of interested attendees through the development of the new project that extracts lithium from brine more than 4,000 m (13,000 ft) above sea level and more than 1,000 miles from Buenos Aires. It’s a harsh environment full of connectivity challenges, salt deposits, and unstable conditions that cause safety concerns for workers.
However, Rio Tinto, with the help of the Rosemount 5408 non-contacting radar embarked on this endeavor to make mining lithium more cost effective. “Each of us uses lithium every day, in our phones, in our laptops,” Kasses said while opening the discussion. Those uses include the growing lithium-ion battery market that is vital for use in electric vehicles.
Getting into the brine business
In the northwest corner of Argentina, near the border with Peru, sits the “Lithium Triangle” an area of the Andes rich with the valuable mineral. Rio Tinto, one of the largest lithium carbonate production companies in the world, has been mining in the region since 1997, but its expansion into extracting lithium from brine, is a new endeavor. Most lithium is extracted from rock and clay, and brine in limited cases.
The production of lithium carbonate from brine begins by pumping brine from underground wells. It is homogenized and directed into solar evaporation ponds to concentrate the lithium and precipitate salts such as sodium chloride and potassium chloride. Once the appropriate concentration is achieved, lime is added to remove boron and other undesirable compounds. A softening process is conducted with reagents such as sodium hydroxide and sodium carbonate, which eliminate traces of calcium and magnesium. The purified brine is treated by ion exchange and heated, then mixed with sodium carbonate to trigger crystallization of the lithium carbonate. Finally, the product is separated, dried, and milled to the desired granulometry, magnetically filtered and packaged for commercialization.
“Brine is a slow process” Kasses said. However, it is inexpensive. It can take a year or more to produce high-concentrated lithium brines. During that time, the large, but shallow evaporation ponds go through various stages requiring accurate monitoring of precipitate and evaporation levels.
Level and temperature measurement challenges
One of the first challenges is to collect the massive amounts of data needed to calculate the evaporation rate and the pond level. The evaporation rate can be calculated with the Penman equation, but it needs data for ambient temperature, humidity, wind speed and solar radiation. It also requires data on brine properties and pond characteristics.
Likewise, the process requires significant data to measure the salt sediments at the bottom of the ponds. As water evaporates, salts are deposited at the bottom of the ponds forming a layer of compact salt, which increases over time. “It is necessary to monitor the level of compacted salt to determine the growth rate and to estimate the harvesting program,” Brunet said. The process of measuring the salt requires that an operator enter the pond, exposing them to unstable pond bottoms.
In addition, there is a danger to monitoring equipment. Anything that contacts the brine will end up coated with salt deposits. Meanwhile, the extremely remote location in the Andes presents a challenge for data communication.
“That’s why we use non-contacting radar for this application,” Brunet said.
They also use wireless means for data communication. WirelessHART guided wave radar was considered for the application but discarded because salt accumulation in the cable created false readings. Non-contacting radar worked perfectly but needed local power. To solve this dilemma, they turned to Wireless THUM adapters to transfer data from the radar and send it to the control room without requiring any communication wiring. Wireless temperature units proved the best solution and reinforced the wireless mesh network among the radar gauges.
Lab testing salt sediment monitoring
To ensure the best solution for monitoring the salt sediments in the ponds, the company performed a laboratory experiment using the Rosemount 5408 wireless level transmitter. “A sample of the brine was taken to a simulated pond, and the radar gauge was installed to simulate the actual field installation,” Carrizo explained. “With a well-defined layer of salt, the radar position and salt deposit were moved up and down.”
Using Rosemount Radar Master Plus software, information was exported for analysis and interpretation. The level was tracked while recreating the natural evaporation process in the lab. Testing continued at actual ponds to determine if the experiment results could be replicated in the field.
The results of the experiments gave the companies what they intended as a goal—a 10% reduction in harvest cycle costs. It also provided the desired increase in safety. “We’re moving people away from an unhealthy environment and making the process more efficient,” Carrizo said.
