Rio Tinto announced that it has commenced production of battery-grade lithium from waste rock at a lithium demonstration plant at the Boron Mine site in California.

The demonstration plant is the next step in scaling up a breakthrough lithium production process developed at Boron, to recover the critical mineral and extract additional value out of waste piles from more than 90 years of mining at the operation.

The company began searching for gold and other metals that might be extracted from the waste pile and discovered lithium.

“We were looking for gold… but we found something better than gold: battery-grade lithium – and the potential to produce a lot of it.” said Alex, a Senior Engineer at our Boron operations in California.

An initial small-scale trial in 2019 successfully proved the process of roasting and leaching waste rock to recover high grades of lithium.

In a statement, Rio Tinto said the demonstration plant has a design capacity of 10 t/a (11 stpy) of battery grade lithium. It will be run throughout 2021 to optimize the process and inform Rio Tinto’s feasibility assessment for progressing to a production scale plant with an initial capacity of at least 5 kt/a (5,500 stpy), or enough to make batteries for approximately 70,000 electric vehicles.

“This is a valuable next step in scaling up our production of lithium at the Boron site, all from using waste material without the need for further mining. It shows the innovative thinking we are applying across our business to find new ways to meet the demand for emerging commodities like lithium, which are part of the transition to a low-carbon future,” said Rio Tinto Minerals chief executive Sinead Kaufman.

Rio Tinto’s lithium pipeline includes the Jadar lithium-borate project in Serbia, for which a feasibility study is expected to complete by the end of 2021.

Development of the lithium project at Boron draws on Rio Tinto’s long standing partnership with the U.S. Department of Energy’s Critical Materials Institute (CMI), which is focused on discovering ways to economically recover critical mineral by-products from existing refining and smelting processes. CMI experts worked alongside Rio Tinto technical leads to help solve a number of key processing challenges to produce battery grade lithium at Boron.

The projected production would be roughly the same as the capacity of Albemarle ’s Silver Peak mine in Nevada, which is currently the only lithium-carbonate producing asset in the country, according to the US Geological Survey.

Until now, the global miner’s incursion in the lithium market has been mostly limited to its 100 percent-owned lithium and borates mineral project in Jadar, Serbia. A feasibility study for the proposed mine is expected to complete by the end of 2021, Rio Tinto said.

Rio Tinto has produced borates — a group of minerals used in soaps, cosmetics and other consumer goods — for nearly a century in the Mojave Desert, about 195 km (120 miles) north of Los Angeles.

In March, Rio Tinto announced an agreement with renewable energy firm Heliogen to explore the deployment solar technology at the mine.
Rio Tinto is not alone on its quest for producing lithium in California. Lithium Americas is also advancing a major project that received final federal approval in January. The Thacker Pass lithium mine is expected to generate 20 kt/a (22,000 stpy) of the battery metal once operational in 2023.

The plant at Boron is one the company’s latest attempts latest to extract valuable materials from waste rock or by-products – including scandium from titanium dioxide production, as well as anhydrite and Alextra from its aluminum operations.