Brazilian Critical Minerals’ Ema ISR field trial hits the right notes with successful REE extraction

Brazilian Critical Minerals’ Ema in-situ recovery field trial has successfully produced a magnet rare earth oxide-rich leach solution.

Brazilian Critical Minerals has proved the viability of ISR at its Ema project after the field trial successfully extracted rare earths. Pic: Getty Images

Special Report: Brazilian Critical Minerals has achieved a major milestone after its Ema in-situ recovery field trial successfully leached, extracted and precipitated rare earths using low concentration magnesium sulphate.

• Brazilian Critical Minerals’ Ema ISR trial has successfully extracted a MREO-rich solution
• Results prove the technical and commercial viability of ISR at the project
• Company to proceed with completing the field trial study at Ema

It also strengthens Brazilian Critical Minerals’ (ASX:BCM) position as a leader in low-impact, next-generation rare earths production and demonstrates the potential for ISR to offer a scalable, low-cost, and environmentally superior alternative to conventional mining methods.

“Our field trials have now conclusively demonstrated that rare earth elements can be successfully leached, recovered, and precipitated from solution via in-situ recovery (ISR) at Ema, exceeding our expectations on all fronts,” managing director Andrew Reid said. 

“This represents a major technical and operational milestone and a critical step in de-risking the project.

“It confirms that ISR can reliably mobilise and extract rare earths under real-world field conditions, positioning the Ema project as a transformative development in the global rare earth supply chain – delivering high ESG performance and sustainable extraction practices.”

Ema is located in the state of Amazonas in Brazil, placing it in the backyard of the US where REE pricing has become increasingly decoupled from Chinese pricing due to export curbs placed by China.

Under the scoping study, Ema is expected to deliver net present value and internal rate of return – both measures of profitability – of US$355m and 52% respectively at the spot price while Capex is estimated at a very palatable US$55m with Opex of US$6.15/kg TREO.

Rare earths precipitated directly in the field after in-situ leaching. Pic: Brazilian Critical Minerals

ISR field trial

BCM had drilled a series of injection and extraction/monitoring holes at site location 2 to determine the time taken for the low strength (0.5M) magnesium sulphate solution to percolate through the clay horizon.

This very quickly reduced the pH of the clay zone to the target level required to leach REEs over short distances.

It also noted the fast reactivity of the reagent to the leaching of REEs into solution via ionic exchange as well as the high-grade of the pregnant leach solution from a small test area.

Additionally, the constant flow of solution through the clays confirmed the permeability of the clays while the steady and elevated rise in solution levels are indicative of a solid impermeable basement.

The company noted that in line with lab-scale tests, there was an expected initial lag phase during which the magnesium sulphate solution saturated the clay-rich horizon and progressively lowered the pH to below the target threshold of 4.

REEs only started mobilising and entering the solution in measurable concentrations after the pH reached this threshold.

Two field locations are currently undergoing magnesium sulphate injection. 

The primary objective of this stage of the trial is not to complete a full leaching cycle, but rather to gather permeability and hydrological performance data critical to ISR system design and collect sufficient REE-enriched PLS to produce a representative mixed rare earth carbonate sample for downstream processing assessment.

View of the field trial injection and extraction wells, water storage and solution preparation tanks and distribution system where solutions samples were sourced. Pic: Brazilian Critical Minerals

Encouraging results

BCM notes the first days of extraction have resulted in strong concentrations of rare earths and volumes of PLS.

All of the wells have thus far displayed a high concentration of the key magnet rare earth oxides within the overall total rare earth oxide grades with H1-F8 and H1-F9 both containing 41% MREO.

These concentrations within the PLS place Ema amongst the highest concentration magnet REE projects.

It will continue to extract solution containing rare earths and then commence the water washing process in order to reduce the levels of magnesium and sulphate levels to their original background levels.

“We now look ahead to completing the current field trial program, initiating the bankable feasibility study, and progressing key workstreams including permitting, financing, and offtake negotiations,” Reid said.

“Ema remains uniquely positioned outside Southeast Asia as the only known rare earth project capable of operating via ISR with exceptionally low capital and operating costs.”

This article was developed in collaboration with Brazilian Critical Minerals, a Stockhead advertiser at the time of publishing. 

This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.