Brazilian Critical Minerals assembling Ema puzzle as ISR leach solution returns high-grade REEs

• BCM’s ISR trial achieves peak 3510ppm TREO result in the ISR pregnant leach solution
• Notably, valuable magnet rare earth oxides make up 40% of the TREO
• Result demonstrates ability to leach high-grade REEs directly from the ground

Special Report: Brazilian Critical Minerals has placed a critical piece of the puzzle needed to advance its flagship Ema rare earths project to development with the pregnant leach solution recovered from the ISR trial returning super high grades.

The ISR field trial was marked a resounding success after it successfully leached, extracted and precipitated a magnet rare earth oxide-rich solution, which demonstrates high in-situ field-leaching efficiencies.

This solution was recovered from the extraction/monitoring holes after a low-concentration, environmentally friendly magnesium sulphate solution was injected and allowed to percolate through the clay horizon.

Brazilian Critical Minerals (ASX:BCM) now notes that all extraction holes achieved grades significantly higher than the original in-situ mineralised grades with a peak of 3510ppm total rare earth oxides.

Notable results include:

• hole H1-F9 averaging 2281ppm TREO including an outstanding 929ppm MREO over 10 days of ISR leaching; and
• hole H1-F6 averaging 1639ppm TREO including 737ppm MREO over 11 days of ISR leaching

Besides the reported high grades, hole H1-F9 also averaged 45ppm dysprosium and terbium – the most important and hence the most valuable elements in high-end permanent magnets – over 10 days of leaching.

This adds to the MREO’s averaging 40% of the TREO content across all holes reported, making Ema one of the richest MREO deposits, which in turn supports a premium basket price.

Adding further interest, the solution returned an average of about 100ppm samarium, which is used to produce samarium-cobalt magnets, which are widely used in defence and aerospace.

‘Extraordinary results’

Managing director Andrew Reid called the latest results “quite extraordinary” while the similarities in the way the actual field mineralisation behaved compared to laboratory tests were also remarkable.

“The Ema field trial results display an incredible composition of the key magnet elements through the key light and heavy elements (40%) most widely used in rare earth end-products,” he added. 

“Remarkably the PLS solution also contains >5% samarium being the key foundation element in many military magnet applications, making it a truly unique rare earth assemblage.

“BCM has conclusively demonstrated the ability to leach high-tenor rare earth elements directly from the ground through very simplistic in-situ techniques, without the need for high CAPEX or complex processing equipment.

“The grades achieved and the timelines for leaching mirror very closely column tests completed by ANSTO (released in March 2025) and tests conducted over many months in laboratories in Brazil.”

ANSTO is Australia’s Nuclear Science and Technology Organisation, headquartered in Sydney.

“The pilot field trials have been a resounding success in every aspect,” Reid continued. 

“Every part of the leaching process from solution injection, rapidly permeating solution through the clays to leaching high-grade rare earths into solution is now without peer in the western world.”

Ema project overview in brief

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 company’s scoping study, it is expected to deliver net present value – a measure of profitability – of US$498m at the NdPr spot price of US$74/kg while Capex is estimated at a just US$55m with Opex of US$6.15/kg TREO.

The last makes it potentially the lowest-cost, near-term source of rare earth feedstock under current market conditions.

Reid said the company will now embark on further de-risking events by completing the bankable feasibility study, solidify offtake agreements and work with the regulators regarding the mine and environmental permits.

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.