Mount Ridley Mines Limited has lifted scandium recovery to 91.8% and heavy rare earth element recoveries to an average of 84.0% using half the reagent dose in the latest testwork for its proprietary Selectro™ Process.

The laboratory-scale leach test, designated Test 3, was conducted on an unbeneficiated sample composite from the Grass Patch Project in Western Australia without prior process optimisation. The results surpass the previous round of testing, where scandium recovery reached 80.0% and heavy rare earths averaged 78.5% using a baseline reagent volume. Light rare earth recoveries also improved, averaging approximately 77% compared to 72.5% previously.

The Selectro™ technology is a closed-loop leach process designed to operate at low temperature and ambient pressure. By adjusting the composition of the leaching molecule, the processing team tuned the chemistry in Test 3 specifically to improve scandium extraction. Gallium recovery moderated to 41.5% from 55.8% under the reduced reagent concentration, a shift the company expects to address through upcoming beneficiation and optimisation steps.

Mount Ridley lodged a provisional patent application for the proprietary leach technology in August 2026 through subsidiary Mount Ridley Tech Pty Ltd. The metallurgical program follows a $2.0 million placement secured in September 2026 to fund technical and development activities at Grass Patch, including ongoing Selectro™ optimisation.

The company is currently undertaking flotation testwork on Grass Patch material to inform a beneficiation pathway ahead of a larger-scale bulk sample testing program.

“Our wholly-owned and patent-pending Selectro™ process results continue to impress, with scandium recovery increasing to 91.8% and REE recoveries improving across the board, HREE averaging 84% and up to 86%. Importantly, these improvements were achieved while halving the reagent dose used in the previously reported Selectro Tests, indicating the potential for further cost benefits, over and above the current closed loop system design,” said Managing Director & CEO Mr Allister Caird.

“We haven't yet established where the reagent concentration breaks for the process, providing further opportunity to optimise the reagent dose and recovery of targeted individual minerals.”

Read the full announcement: Selectro Delivers Best Scandium and REE Recoveries to Date