Mount Ridley Mines leach tech doubles critical mineral recoveries

Mount Ridley’s proprietary Selectro leach process has more than doubled recoveries of rare earth elements compared to conventional leaching. Credit: File

Mount Ridley Mines (ASX: MRD) appears to have delivered a metallurgical knockout punch with its in-house developed leach technology achieving recoveries for a suite of critical minerals that more than double those of the industry-standard hydrochloric acid leach (HCL) process.

In what could be a pivotal moment for the company its proprietary Selectro process has returned exceptional results from historical drill samples at its Grass Patch rare earths project near Esperance in Western Australia.

Notably, Mount Ridley's Selectro leach process recovered an average of 56 per cent of gallium while the conventional HCL process recovered zero. The results could be a potential game-changer given that China recently slapped export controls on gallium, a critical component in semiconductors and defence applications, putting global supply chains under serious pressure.

The test work also achieved outstanding heavy rare earth element (HRE) recoveries of between 77 and 83 per cent for sought-after magnet metals including terbium, yttrium and dysprosium. The conventional HCL process only recovered between zero and 51 per cent of the same elements. Light rare earth element (LREE) recoveries for neodymium and praseodymium also hit an eye catching 70 to 77 per cent.

Rounding out the trifecta of results, scandium recovery hit a massive 80 per cent - a figure that dwarfs the 25 per cent achieved using the standard HCL method. The company says this is a pivotal result for what is considered by many as one of the largest scandium resources globally.

The sheer scale of Mount Ridley’s resources at Grass Patch lend significant weight to the outstanding processing results. The project hosts a JORC-inferred resource of 838.7 million tonnes at 29.3 parts per million (ppm) gallium, and one of the world’s largest scandium resources at 367.98 million tonnes at 57.3 ppm scandium.

Importantly, Mount Ridley says all three critical mineral streams HREEs, scandium and gallium can be recovered through a single proprietary leach circuit. The company says the Selectro process is designed as a closed-loop system which could deliver much lower reagent costs and a cleaner environmental profile than more commonly used hydrometallurgical approaches.

Perhaps most impressively is, that all results were achieved on unbeneficiated ore before any process optimisation. This suggests that there looks to be plenty of blue sky to further improve the Selectro process's performance and push on with its future commercial development.

These are the first metallurgical testwork results the Company has produced since the definition of our HREE, scandium and gallium mineral resources and the establishment of the current management team and corporate strategy. The Selectro Process results validate what we believed to be true about Grass Patch, that we have a genuinely polymetallic system where all three critical minerals can be recovered from a single leach process.   Mount Ridley Mines Managing Director and CEO Allister Caird

The exceptional results come just weeks after the company's new hire Chris Larder was appointed as chief technology officer to head processing and metallurgy, signalling a strategic shift from boots on the ground resource definition to more hi tech processing and development.

The breakthrough arrives hot on the heels of Mount Ridley's recent listing on the OTC market in the United States, a move the company says is designed so it can more readily engage with US institutional and strategic investors. With HREEs, scandium and gallium all designated as critical minerals by the US Government the timing of the metallurgical success couldn't be better.

Finding a large mineral resource is one thing but economically extracting the metals is the real key to unlocking value particularly in clay-hosted deposits such as Grass Patch. With its proprietary Selectro process Mount Ridley might potentially be on the path to becoming a multi-commodity critical minerals producer. The company will now test the process on a bulk sample from Grass Patch, evaluate its performance on beneficiated feed and assess its potential for licensing to third parties.

With a potential processing solution in hand for three separate critical mineral streams, punters will likely be watching Mount Ridley as it looks to turn this new metallurgical breakthrough into a commercial money spinner.

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