Mount Ridley Mines (ASX:MRD) says automated mineralogy has confirmed rare earth elements (REEs) at its Grass Patch Project are hosted almost entirely in discrete phosphate minerals, supporting further investigation of flotation ahead of leaching.
The study, completed by AXT using TESCAN Integrated Mineral Analyser (TIMA) technology, examined a composite prepared from five diamond holes across the project, 25km north of Esperance in Western Australia.
According to Mount Ridley, the analysis identified xenotime, crandallite group phosphates, and monazite/rhabdophane within the shallow, weathered regolith. The company says xenotime, which can host heavy rare earths, was the most common of the three minerals.
The study found the phosphate minerals were fine-grained and closely associated with clay. The sample comprised predominantly clay, with smaller amounts of pyrite and quartz.
Mount Ridley says the mineralisation differs from ionic clay deposits, where rare earths are loosely adsorbed onto clay surfaces and may be recoverable through salt leaching. At Grass Patch, the company says the rare earths occur within distinct minerals.
Based on these findings, Mount Ridley believes flotation could concentrate the minerals into a smaller, higher-grade product before leaching. However, test work is required to determine achievable concentrate grades and recoveries.
Managing Director Allister Caird says the results provide a basis for assessing a beneficiation pathway used by companies exploring comparable regolith-hosted heavy rare earth deposits.
“The TIMA results inform us exactly how the rare earths sit in our deposit. Some of our peers have had outstanding results applying flotation to comparable regolith hosted HREE deposits and these results provide a basis for MRD to investigate a similar beneficiation pathway,” Caird says.
Mount Ridley says it will fast-track bench-scale liberation and flotation test work across a range of grind sizes. The work will run alongside its broader Phase one metallurgical test work program.
Grass Patch hosts an inferred mineral resource estimate of 122.5 million tonnes at 889 parts per million total rare earth oxide, containing 108,954 tonnes of rare earth oxide.
Write to France Pinzon at Mining.com.au
Images: Mount Ridley Mines
