Mount Ridley Mines Ltd (ASX:MRD) has confirmed that rare earth elements at its Grass Patch Project in Western Australia are hosted predominantly in discrete phosphate minerals, supporting flotation as a potential method to concentrate mineralisation before leaching.
The findings came from the company’s first TESCAN Integrated Mineral Analyzer (TIMA) study on material from Grass Patch, about 25 kilometres north of Esperance. The study identified xenotime, crandallite-group phosphates and monazite/rhabdophane as the principal rare earth-bearing minerals.
Results point to flotation pathway
Mount Ridley said the mineralogy results represented an important step in defining a processing flowsheet for the project.
The phosphate minerals were fine-grained and closely associated with clay in the shallow, weathered regolith profile. Xenotime, which can host valuable heavy rare earth elements, was the most common of the 3 phosphate minerals identified.
Because the rare earths occur in discrete minerals rather than being solely adsorbed onto clay surfaces, the company believes they may be amenable to physical concentration before leaching.
A flotation stage could potentially produce a smaller, higher-grade concentrate, reducing the volume of material entering the extraction process. However, further testwork is required to establish achievable recoveries and concentrate grades.
Mount Ridley managing director and CEO Allister Caird said the findings provided a basis for the company to investigate a beneficiation pathway used at comparable regolith-hosted heavy rare earth deposits.
“The TIMA results inform us exactly how the rare earths sit in our deposit,” Caird said.
“We’re excited about the prospect of flotation to concentrate our ore and results from that work will dovetail into the outcomes from our Phase 1 metallurgical testwork.”
Testwork to assess grades and recoveries
Mount Ridley will advance bench-scale flotation testing across a range of grind sizes as part of its broader metallurgical program.
The work will assess potential concentrate grades and recoveries and help determine whether flotation should form part of the project’s beneficiation flowsheet.
The TIMA analysis was conducted on 1 composite sample prepared from material sourced from 5 previously drilled diamond holes. The company noted that the results related only to the tested material and did not include new drilling results, grades or intercepts.
Grass Patch Project
Grass Patch is Mount Ridley’s flagship project and hosts defined heavy rare earth, scandium and gallium resources identified through about 70,000 metres of historical drilling.
Much of the tenure is centred on the Grass Patch Complex, which is interpreted as the primary source of rare earth enrichment across the project area.
Mount Ridley said the project remained underexplored, with several priority targets identified from historical drilling, geophysics and technical reviews for potential future drilling.
About Mount Ridley Mines
Mount Ridley Mines is an Australian critical minerals explorer focused on heavy rare earth elements, gallium and scandium at its wholly owned Mount Ridley and Weld Range projects in Western Australia.
The company is also assessing longer-term downstream processing and separation opportunities aimed at supplying critical minerals into allied markets.