Mount Ridley metallurgy breakthrough lifts rare earth outlook

A review by Mount Ridley Mines of historical metallurgical test work on its Grass Patch project near Esperance in WA has confirmed an outstanding leach response, with heavy rare earths recoveries as high as 86.5 per cent.

The punch results were achieved under conventional hydrochloric acid leach conditions, providing a clear green light for further investigation.

The metallurgical magic wasn’t just limited to leaching. Initial screen beneficiation test work also delivered the goods. At the company’s Vincent prospect, standout results delivered an eye-popping 200 per cent total rare earth oxide (TREO) upgrade. Additionally, its Mia and Jody prospects provided an excellent upgrade average of 164 per cent.

Magnetic rare earths potential is also looking extremely healthy, with recoveries of neodymium and praseodymium hitting a substantial 85.2 per cent.

The findings have given Mount Ridley confidence it can significantly beef up the feed grade before it even hits the leach tanks, simply by screening out the barren material. This may offer a major bottom-line saving for the company.

Mount Ridley’s consistent, hefty extraction results of heavy rare earths such as dysprosium and terbium, specifically at the Winston, Vincent, and Jody prospects, have highlighted a major project advantage. The company attributes this superior metallurgical performance to the project’s mafic-dominated geology.

This unique geology ensures the mineralisation is compatible with standard hydrometallurgical processing, providing a potentially significant cost-competitive edge in the sector.

These historical metallurgical results clearly show a strong heavy rare earth response across the Grass Patch Complex.

Interestingly, Mount Ridley has discovered that the more valuable heavy rare earth elements leach more effectively than their light rare earth cousins. This unique characteristic sets the project apart from typical regolith-hosted systems.

This metallurgical breakthrough follows closely on the heels of an outstanding milestone in late March, when Mount Ridley unveiled a new inferred resource, which weighed in at an impressive 122.56 million tonnes grading 889 parts per million (ppm) TREO, hosting 108,954 tonnes of contained TREO. Notably, 44,610 tonnes of that sits in the heavy rare earth (HREO) basket, giving the resource a head-turning 41 per cent HREO ratio.

With the global supply of heavy rare earths largely dominated by China, Mount Ridley looks to be positioning itself as a vital player in the emerging Australian and allied strategic metals supply chain.

The company is now looking to supercharge the project’s economics using the test results as a strong technical foundation for ongoing metallurgical optimisation and flowsheet development. Notably, this may also include investigating the recovery of scandium and gallium as valuable by-products.

The company is steadily moving ahead as it transitions into the next phase of metallurgical optimisation. With high recoveries and a clear development path, the momentum is firmly running in Mount Ridley’s direction.

For now, the new findings from old samples appear to be a great result for the company and show that sometimes the most valuable secrets might be unearthed from the data you already have.

Is your ASX-listed company doing something interesting? Contact: matt.birney@wanews.com.au