West Cobar has hit a key milestone for its Salazar clay-hosted REE project after metallurgical testing returned excellent recoveries of valuable magnet rare earths.

The test work by the Australian Nuclear Science and Technology Organisation (ANSTO) recovered up to 94% magnet rare earth oxides (MREO) from samples sourced from the Newmont deposit using a hydrochloric acid pathway, a result that managing director Matt Szwedzicki was “thrilled” at receiving.

Additionally, testing using an eight hour liquor test achieved 68% to 78% MREO recovery while the three hour liquor test returned 61% to 76% MREO recovery.

To top it off, West Cobar Metals (ASX:WC1) was able to upgrade the REE grades by up to 151%, or to an average grade of 3,149 parts per million (ppm) total rare earth oxides (TREO), using simple screening.

Szwedzicki said that simple screening proved that the Newmont clays are amenable to significant beneficiation which will improve the front-end economics and reduce the downstream processing and capital costs.

“With phase 1 testing now complete, we are confident that we can reduce the acid strength and our focus will be to further optimise the leaching performance, undertake more variability studies and further develop the process flowsheet of the Newmont deposit,” he added.

ANSTO testwork

The testwork by ANSTO was carried out on eight samples selected from the Newmont deposit to test for head assays, screening, and leach testing.

These are made up of rare earth enriched saprolitic clays that have been selected from both an amphibolite basement and granitic gneiss basement.

Each sample underwent a series of screening tests to determine the TREO grade and mass deportment with size as well as wet and dry screened to test for potential low cost beneficiation upgrades.

The program was designed to determine the baseline leachability of the rare earth element mineralogy from the Newmont samples, under various acidic conditions and assess the potential to upgrade the TREO by sizing, supplemented by associated leach data.

While testing using hydrochloric acid delivered the best results, lower acid concentrations using 25g acid per litre and 12.5g/l liquor also demonstrated strong results.

Notably, the ability of the 12.5g/l liquor to recover up to 78% MREO over 24 hours is an indication that further optimisation and reduction in acid strength is achievable.

West Cobar also noted that the best recoveries came from the lower saprolite samples within the saprolitic clays in samples SAC 21, SAC362, whereas for SAC 384 and SAC 394, the upper saprolitic samples performed better.

Salazar REE project

Salazar is located about 150km northeast of Esperance, Western Australia, and contains the Newmont deposit that already hosts an Inferred Resource of 43.5Mt grading 1,192ppm TREO.

Aircore drilling has defined consistent zones of mineralisation up to 34m thick with the mineralised saprolite overlain by 4m to 16m of transported alluvium including some black sand beds, and barren saprolite.

The mineralised saprolite is divided into an upper zone consisting almost entirely of clay and a lower zone containing loose resistate minerals such as quartz, felspar, and mica in clay.

Some deeper drilling carried out by previous explorers has indicated that bedrock REE mineralisation is controlled by shear zones near the amphibolite/ granitic contacts.

There is also a tendency for the best rare earth grades to be concentrated around the contact between the upper and lower saprolite.

More testwork

The success of the Phase 1 each test work and kinetic outcomes has led to the company starting a second phase of work at ANSTO.

West Cobar will carry out more diagnostic tests to further define optimum leach conditions.

This includes a series of contingency leach tests – including the use of lower acid concentrations, increased residence time and leachability on fine fractions – to infill data and knowledge arising from the Phase 1 leach tests.

In addition, front-end beneficiation trials are continuing at mineral processing company Nagrom’s Perth facilities and at the ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals.




This article was developed in collaboration with West Cobar Metals, a Stockhead advertiser at the time of publishing.


This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.