West Cobar Metals reports ‘excellent’ recoveries from testing of Salazar rare earth samples

Junior explorer West Cobar Metals (ASX: WC1) has reported the achievement of “excellent” rare earth recoveries from a metallurgical program using samples from the Salazar clay rare earth element project near Esperance in Western Australia.

The program was conducted with Australian Nuclear Science and Technology Organisation (ANSTO) to determine the baseline leachability of rare earth mineralogy at Salazar under various acidic conditions.

It used eight samples from the Newmont deposit comprised of rare earth-enriched saprolitic clays selected from an amphibolite (mafic/ultramafic) basement and a granitic gneiss basement.

The samples underwent a series of wet and dry screening tests to determine total rare earth oxide (TREO) content and mass deportment with size, as well as the potential for low-cost beneficiation upgrades.

The Newmont deposit contains an inferred resource of 43.5 million tonnes of 1192ppm TREO at a 500ppm cut-off.

Leach tests

A total of 63 leach tests were performed under several acidic conditions to define upper and lower rare earth recovery limits, with recoveries calculated at regular intervals.

Recoveries of up to 94% magnet rare earth oxide (MREO) were achieved using a hydrochloric acid pathway.

An average of 68% to 78% MREO recovery was achieved from seven of the samples following an eight hour liquor test, while an average of 61% to 76% MREO recovery was achieved after three hours.

The remaining sample did not perform as well kinetically, and was reported to be a result of locally-intense kaolinisation during weathering which removed the more acid soluble rare earth element compounds, leaving only a relatively large refractory component.

Simple screening delivered up to 151% upgrade of rare earth grades, with the average TREO grade across the eight samples averaging 3149 parts per million at less than 38 micrometres.

Further reductions

Managing director Matt Szwedzicki said the impressive leaching kinetics indicated that further reductions in acid strength could be achieved.

“Simple screening tests have shown the clays are amenable to significant beneficiation which will improve the front-end economics [of Salazar] and reduce our downstream processing and capital costs,” he said.

“With Phase 1 testing now complete, we are confident 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.”