Castillo Copper Ltd (ASX:CCZ, LSE:CCZ) has fielded encouraging initial test results on a composite sample from the Fence Gossan Prospect at Broken Hill that confirm rare earth elements (REEs) can be readily separated from clay and potentially beneficiated to a higher-grade concentrate.
Preliminary metallurgical test-work was carried out on a 20-metre composite sample from the prospect in East Zone discovery area of the BHA Project with clays subjected to froth flotation.
This work resulted in two to three times REE enrichment from the head grade being obtained at up to 70% recovery.
“Forward value-creating potential”
Castillo Copper’s chairman Ged Hall said: “On a holistic basis, the board is delighted with results from the drilling, surface sampling and metallurgical test-work at Broken Hill as they collectively demonstrate the forward value-creating potential of the BHA Project’s East Zone.
"In short, the underlying REE system is shallow, extends over at least 4.5 square kilometres, delivered results up to 3,491ppm TREO and produced up to 38.9% MREO in diamond core.
"Moreover, the metallurgy test-work proves REE mineralisation readily separates from clay and can potentially be beneficiated to a higher-grade concentrate.
“By all accounts, this is an excellent report card ahead of exploratory work ramping up.”
Specialist consultancy appointed
To follow up on these encouraging results, CCZ's board has approved the appointment of a specialist metallurgy consultancy with extensive experience in how REE mineralisation liberates from various host rocks, including clays.
This is expected to assist the company in its wish to gain a deeper understanding of the potential to extract REE mineralisation from the East Zone discovery area.
The board believes this information will be key to securing interest from potential off-take partners that can provide a clear path to market.
Reefs Tank re-assays
CCZ has also received 1-metre re-assays for all four drill holes from the Reefs Tank prospect and these further verified that there is an extensive, shallow REE system apparent across the central part of the BHA Project’s East Zone.
The best result from this work was 3 metres at 2,587ppm total rare earth oxides (TREO) from 14 metres.
Meanwhile, reconciling all assays from the recent drilling and auger campaigns across the Fence Gossan, Tors and Reefs Tanks prospects has enabled the company’s geology team to create heat maps which identify zones of high TREO and magnetic rare earth oxides (MREO).
These areas will no be subject to further surface sampling and geophysical campaigns, including trial transects of ground radiometric and EM surveys, then potentially drill-testing in a bid to extend known mineralisation.