Viridis’ best step-out drilling results could upgrade Colossus high-grade feed
Mining
Mining
Special Report: Viridis Mining & Minerals’ Colossus project is living up to its name after step-out drilling outside the existing resource delivered record results – of up to 9m at 6551ppm total rare earths oxide.
Located on the adjoining licence outside the Cupim South ionic clay-hosted deposit, step-out auger drilling has established a continuous large, high-grade zone with a footprint in excess of 4000 parts per million TREO.
Adding further interest, high-grade dysprosium and terbium mineralisation have been found in the new step-out areas from near surface.
These ‘heavies’ are, like light rare earths neodymium and praseodymium, used in permanent magnets for EVs and wind turbines. Unlike NdPr, however, production is virtually non-existent outside China, with Western OEMs and governments crying out for ex-China supplies.
Viridis Mining & Minerals (ASX:VMM) says the results redefine the initial high-grade mining feed potential for Colossus while establishing a pathway to develop a resource upgrade that can support a long life feed plan that sends ore grading over 4500ppm to a future process plant.
Notable auger drill results are:
Colossus currently has a global resource of 201Mt at 2590ppm TREO, while Cupim South has a resource 28Mt at 3061ppm TREO and one of the world’s largest concentrations of valuable magnet rare earth oxides: 857ppm neodymium and praseodymium.
This could grow very quickly with VMM noting the step-out auger results could “multi-fold” the current high-grade Colossus feeds and substantially improve the Cupim South resource.
It pointed out that the latest drilling at the Cupim South extension had the scope to substantially increase both the size and grade of the current interpolated high-grade feed at Colossus from the grade vs tonnage curve of 47Mt at 4000ppm TREO.
Meanwhile infill reverse circulation and diamond drilling at the Northern Concessions and Cupim South has outlined numerous higher-grade zones within the mining licences than previous block modelling had shown.
Notable examples include:
VMM noted that in some areas at the Northern Concessions, the infill drilling returned grades over twice that of the grade model’s, indicating significant scope for improvement to the current resource.
“Another outstanding set of results which reaffirm the remarkable resource we are dealing with at Colossus,” chief executive officer Rafael Moreno said.
“The very high-grade core being identified at our Cupim South Extension supports our development strategy to focus on the exceptionally high areas of TREO/MREO in our Northern Concessions and Cupim South Extension.
“With the RC infill drilling at our Northern Concessions revealing a significant improvement in grade and mineralisation depth compared to our existing resource block model, we are excited to showcase the enormous potential of our resource upgrade at the end of this year.
“The contiguous nature of both our Northern and Southern areas, plus high grades from surface, means both mine development and processing flowsheet are simplified and support a low-cost operation.
“The high levels of MREOs, in particular Dy/Tb, and industry-leading recoveries, all bode extremely well for project economics.”
Colossus has been one of the standout IAC projects operated by ASX juniors in Brazil thanks to its sizable resource and high MREO content.
IAC deposits are of course known for their potential to deliver low-cost, high-margin operations despite their lower grades compared to their hard rock counterparts, thanks to their shallow, free digging nature and are common in southern China.
While hard rock deposits are higher in grade, they require more intensive processing to liberate the metals from the ore. In IAC deposits, natural weathering has already done much of that work.
This ease of processing has been backed up by metallurgical testing conducted by ANSTO on a bulk composite sample, which returned world-leading recoveries of MREOs.
The standard ammonia sulphate (AMSUL) test at 0.5M, pH4, room temperature and a 30-minute leach cycle on the composite sample with a head grade of 4472ppm total rare earth oxides (with 32% MREOs) returned strong recoveries of 76% for NdPr and 65% for DyTb.
Adding interest, further work found that exceptional recoveries can be achieved at lower molar concentrations, higher pH and shorter residence times, all of which could reduce both the capital and operating costs of the project and provide great optionality on reagent selection.
VMM is continuing infill drilling and continuing the metallurgical testing with ANSTO.
The latter work will determine optimal conditions for key processing aspects of the flowsheet.
The company also expects to complete its scoping study in the coming months and continue with its critical permitting activities.
This article was developed in collaboration with Viridis Mining & Minerals, 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.
Notifications