Viridis demo plant delivers rare earths recovery boost in Brazil

Viridis Mining and Minerals has chalked up another development win at its Colossus rare earths project in Brazil, with its demonstration plant beating key prefeasibility (PFS) recovery assumptions during continuous production of mixed rare earth carbonate (MREC).

The company says July recoveries from the plant averaged 78.8 per cent for magnet rare earth oxides (MREO) and 64 per cent for total rare earth oxides (TREO), compared with PFS assumptions of 76 per cent and 57 per cent respectively. It says MREO recoveries also exceeded 80 per cent during the month.

The results matter because the key magnet rare earth elements - neodymium, praseodymium, dysprosium and terbium - are typically the higher-value part of the rare earths basket and are central to the manufacture of permanent magnets used in electric vehicles, wind turbines, defence and high-tech applications.

The enhanced recovery results also highlight the potential for significant improvements to project economics as they are incorporated into the definitive feasibility study (DFS). With optimisation work still underway, management says it sees potential for further recovery gains before the DFS and financial model are finalised next month.

Viridis says the plant has been running reliably on a 24-hour, fully automated basis since May, using integrated water and reagent recycle circuits and an on-site laboratory to fine-tune ore-feed blends, pH ranges and other key processes that influence recoveries.

The company has been feeding the demonstration plant with run-of-mine ore from its Northern Concessions, the same area expected to underpin the first 18 to 24 months of commercial operations. That ore source gives Viridis a live set of recovery data it can feed straight into its economic modelling.

The latest update follows a busy run for the company. Earlier this month, Viridis upgraded its Colossus resource to 473 million tonnes grading 2505 parts per million (ppm) TREO and 592ppm MREO, including a measured resource of 31Mt grading 2858ppm TREO and 758ppm MREO.

The company said the new measured resource inventory is expected to support conversion of its early mine schedule into proven reserves as part of the DFS, satisfying a key technical requirement for project debt financing.

The Demonstration Plant continues to exceed our expectations and marks another important milestone in the development of the Colossus Project. Successfully operating under continuous 24-hour automated conditions is a significant achievement in itself, however the most vital outcome is that we are consistently achieving metallurgical recoveries above those assumed in our PFS.

In June, the company also locked in a fixed-price power transmission package to connect Colossus to Brazil’s electricity grid, securing an initial 27-megawatt allocation for phase-one operations from December 2027 and a 90-megawatt transmission-line design capacity to support future expansion.

Viridis says the demonstration plant has also helped validate key commercial-scale equipment and circuits, including counter-current decantation (CCD), product and residue filtration, water treatment, zero-liquid-discharge design and ammonium sulphate reagent recovery.

CCD is a continuous washing process used in mining and chemical processing to separate and recover dissolved valuable metals from solid ore residues. It uses a series of thickener tanks in which solid slurry and wash liquid move in opposite directions.

As the cleaner wash water moves through the circuit, it captures remaining dissolved metals from the solids, producing a concentrated metal-rich liquid at one end and cleaner waste solids at the other. The advantage is that CCD can separate liquids and solids using gravity and sedimentation, reducing reliance on more expensive mechanical filtration.

The company is also continuing its product qualification work with strategic offtake partner Solvay. High-grade MREC samples have now been shipped to Solvay’s La Rochelle processing facility in France for testing.

With demonstration plant recoveries tracking above the current numbers in the PFS, a world-scale resource underpinning the mine plan and power infrastructure moving into the delivery phase, Viridis is steadily lining up the critical pieces as it edges towards a final investment decision.

If the upcoming DFS can bottle these latest demo-plant results, the market may soon get a clear look at just how much extra spark sits within Viridis’ aptly named Colossus rare earths play.

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