Project manager Darren Smith onsite in northern Quebec.
A simplified flowsheet has reduced the number of steps to process rare earths from Commerce Resources’ (TSXV:CCE) Ashram deposit in Quebec. Announced February 9, the results point to lowered costs while maintaining efficiency. Metallurgical tests continue to advance the project towards pre-feasibility.
Last year’s pilot plant tests used a double-leach process that achieved over 99% stage recovery with complete carbonate removal. But the results also suggested the process could be simplified by using only a single leach. That’s now been confirmed, as the single-leach mini-pilot plant achieved similar efficiency with fewer stages while operating at a larger scale.
“For the single-leach pilot, both batch and continuous methods were tested, using flotation concentrate produced from piloting as feed, with a total throughput of approximately 50 kilograms and 11 kilograms respectively,” the company stated. “Stage recovery exceeded 98% for both methods and is expected to exceed 99% after a minor operational adjustment is incorporated.”
Leach residues went through magnetic separation to confirm the residue quality, producing high-grade mineral concentrates. The batch method produced 41% total rare earth oxides at 71% recovery, while the continuous method reached 43% TREO at 71% recovery. Tests also indicated overall recoveries might surpass those of the double-leach process. Follow-up tests will further evaluate that finding.
“The validation of the single-leach process at the pilot scale is an advancement that allows for basic cost reductions as fewer process steps are now required, and fewer reagents are now consumed, while process efficiency is maintained,” commented president Chris Grove.
Ashram’s flowsheet includes three stages of processing “to produce among the highest-grade mineral concentrates in the rare earth development space,”Commerce stated. The company intends to follow last year’s work on the flotation and HCl leach stages with a magnetic separation pilot plant and further downstream processing this year.
Pre-feas work has also included infill drilling for a resource update, with high-grade, near-surface assays. A new infrastructure model, meanwhile, points to further potential cost reductions. In October Commerce won an award for responsible exploration from l’Association de l’exploration minière du Québec. Last month the company closed the second tranche of a private placement that totalled $1.97 million.
Commerce also holds the Blue River tantalum-niobium deposit in southeastern British Columbia, with a 2011 preliminary economic assessment.