Ucore Rare Metals has completed further bulk scale ore beneficiation testing on material from the Bokan – Dotson Ridge rare earth deposit on Prince of Wales Island in Alaska, USA. A 20 t sample, collected from three locations within the Dotson Ridge deposit, was sent to TOMRA of Wedel, Germany and processed by a large scale x-ray transmission (XRT) ore sorter. Results show that 52% of the feed was rejected as waste, with 96.3% recovery of rare earth oxides (REO), and a net increase in grade from a 0.77 wt % REO feed to a 1.56 wt % output.
The group said current testing “improves upon the results of previous ore sorting analysis on bulk samples of lesser size.” In an announcement dated March 6, 2012, Ucore released the results of XRT sorting on three 1 t samples collected from trenches situated at separate locations within Dotson Ridge deposit. The 2012 work, also carried out by TOMRA, resulted in 46% rejection of waste and 93% recovery of REO, so the more representative 2013 work shows a significantly improved output grade and REO recovery.
Ucore states: “These tests confirm the effectiveness of XRT at successively larger ore throughput volumes. The results also support Ucore’s plan to construct a significantly smaller mill facility than would otherwise be required in the absence of an XRT sorting circuit at Bokan. The reduction in mill size will have a significant effect on the lowering of capital and operating costs associated with the mill facility, as set out in the Preliminary Economic Assessment (PEA) released on January 15, 2013. At present, a 30 t bulk sample collected from Dotson Ridge in December 2012 is being prepared for XRT sorting. The output of that sorting process, scheduled to take place within the next four weeks, will generate the final feed stock required by Ucore to conduct a comprehensive pilot plant for the Bokan – Dotson Ridge project.”
The pilot plant, scheduled for Q4 2013, is the final stage of bulk scale testing of the production circuit prior to the release of a Bankable Feasibility Study and the prospective commencement of mine construction. “The confirmation of XRT effectiveness at large scale is an important milestone in Ucore’s march to mine construction”, said Jim McKenzie, President & CEO of Ucore. “The company is the first in the rare earth industry to demonstrate XRT as a beneficiation technique; a technology already well-established in the tungsten and diamond mining sector. XRT shows the clear potential to dramatically reduce the volume of material feeding the mill facility and an equally dramatic increase in TREO ore grade without a great deal of processing. The current results justify the plan set out in Ucore’s recently released PEA. The addition of an XRT circuit prospectively reduces capital and operating costs, with a smaller processing footprint than is the norm for REE facilities, and with no tailings facility at surface upon mine closure. A zero tailings footprint is a unique environmental objective, and we are aware of no other mine, rare earth or otherwise, that has accomplished such a design feature.”