Studies suggest a cost effective domestic rare earth supply in the United States
US Rare Earths, Inc. (OTCQB: UREE) reported in February 2015 on its promising development of low-cost metallurgical processes for the domestic production of rare earths from its Last Chance Mine is located in the Lemhi Pass Area of Idaho and Montana, which holds one of the longest identified mineralized veins in the region.
A fundamental aspect of the Company’s business approach, which is supported by independent data, is that the unique mineralogy of the Last Chance Mine provides multiple avenues for novel process development with a potential for a very significant reduction in the costs and expenses related to acid consumption in comparison to other deposit processing methods. Rare earth acid leaching typically adds a significant contribution to the process operating costs.
Test work by the Idaho Geologic Survey (IGS) addressed the separation of enriched monazite from the gangue minerals at the laboratory scale level with methods appropriate for scaled up evaluation of the unique mineralogical conditions to western MT & Eastern ID, commonly known as the Lemhi Pass Region.
During the last several quarters, the Company has pursued advanced exploration of the Last Chance Mine project, where to date over two short tons of material have already been removed, (from the mine-stockpile) and sampled for advancing metallurgical test work by arm’s length parties.
Rare Earth mineralogy test work and assays conducted by Hazen Research suggest that the main high-value rare earth minerals (dark-monazite and xenotime) are enriched in Europium and disassociated from the other gangue minerals.
More particularly work on a 1,5 ton bulk sample by Hazen Research yielded Europium content at 5.25% of total rare earth, which is consistent with the currently understood deposit grade ratios.
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The initial liberation and magnetic separation tests indicate that the cost of grinding (comminution) has the potential to be greatly reduced. These tests indicate that less than 0.1% of total rare earths plus Yttrium are contained in size fractions greater than +14 mesh and that grinding to fractions less than 14 mesh may not be required for beneficiation. Mesh gives a rough estimate of particle size where 14 mesh is approximately .055 inches is related to particle size.
Initial result of magnetic separation work allows us to process only 38% of the bulk weight that has approximately double the “as mined” rare earth concentration. Downstream leaching acid consumption and processing costs will be greatly reduced from this result.
Magnetic separation was able to reject 62% of the bulk sample as waste rock with a recovery of the following assayed rare earths, based on feed to testing, La-94.1%, Ce-94.1%, Nd-93.8%, Pr-93.8%, Sm-88.2%, Eu-92.8%, Gd-91.6% and Y-93.1% in 38% of the feed. The heavy rare earth fractions were not assayed at Hazen research during these initial test sequences.
Bulk sampled material (-6 mesh) that was subjected to a series of tests that included an extensive mineral liberation and grinding study, and various types of magnetic separations conducted by Hazen Research, which included both wet magnetic and induced roll magnetic separations.
The magnetic separation work provide a higher (~2 times) concentrate of rare earth minerals for further physical beneficiation and hydrometallurgical work with the reduced ore processing of only 38% of the material and above 92% recovery.
Hazen Research conducted results from multiple leaching tests independently and SGS Mineral Services Canada yielded recoveries of 79-78% for the light to heavy rare earth fractions and demonstrated the technical feasibility of higher recoveries.
Together these results are promising, and offer to potential to provide a cost effective domestic rare earths supply in the United States. Over the next months, the editorial board of InvestorIntel will monitor the Company’s progress to report to investors.
Dr. Luc C. Duchesne is a Speaker and Author with a PhD in Biochemistry. With three decades of scientific and business experience, he has published ... <Read more about Dr. Luc Duchesne>