Ms. Luisa Moreno reports
DEFENSE METALS ACID-BAKE PROCESS YIELDS IMPROVED RARE EARTH ELEMENT RECOVERIES AT WICHEEDA
Defense Metals Corp. has released the initial results of alternative acid bake process testwork under way at SGS Lakefield on Wicheeda rare earth element (REE) project mineralized feed. The initial testwork shows that adoption of the acid bake process results in improved REE extraction, and potentially improvements in capital and operating costs.
The previous hydrometallurgical flow sheet that was included in the PEA (preliminary economic assessment
(1)) was based on a more costly and complex gangue-leach, caustic-crack process. Upon joining the team, Defense Metals' lead metallurgical consultant, John Goode, PEng, recommended investigation of the acid bake process for the Wicheeda ore, and the preliminary results show that the acid bake process is more efficient, yielding greater-than-95-per-cent recovery of neodymium and praseodymium from flotation concentrate into a leach solution.
This hydrometallurgy program that started in December, which includes pilot plant operations, will be concluded in the last quarter of 2022. It will provide data to allow detailed design and capital and operating cost calculations. Updates on the testwork will be provided periodically as results become available.
Luisa Moreno, president of Defense Metals, commented, "We are delighted that the acid bake process has yielded higher recoveries of rare earths, and offers the potential to significantly reduce operating and capital costs, thus improving project economics and further establishing Wicheeda as a potential near-term source of rare earths."
(1) Independent preliminary economic assessment for the Wicheeda rare earth element project, British Columbia, Canada, dated Jan. 6, 2022, with an effective date of Nov. 7, 2021, and prepared by SRK Consulting (Canada) Inc., is filed under Defense Metals' issuer profile on SEDAR.
Testing of the acid bake process started in late 2021, with over 20 tests on several concentrate samples completed to investigate the impact of bake conditions, including acid addition, concentrate grade and bake temperature.
Tests continue to show that the sulphuric acid bake approach is highly effective. Across all tests, including those under suboptimal conditions, the neodymium/praseodymium extraction is 94 per cent with better test results showing 97- to 99-per-cent extraction.
Short-duration acid bake pilot operations using the SGS Lakefield 165-millimetre-diameter kiln are continuing.
Pregnant leach solution from the static acid bake tests is now being tested for impurity removal and the precipitation of a refined rare earth product suitable for sale.
Details of the acid bake/water leach (AB/WL) process
In the AB/WL process, Wicheeda's mineral concentrate will be treated with concentrated sulphuric acid at high temperatures (200 C to 600 C) converting the rare earths in the minerals to water-soluble sulphates, which readily dissolve during the subsequent water leach. The leachate is then purified and the rare earth elements recovered by a simple precipitation process. This process requires less equipment, and involves fewer steps and circuits. Importantly, this flow sheet is the same as that used by Lynas at its Kuantan REE production facility and by Baogang at the Bayan Obo REE recovery plants (using a bastnasite and monazite ore). Most of the world's REE is produced by the acid bake process.
About the Wicheeda REE property
The 100-per-cent-owned 2,008-hectare Wicheeda rare earth project, located approximately 80 kilometres northeast of the city of Prince George, B.C., is readily accessible by all-weather gravel roads and is near infrastructure, including power transmission lines, the CN railway and major highways.
The Wicheeda rare earth project yielded a robust 2021 PEA that demonstrated an after-tax net present value (discounted at 8 per cent) of $517-million and an 18-per-cent IRR (internal rate of return). A unique advantage of the Wicheeda rare earth project is its ability to produce a saleable high-grade flotation concentrate. The PEA contemplates a 1.8-million-tonne-per-year mill throughput open-pit mining operation with 1.75 to 1 (waste to mill feed) strip ratio over a 19-year mine (project) life, producing an average of 25,423 tonnes rare earth oxides annually. A phase 1 initial pit strip ratio of 0.63 to 1 (waste to mill feed) would yield rapid access to higher-grade surface mineralization in year one and payback of $440-million initial capital within five years. The acid bake process is expected to improve upon the 2021 PEA economics.
The scientific and technical information contained in this news release as it relates to the Wicheeda rare earth project has been reviewed and approved by John Goode, PEng, who is a qualified person as defined by National Instrument 43-101 and has provided the technical information relating to metallurgy in this news release.
About Defense Metals Corp.
Defense Metals is a mineral exploration and development company focused on the acquisition, exploration and development of mineral deposits containing metals and elements commonly used in the electric power market, defence industry, national security sector and the production of green energy technologies, such as rare earth magnets used in wind turbines and in permanent magnet motors for electric vehicles. Defense Metals owns 100 per cent of the Wicheeda rare earth project located near Prince George, B.C., Canada. Defense Metals trades in Canada under the symbol DEFN on the TSX Venture Exchange, in the United States under DFMTF on the OTCQB and in Germany on the Frankfurt Exchange under 35D.
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