Mr. Craig Taylor reports
DEFENSE METALS UPDATED BENEFICIATION RESULTS CONFIRM THE PRODUCTION OF A HIGH GRADE FLOTATION CONCENTRATE AT HIGH RECOVERY
Defense Metals Corp. has released the most recent results of the extensive comminution and beneficiation test work that has been conducted by SGS Canada Inc. in Lakefield, Ont., on variability samples from the Wicheeda rare earth deposit.
Craig Taylor, chief executive officer of Defense Metals, stated:
"Our recent results shows that the Wicheeda feedstock can be crushed, ground and floated to produce a rare earth flotation product with similar or better recoveries and grades to the top producers globally. Our project has many favourable conditions for success: mineralogy, metallurgy, infrastructure and community collaboration, further supporting a path to production."
A total of 90 open-circuit flotation tests, using one kilogram or two kg of feed, were conducted on 17 individual variability samples, various composites and blends. Considering all open-circuit flotation tests, at a feed grade of 3 per cent TREO (total rare earth oxides), the best fit line indicated 80-per-cent recovery to a 45 per cent TREO concentrate. Closed circuit operations, as practiced in flotation plants, can be expected to deliver higher recovery and grade.
- In addition to the smaller-scale tests, 29 bulk flotation tests using 10 kg or 12 kg charges were completed to both further optimize parameters and generate 16 kg of 46 per cent TREO content with a recovery of 78 per cent, for use as feed for hydrometallurgical tests.
- Very favourable results were obtained in a locked cycle test on a deposit composite giving a recovery rate of 85 per cent of the rare earths at a concentrate grade of 50.7 per cent TREO.
The beneficiation tests were aimed at confirming the reagent suite and operating parameters developed in earlier test work and in the 2020 flotation pilot plant operated on a 26-tonne bulk sample. The variability samples responded well to the flowsheet, and the selected reagent suite and operating regimes (temperature, density). Details of the test work are provided below.
SMC and bond comminution tests were completed on all variability samples. The recent work confirms, and significantly expands on, the data obtained during the 2020 pilot plant work.
- The data indicate that grinding energy will be relatively low, in particular in the upper portions of the deposit when the softer dolomitic carbonatite (DC) material, with a bond ball mill work index of nine kilowatt-hours per tonne (kWh/t), is the majority of the potential mill feed.
- Autogenous or semi-autogenous grinding system followed by a ball mill will be very satisfactory for the Wicheeda comminution plant.
John Goode, consulting metallurgist to the company, commented:
"SGS has performed a very thorough investigation of the comminution and beneficiation characteristics of a wide variety of samples from the Wicheeda deposit. The new results are close to those reported earlier and used in previous studies. Grinding energy requirements have been shown to be relatively low, and flotation recovery and concentrate grades are high and very favourable."
The three key rare-earth-bearing lithologies in the Wicheeda deposit are: (1) the higher-grade dolomite carbonatite (DC) which makes up 73 per cent of the deposit; (2) the xenolithic carbonatite (XE) that represents 24 per cent of the deposit; and (3) the syenite (SYN). Based on its near-surface location, the DC material is expected to comprise the majority of the mill feed, with the XE and SYN lithologies deeper in the deposit mined later. The primary rare earths minerals are monazite, bastnasite and synchysite/parisite.
The comminution and beneficiation tests were done at SGS by a team headed by Dr. Jing Liu, senior metallurgist. Test material comprised a 260 kg master composite and 17 variability samples, each nominally 36 kg, prepared from drill core and representing the three main lithologies in the Wicheeda deposit. The variability samples were selected to cover the three dominant lithologies, a range of grades (1.1 per cent to 4.5 per cent TREO), depths (seven metres to 221 metres downhole) and locations in the deposit (for additional results on different grades and lithologies, please see news release dated Oct. 11, 2022, and Feb. 14, 2023). Extensive mineralogy was completed on the samples and test products to better define the deposit and process results.
A total of 90 open-circuit flotation tests, using one kg or two kg of feed, were conducted on a DC composite, xenolithic and syenite composites, the individual variability samples, the master composite, and various other composites and blends. At a feed grade of 3 per cent, the best fit line indicates 80-per-cent recovery to a 45 per cent TREO concentrate. Closed-circuit operations, as in a flotation plant, would deliver higher recovery and grade. The lower-grade XE and SYN material that are expected to be encountered late in potential mine life delivered somewhat lower concentrate grades and recoveries.
Three locked-cycle tests were completed, with LCT-3 operated on 12 kg batches of a new master composite made up from all variability samples, blended according to the lithology distribution. The flowsheet was operated over seven cycles and showed good stability. The feed grade to LCT-3 was 2.9 per cent TREO and the concentrate assayed 50.7 per cent TREO with a recovery of 85.4 per cent.
Comminution test work was completed by SGS using standard bond comminution tests and the SMC test, which measures the competence of primary grinding mill feed. The SMC results were provided to JKTech for interpretation. The bond ball mill work indices were nine, 11 and 13 kWh/t for the DC, XE and SYN samples, respectively. The SMC report categorized the DC samples as being very soft and the XE samples as medium.
The scientific and technical information contained in this news release, as it relates to the Wicheeda rare earth element project, has been reviewed and approved by Mr. Goode, PEng, and Kris Raffle, PGeo, a director of the company, both of whom are qualified persons as defined by National Instrument 43-101. Mr. Goode provided the technical information relating to metallurgy in this news release.
About the Wicheeda rare earth element project
Defense Metals' 100-per-cent-owned, 6,759-hectare (approximately 16,702-acre) Wicheeda project is located approximately 80 kilometres northeast of the city of Prince George, B.C. (population 77,000). The Wicheeda deposit is readily accessible by all-weather gravel roads and is near infrastructure, including hydropower transmission lines and gas pipelines. The nearby Canadian National Railway and major highways allow easy access to the deep-water port facilities at Prince Rupert, the closest major North American port to Asia.
Defense Metals Corp.
Defense Metals is a mineral exploration and development company focused on the development of its 100-per-cent-owned Wicheeda rare earth element project located near Prince George, B.C., Canada.
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