Bradda Head Lithium Ltd, the North America-focused lithium development group, has announced positive metallurgical heavy liquid separation (HLS) results from test work undertaken by the SGS Metallurgical Process Facility in Lakefield, Canada (SGS Canada) on quartered drill core samples taken from its Jumbo Exploration Target at San Domingo District, Arizona, US.
- Three composite samples were selected for test-work, representing the low grade, medium grade, and high-grade environment reflected in the maiden 2022/2023 exploration programme previously reported from drilling undertaken at the Jumbo Target in the San Domingo Pegmatite district in Arizona.
- After discussion with SGS Canada, an initial HLS test was undertaken to evaluate the potential for dense media separation (DMS) to produce a sellable Li-oxide concentrate product. This test work is predominantly preliminary in its approach. The measured head grade of the samples was 3.05% Li2O, 1.03% Li2O and 0.34% Li2O, reflecting the high, medium, and low-grade range seen in drilling results to date.
- Despite the preliminary nature of this test-work programme, the medium-grade sample produced an ‘in spec’ lithium oxide concentrate product with a 6.0% Li2O grade and an interpolated recovery of contained lithium to the concentrate of 50.3%, at a ¼ in. size crush size. Tailings rejection was considered efficient in this scenario with the rejection of 60.6% mass and a loss of only 2.1% lithium.
- Alternately, at a crush size of 3/8 in., a concentrate was produced with a grade of 5.5 % Li2O at a 55.5% recovery of contained lithium oxide. This is still considered in spec in the current market. ‘In spec’ Li concentrate currently sells in the Lithium-Oxide Spot Market for circa US$2100/ t.
- Using the medium-grade sample, the flotation feed, a combination of middling product from the HLS testing at a crush size of ¼ in. and under sized fraction, recorded an upgraded value of 1.57% Li2O with Li distribution of 47.0% and a mass distribution of 30.5%.
- At Bradda’s request, SGS Canada also undertook Tescan Integrated Mineral Analyzer analysis of the medium grade sample, finding a dominance of spodumene as the primary lithium mineral with possible, but very minor, petalite and eucryptite, along with muscovite, minor beryl, tourmaline, calcite, and apatite. The overall iron content is low, <1.0%, indicative of a very good concentrate product.
- Bradda is currently undertaking a second drilling programme at its San Domingo Pegmatite District, with approximately 75% of the programme being complete. Assay results to date were released on 12 November 2023, highlighted by drill hole SD-DH23-049 which contains 6.35m @ 0.83% Li2O followed by 3.05m @ 1.03% Li2O, with more results arriving in the near future.
- Metallurgical test work is now currently on hold whilst Bradda collects more representative samples from this next phase of drilling to undertake a more detailed test work programme.
Bradda has 33 km2 license area under its control within this promising pegmatite district. It is a historical lithium mining environment with over 7 historic mines that focused on shallow open pit extraction of spodumene during the late 1940s and early 1950s. Bradda commenced drilling in 2H22 (7300 m) and is on its second campaign of 6100 m of core drilling, designed to expand on existing mineralised intercepts and drill-test newly developed high-quality lithium in pegmatite targets derived from soil sampling and surface mapping.
Diamond core drilling continues at the San Domingo Pegmatite project with approximately 75% of the programme completed, where many of the holes have encountered long intervals of pegmatite with visible spodumene mineralisation. Assay results have been slow to arrive, but drilling is progressing. Additional permits were received from the State and BLM, sites are being constructed at the historic Morning Star lithium mine, and drilling there is planned to commence shortly. The company hopes to have news on San Domingo within the next few weeks as preliminary results have started to arrive.
Ian Stalker, Executive Chairman, commented:
“These results are highly encouraging, and quite simply better than expected from what can only be described as preliminary non-detailed scoping test work. To produce an ‘in spec’ sellable gravity concentrate reflecting over 50% recovery to the concentrate from a sample grading 1.03% Li2O on first pass test work is very promising. Gravity Concentration, in this case, otherwise referred to as dense media separation, is a standard, low cost, simple process with a small, relatively non-invasive footprint.
“It is the kind of process operation that is quick to design and install, and yet can deliver very attractive economic returns. We are therefore highly encouraged, and when the next phase of drilling at San Domingo is complete and sufficient sample material is available, we will revert quickly to SGS with a more detailed test work and study programme to further the above objective.”
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