お知らせ • Dec 19
Essential Metals Limited Reports Results from Metallurgical Test Work Programme Completed on Mineralization from the Cade Deposit
Essential Metals Limited (the "Company") reported highly encouraging results from the first metallurgical test work programme completed on mineralisation from the Cade Deposit, part of its 100%-owned Dome North Lithium Project in Western Australia. The results demonstrate that the lithium mineralisation (spodumene) from the deposit can be processed into a concentrate that should meet market specifications while achieving a high global lithium recovery rate. In summary, the following results were achieved: The Dome North Lithium Project, part of the greater Pioneer Dome Project, is located in Western Australia's Eastern Goldfields approximately 130km south of Kalgoorlie and 275km north of the Port of Esperance. The southern Yilgarn area is recognised as highly endowed with spodumene deposits, including the Bald Hill Mine, Mt Marion Mine and the Buldania Project. The Earl Grey deposit and the Mt Cattlin Mine are located further west and south, respectively. The Company engaged Primero Group Limited to design and conduct the metallurgical test work programme. A multi-disciplinary engineering group specialising in the design, construction and operation of resource projects, Primero has been involved in several of WA's spodumene projects including Pilgangoora, Mt Cattlin and Bald Hill. The test work was conducted at Nagrom, a well-known mineral processing laboratory in WA that specialises in spodumene dense medium separation (DMS) and flotation test work. Composites for the test work programme were selected from five core drill holes from the Cade Deposit, with each composite intended to represent the mean grade and lithology of the Cade deposit. Geological logging, elemental assays and an open pit optimisation were used to check that the composites were as representative of the deposit as is practical, given the samples available. Intersections from the five holes were previously reported as follows: 31.6m @ 1.31% Li2O from 72 metres PDRCD292), 27.4m @ 1.38% Li2O from 131 metres (PDRCD294), 27.2m @ 1.46% Li2O from 209 metres including 11m @ 1.79% Li2O (PDRCD295), 22.2m @ 1.72% Li2O from 128 metres (PDRCD318), 16.5m @ 0.86% Li2O from 166 metres (PDRCD293).Two composite samples were prepared from the drill core. The tests conducted on the first composite included: Head Assay and X-Ray Diffraction (XRD); Crusher work index (CWi) and Abrasion Index (Ai) tests; and Size by assay (SxA) and Heavy Liquid Separation (HLS) at a series of different crush sizes. The first composite was noted to include a portion of mineralisation containing petalite, a lithium-bearing mineral that typically requires a different process flowsheet to spodumene. This material was situated towards the edge of the Resource. A second composite was generated from the same drill holes as the first but excluded the 3.7m wide petalite wall zone identified in hole PDRCD318. The tests conducted on the second composite included: Head Assay and X-Ray Diffraction (XRD); Size by assay (SxA) and Heavy Liquid Separation (HLS) at a series of different crush sizes; and Batch flotation test work on head and DMS mid samples. This work included de-sliming, magnetic separation and mica pre-flotation steps. The XRD scan showed that no petalite was detected in the second composite sample, providing evidence that petalite occurrences outside the identified wall zone in hole PDRCD318 may be low. The lithium grades of the two composites were 1.41% Li2O and 1.56% Li2O respectively. The second composite was then used for the dense medium separation (DMS) and flotation test work. A series of HLS tests was conducted, including one to investigate production of an upgraded direct-shipped ore (DSO). This test, using a crush size of P100 6.3mm, showed that up to 81% Li2O can be recovered into approximately 42% of plant feed mass, producing an upgraded material containing 2.0% Li2O. These HLS results represent a theoretical maximum recovery for this sample and variability testing with a DMS cyclone and larger sample mass is recommended to verify any results. In an improved lithium pricing environment, a lower CAPEX DSO style operation can be assessed against a more capital intensive value-adding operation involving DMS + flotation processing, provided that a market for DSO product is available. Under the DMS pilot test stage, a concentrate of 5.7% Li2O was achieved at a global recovery of 28.6% Li2O. The Secondary DMS floats were then composited with -0.85mm material and used as feed to flotation test work,containing an assayed grade of 1.67% Li2O. The flotation test work based on the DMS feed included a series of tests with each one preceded by grinding the feed to P80 150µm and de-sliming via screen or cyclone at a cut size of 20 µm before performing the batch flotation tests. The T12 test (flotation + DMS) achieved a concentrate of 5.66% Li2O with very high recovery rate of 82% lithia, however the iron content of 1.3% Fe2O3 is considered high in comparison to the `industry standard' limit of 1% Fe2O3. Test T15 included a `mica pre-flotation' step to remove paramagnetic gangue minerals. This resulted in a similarconcentrate grade of 5.65% Li2O but a much lower iron content of 0.7% Fe2O3 with a reduction in the global lithia recovery rate to 74%. In addition, a `whole-of-ore' flotation test was carried out (`T11 Flot Con'). It achieved the highest concentrate grade of 6.06% Li2O with 0.6% iron (Fe2O3) and a global lithia recovery rate of 66% Li2O. Given the investigative, scoping nature of this test work programme, variations of each flotation parameter were not explored. Primero has recommended that grind size, de-slime cut point, two-stage de-sliming, magnetic separation gauss, mica pre-flotation conditions and spodumene conditioning and flotation conditions all be tested to reduce lithium losses to tail while maintaining satisfactory concentrate grade and recovery. Next Steps -Exploration: Continue with reconnaissance field trips involving mapping and sampling and updating the prioritized prospect list with the objective of having drill-ready targets by the June Quarter 2021. Scoping Study: The timing of further studies, including a Scoping Study, will be reviewed towards the end of the 2021 March Quarter to coincide with further exploration progress and the anticipated continued improvement in the lithium market.