Essential Metals (ASX:ESS) reports it has received ‘positive’ lithium results from metallurgical test work at the North Dome Prospect, located in the Pioneer Dome Lithium Project in Western Australia.
Three composite samples were selected from drill core for metallurgical test work, representing the 3 mineral domains (Cade Weathered, Davy Weathered and Davy Fresh), complementing the successful test work already completed on the Cade Fresh mineralisation.
The grade and recovery data from Heavy Liquid Separation (HLS) and batch Whole of Ore Floatation (WOF) test work was then compared to the previous Cade Fresh test work to assess if the 3 composites are expected to be amenable to the previously tested hybrid pilot Dense Media Separation (DMS) and floatation flowsheet and reagent regime.
The 3 composites for the test work program were selected from core drillholes from the 3 domains.
Geological logging, elemental assays and open pit optimisation were used to check the composites were as representative of the domains as is practical, given the samples available. The test work was designed to determine the lithia recoveries based on a hybrid pilot DMS and floatation flowsheet.
The results show that the Cade Weathered mineralisation is expected to return an overall recovery similar to the 74% to 82% Li2O overall recovery rates returned from the previously tested Cade Fresh composite sample.
Essential Metals notes the whole Cade deposit represents 73% of the Mineral Resource. The results show that the Davy Fresh mineralisation is expected to return a marginally lower overall recovery at around 64% Li2O.
Due to the higher degree of weathering in the Davy Weathered composite, it is difficult to estimate from these results the expected overall lithia recovery for this domain via a hybrid pilot DMS and floatation flowsheet.
However, the results suggest it could be in the range of 30% to 50% Li2O recovery at a target concentrate grade of 5.7% Li2O.
All test work to date indicates that the vast bulk of the Dome North resource will result in ‘high’ recoveries with the production of marketable concentrate grades.
Essential Metals Managing Director Tim Spencer said these results provide more evidence pointing towards ‘high-quality’ lithium at the project.
“The metallurgical test work results provide further evidence of the high-quality nature of the Dome North lithium resource, providing a key input for the ongoing scoping study, which is scheduled for delivery in December”
“The metallurgical test work results provide further evidence of the high-quality nature of the Dome North lithium resource, providing a key input for the ongoing scoping study, which is scheduled for delivery in December, and further enhancing the attractiveness of the project to prospective off-take and project partners on terms favourable to Essential Metals.”.
Although the Davy Weathered and Davy Fresh composites have returned lower recoveries, they represent smaller components of the Mineral Resource. The Davy weathered and transitional zones represent 4% of the Mineral Resource, whilst the Davy fresh zone represents 16% of the Mineral Resource.
Essential Metals reports the scoping study will determine how much each domain represents in terms of mining inventory. Heavy liquid separation (HLS) testing was conducted to understand how the material processed will behave in a dense medium separation (DMS) process flowsheet.
The tests were conducted at a crush size of P100 3.1mm plus 0.85mm, the same was used for the 2020 test work program.
The batch WOF testing was conducted to understand how the finer grain sized material behaves in the floatation stage of the process flowsheet.
The tests also included Wet High Intensity Magnetic Separation (WHIMS) to reject iron and mica pre-floatation for the rejection of mica which can contaminate the final concentrate.
The spodumene floatation stage was conducted at a comparatively coarse grind size of 80% (P80) passing 0.15mm, as was used in the 2020 test work program.
The Cade Weathered composite returned very similar results for HLS and floatation when compared to the Cade Fresh test results at a target grade of 5.7% Li2O.
The composite performed as follows:
- The HLS recovery was 40% Li2O at a grade of 5.7% Li2O, and it is expected that DMS performance for this samples may be similar to the Cade Fresh composite samples.
- The WOF recovery was 68% at a grade of 5.7% Li2O, and it is expected that floatation circuit performance for this sample may be similar to the Cade Fresh composite sample.
- On this basis, it is expected that the Cade Weathered composite can achieve an overall recovery of 74% to 82% Li2O via a hybrid pilot DMS and floatation flowsheet.
The Davey Fresh composite returned very similar results for HLS when compared to the Cade Fresh test results at a target grade of 5.7% Li2O.
However, this composite returned marginally lower WOF recovery at a target grade of 5.7% Li2O.
The composite performed as follows:
- The HLS recovery was 41% Li2O at a grade of 5.7% Li2O, and it is expected that DMS performance for this sample may be similar to the Cade Fresh composite sample.
- The WOF recovery was 57% at a grade of 5.7% Li2O, and it is expected that floatation circuit performance for this sample will be marginally lower compared to the Cade Fresh composite sample.
- On this basis it is expected that the Davy Fresh composite can achieve an overall recovery of 64% Li2O via a hybrid pilot DMS and floatation flowsheet.
Essential Metals highlights that the floatation tests conducted were based on the baseline reagent regime and test methodology applied to the other composites, which it notes are significantly less weathered.
Further testing specifically designed to optimise recovery for the Davy Fresh mineralisation will be conducted as part of the future studies.
The company adds that these tests will also analyse whether the recovery rate could improve if Davey Fresh mineralisation is blended with mineralisation from other zones during commercial production.
The Davy Weathered composite WOF and HLS results returned lower recoveries, ‘lower-grades’ and ‘higher gangue grades’ when compared to other composites.
The composite performed as follows:
- The HLS Li2O recovery was 26% at 5.7% Li2O concentrate grade and higher iron levels of 1.8% Fe2O3.
- The WOF recovery was 38% Li2O at a grade of 5.7% Li2O.
Essential reports the impact of the lower recovery rates for the Davy Weathered composite sample will be mitigated by the fact that the Davy Weathered mineralised zone represents less than 5% of the overall Dome North Mineral Resource tonnes.
As with the Davy Fresh tests, floatation tests conducted were based on the baseline reagent regime and test methodology applied other composites which are significantly less weathered.
Further testing specifically designed to optimise recoveries for the Davy Weathered mineralisation will be conducted as part of future studies.
These tests will also analyse whether the recovery rate could improve if Davy Weathered mineralisation is blended with mineralisation from other zones during commercial production.
The results will be incorporated into the ongoing scoping study for the Pioneer Dome Lithium Project, with the study outcomes to be used to help finalise a framework for potential partners to be involved in advancing the Pioneer Dome Lithium Project to production.
Throughout October, Essential Metals will be completing an interpretation of the Pioneer Dome structural setting and controls of caesium-tantalum pegmatite emplacement, and it will also be receiving assays from the resource extension drill program.
In November, the company will complete the Dome North Mineral Resource Estimate (MRE).
In December Essential Metals will complete the Pioneer Dome scoping study, and will receive a non-binding expression of interest from parties seeking a financing and off-take partnership to assist with advancing the Pioneer Dome Lithium Project into production.
Exploration activities will continue in parallel with these activities, focusing on discovering new spodumene-bearing pegmatites at the Pioneer Dome Project.
In March this year, a diamond drilling program was completed, consisting of 6 holes drilled into the weathered profile of the Cade deposit (Cade weathered), 4 holes drilled into the weathered profile of the Davey deposit (Davy Weathered) and 3 into the fresh rock of the Davy deposit (Davy Fresh).
In December 2020, the company reported ‘highly encouraging’ results from the first metallurgical test work program completed on fresh rock mineralisation from the Cade Deposit.
This domain represents 63% of the Dome North Mineral Resource tonnes.
The results demonstrated that lithium mineralisation (spodumene) from the deposit can be processed into a concentrate that should meet market specifications while achieving a ‘high’ overall lithium recovery rate.
The 450km-square Pioneer Dome Project is located in the core of Western Australia’s lithium corridor in the Eastern Goldfields, approximately 130km south of Kalgoorlie and 275km north of the Port of Esperance.
A Mineral Resource of 11.2Mt @1.21% Li2O has been defined at Dome North in the northern area of the project.
The Southern Yilgarn area is recognised as being ‘well-endowed’ with spodumene deposits, including the Bald Hill Mine, the Mt Marion Mine and the Buldania Project, all of which are located within 80km of the Pioneer Dome Project.
The ‘world-class’ Greenbushes Deposit, the Mt Holland Mine and the Mt Cattlin Mine are located further west, south-west and south-southwest respectively.
Essential Metals is an exploration company focused on the discovery of lithium and other key global demand-driven commodities, for the creation of shareholder wealth through exploration and project development.
The company operates 3 lithium and gold projects in Western Australia, including the Pioneer Dome Lithium Project, the Juglah Dome Gold Project, and the Golden Ridge Gold Project.
Images: Essential Metals Limited & iStock
