Ewoyaa Lithium Resource Increases to 21.3Mt at 1.31% Li2O
Cape Coast Lithium Portfolio, Ghana West Africa
SYDNEY, AUSTRALIA / ACCESSWIRE / December 1, 2021 / Atlantic Lithium Limited (AIM:ALL)(OTCQX:ALLIF) ('Atlantic Lithium' or the 'Company'), the African focussed minerals exploration company, is pleased to report a significant Mineral Resource Estimate ('MRE') upgrade to 21.3Mt at 1.31% Li2O for the Ewoyaa deposit and surrounding pegmatites (collectively the 'Ewoyaa Project' or 'Project') within the Cape Coast Lithium Portfolio in Ghana, West Africa. The Mineral Resource is reported in accordance with the JORC Code (2012).
Figures and Tables referred to in this release can be viewed in the PDF version available via this link:
- 47% increase in Mineral Resource Estimate to 21.3Mt at 1.31% Li2O reported in accordance with the JORC Code (2012) in Indicated and Inferred status at the Ewoyaa deposit.
- The total resource grade remains unchanged, highlighting its robust geological fundamentals and the estimate includes 5.2Mt at 1.39% Li2O of Indicated Mineral Resource.
- Significant exploration upside within broader 560km2 Cape Coast lithium portfolio; including historic 1.48Mt at 1.67% Li2O Egyasimanku Hill deposit (non JORC, refer RNS of 14 June 2017).
- Current resource upgrade based on c.56,500m of drilling; an additional c.28,000m of infill and extensional drilling completed with results pending are not included in this resource upgrade.
- Mineralisation remains open at depth and along strike with additional untested pegmatites within the immediate deposit area, providing potential for further resource upgrades.
- Regional exploration and target definition on going with 4 Auger rigs on site, with resource drilling to re-commence in early 2022.
- Resource exceptionally well located; adjacent high-power transmission lines, within 1km of national highway and within 110km along sealed road to the operating Takoradi deep-sea port.
Commenting on the Company's latest progress, Vincent Mascolo, Chief Executive Officer of Atlantic Lithium, said:
'We are pleased to have increased Ghana's first lithium resource by nearly 50% to 21.3Mt at 1.31% Li2O and will continue to further enhance this compelling project with ongoing drilling programs.
'With some 28,000m of infill and extensional drilling not included in the current resource estimate and with mineralisation open at depth and along strike we are confident of further resource upgrades.
'The current resource can be reported at a significantly larger tonnage by reducing the cut-off grade - for example 27.1Mt at 1.09% Li2O at a 0.25% Li2O cut-off. Future studies will assess the benefits of increased production profiles to the overall project economics by reducing the cut-off grade.
'Due to the coarse nature of the spodumene dominant mineralisation, metallurgical test-work to date has consistently delivered high-purity, low contaminants >6% Li2O spodumene concentrate at a coarse 6.3mm crush utilising conventional DMS gravity separation; boding well for low capital, operating and carbon intensities.
'The Mineral Resource is exceptionally well located, being only 1km from the sealed national highway and 110km from the operating deep-sea port of Takoradi with adjacent grid power; it is challenging to find other lithium pegmatite projects better located.
'Delivery of the upgraded 21.3Mt at 1.31% Li2O Mineral Resource estimate is an important de-risking milestone for this industry standout project. With Ewoyaa being fully funded to production through our agreement with Piedmont Lithium, this upgrade highlights the exceptional potential of the project and the value that it brings to the Company.'
Mineral Resource Estimate Upgrade
An upgraded Mineral Resource estimate ('MRE') of 21.3Mt at 1.31% Li2O was completed for the Ewoyaa deposit and surrounding pegmatites; collectively termed the Ewoyaa Project. The Mineral Resource is reported in accordance with the JORC Code (2012). The MRE includes a total of 16.1Mt at 1.28% Li2O in the Inferred category and 5.2Mt at 1.39% Li2O in the Indicated category (refer Table 1).
The independent MRE for Ewoyaa was completed by Ashmore Advisory Pty Ltd of Perth, Western Australia with results tabulated in the Statement of Mineral Resources in Table 1. The Statement of Mineral Resources is reported in line with requirements of the JORC Code (2012) and is therefore suitable for public reporting.
High-level Whittle optimisation was completed by Mining Focus Consultants Pty Ltd of Perth, Western Australia and demonstrates reasonable prospects for eventual economic extraction.
A tonnage and grade by bench elevation and grade tonnage curve are shown in Figure 1 and Figure 2 for the constrained pegmatite model respectively.
A plan view of the deposit areas is shown in Figure 3 with a long section shown in Figure 4 and cross-section within the Ewoyaa Main indicated category zone shown in Figure 5.
JORC Table 1, Section 1 (Sampling Techniques and Data) and Section 2 (Reporting of Exploration Results) are included in Appendix 1.
JORC Table 1, Section 3 (Estimation and Reporting of Mineral Resources) is included in Appendix 2.
There are four main geometallurgical domains at Ewoyaa; coarse grained type P1 and finer grained type P2 pegmatites and their weathered equivalents. Their estimated relative abundances, metallurgical recoveries and concentrate grades are shown in Table 2.
To show the tonnage and grade distribution throughout the entire deposit, a bench breakdown has been prepared using a 10m bench height which is shown in Error! Reference source not found. and grade-tonnage curve for the classified resource in Figure 2.
The current resource model is estimated from a pegmatite body that utilises a 0.4% Li2O wireframing cut-off grade. However, when assessing all pegmatite volumes (with no cut-offs applied), there is significant scope to increase the resource tonnage. Table 3 and Figure 6 below show the overall resource tonnage and grade for the deposit, inclusive of all pegmatite material. For example, the resource can be reported at a significantly larger tonnage by reducing the cut-off grade to 0.25% Li2O giving an increased resource of 27.1Mt at a grade of 1.09% Li2O.
Further studies will assess the potential benefits of increased production by reducing the cut-off grade on overall project economics, consistent with market price predictions and price trends realised by existing producers.
Geology and Geological Interpretation
The Ewoyaa Project area lies within the Birimian Supergroup, a Proterozoic volcano-sedimentary basin located in Western Ghana. The Project area is underlain by three forms of metamorphosed schist; mica schist, staurolite schist and garnet schist. Several granitoids intrude the basin metasediments as small plugs. These granitoids range in composition from intermediate granodiorite (often medium grained) to felsic leucogranites (coarse to pegmatoidal grain size), sometimes in close association with pegmatite veins and bodies.
Pegmatite intrusions generally occur as sub-vertical dykes with two dominant trends: either east-southeast (Abonko, Anokyi, Ewoyaa Northeast, Grasscutter, Kaampakrom and Okwesi) dipping sub-vertically northeast; or north-northeast (Ewoyaa Main) dipping sub-vertically to moderately to the east. Pegmatite thickness varies across the Project, with thinner mineralised units intersected at Abonko and Kaampakrom between 4 and 12m; and thicker units intersected at Ewoyaa Main between 30 and 60m, and up to 100m at surface.
The database contains data for the auger, reverse circulation ('RC') and diamond core ('DD') drilling conducted by ALL since 2018. The drilling was completed by ALL in five phases commencing in April 2018. All the drilling was undertaken by GeoDrill (Ghana), using both RC and DD rigs.
Drilling at the deposit extends to a vertical depth of approximately 180m and the mineralisation was modelled from surface to a depth of approximately 200m below surface. The estimate is based on good quality RC and DD drilling data. Drill hole spacing is predominantly 40m by 40m in the well drilled portions of the Project and up to 80m by 80m to 100m by 100m across the breadth of the known mineralisation.
The RC drilling used a combination of 5.25' and 5.75', face sampling hammers. The DD used PQ and HQ (85mm and 63.5mm) diameter core barrels. The DD holes were completed from surface with PQ to maximise recovery in weathered zones, with reversion to HQ once ground conditions improved within fresh material.
In 2018, Phase 1 RC holes were completed on a nominal 100m by 50m grid pattern, targeting the Ewoyaa Main mineralised system. Phases 2 to 5 reduced the wide spacing to 80m by 40m and down to 40m by 40m in the well drilled portions of the Project. Eleven DD twins of RC holes were completed.
During Phase 1 and 2, RC drilling bulk samples and splits were collected at the rig for every metre interval drilled, the splits being undertaken using a riffle splitter. During Phase 3 and 4, RC samples were split with a rig mounted cone spitter which took duplicate samples for quality control purposes.
Diamond core was cut with a core saw and selected half core samples totalling 427.1kg was dispatched to Nagrom Laboratory in Australia for preliminary metallurgical test work.
Selected core intervals were cut to quarter core with a saw at one metre intervals or to geological contacts; and since December 2018 were sent to Intertek Laboratory in Tarkwa, Ghana for sample preparation. Prior to that, samples were sent to SGS Laboratory in Tarkwa for sample preparation.
All Phase 1 samples were submitted to SGS Tarkwa for preparation (PRP100) and subsequently forwarded to SGS Johannesburg and later SGS Vancouver for analysis (ICP90A).
PRP100 - Samples <3kg are dried in trays, crush to 100% passing 2mm, split using a rotary splitter to 5kg and pulverised in a LM2 to a nominal 85% passing 75µm. Approximately 100g sub-sample is taken for assay. All the preparation equipment is flushed with barren material prior to the commencement of the job. Coarse reject material was kept in the original bag.
Since December 2018, samples were submitted to Intertek Tarkwa (SP02/SP12) for sample preparation. Samples were weighed, dried and crushed to -2mm in a Boyd crusher with an 800-1,200g rotary split, producing a nominal 1,500g split crushed sample; which was subsequently pulverised in a LM2 ring mill. Samples were pulverised to a nominal 85% passing 75µm. All the preparation equipment was flushed with barren material prior to the commencement of the job. Coarse reject material was kept in the original bag. Lab sizing analysis was undertaken on a nominal 1:25 basis. Final pulverised samples (20g) were airfreighted to Intertek in Perth for assaying.
Sample Analysis Method
Since December 2018, samples were sent to Intertek Laboratory in Perth for analysis (FP6/MS/OES). FP6/MS/OES is an analysis for lithium and a suite of 21 other elements. Detection limits for lithium range between 5ppm and 20,000ppm. The sodium peroxide fusion (in nickel crucibles) is completed with hydrochloric acid to dissolve the sub-sample and is considered a total dissolution. Analysis is conducted by Inductively Coupled Plasma Mass Spectrometry ('ICP-MS').
Prior to December 2018, Phase 1 samples were submitted to SGS Johannesburg and later SGS Vancouver for analysis (ICP90A). ICP90 is a 28-element combination Na2O2 fusion with ICP-OES. ICP-MS was added to some submissions for additional trace element characterisation purposes.
Mineral Resource Classification Criteria
The Ewoyaa lithium deposits show good continuity of the main mineralised units which allowed the drill hole intersections to be modelled into coherent, geologically robust domains. Consistency is evident in the thickness of the structure, and the distribution of grade appears to be reasonable along and across strike.
The Ewoyaa Mineral Resource was classified as Indicated and Inferred Mineral Resource based on data quality, sample spacing, and lode continuity. The Indicated Mineral Resource was defined within areas of close spaced RC and DD drilling of less than 40m by 40m, and where the continuity and predictability of the lode positions was good. In addition, Indicated Mineral Resource was confined to the fresh rock. The Inferred Mineral Resource was assigned to transitional material, areas where drill hole spacing was greater than 40m by 40m, where small, isolated pods of mineralisation occur outside the main mineralised zones, and to geologically complex zones. In addition, zones of pegmatite where grade was estimated to be greater than 0.5% Li2O were classified as Inferred.
A Surpac block model was created to encompass the extents of the known mineralisation. The block model was rotated on a bearing of 30°, with block dimensions of 10m NS by 10m EW by 5m vertical with sub-cells of 2.5m by 5m by 1.25m. The block size was selected based on results of Kriging Neighbourhood Analysis ('KNA') and also in consideration of two predominant mineralisation orientations of 30° and 100 to 120°.
The parent block size was selected based on KNA, while dimensions in other directions were selected to provide sufficient resolution to the block model in the across-strike and down-dip direction.
Bulk densities ranging between 1.7t/m3 and 2.75t/m3 were assigned in the block model dependent on lithology, mineralisation and weathering. These densities were applied based on 1,515 bulk density measurements conducted by ALL on twelve DD holes conducted across the breadth of the Ewoyaa Main and Ewoyaa Northeast deposits. The measurements were separated using weathering surfaces, geology and mineralisation solids, with averages assigned in the block model.
The Statement of Mineral Resources has been constrained by the mineralisation solids and reported above a cut-off grade of 0.5% Li2O. The reporting cut-off grade is supported by a high-level Whittle optimisation.
Mining and Metallurgical Methods and Parameters
A high-level Whittle optimisation and Scoping Study demonstrates reasonable prospects for eventual economic extraction using open pit mining techniques. Preliminary metallurgical test work indicates that there are four main geometallurgical domains; weathered and fresh coarse grained spodumene bearing pegmatite (P1); and weathered and fresh medium grained spodumene bearing pegmatite (P2). From test work completed to date at a 6.3mm crush, the P1 material produces a 6 to 6.6% Li2O concentrate at approximately 70 to 85% recovery (average 75% recovery), whilst P2 material produces 5.5 to 6% Li2O concentrate at approximately 35 to 65% recovery (average 47% recovery).
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Information in this report relating to the exploration results is based on data reviewed by Mr Lennard Kolff (MEcon. Geol., BSc. Hons ARSM), Chief Geologist of the Company. Mr Kolff is a Member of the Australian Institute of Geoscientists who has in excess of 20 years' experience in mineral exploration and is a Qualified Person under the AIM Rules. Mr Kolff consents to the inclusion of the information in the form and context in which it appears.
Information in this report relating to Mineral Resources was compiled by Shaun Searle, a Member of the Australian Institute of Geoscientists. Mr Searle has sufficient experience that is relevant to the style of mineralisation and type of deposit under consideration and to the activity being undertaken to qualify as a Competent Person as defined in the 2012 Edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves'. Mr Searle is a director of Ashmore. Ashmore and the Competent Person are independent of the Company and other than being paid fees for services in compiling this report, neither has any financial interest (direct or contingent) in the Company.
Information in this report relating to metallurgical results is based on data reviewed by Mr Noel O'Brien, Director of Trinol Pty Ltd. Mr O'Brien is a Fellow of the Australasian Institute of Mining and Metallurgy (AusIMM) and has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the December 2012 edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves' (JORC Code). Mr O'Brien consents to the inclusion in the report of the matters based upon the information in the form and context in which it appears.
This announcement contains inside information for the purposes of Article 7 of the Market Abuse Regulation (EU) 596/2014 as it forms part of UK domestic law by virtue of the European Union (Withdrawal) Act 2018 ('MAR'), and is disclosed in accordance with the Company's obligations under Article 17 of MAR.
Notes to Editors:
About Atlantic Lithium
Atlantic Lithium (formerly 'IronRidge Resources') is an AIM-listed lithium company advancing a portfolio of projects in Ghana and Côte d'Ivoire through to production.
The Company's flagship project, the Ewoyaa Project in Ghana, is a significant lithium pegmatite discovery on track to become West Africa's first lithium producing mine. The project is fully funded to production under an agreement with Piedmont Lithium for US$102m and set to produce a premium lithium product. A robust Scoping Study indicates Life of Mine revenues exceeding US$1.5bn.
Atlantic holds a 560km2 & 774km2 tenure across Ghana and Côte d'Ivoire respectively, comprising significantly under-explored, highly prospective licenses.
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SOURCE: Atlantic Lithium Limited
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