High-Grade Goulamina Lithium Deposit Resource Expansion
Birimian Limited (ASX:BGS; “Birimian” and “Company” - https://www.commodity-tv.net/c/mid,2697,Company_Presentation/?v=297188 ) ) is pleased to report an updated Mineral Resource estimate for the Goulamina deposit, at its Bougouni Lithium Project in Mali.
The Mineral Resource at Goulamina now comprises 27.8 Mt @ 1.42 % Li2O, for 393,000 tonnes of contained Li2O (Table 1). This nearly doubles the previous estimate for contained lithia and further confirms Goulamina as among the highest grade, hard rock lithium deposits of significant size globally today.
Commenting on the milestone, Birimian Managing Director Mr Kevin Joyce said, "The latest resource estimate is an outstanding result, which includes extensions to mineralisation at West Zone and the new discovery at Sangar Zone. The combination of these increased resources and expected near-term resource category upgrades will underpin the project Pre-Feasibility Study which is currently in progress.
"Present resources are beyond our early expectations and now exceed the Company’s original exploration target for contained lithia. Importantly, there is significant potential to further expand the Goulamina resource.
"Birimian is in a strong cash position with sufficient capital to fund development activities through to completion of the Project Pre-Feasibility Study, which is expected in the June quarter.”
Mineral Resource Estimate
Cube Consulting (Cube) was engaged to carry out the updated Mineral Resource estimate for the Goulamina deposit. This estimate now includes extensions at West Zone and the recently discovered Sangar Zone to the south west. Detailed information relating to data, quality control, and estimation methodology are documented in Appendix 1 - JORC Table 1, Sections 1 to 3.
Combined resources, estimated to Indicated and Inferred confidence levels, are shown in Table 1. The resource area at the Main Zone pegmatite has not been re-modelled and remains unchanged from the maiden resource estimate (ASX: 27 October 2016).
Table 1. Goulamina Mineral Resource classifications.
Birimian provided the principal sources of information used in this Mineral Resource estimate including drilling databases, a topographic surface, mapping information and a geological interpretation of the mineralised pegmatites. An additional 29 holes have been included in the updated estimate, which augment the 51 holes which informed the maiden resource model.
Approximately 65 holes were pending assay results at the time of resource estimation and have not been included in the current estimate. These holes include some extensional drilling at Main and West Zone, but largely relate to 25m spaced infill drill sections designed to improve geological and resource confidence. Further resource expansion and resource category upgrades are likely when this drilling is included in a subsequent estimate which is expected in early May.
The mineral resources are defined by reverse circulation (RC) and diamond (DD) drilling. The majority of the new drilling included in the estimate is at 50m x 50m spacing over the West and Sangar pegmatite zones. This spacing is adequate to establish the geological and grade continuity for reporting an Inferred category resource.
The spodumene (lithium) pegmatite mineralisation at Goulamina occurs as three well defined, broadly parallel and highly continuous dykes; the Main Zone, West Zone, and Sangar Zone (Figure 1, 2 and 3). Cross cutting mineralised dykes, identified in outcrop and drilling, are less well-defined and have not been included as classified resources at this point in time.
Mineralised domains for separate pegmatite dykes were digitised in cross-section and then wireframed to generate solids. There is a very strong correlation between the mineralised portion of the pegmatite dykes and the total dyke mineralised intercept. Very little pegmatite material is not significantly elevated in lithium content; thus the mineralisation boundaries generally match the lithological boundaries of the dykes. Wireframe solids were used to populate the block model and interpolated Li2O grade by ordinary kriging methods.
It has been assumed that the resource would be mined using open pit methods, which is supported by conceptual mining studies. The previous metallurgical studies provide a sufficient basis for the assumption regarding metallurgical amenability, and determining reasonable prospects for eventual economic extraction.
Goulamina – A Large Tonnage High Grade Lithium Deposit
The updated resource estimate at Goulamina confirms a high-grade and bulk tonnage lithium deposit.
The grade-tonnage curve for updated inferred resources at West Zone is shown in Figure 4. The global resource is reported at 0% Li2O cut-off. At elevated cut-off grades, the tonnages of mineralisation do not vary substantially. This confirms the robust grade and good continuity of the modelled mineralisation. Increased resource tonnages have resulted in a slight reduction of resource grade, but significantly increased contained lithia. Resource grade remains substantially higher than the estimated mining cut-off grade of 0.82% Li2O. (ASX: 13 March 2017). The latest resource estimate satisfies Milestone One of the management incentives plan.
Mineralisation is still open at all three mineralised zones and there remains significant untapped exploration potential within the 250km2 project area. Birimian remains confident that as project development work evolves, it will progressively increase the lithia inventory at Goulamina.
On 30 January 2017, Birimian announced that the Scoping Study for the Bougouni Lithium Project had confirmed the outstanding potential of the Project, leading to the decision to commence a Pre‐Feasibility Study (PFS). Scoping Study results suggest that the Goulamina deposit will be amenable to low cost, open pit mining and staged processing plant development, benefiting from low mining strip ratios, high grade at surface mineralisation, and the low cost operating environment in Mali. The PFS remains on track to be completed during the June 2017 quarter.
Drilling at the Project has paused briefly while the company awaits assay results to undertake further detailed resource estimation work and other resource related technical studies. Given the relatively steady progress with recent drilling and the extended time required for assay to be returned, a further update to the resource model is now anticipated by early May. This estimate is expected to include all results from infill drilling to support significant resource category upgrades and facilitate detailed Pre-Feasibility studies.
In parallel with resource estimation, Birimian continues to advance a number of studies as it works towards completion of the PFS. The Company's strategy is to expedite development of the currently defined resources at the Bougouni Project in lieu of targeting major resource expansions by drilling. The next phase of development drilling is currently being planned. This program will be designed to:
- Further upgrade resource categories
- Confirm geotechnical parameters for open pit mine planning
- Confirm plant, associated infrastructure, waste dump and Tailings Storage Facility locations
Digby Wells Environmental has completed field work relating to the next phase of detailed sustainability studies at the Project and in the broader community. This is important as findings will facilitate ongoing engineering studies and development drilling planning, and will enable Digby Wells to prepare the Terms of Reference for the Environmental and Social Impact Assessment (ESIA). At this stage it is proposed to present the Project Terms of Reference to government at the end of April, signaling the formal commencement of the project ESIA and leading to mine permitting.
Birimian is seeking to fast-track commercialisation of Bougouni. As such, the other key milestones to look forward to are metallurgical test work results and an upgraded resource estimate, both of which are expected to be completed in the current quarter. Following this, the PFS is expected to also be completed in the June 2017 quarter, enabling the Company to progress project financing and offtake arrangements, in parallel with the mine permitting process.
ASX Additional Information - Material Assumptions
The following is a summary of Material Information used to estimate the Mineral Resource as required by Listing Rule 5.8.1 and JORC 2012 Reporting Guidelines.
Mineral Tenement and Land Tenure Status
The deposit lies within the Torakoro Research Permit which is owned 100% by Timbuktu Ressources, a wholly owned Malian subsidiary of Birimian Limited. The mineral property is in good standing and there is no known impediment to obtaining a license to operate.
The project area is located within the Bougouni region of the southern Mali, where broadly north-south trending belts of Birimian-aged (Paleoproterozoic) metavolcanic and metasedimentary rocks are intruded by syn-and post-orogenic granitoids.
Within the Project area, outcrop is limited and basement geology is therefore poorly understood. Regolith typically comprises a surficial transported gravel horizon (locally termed Cuirasse) overlying a thin lateritic weathering profile. Mapping indicates NE-striking metapelite and metagreywacke rocks in the north and eastern parts of the property. The southern portion of the project area is dominated by granodiorite.
All pegmatite bodies contain anomalous or significant amounts of the mineral spodumene (a lithium-bearing pyroxene), along with the other major minerals of quartz and feldspar (albite and microcline); From the geological logging, there are also accessory amounts of muscovite, tourmaline, apatite, and biotite at the granite contacts.
Drilling Techniques and Hole Spacing
Holes were drilled in two phases, from May to September 2016, and December 2016 to February 2017. In total 80 holes inform the current resource estimate.
RC drilling was completed by Foraco Drilling and International Drilling Company (IDC), using nominally 5.5” diameter equipment, with a face sampling downhole hammer. The Foraco rig had an outboard compressor, with specifications of 1100CFM@350PSI. The IDC rig had an onboard compressor with specifications of 1150CFM@500PSI
Core drilling was completed using equipment supplied and operated by Foraco Drilling and IDC. All holes are standard HQ sized holes (core diameter 64mm). DD holes are a combination of some drilled from surface and some as diamond tails on RC holes (including extensions to previously drilled Phase 1 holes).
All samples collected from the RC rig were collected at 1m downhole intervals. Samples were split into pre-numbered calico bags at the rig using a 3-stage riffle splitter yielding a sample of between 3 to 5 kilograms. In addition to the 1m sample, duplicate samples were taken every 20m downhole. Blanks and standards were inserted into the sample stream at a rate of 1:40 for Blanks, and 1:40 for Standards.
All data is documented in a sampling ledger, including hole number, date drilled, sample id, depths from and to, sample condition, sample type, percentage sample return and all certified standards blanks and duplicates.
Drill core was sawn in half along its long axis. One half of the drill core was taken for geochemical analysis. All samples were collected at 1m intervals down the hole. 100% core recoveries were typically achieved.
Sample preparation work was conducted in the ALS Laboratory in Ouagadougou, Burkina Faso. At the laboratory, samples were weighed, dried and crushed to -2mm in a jaw crusher. A 1.0kg split of the crushed sample was subsequently pulverised in a ring mill to achieve a nominal pulp particle size of 85% passing 75μm. Sample sizes and laboratory preparation techniques are considered to be appropriate.
After pulverisation, sub-samples were sent to ALS Laboratory in Perth for assay. Analysis for lithium and a suite of other elements was undertaken by ICP-AES, after a sodium peroxide (Na2O2) fusion – ALS Method ME-ICP89. Some of the multi-element analysis uses a MS finish – ALS Method ME-MS91. This fusion technique is considered to be a “total” dissolution technique for lithium-bearing silicate minerals. Detection limits for lithium are 0.01-10%.
Interpreted sections were wireframed using Surpac software to create 3D solids for each pegmatite domain within the resource area. The drillhole data was sliced on 50m spaced sections for modelling of the geology and the mineralised envelopes. Solids were constructed for 4 discreet pegmatite dykes, as well as for the near surface colluvium and lateritic material.
Mineralisation in the Main Zone and West Zone pegmatites was composited to 3m downhole intervals to reduce the variability inherent in raw samples or a smaller composite length relative to estimation resource model block dimensions.
Surpac software was used for the modelling and estimation, with SuperVisor software used to conduct geostatistical analysis. The main pegmatite domains in the block model were estimated using interpolation of grade via Ordinary Kriging (OK), which was considered to be an acceptable method given the strong geological control, the drilling density and the data distribution downhole.
A single block model was created by Cube with dimensions extended out to fully cover all of the mineralisation, plus surrounds that may be contained within pit optimisation shells. The parent block size used is 20mN x 20mE x 5mRL and sub-blocked to 1.25mN x 2.5mE x 2.5mRL.
A range of criteria were considered by Cube when addressing the suitability of the classification boundaries. These criteria include:
- Geological continuity and volume;
- Drill spacing and drill data quality;
- Modelling technique; and
- Estimation properties including search strategy, number of informing composites, average distance of composites from blocks and kriging quality parameters.
Blocks have been classified as Indicated or Inferred, mostly based on drill data spacing in combination with kriging parameters.
For the global resource estimation, no lower cutoff grade for reporting is used, as the model is essentially developed within a geological boundary, and the resource incorporates everything within the modelled pegmatite dykes.
Mining and Metallurgy
Conceptual mining studies are based on open cut mining methods using a contract mining fleet and conventional drill and blast mining methods. Limited inspection of core photography indicates that ground conditions are suitable for this mining method.
The resource has been trimmed by intersecting with a pit shell based on a Whittle optimisation at a revenue factor (USD$650/t for a nominal 6% Li2O concentrate). Material falling outside of this shell is considered to not meet reasonable prospects for eventual economic extraction. Reasonable prospects for eventual economic extraction have been determined with reference to the results of previous Whittle optimization studies, and the depth of the selected open pit shell (at a revenue factor of USD$650/t for a nominal 6% Li2O concentrate) was used as an analogy to help limit the depth for reporting the Sangar Zone.
The criteria for assumptions and predictions regarding metallurgical amenability – required to determine reasonable prospects for eventual economic extraction – are based on the bulk sampling and test program undertaken in 2008 by CSA Global (UK), work that was commissioned and funded by the World Bank as part of the SYSMIN economic development program. CSA Global undertook systematic sampling of outcropping material at Goulamina to collect a representative bulk sample comprising 3,150kg of material, which was subsequently crushed and split to 750kg for detailed processing test work. This work included evaluations of screen sizing to optimize spodumene (lithium) recoveries and preliminary dense media separation tests. The results of this study indicated good spodumene recoveries and a high mass yield, to produce a high quality chemical grade spodumene concentrate.
For further information contact:
Mr Kevin Joyce
08 9286 3045
Competent Persons Declaration
The information in this announcement that relates to exploration results and the Exploration Target is based on information compiled by or under the supervision of Kevin Anthony Joyce. Mr Joyce is Managing Director of Birimian Limited and a Member of the Australian Institute of Geoscientists. Mr Joyce has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and the activity he is undertaking 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 ('the JORC Code')”. Mr Joyce consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.
The information in this announcement that relates to Mineral Resources is based on information compiled by or under the supervision of Mr. Matt Bampton, who is a Member of The Australasian Institute of Mining and Metallurgy and a Member of the Australian Institute of Geoscientists. Mr Bampton is a full-time employee of Cube Consulting Pty Ltd and has sufficient experience which is relevant to the styles of mineralisation and types of deposit under consideration and to the activity which he is undertaking 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 ('the JORC Code')”. Mr Bampton consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.
Previous Reported Results
There is information in this announcement relating to previous Exploration Results at the Bougouni Project. The Company confirms that it is not aware of any other new information or data that materially affects the information included in the original market announcement, and that all material assumptions and technical parameters have not materially changed. The Company confirms that the form and context in which the Competent Person’s findings are presented have not been materially modified from the original market announcement.
Forward Looking Statements
Statements regarding plans with respect to the Company’s mineral properties are forward looking statements. There can be no assurance that the Company’s plans for development of its mineral properties will proceed as expected. There can be no assurance that the Company will be able to confirm the presence of mineral deposits, that any mineralisation will prove to be economic or that a mine will successfully be developed on any of the Company’s mineral properties.