Nayega Manganese Project
Keras has an 85% interest in Société Générale des Mines SARL (SGM) which holds the research permits for the Nayega manganese project in northern Togo, West Africa.
The project at a glance
- Four Research Permits covering 29,819ha in northern Togo
- JORC Code Mineral Resource of 13.97Mt @ 12.4% Mn and Ore Reserve of 8.48Mt @14.0% Mn with additional upside identified
- Known deposit covers 2.2km by 500m and averages 3.3m thick
- Mineralisation starts at surface meaning it is amenable to shallow open pit operation with no waste stripping
- Metallurgical testwork supports implementing a simple beneficiation process to produce a saleable product of 38% Mn
- 10,000t bulk sampling metallurgical testwork programme due to be completed mid-January 2019 targeting a beneficiated -75+10mm 35% Mn product from a
simplified screening and scrubbing operation
- Testwork is fully funded by the end user, a major producer of manganese-based alloys, which is processing the ore to assess its suitability for
Nayega is located in northern Togo, 30km from the N1 National Road, which provides direct access to the regionally important deep water port of Lomé 600km to the south. The port of Lomé has in excess of 500,000t per annum back loading capabilities. The project comprises 4 Exploration Permits, covering 29,819Ha namely:
- Pana Permit (Tône Prefecture)
- Tandjoaré Permit (Tandjoaré Prefecture)
- Naki-Est Permit (Kpendjal-Ouest Prefecture)
- Borgou Permit (Kpendjal Prefecture).
Subsequent to the completion of the exploration activities and internal Feasibility Study, an application has been submitted to convert 1,397ha of the Naki-Est and Borgou Exploration Permits to an Exploitation Permit.
MINERAL RESOURCE & ORE RESERVES
The Nayega mineralisation is considered to be superficial, formed by leaching and residual enrichment in a lateritic weathering environment. The Nayega deposit comprises eluvial rubble of manganese oxides ranging in size from flakes to cobbles, overlying detrital and in-situ manganese ore extending up to 10m below surface blanketed by a veneer of detrital material that averages 0.5m thick. Mineralisation extends over a strike length of 2.2km at widths of up to 500m.
The database for the resource estimation consists of information collected from pits hand excavated on the deposit between November 2011 and April 2013. A total of 193 pits were excavated in three phases, for 767.49m cumulative total depth.
The orebody is layered, directly reflecting the intensity of weathering comprising an in-situ ore subdivided into lateritic, transitional (laterite-saprolite) and saprolitic zones, overlain by a detrital ore.
- Detrital ore comprises fragments of hard manganese oxides in a loosely cemented ferruginous clay and goethite matrix.
- Lateritic (most weathered) ore consists of bands and nodules of hard manganese oxides with small inclusions of quartz and clay in a gangue of red ferruginous clay and goethite.
- Transitional ore has characteristics of both lateritic and saprolitic mineralisation, with bands and nodules of hard manganese oxides trending downwards into fine grained, platy manganese oxides in a variably goethitic and ferruginous clay matrix.
- Saprolitic (least weathered) ore consists of platy, fine grained (typically up to a few millimetres) manganese oxides set in a white clay-quartz gangue.
The Nayega resource has been classified in the Measured and Indicated categories. The majority of the mineral resource has been classified as Indicated, with a Measured area outlined where 50m infill pits have been excavated within the northern third of the resource footprint. The Mineral Resource and Ore Reserve estimation was undertaken independently by Widenbar & Associates in Perth, Australia in accordance with JORC Code, 2012 definitions.
In addition to the Nayega resource, there are two additional satellite deposits in close proximity to the main orebody, namely the T27 and T48 deposits which are both classified as Inferred Mineral Resources.
The Mineral Resource estimated for Nayega (5% Mn cutoff) is tabulated below.
|(MT)||Mn Grade (%)|
The Ore Reserve generated from the Measured and Indicated Mineral Resources by optimization studies is tabulated below.
|DILUTED (Mt)||MN GRADE (%)|
The T48 and T27 project areas lying adjacent to the main orebody comprise 100% of the Inferred Mineral Resources. The T48 and T27 mineral resources have been included in the optimisation and the mining schedule post year 5 and have been classified as additional in-pit Mineral Inventory.
|DILUTED (Mt)||MN GRADE (%)|
Resource Expansion Potential
In September 2018 Keras identified an additional area initially estimated to cover approximately 8ha of manganese mineralisation at a new prospect known as Ogaro. This is located 5km east-southeast of the main Nayega deposit and 4km south of the T27 deposit.
Pits excavated to test the core area of mineralisation at Ogaro have returned positive results, with best intercepts including 1.76m @ 18.6% Mn from 0m, 2.05m @ 15.8% Mn from 0m and 2.00m @ 16.2% Mn from 0m.
The discovery demonstrates the wider reaching propectivity and further value uplift potential of Nayega. Further exploration work is to be undertaken to better prove up confidence in Ogaro with a view to enhancing the total resource inventory at Nayega.
Metallurgical Testwork and Bulk Sample
Metallurgical testwork conducted on the Nayega ore shows that a simple scrubbing, screening and dense media separating (DMS) circuit will be required to upgrade the mined ore.
The testwork indicates that all types of ore require standard wet scrubbing to assist with manganese liberation from gangue phases and importantly the scrubbed material shows an affinity to pre-concentration by simple screening. The testwork indicates that recoveries of over 90% Mn are achievable whilst rejecting 50 to 60% of the mass feed. The screening produces an oversize fraction (+25mm) which is transferred directly to an ore stockpile.
The -25/mm +1mm screened material will be conveyed from the scrubber product screen to the DMS. The average feed grade to the DMS will be approximately 32.5% Mn post the screening. DRA Pacific undertook some DMS simulations and proposes to use a density cut-point of approximately 3.1g/cc to achieve the desired 38% Mn product.
To build upon these results and this metallurgical understanding, in August 2018 a bulk sampling metallurgical testwork programme commenced at Nayega. 10,000t of beneficiated manganese ore (Mn) is being excavated and will be sampled and processed by a major producer of manganese-based alloys in order to assess the suitability of the ore in their smelting facilities. The testwork, which will cost an estimated US$1.5m, is being fully funded by the end user, including capital equipment, operating and logistics costs and Keras management fees.
Although this is a single bulk sample exercise, Keras has opted to purchase the bespoke scrubber plant rather than outsource to ensure that the optimal grade is achieved during this programme and so the Company can seamlessly transition to commercial production once relevant approval is granted. The entire bulk sampling programme is estimated to be completed in mid-January 2019.
Based on work conducted to date, the Company is confident that Nayega will provide positive cash flow through the rapid development of a low-capex, 250,000tpa open pit, 38% manganese product operation. The orebody lends itself to a low cost free-digging with a screening operation followed by dense media separation (DMS) for the material that requires additional upgrading. The following parameters have been used for the internal feasibility study:
- Mining will be undertaken from an open pit utilising excavators, front-end-loaders and haul trucks.
- Treatment will involve crushing the ROM ore before processing through a scrubber/DMS circuit. It is intended that SGM will own the process plant to be constructed by a reputable contractor.
- Product will be trucked from Nayega to the Port of Lomé.
- Tailings will be disposed of in a purpose-built facility located adjacent to the plant and later in mined out pits.
- Water will be sourced via boreholes that have been drilled.
- Power will be sourced from the local grid and on-site generators.
- No accommodation is planned with employees being paid a suitable housing allowance as part of their remuneration.
The environmental and social study was submitted to the Ministry of Environment earlier in 2014 and was granted in October 2014. With the Environmental Permit secured, Keras is continuing to focus on finalising securing the Exploitation Permit and is engaged in constructive discussions with the Ministry of Mines and other regulatory bodies in Togo on how to progress the Nayega project into a profitable mine. The approval for the large-scale metallurgical bulk sample is a significant step forward in these discussions, marking a milestone development in the progression towards regulatory approval for commercial production.