Exploration
Overview
The Sartenga copper-gold-molybdenum project is a large tonnage porphyry system which is unique in the Biriman rocks of West Africa. The Inferred Mineral Resource contains 174,000t copper and 651,000oz gold. The dominant sulphide is bornite and therefore mineralisation has the potential to create a high-grade copper-gold concentrate. The project is close to infrastructure including rail to port less than 40km from the project.
Tenure
The Company acquired a 100% interest in the Sartenga Permit in 2012.
Geology
The mineralised zone at Sartenga is contained within a southwest-northeast trending envelope parallel to the regional shear direction and is associated with a steeply north west dipping shear corridor at the contact between meta-sediments to the north west, and silicified intermediate porphyritic diorites to the southeast. The metasediments are represented by greenschist facies quartz-sericite schists. Drilling has shown that the contact zone between the mafic-intermediate rocks and the metasediments is complex and strongly overprinted by shearing and a series of alteration assemblages throughout. The occurrence of the mineralisation suggests a process of extensive alteration of wall rock lithologies resulting from proximity to the mineralising fluid pathways within the shear corridor.
The dominant sulphide mineral in the primary sulphide at Sartenga is bornite (Cu5FeS4) representing more than 95% of copper metal in the samples studied. Molybdenite (MoS2) is the second most dominant sulphide mineral. Free gold was also noted in the study and is generally located along sulphide mineral boundaries. No gangue minerals were identified during the mineralogical assessment that would cause deleterious effects to the flotation of economic sulphides. Very rare amounts of pyrite were noted in the drill core samples studied.
Magnified polished thin section of Sartenga primary mineralisation showing relationship with bornite, molybdenite and gold – Sartenga Project
Resources
In June 2013, WAF reported a maiden JORC (2004) Inferred Resource Estimate for the Sartenga Copper Gold Project. The Mineral Resource was independently calculated by Ravensgate Mineral Industry Resource Consultants and is discussed in the following sections.
The block model was constructed using 10mX, 25mY, and 5mZ blocks (East, North, Elev) and utilised a zone and zone percent coding to accurately represent material volumes. The model was rotated 45 degrees to parallel the main strike of mineralisation.
Ordinary kriging was selected as the most appropriate method for estimating Cu, Au and Mo, the main elements of economic significance. Inverse distance interpolation was used to estimate Ag which is of minor significance. Check estimates using inverse distance interpolation were also completed.
The resource extends over an area of approximately 1,600m of strike, 800m width and is interpreted to a depth of between 150 and 300m below surface. As this is a maiden resource for the prospect no scoping study assessment has been completed. However given the grade and location of the deposit it is assumed the most likely development scenario for the deposit would be as an open pit. Based on this a 0.45% CuEq* cut-off is considered to be appropriate for reporting purposes at this stage.
The maiden Inferred Mineral Resource comprises 70 million tonnes at 0.2% copper, 0.3g/t gold, 166g/t molybdenum and 1.1g/t silver using a 0.45% Copper Equivalent cut-off. The table below shows a breakdown of the resource by material type.
| Sartenga Inferred Mineral Resource - June 2013 – using a 0.45% Cu equivalent cut-off | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Grade | Contained Metal | |||||||||
| Zone | Tonnes (Mt) | Cu (%) | Au (g/t) | Mo (g/t) | Ag (g/t) | Copper (Kt) | Gold (Koz) | Mo (Kt) | Silver (Koz) | Copper Eq (Kt) |
| Oxide | 13.5 | 0.3* | 0.3 | 87 | 1.1 | -* | 112 | 1 | 470 | -* |
| Transition | 4.0 | 0.3 | 0.4 | 65 | 1.0 | 11 | 48 | - | 124 | 24 |
| Fresh | 52.8 | 0.2 | 0.3 | 194 | 1.1 | 119 | 491 | 10 | 1868 | 292 |
| Total | 70.4 | 0.2* | 0.3 | 166 | 1.1 | 130* | 651 | 11 | 2463 | 316* |
| Note: Rounding may cause minor discrepancies.*Cu oxide contained metal and Cu equivalent metal are not included in headline reported Inferred Resource (further metallurgical testwork required to demonstrate it can be economically extracted). Cu oxide grades are provided to show tenor of grade Copper equivalent formula = Cu % + Au g/t x 0.70 + Mo g/t x 0.0006 + Ag x 0.016, Price Assumptions: Au (US$1300/oz) Cu (US$2.70/lb) Mo (US$15/lb) Ag (US$30/oz) | ||||||||||
Metallurgy
Preliminary metallurgical test work has been carried out on a composite sample of Sartenga primary ore with a head grade of 0.23% Cu and 0.43g/t Au, at a relatively coarse primary grind size of 106 microns. Flotation rougher recovery of 97.9% was returned for gold, while a recovery of 96.1% was recorded for copper. These very high rougher recoveries indicate that final copper and gold recovery levels into a commercial grade concentrate will also be quite high, potentially in excess of 90%. Future metallurgical work will be directed towards further rougher flotation tests at coarser grind sizes and cleaner flotation test work in advance of producing a commercial grade copper-gold concentrate from Sartenga primary ore.
Also, indicative Bond Ball Mill Work Index (BBMWI) for Sartenga primary ore is in the order of 10kwh/t classifying primary ore as soft. This is very positive for the potential economics for the project indicating lower milling and power costs, per tonne of ore, in comparison to other gold projects in the West African region, which are generally in the order of 15 kwh/t to 20 kwh/t for fresh (primary) ore. These first results provide a very solid foundation from which to carry out further optimization of the metallurgical flow sheet for the Sartenga Copper-Gold Project.
| Sartenga Primary Ore - Rougher Flotation Test Work | ||||||
|---|---|---|---|---|---|---|
| Rougher Products | Cum Wt (g) | Wt % | Cu % | Cum % | Au g/t | Cum % |
| Ro Comp 1 | 17.4 | 1.73 | 11.4 | 84.1 | 19.3 | 77.5 |
| Ro Comp 2 | 30.1 | 2.99 | 7.11 | 90.8 | 12.9 | 89.3 |
| Ro Comp 3 | 48.1 | 4.78 | 4.59 | 93.7 | 8.50 | 94.3 |
| Ro Comp 4 | 75.5 | 7.51 | 3.00 | 96.1 | 5.62 | 97.9 |
| Total | 1005.4 | 100.0 | 0.23 | 100.0 | 0.43 | 100.0 |
Exploration near Sartenga
The Sartenga South prospect is 4km southeast of the Sartenga copper-gold project, and was highlighted by the original 800m by 200m regional auger program covering the entire Sartenga permit. An infill auger program on a 200m by 50m sample spacing was completed in December 2012 and January 2013, which further highlighted a northeast – southwest mineralised trend, which was subsequently followed up with an aircore drilling program on 400m spaced lines across the most anomalous auger results in June and July 2013. Mineralisation at the prospect is more typical gold only style. The best results from aircore drilling to date include 20m at 2.52g/t Au from 36m in SAC1237. The most recent aircore intercepts are shown below.
AC Drillling on auger anomalies at Sartenga South (Gold Zone)