Focused on Growing Production
Phase 1: 250,000 - 350,000 ounces annual production by leveraging off existing infrastructure
Phase 2: 400,000 to 500,000 oz annual production
Sabodala Gold Mine - Operations
The Sabodala Gold Mine that anchors Teranga's West African operations is located in a region of Senegal that has only recently been opened for mining and exploration. The region is emerging as a significant new gold camp, with more than 10 million ounces of resources already discovered. The Sabodala gold project is the only large-scale gold mine to come into operation in Senegal.
Mining of the Sabodala gold mine commenced in June 2008, commissioning of the plant occurred in early 2009, and the mine’s first gold was poured in March 2009. The mine was officially opened on June 3, 2009 by the President of Senegal, His Excellency Abdoulaye Wade.
Mining of the Sabodala open pit is carried out by owner operated conventional truck and shovel open pit mining. The loading fleet is made up of two PC3000 hydraulic excavator, one PC2000 hydraulic excavator and two WA900 wheel loaders. The primary material mover is carried out with 19 HD785-7 Komatsu haul trucks. Manpower consists of approximately 130 operators, an increase from early 2012 as a result of the plant expansion. An additional PC-3000 and 5 HD785 haul trucks have been ordered and are expected to be delivered to site late in Q2-2013 for additional material movement capacity.
The mine plan uses two cut-off grades for production assumptions. The higher cut-off grade is used to define material that can be treated economically in the plant at the time of production, whereas the material above the incremental cut-off grade will be mined and stockpiled and, depending on the economics of production at the time, will be treated at the end of the mine life.
The mining schedule is driven by balancing the truck hours required to deliver ore to the ROM pad and waste to the dumps annually in concert with the loading capacity. Ore in excess of process plant requirements is selectively stockpiled throughout the life of the operation.
Based on the mining schedule, the average cost of mining is U.S.$2.25 per tonne for oxide/softer material and U.S.$2.65 per tonne for fresh/harder material. This mining cost is based on a diesel cost of $1.10/1.20 per liter, a 685CFA per U.S.$ exchange rate and a U.S.$1.25/1.37 per Euro exchange rate. Mining phases or pit stages are sequenced to maximize gold production annually.
The Sabodala pit has a final depth of 300 metres at the end of the fourth mining phase, with final dimensions at the pit surface of 900 metres by 1100 metres. The Gora pit is approximately 350m wide by 1000 meters long, with a depth to 120 meters depth from surface. The pit dimensions for the Niakafiri Pit at surface are 360 metres by 460 metres, with a final mined depth of 90 metres.
Over $500 million has been invested to date.
Somigol owns 100% of the OJVG Golouma Gold Project subject to a 10% carried interest held by the government of Senegal. The Golouma Gold Project is being integrated into the Sabodala Mine License.
OJVG Golouma Gold Project
The OJVG Golouma Gold Project (the "Project") is an advanced stage low risk, construction ready gold project located in Senegal.
The Project is located in eastern Senegal, 600 km southeast of the capital city of Dakar, within an emerging West African gold-mining district similar to nearby producing gold camps across the border in Mali. The 212 km² project is accessible year round by air and all weather roads, which provide excellent operational logistics.
The Project is underlain by the Early Proterozoic, Birimian-age Mako Group, an orogenic greenstone belt comprising metavolcanics, sediments and lesser intrusives. These rocks are part of the Kedougou-Kinieba inlier and are locally crosscut by splays of the Kakadian-Kerekoto shear zone. The structural and geological setting is similar to world-class gold camps in West Africa and Canada, known for hosting multiple long-lived mines with extensive lateral and vertical dimensions.
Oromin and its partners secured rights to the Project through an open tender process in 2004. Initial exploration focused on methodical evaluation on a property-wide scale which included reconnaissance prospecting, geochemical sampling, geophysical surveys and geological/structural mapping. Subsequent exploration activities advanced to detailed sampling, mechanical trenching and extensive drilling, both reverse circulation and diamond core drilling.
Currently, 14 gold deposits have been discovered on this advanced exploration property, all of which remain open to further expansion. In addition, a minimum of 14 early-stage prospects have also been identified by ongoing exploration activities.
The total indicated resource for all deposits at the Project is 75.21 million tonnes grading 1.56 g/t Au containing 3.78 million ounces of gold. The total inferred resource for all deposits at the Project is 17.33 million tonnes grading 1.73 g/t Au, containing 0.96 million ounces of gold. The Project's current Probable Reserve is 2.34 million ounces (28 Mt grading 2.59 g/t Au). This is currently the largest gold reserve in Senegal.
Processing and Engineering - Sabodala
The Sabodala ore is a medium to hard silicified breccia with fine grained gold, mainly associated with pyrite but also with a small amount of liberated gold present.
The gold is recovered in the 89%-92% range with an average grind of 80% passing 75μm. There is potential for additional recovery and performance improvement with installation of a gravity circuit. The gold extraction process uses a conventional carbon-in-leach (“CIL”) flowsheet. The major equipment comprises of two stage crushing with a primary jaw and secondary cone crushing system. This is followed by one SAG mill transferred into a return pebble crusher, sizer by cyclone and two ball mills. During the leaching process, the gold leaches into solution in leach tanks when in contact with cyanide, then absorbs onto the carbon to liberate gold from the ore before being captured with the activated carbon. After elution and electrolysis, the gold is recovered by fusion and poured into ingots.
The major equipment in the process plant includes:
• Primary crusher: Nordberg C140S single toggle jaw crusher
• Secondary crusher: Sandvik CH660 cone crusher
• SAG Mill Outotec 7.3m x 4.3m EGL, 4000 kW
• Ball Mills (x2) Outotec 5.5m x 7.85m EGL 4000 kW
• Recycle (Pebble) crusher: Metso HP200SX Cone crusher
• CIL circuit: 9x 1240m³ with compressed air injection
• Elution circuit: 5t batch capacity, split AARL elution
• Tailings Thickener (x2) Outotec 23m high rate thickener
Since completion of the expansion project, the capacity of the process plant is approximately 3.5 Mtpa of purely fresh ore and is expected to exceed 4.0 Mtpa with a blend of 75% fresh and 25% oxidized ore.
Actual plant performance has met throughput predictions but is still going through the final optimization stages for maximum mill throughput with the revised design (~380tph at present ramping to 420tph for fresh ore). The gold recovery has exceeded expectations with 89%-92% achieved without a gravity circuit. A recovery model has been developed showing 92.8% for oxide ore and with a head grade dependent algorithm for fresh ore of the form 86.7% + 1.55 Au(g/t), capped at 94.5%. For a typical 75/25 fresh/oxide blend and head grades of 2g/t the predicted recovery of 90.6% is in line with plant performance.
The mine power is sourced from a 30 MW heavy fuel oil power station and has an installed reserve 6 MW unit. Water is drawn from two dams with a combined capacity of approximately 11 million cubic metres, which can also be supplemented from water sourced via a pipeline from the Faleme river.
In Kédougou, the highest monthly average temperatures are between March and May, 31ºC to 40ºC. The lowest monthly average minimum temperatures are between December and January, 17ºC to 26ºC. The annual Harmattan is a dry wind which blows from the north, usually from December to February, resulting in dusty and hazy skies. There is a distinct tropical wet season from June to October, with the most rain falling from storms between August and September, and a dry season from December to April. Mean annual rainfall at the Sabodala project is estimated to be 1,130 mm.
It is possible to operate in Senegal on a year-round basis, but the schedule allows for a reduced mining rate and for predominantly fresh ore to be processed during the height of the wet season, mainly the third quarter.
Local Resources, Personnel and Infrastructure
The main camp is located approximately 3 km from the mine and 2 km from the plant and is designed to house up to 680 employees. Sufficient capacity exists in the fuel farm to accommodate the expanding mining fleet.
Teranga provides for the majority of its own infrastructure needs. Power is generated at the site using low speed, heavy fuel oil generators. A 30MW 5 unit engine heavy fuel oil power plant was constructed by MDL, and subsequently expanded to 36MW with the mill expansion in 2012. Water supply to service the processing plant and mine comprises two surface water storage dams from local catchment areas. These dams are designed to store adequate water from seasonal rainfall events to provide for all production needs on a year-round basis. For emergency purposes, the site has a water pipe, including water access rights, to pump water from the Faleme river, if required. There are sufficient waste disposal areas and tailings storage areas. The Company constructed a plant and supporting facilities at the site including offices, shops and warehouses. Existing port facilities at Dakar are utilized for unloading of all equipment, spares and consumables for the mine. A significant proportion of the personnel involved in the mining operations have been sourced from the local villages, surrounding regions and Dakar.
The Sabodala Mining Concession and the surrounding exploration permits are located in the 2,213 Ma to 2,198 Ma age Kedougou-Kenieba Inlier (see schematic below), which lies within the Paleoproterozoic age Birimian Terrane of the West African Craton. The permits straddle two major divisions of the Inlier – the volcanic-dominated Mako Supergroup to the west, and the sediment-dominated Diale-Dalema Supergroup to the east. The Sabodala deposit and western portions of the company's concessions in the Faleme and Near Mine projects are hosted in the Mako belt.
To the east the Diale-Dalema metasedimentary sequence is composed dominantly of a folded, sandy turbidite succession that is intruded by small stocks and dykes of various composition.
The Mako and Diale-Dalema supracrustal sequences are intruded by a series of variably deformed granitoid intrusions that range in age from 2,160 Ma to 2,000 Ma. These include the Karkadian Batholith which bounds the Mako Belt to the west, and several major large stocks in the central Mako Belt in the project areas. Lithologies in the region are affected mainly by lower green schist grade metamorphism. Northeast trending intermediate to felsic and later, post-tectonic mafic dykes are present throughout the region, the latter forming prominent linear magnetic features. Felsic and intermediate composition dykes are often spatially associated with shear zones hosting gold mineralization, and locally are host to significant gold mineralization themselves.
The Sabodala deposit is situated in the Mako Volcanic Belt. Locally the volcanics are intruded by subvolcanic dolerite and gabbro sills and dykes and also quartz- feldspar porphyry and unfoliated rhyolite dykes. Interflow sediments parallel the layering in the sequence. There are excellent outcrops of the volcanics to the east of the deposit, which indicate a general north-northeasterly striking sequence dipping steeply to the west. The lowest unit of the volcanic stratigraphy consists of magnesium-rich (komatiitic) basaltic rocks including massive, variolitic textured flows. Interflow carbonaceous and siliceous sediments, that are discontinuous along strike, have variable thickness between 0.2 metres and 1.0 metres.
The Sabodala Shear Zone is approximately 2 km wide and is identified by a subtle magnetic trend that extends through the 7 km long permit and transects volcanic stratigraphy.
The largest and best understood deposit in the company's properties is Sabodala due to its production status and size, so this deposit is described in most detail. Gold deposits on the adjacent properties of Oromin are of similar style, and include primarily shear vein systems and bulk tonnage, lower grade mineralization in carbonate altered ultramafic rocks along shear zones.
For more information on Property Geology, please click here.