The Namdini has many characteristics typical of mesothermal Birimian gold deposits.

The Namdini gold deposit is a large, structurally controlled, orogenic gold deposit within the Nangodi Greenstone Belt, with numerous features similar to deposits found elsewhere in late Proterozoic Birimian terranes of West Africa. To date the Namdini gold deposit has been delineated over a strike length of 1.15 km, up to 300 m wide and 700 m deep.

The rock types comprising the Namdini Gold Project included a steeply west dipping Birimian sequence of interbedded, foliated, metasedimentary and metavolcanic units which have been intruded by a medium-grained granitoid and diorite. The southern part of the Project is covered by flat-lying Voltaian Basin clastic sedimentary rocks that have been deposited unconformably on the Birimian sequence and postdate mineralization and the host sequence.

Underneath the weathering profile, the Birimian units include metasedimentary, metavolcanic, granitoid (tonalite) and diorite. The metasedimentary and volcaniclastic lithologies have been intensely altered with a resulting pyrite-carbonate-muscovite-chlorite-quartz assemblage. Alteration is most prevalent in the volcaniclastic units. Similarly, the tonalite is extensively altered and has been overprinted by silica-sericitecarbonate assemblages.

In all rock types, the mineralization is accompanied by visible disseminated sulfides of pyrite and very minor arsenopyrite in both the veins and wall rocks. In diamond drill core, the mineralized zones are visually distinctive due to the presence of millimetre to centimetre wide quartz carbonate veins that are commonly folded and possess yellow-brown sericite-carbonate selvages. Rare visible gold occurs in strongly altered granite and is associated with sub-millimetre wide silica-sericite shears.

Typical shallow weathered zone:
- Average base of strong oxidation: 7m
- Average depth to fresh bedrock: 15m

Gold mineralisation:
- Localised in the 300-400m wide Namdini mineralised “corridor”
- Dominantly hosted by the three main lithologies located within it: Metavolcanics, granitoid and diorite.

Gold at Namdini is dominated by electrum (80% of measured grains) with the remainder as native gold.

Gold grains are generally fine; QEMScan analysis indicates 89% <10 microns.

Visible gold is rare and usually occurs as a vein selvage with chlorite in late-stage remobilised veins.

Gold dominantly occurs as inclusions and fractures in;
- Pyrite (75%)
- Arsenopyrite (8%)
- Quartz and other silicates (6%)
- Chalcopyrite (2.5%).

Circa 5% of gold grains are free gold.

Sulphides in decreasing order of abundance are:
- Pyrite, arsenopyrite, chalcopyrite, galena
- Trace sphalerite, molybdenite, pyrrhotite, gersdorffite and tennantite
- Rutile, ilmenite and magnetite are alsob associated with gold mineralised zones
- Pyrite mostly exhibits grain sizes in the 20 to 140 micron range.

Drilling has outlined mineralization with three-dimensional continuity, with a size of approximately 1,500 m long, 550 m wide, and 450 m in depth.

The primary rock is a muscovite rich phyllite that shows extensive carbonate replacement. The phyllite hosts a major sulfide content and significant gold. The fine-grained muscovite shows a moderate preferred orientation and is heavily impregnated with ankerite carbonate.

The dominant ore minerals are pyrite and arsenopyrite that occur relatively commonly through much of the phyllite matrix. Tennantite, chalcopyrite, pyrrhotite, galena, and sphalerite all occur as fines within some pyrites. Magnetite was also detected once.

About 25 occurrences of gold were detected optically. The vast majority occur as inclusions in pyrite. The gold appeared low in silver. These included golds in pyrites that were predominantly under 5 µm, with the exceptions of a linear nature, reaching 25 µm. Most were single particles plus a rare trio.

The host pyrites had a wide range of grainsizes from 50 to 600 µm. Two occurrences of gold were single, fine grains of 2 µm within silicate.

Mining will consist of a conventional hydraulic shovel operation typically using 400 t class excavators in a face shovel configuration and 150 t class (Cat 785 or similar) rigid body dump trucks hauling on designed access roads. An auxiliary mining fleet of dozers, graders, water carts and utility vehicles will support the mining operation.

The mine design for the Namdini Gold Project consists of a series of nested conventional open pit layouts with orebody access provided through a series of ramps. For mining purposes, the Namdini orebody can be considered a layered sequence consisting of:
* strongly Oxidized upper weathered zone
* moderately Oxidized zone with total oxidization of sulfides extending to approximately 10 m average depth (this and the material above it comprise the Oxide zone)
* Transition zone with partial oxidization of sulfides extending to approximately 18 m average depth
* Fresh non-mineralized meta-sediment sequence
* Fresh mineralized host sequence of meta-volcaniclastics, granitoids (tonalite), and diorites.

In the Oxide and Transition zones, a mixture of free-digging, ripping and blasting (after drilling) will be used. In the Fresh zone, competent material at depth will need conventional pre-splitting, drilling and blasting to fragment the rock for excavation. The Oxide and Transition zones are limited in extent with the Oxide zone seldom greater than 20 m below surface. The Transition layer appears more pronounced at the southern end of the final pit mining area and is of limited thickness throughout the remainder of the planned mining area. Figure 80 shows the Oxide, Transition and Fresh zones within the planned final pit extent.

The Mid Case option was used to estimate the ore and waste trucking requirements by period based on the tonnes mined by bench for that period. The Mid Case option requires a peak truck requirement of about 23 trucks. The schedules considered only a single size truck, with minimal selective ore mining requirement.

Mining is expected to be carried out on 10 m benches, with two 5 m flitches for ore mining within a 10 m bench.

High level mine production schedules were evaluated for the three scenarios considered (9.5, 7.0 and 4.5 Mtpa mill throughputs) using a Starter Pit with subsequent pushbacks to the final LOM pit extent.

The schedules allowed an initial ramp up for the process plant in each case before full process plant production was assumed. In order to gain maximum value from the 9.5 Mtpa option, an estimated total peak rock movement of some 30 Mtpa is required in year 7 of the schedule, whereas the 7.0 Mtpa option indicated a total peak required movement of some 17 Mtpa. The 4.5 Mtpa option saw a peak total required rock movement of some 15 Mtpa.

The key project and ore specific criteria that the plant design will meet are:
* The plant is designed for an initial throughput of 7 Mtpa
* Crushing plant mechanical availability of 75%
* Mechanical availability for the remainder of the plant of 91.3%
* A moderate level of automation to provide control of the key process parameters.

The proposed plant incorporates primary crushing, grinding and re-crush (SABC), gravity, flotation, concentrate regrind and CIL gold extraction.

The process plant design incorporates the following unit process operations:
* Single stage primary crushing with a gyratory crusher to produce a crushed product size of 80% passing (“P80”) 150 mm.
* Crushed ore feeding a coarse ore stockpile (12 hours live). Ore reclaim by two apron feeders.
* Two stage SAG/Ball milling in closed circuit with cyclones to produce a P80 grind size of 106 µm and includes recycle and crush of pebbles from the SAG mill (SABC grinding).
* Gravity recovery includes a scalping screen, a single 70 inch centrifugal concentrator and a CS4000 intensive leach reactor.
* Rougher scavenger flotation to produce a gold-rich sulfide concentrate.
* Thickening of the flotation tails for water recovery prior to disposal in a separate non-cyanide Tailings Storage Facility.
* High Intensity Regrind of the flotation concentrate to a P98 grind size of 15 µm followed by thickening to minimize carbon-in-leach (“CIL”) tankage and reduce overall reagent consumption.
* A concentrate CIL circuit incorporating one pre-leach tank and seven CIL tanks for gold and silver adsorption.
* A 3.5 tonne split AngloAmerican Research Laboratory (“AARL”) elution circuit, electrowinning and smelting to recover gold and silver and produce doré.
* CIL tailings treatment incorporating cyanide destruction by sulfur dioxide and oxygen.
* Concentrate CIL Tailings disposal in a lined tailings storage facility.

Ore will be trucked and either direct tipped or dumped onto the ROM Pad for blending and rehandling into the ROM feed pocket.

Crushing circuit.
ROM ore will generally be deposited into the feed pocket by direct tip with front-end loader (FEL) reclaim where required. A fixed rock breaker will be used to break up any oversize material. The crusher selected is a 45'' by 65'' gyratory crusher with a 375 kW motor. The gyratory crusher product will discharge into a chamber with two trucks live capacity. From the discharge chamber, the primary apron feeder will transfer crushed ore onto the primary discharge conveyor in turn feeding the stockpile feed conveyor onto the coarse ore stockpile. A 5 t capacity maintenance crane will be provided for the crusher and a 2 t hoist for the apron feeder.


Grinding and classification circuit.
The grinding circuit will consist of an SABC circuit with hydrocyclones. Feed from the coarse ore stockpile will be conveyed to the SAG mill feed chute where it will be diluted with water. A 10.36 m diameter * 6.15 m EGL SAG mill will grind crushed ore from a F80 of 150 mm to produce the target transfer P80 size of 1,000 to 2,500 ^m. The SAG mill will be equipped with two 7.35 MW variable speed drives to provide a total of 14,700 kW installed power.

SAG mill grinding media typically 125 mm diameter balls will be loaded by FEL into a SAG mill ball hopper for transfer to the mill feed conveyor.

Product from the SAG mill will discharge to a vibrating single deck pebble dewatering screen fitted with a nominal 12 mm slotted aperture screen. Pebble screen undersize will flow to the cyclone feed hopper.

The SAG and ball mill discharge will feed a combined cyclone feed hopper and will be diluted with water prior to classification. The mill discharge slurry will be pumped using duty/stand-by pumps to the classifying cyclones. The cyclone cluster will comprise 11 * 650 mm diameter cyclones operating at 80 kPa. The cluster will have eight cyclones in duty and three in stand-by for maintenance purposes. Cyclone overflow will report to trash screening and cyclone underflow will feed the ball mill with a portion reporting to the gravity circuit.

The ball mill will be a 7.31 m diameter * 11.55 m EGL overflow mill with a target grind P80 size of 106 pm. The ball mill will be equipped with two 5.85 MW fixed speed drives giving a total installed power of 11,700 kW. The design mill rotation speed will be 75% of critical speed.

Gravity circuit.
A bleed from the classification cyclone underflow will feed a 3.7 by 7.0 m scalping screen with 2.4 mm apertures. The screen oversize will flow to the ball mill feed while the screen underflow will feed the gravity concentrator. The concentrator will be a 70 inch diameter centrifugal unit complete with variable speed drive and a dedicated fluidising water system.

The unit will operate on a 60 minute (nominal) cycle time. After 60 minutes it will bypass feed to ball mill feed and start a flush cycle. Gravity concentrate will gravitate to an intensive leach reactor.

Flotation and regrind.
Slurry from the trash screen will flow to the flotation conditioning tank where frother and collector will be added.

The conditioned slurry will then flow to the first of six 200 m3 capacity forced air flotation cells arranged in a straight configuration with total residence time of 32 minutes. Flotation tails will discharge from the last cell to the flotation tails hopper from which it will be pumped to the float tails thickener. The design assumes a mass pull of 7.5%. Two sump pumps are provided for spillage handling in this area.

Flotation concentrate will be pumped to the regrind classifying cyclones for classification prior to regrind. The regrind cyclone cluster will consist of 6 * 250 mm diameter cyclones operating at 80 kPa. The cluster will have four cyclones in duty and two in stand-by for maintenance purposes. The cyclones will cut at a P98 of 15 pm to produce an overflow containing 30% of the feed with the overflow passing to the flotation concentrate thickener.

The cyclone underflow will flow to a HIG Mill equipped with a 2,300 kW variable speed drive. The regrind mill product with a P98 size of 15 pm will then flow to the float concentrate thickener.

The HIG mill will be charged with 3 mm ceramic media, which will be loaded by a media hopper and screw feeder. A single sump pump will be provided for this area.

Concentrate will be thickened in an 18 m diameter high rate thickener ahead of the CIL circuit to provide a higher slurry density to the CIL. Flocculant will be added to the feed and the underflow at 55% w/w solids will be pumped to the CIL feed box.

Leach and carbon adsorption circuit.
The leach process will include one pre-leach tank and seven CIL tanks. The pre-leach tank and the CIL tanks will have a volume of 1,000 m3. Each tank will be fitted with a dual impeller mechanical agitator to ensure uniform mixing. The CIL tanks will have a mechanically swept wedge wire inter-tank screen to retain carbon and facilitate controlled transfer. The CIL process will have a residence time of 72 hours at 66 t/h solids at 50% w/w density to provide optimal recovery of gold.

Stripping plant and gold room.
The following operations will be carried out in the stripping and gold room areas:
* Acid washing of carbon
* Stripping of gold from loaded carbon using the split AARL method
* Electrowinning of gold from pregnant solution
* Smelting of electrowinning products.