Name and Location
Bibiani gold project, Ghana.

Client
Resolute Mining.

Project Description
The Bibiani project has an initial ore reserve of 5.4-million tonnes grading 3.7 g/t containing 640 000 oz of gold and mineral resources of 1.9-million tonnes grading 3.6 g/t for 1.1-million ounces of gold.

Resolute aims to re-establish an underground mine at the project.
A feasibility study completed on the project has confirmed a viable development pathway.
The study contemplates production of up to 1.2-million tonnes a year from long hole, open stope underground mining.

The stope will be started through a slot raise at one end of the ore drive and then mined by progressively firing the drill rings and retreating along strike.
Level designs will comprise:
• main level access, excavated 5.5 m wide × 5.5 m high with an arched profile;
• footwall drives, excavated 5.5 m wide × 5.5 m high;
• cross cuts and ore drives designed to fit long hole drills and loaders;
• stockpiles for storing stope ore ready for truck loading, placed every 150 m along the footwall drive; and
• a sump, placed in the main level access and linked to the lower levels through a drain hole.
The study proposes mining 100 000 t/m of ore, with about 25 000 t/m of waste providing a total rock movement of 125 000 t/m.
Ore processing will occur at the existing Bibiani processing plant.

A review of the current ore treatment plant at Bibiani and the results of testwork to date have been used to develop an effective processing flowsheet to achieve satisfactory recovery. Gold is predominantly fine and occurs along edges or cracks in pyrite and arsenopyrite sulphide minerals.
The process design produces a sulphide concentrate by flotation at a primary grind size of P80 106 μm. Concentrate is fine ground to P80 25 μm before cyanidation. The flotation tails are also cyanide leached. Gold recovery is by carbon-in-leach (CIL).
Key process design parameters include:
• primary crushing to a P80 of 120 mm;
• milling, using the existing semiauto-genous mill operation in single-stage closed circuit, producing a product size of P80 106 μm;
• flash flotation to a target mass pull of 2%;
• scavenger flotation, which together with the flash flotation concentrate recovers a total combined concentrate of 93% gold, 98% sulphides and 60% organic carbon, into a concentrate mass that comprises 10% of new feed;
• concentrate regrind; and
• leaching of concentrate in a CIL circuit.

Gold production is expected to be maintained at an estimated 100 000 oz/y, which will sustain a five-year mine life on the initial ore reserve.

Net Present Value/Internal Rate of Return
Not stated.

Value
Preproduction capital expenditure is estimated at $72-million, including $29-million for underground mining equipment.

Duration
The project has a short lead time of only nine months to production from the start of construction.

Latest Developments
Resolute has indicated that substantial opportunity exists to enhance the outcomes of the feasibility study. While defining a viable development pathway based on the initial ore reserve, the study has also highlighted the strong economic benefit of upgrading the higher-grade portions of the inferred resource.
The existing inferred resource of 4.5-million tonnes grading 4.1 g/t could be upgraded to indicated resources, with a modest investment in additional drilling.
Most of this material occurs close to the current probable reserves. Consequently, any development planned to access the current reserves could be used to extract this material at minimal additional cost.
The company will consider options for undertaking the necessary drilling to upgrade this resource in the coming months. Substantial potential for the discovery of additional mineralisation below the current reserves is also possible. The original workings at Bibiani extend to about 800 m below surface. The current 1.9-million-ounce resource considers only the area between the base of the pit at about 200 m below surface, and the limit of Resolute’s drilling at about 450 m below surface. There is considerable exploration upside in these areas and along strike to the north.
Resolute sees opportunities to introduce emerging technologies in mining and processing at Bibiani to improve productivity and safety and reduce costs.

Key Contracts and Suppliers
None stated.

On Budget and on Time?
Not stated.

Contact Details for Project Information
Resolute Mining, tel +61 8 9261 6100, fax +61 8 9322 7597 or email contact@rml.com.au.