Modern Mining October 2018

GOLD

cyclones, re-crush, flotation (to produce a 15 to 17 g/t Au concentrate), regrind and a car- bon-in-leach circuit comprising one pre-leach tank and seven CIL tanks for gold and silver adsorption. A gravity concentration circuit has been incorporated given the presence of gravity recoverable gold (GRG) and will consist of a gravity scalping screen, a single 70-inch cen- trifugal concentrator and a CS4000 intensive leach reactor. A 3,5-tonne split AARL elution circuit, elec- trowinning and smelting will recover gold and silver and produce doré on site. A metallurgical recovery of 86 % is esti- mated for the Starter Pit and 84 % for the Life of Mine (LOM). In terms of infrastructure, the site will be accessed by road from the west with a new, approximately 25 km, gravel road linking the site to the existing national road N10 between Pwalagu and Winkogo. The N10 provides good access to the major cities and ports in southern Ghana and no upgrades of the N10 will be required. Serviced camp-style accommodation will also be integrated in the proximity of the opera- tion. A shuttle bus service will operate to and from site as required. The project will run on grid power although it is envisaged that emergency power for pro- cess plant essential drives/facilities during grid power supply outages will be supplied from two 2,5 MVA, High Speed (HS) diesel genera- tor units operating on diesel fuel oil. Two tailings storage facilities are required. The Flotation Tailings Storage Facility (TSF) will be constructed as a side valley-type stor- age facility to the south-west of the open pit. The facility will be constructed as two cells with zoned earth fill perimeter embankments and will be lined with a low permeability com- pacted soil liner. The total basin area will be

311 ha and is designed to accommodate 113 Mt of tailings. The CIL TSF will be constructed as a pad- dock-type storage facility to the south of the open pit. The facility will be constructed as a single cell with zoned earthfill perimeter embankments and will be lined with com- pacted soil liner overlain by a synthetic HDPE geomembrane. The total basin area will be approximately 45 ha and is designed to accom- modate 16 Mt of tailings. Commenting on the results of the PFS, Koimtsidis said: “We now have a compel- ling Business Case to move into the Definitive Feasibility Study (DFS) phase for the 9,5 Mt/a throughput processing facility based upon the optimum Return On Capital Employed (ROCE). The Feasibility Study (FS) is fully funded and will form the basis for the development of our Namdini project in Ghana with completion anticipated in Q3 2019. “The PFS study confirms the Namdini project as one of Ghana’s and Africa’s most promising undeveloped, large gold assets. The financial modelling of the project shows it to be techni- cally sound and financially viable and could generate US$ 1,4 billion free cash flow (pre-tax) utilising the 9,5 Mt/a throughput model.” 

Long section through the Namdini pit showing grade distribution.

October 2018  MODERN MINING  33