Oromin Explorations has reported the results of two engineering studies for the OJVG gold project in eastern Senegal: a feasibility study for a carbon-in-leach (CIL) project and a preliminary economic assessment (PEA) for a heap leach project.
The CIL project would draw ore from four deposits and would produce 182,000 oz/y during its first three years of production and an average of 144,000 oz/y over a mine life of 17 years.
The heap leach project would be developed independently and would draw ore from separate, lower-grade deposits than the CIL project. The heap leach project would produce 36,000 oz/y during its first three years of production and an average of 27,000 oz/y over a mine life of 14 years.
Oromin Explorations operates and owns 43.5% of the Oromin Joint Venture Group (OJVG), which holds 100% of the OJVG gold project. The balance of the OJVG is held by private companies Bendon International (43.5%) and Badr Investment and Finance (13%).
CIL Project: The OJVG CIL project will include both open-pit and underground mines, with ore trucked to a central plant for crushing, grinding and CIL processing. The mine plans are based on probable mineral reserves of 28 million mt grading 2.59 g/mt and containing 2.335 million oz of gold. Life-of-mine gold recovery is estimated at 90.8%
The total CIL pre-production capital cost is estimated at $297.1 million, including a $27.9-million contingency. Operating costs are estimated at $489/oz during the first three years of operation and $654/oz over the life of the mine.
CIL throughput rates will vary between 4,500 and 7,500 mt/d based on the ratio of oxide to sulphide ore being processed. On average, mill feed is expected to include about 1.7 million mt/y of sulphide ore and 2.7 million mt/y of oxide ore. The plant has been designed with sufficient flexibility for treatment of all ore types.
Exploration potential for CIL ore remains excellent, both at the known gold deposits, all of which remain open to possible further expansion, and throughout the remaining project area. This exploration upside could potentially support future plant expansion, increased throughput capacity, extended mine life and increased annual gold production.
Heap Leach Project: The OJVG leap leach project will draw ore only from open-pit mines. The production plan is based on a potentially mineable portion of an indicated plus inferred mineral resource of 28.4 million mt at a grade of 0.61 g/mt containing 560,000 oz of gold. The mine production rate is planned at 2 million mt/y.
Heap leach start-up capital cost is estimated at $54 million, including a $10.5-million contingency. Operating costs are estimated at $760/oz during the first three years of operation and $929/oz over the life of the mine.
The capital and operating costs for the heap leach operation are assumed to be incremental to the costs for the CIL project. For example, general site facilities and administration services will be borne by the CIL project, and hence only specific costs for bringing on the heap leach operation are considered.
Exploration potential is considered excellent at the known heap leach gold deposits, all of which remain open to further expansion, as well as throughout the project area, where more than a dozen exploration targets and prospects have been identified thus far. This exploration upside could support extending the heap leach processing life further into the future and might support an expanded operating capacity.