PERTH (miningweekly.com) – A prefeasibility study (PFS) into an underground operation at gold miner Resolute Mining’s Syama project, in Mali, has resulted in a 54% increase in the project’s ore reserves.

With the addition of some 14.3-million tonnes of underground ore, the Syama ore reserve has grown to 3.15-million ounces, up by 1.1-million ounces on the previous estimate.

“This is a significant addition to the reserve inventory complementing the successful work by our development and operating teams to reduce costs, improve plant performance and optimise capital spend at Syama,” said Resolute CEO Peter Sullivan.

He noted that the increased ore reserve also supported long-term gold production beyond 2025.

In August last year, Resolute flagged a potential underground development at its Syama project. A conceptual study has indicated the potential for an underground development, which could deliver between 1.5-million and 2-million tonnes of ore a year, over an initial five-year period.

Resolute said on Friday that results from the PFS confirmed that sublevel caving provided an opportunity to establish a large volume, low-cost and economically viable underground operation that would maintain mill production for at least seven years beyond the completion of the openpit mining currently scheduled to last until 2020.

The study estimated that the underground mine would require a capital investment of some $85.6-million to deliver the 1.1-million ounces of gold, and would deliver total revenue of more than $1.1-billion.

Sullivan said that over the next 12 months, Resolute would complete a more comprehensive second-phase diamond drilling programme to infill and extend the resource at the underground operation.

The results of the drilling programme would be incorporated into a definitive feasibility study, which was planned for 2015.