JOHANNESBURG (miningweekly.com) – A definitive feasibility study (DFS) of Aim-listed Hummingbird Resources’ Yanfolila gold project, in Mali, has demonstrated “significant enhancement” to its economics as an openpit, low-cost gold mining operation, the company said on Monday.

The study had almost doubled the project’s net present value (NPV) to $142-million, using a $1 250/oz gold price, while the forecast internal rate of return (IRR) was increased to 55% at the same gold price.

The project, meanwhile, remained robust at current gold prices, with an IRR of 37% at a gold price of $1 100/oz.

The study further pointed to all-in sustaining costs of around $720/oz.

The DFS life-of-mine (LoM) plan entailed progressively mining five openpits, starting initially with Komana East and Komana West, before progressing to Guirin West, Sanioumale East and Sanioumale West. 

Hummingbird was also considering developing the high-grade Gonka resource, initially as an openpit, then moving to an underground mine. 

The plant would have a throughput capacity of 1.24-million tons a year, producing up to 121 000 oz/y of gold.

The ore would be nonrefractory and the simple process plant design used gravity and carbon-in-leach for the processing and recovery of the gold, which averaged 92.5% over the LoM. 

The plant design incorporated industry standard unit process operations, comprising primary and secondary crushing, closed-circuit ball milling with gravity concentration, intensive leach of the gravity concentrate, carbon-in-leach of the gravity tailings, elution, electrowinning and smelting to produce gold doré. 

Mining would be carried out by a mining contractor with significant West African experience, Hummingbird noted.

“We are delighted to see such an impressive improvement in Yanfolila’s economics. The increase in the NPV is a major achievement for Hummingbird and I would like to take this opportunity to thank the team who have helped complete this study,” commented CEO Dan Betts.

The Yanfolila project was situated within one of several sub-basins along the eastern margin of the Greater Siguiri basin, which straddled the Mali–Guinea border and formed the western margin of the Birimian Volcano-Sedimentary basin.