Name and Location
Yanfolila gold project, Mali.

Client
Hummingbird Resources.

Project Description
The Yanfolila gold project comprises two main clusters of ore deposits: Komana East (KE), Komana West (KW), Guirin West (GW) and Gonka GK, in the south, and located in the north are Sanioumale East (SE) and Sanioumale West (SW).

A definitive feasibility study (DFS) has demonstrated significant enhancement to the project’s economics as an openpit, low-cost gold mining operation.

The DFS life-of-mine (LoM) plan envisages the progressive mining of five openpits, starting initially with KE and KW, and then progressing to GW, SE and SW.

Hummingbird is also considering developing the high-grade Gonka Resource, initially as an openpit, and then as an underground mine.

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

The ore is nonrefractory and the simple process plant design uses gravity and carbon-in-leach (CIL) for the processing and recovery of the gold, which averages 92.5% over LoM.

Mining will be undertaken by a mining contractor with significant West African experience.

Mining operations will be conducted using conventional drill-and-blast and load-and-haul mining methods.

Plant production during the mine life is currently planned for seven years, mining an estimated 8.8-million tonnes of ore and 106.7-million tonnes of waste.

Waste rock will be relocated to designated wasterock facilities at each pit and will be progressively rehabilitated.

During an initial mining preproduction period of about five months, the selected mining contractor will mobilise and establish operations, ore will be stockpiled, ready for plant commissioning; and much of the waste material removed will be used to build up the run-of-mine stockpile pad and tailings storage facility (TSF) starter embankment.

During peak production – the first three years of mine life – the mining schedule calls for an estimated one-million bank cubic metres to be mined a month.

The mining contractor equipment fleet is sized on this basis.

Drill-and-blast activities will be required once the hardness of the material to be excavated becomes too difficult or inefficient to free dig.

Once started, 10 m blast holes will be drilled in a dense pattern for blasting.

The pit dewatering programme is an integration of 27 ex-pit water wells and in-pit sumps designed to reduce pore pressure in the surrounding rocks and reduce inflow to the in-pit sumps.

Based on the metallurgical testwork results, trade-off studies and simulations from consultants, the design criteria of the Yanfolila process plant assumes treatment of up to 1.24-million tonnes on a blend of oxides and fresh ore, and up to one-million tonnes a year when treating mainly fresh ore.

The Yanfolila process plant design uses a CIL process for the processing and recovery of gold from oxide and a blend of oxide and fresh ore.

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

A two-stage crushing facility is installed to treat all ore types.

To maintain mill throughput, a tertiary crushing facility will be added when the proportion of hard fresh ore increases. A 12-hour live stockpile will ensure continuous and consistent feed to the mill.

Recovery of gold will be through a combination of gravimetric methods and direct cyanidation.

Gravity concentrate will be treated through an intensive cyanidation process, with the pregnant solution pumped to
an independent gravity electrowinning circuit.

The CIL circuit will consist of one preleach tank and six CIL tanks in series.

The design of the TSF for the Yanfolila project was originally undertaken by Gold Fields in 2013, which considered several locations with respect to the mineral deposits for the project. In late 2014, Hummingbird engaged Ausenco to develop the TSF for the project.

The outcome of the study identified that a rockfill-centreline raise was the preferred option, since it was more robust from a construction and water management perspective, although it had a slightly higher sustaining capital cost than the upstream-rockfill raise.

Net Present Value/Internal Rate of Return
The project has a net present value, at an 8% discount rate, of $142-million using a $1 250/oz gold price.

The project has an internal rate of return of 55% based on a gold price of $1 250/oz.

Value
$79.36-million.

Duration
Not stated.

Latest Developments
None stated.

Key Contracts and Suppliers
DRA Projects (DFS); CSA Global (Mineral Resource and Ore Reserves reports); SENET (metallurgical testwork, process design and engineering, and capital and operating cost estimates for the processing plant and the associated plant infrastructure); Schlumberger Water Services (hydrology and hydrogeological studies); and Ausenco Engineering Canada (design and cost estimates for the TSF).

On Budget and on Time?
Not stated.

Contact Details for Project Information
Hummingbird Resources, tel +44 20 3416 3560.
DRA Projects, tel +27 11 202 8600 or email info@DRAglobal.com.
CSA Global, tel +27 11 568 2724, fax +27 11 676 6689 or email csasouthafrica@csaglobal.com.
SENET, tel +27 11 409 1300 or fax +27 11 409 1301.
Schlumberger Water Services, tel +27 11 6841122 or fax +2786 576 6034.
Ausenco Engineering Canada, tel +27 11 258 8591.