The Éléonore Operations host the Roberto gold deposit, which includes the Roberto, East Roberto, and Zone du Lac lenses.

The Roberto deposit is considered to have many aspects in common with classic greenstone hosted quartz–carbonate vein deposits, but represents a clastic sedimenthosted stockwork-disseminated end member.

Features of the deposit that indicate it is part of the greenstone-hosted quartz–carbonate vein deposit continuum include:

• Spatially associated with major crustal features developed in deformed greenstone rocks; mineralization is considered to pre-date the final deformation phase;
• Associated with large, district-scale carbonate alteration;
• Gold mineralization hosted in laminated fault-fill quartz–carbonate veins of varying thicknesses;
• Association of gold with arsenopyrite, löllingite, pyrrhotite and pyrite.

The sulphide concentration within the mineralized zones varies between 1% and 5%, and primarily consists of arsenopyrite, löllingite, pyrrhotite and pyrite. The “waste” rock may contain sulphides, usually pyrrhotite, but this is in lesser amounts, from trace to 2%, and occurs mostly in the structural hanging wall.

The mineralized zones are generally 5 m to 6 m in true thickness, varying between 2 m and more than 20 m locally. Mineralization is considered to pre-date the final deformation phase (Ravenelle et al, 2010).

The mineralized zones are folded with increased thicknesses in the hinge of the folds while limbs are fairly straight and continuous. Transposition of the sedimentary beds post-mineralization may also explain some of the thickening of the mineralized zones.

The Roberto gold zones dip steeply to the east and rake (plunge) steeply to the northeast. All zones remain open at depth and along strike.

Open stope mining (down-hole drilling) and longitudinal retreat with consolidated backfill (paste backfill mixed with crushed waste rock) is utilized. A transverse open stope approach is used where the mineralized lenses are wider than 7 metres.

For mine scheduling purposes, the vertical extent of the orebody is subdivided into two parts: the upper part of the orebody located between 65 metres and 650 metres below surface (Upper Mine), and the lower part of the orebody located between 650 metres and 1,190 metres below surface (Lower Mine). Dividing the orebody into two parts has accelerated the production start-up.

Mining started from the 440 metre level and the 650 metre level. Production will be at the nominal rate of 5,000 tonnes per day with four mining horizons starting on the 230 metre level, 440 metre level, 650 metre level and 800 metre level. At this stage, it is expected that all the ore and waste of horizon 1 (65 metre level to 230 metre level) will be trucked to the surface; the ore and waste of horizons 2, 3 and 4 (230 metre level to 800 metre level) is hoisted up the production shaft.

Studies to increase and sustain the production rate will be conducted as more drilling information becomes available. Based on the current Mineral Reserves, the planned operation has a 10-year mine life. The mine plan is under evaluation for including the mining of the zone above 55 metres below surface (crown pillar recovery project), however economics do not currently support including this into mineral reserves.

The ramp is currently used as the air exhaust and will continue to do so when completed. The main ventilation raise is the Gaumond shaft. From the shaft, the air is distributed into two internal ventilation raises, one located in the North Zone and one in the South Zone, each of which will bring fresh air to work places. Currently, ventilation on demand is partly operational, and once completed it will help to reduce this preliminary estimation.

Stope widths vary between 2.5 metres and 20 metres. Stopes have a maximum length of 25 metres, and can reach a height of 30 metres. Ground support consists of various combinations of rebar bolts, friction bolts, cables, screen and shotcrete depending on the rock quality and particular requirements of each heading.

Stopes are backfilled with paste fill. Unconsolidated backfill is used wherever is possible in order to avoid hoisting waste rock to the surface. The current paste backfill mixture consists of 70% mill tailings, 25% fine sulphide concentrate, and between 4% to 7% binder. The sulphide tailing concentration can be up to 25% without having effect on the paste strength. Crushed waste is typically added to the fill, so the percentage of the mill tailings decreases.

A fully-mechanized mining equipment fleet is used. Equipment includes scoop trams, dump trucks, mine service and personnel vehicles, jumbo drills, bolting platforms, scissor lifts, land cruiser and forklifts.

There is potential to extend the mine life and potentially sustain the 7,000 tonnes per day throughput rate if some or all of the Inferred Mineral Resources identified within the life-of- mine production plan can be upgraded to higher confidence Mineral Resource categories, and eventually converted to Mineral Reserves. Mineralization remains open at depth, with the deepest drill hole encountering mineralization at 1,400 metre depth; the current mine plan extends to 1,190 metre depth.

The Éléonore plant uses conventional mineral processing equipment to produce a marketable gold doré.

The process flowsheet is standard, consisting of three stages of crushing, grinding, gravity concentration, sulphides flotation, cyanide leaching, and gold recovery in a CIP circuit.

The plant capacity is controlled by the underground mine capacity. The plant initially operated at 3,500 t/d. The crushing area is designed for a capacity of 8,500 t/d including waste crushing (1,500 t/d), and the other plant areas were designed for a processing capacity of 7,000 t/d.

The comminution process consists of three stages of crushing followed by a single stage ball mill grinding. The primary crusher (jaw crusher), the secondary crusher (standard cone crusher) and tertiary crushers (two short-head cone crushers will be required for a 7,000 t/d throughput rate) are located on the surface. The fine crushed ore is ground by a single stage ball mill in a closed circuit with cyclones. A portion of the cyclones underflow is directed to a gravity concentration circuit consisting of two Knelson Concentrators and an Acacia Reactor to recover liberated native gold. The cyclones overflow (grinding circuit product) is directed to the flotation cells for iron sulphides separation in a low mass sulphur concentrate. The flotation tail slurry density is adjusted with a thickener and the material is leached with cyanide for 36 hours in five leach tanks.

The flotation concentrate is thickened and reground to a P80 of 10–15 µm in a fine grinding mill and is leached with cyanide for 48 hours in five other leach tanks. The gold in solution is recovered in carousel carbon-in-pulp (CIP) circuits (one for each leach circuit). The carbon from each CIP circuit is stripped as required in a Zadra stripping circuit.

Each elution circuit (flotation concentrate and flotation tails) has its own electrowinning circuit. The pregnant solution is pumped into series of two electrowinning cells in each circuit.

The carbon is regenerated and returned to the CIP circuits. The tails from each leaching circuit are detoxified in a conventional cyanide destruction circuit, and are filtered for addition in the paste backfill or stored in a covered shed before transportation to the tailings management facility.