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

The Roberto deposit is a clastic sediment-hosted stockwork-disseminated gold deposit.

Roberto Deposit
The Roberto deposit has historically been divided into the Roberto, Roberto East, Zone du Lac, North and Hanging Wall Zones. This nomenclature is based on their geographical location and the main alteration types observed. All of the zones are made up of many individual mineralized lenses.

The host rock of the mineralized zones is typically a thinly-bedded greywacke (bed thickness approximately 10 cm) near the contact with a massive greywacke unit, and locally, with a thin conglomerate unit. The steeply east-dipping Roberto East fault, marked by a thin black tourmaline marker band, forms the eastern limit of the mineralized vein cluster.

The structural hanging wall of the mineralized zones is characterized by a greywacke containing centimetre-scale aluminosilicate porphyroblasts overlain by a thin conglomerate unit. The aluminosilicate-bearing greywacke and the conglomerate appear tightly folded, with axes generally oriented in the east–west direction and refolded by the F2 event. This folding is in sharp contrast with the generally north– south-trending bedding in the mineralized zones. The structural footwall of the mineralized zones is characterized by greywacke, locally exhibiting a higher metamorphic grade, which contains a higher amount of pegmatite dikes and quartz veins.

The bulk of the gold mineralization at the Roberto deposit includes a wide range of mineralization styles (Fontaine et al., 2015a):
- Stockwork of quartz, dravite veinlets with microcline, phlogopite, and sulphides;
- Replacement zones (microcline, phlogopite, dravite) with traces of pyrrhotite, arsenopyrite, and rare löllingite (FeAs2; Roberto zone);
- Quartz, diopside, schorl, arsenopyrite veins (East Roberto zone);
- Atypical mineralized zones in quartz–feldspathic veinlets, high-grade quartz veins, high-grade paragneiss (North Zone and Hanging Wall Zone).

Mineralization shows variable proportions of disseminated arsenopyrite, löllingite, and pyrrhotite. Traces of pyrite, sphalerite, bornite, and chalcopyrite are also locally present.

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.

The current mining method is longitudinal longhole retreat stoping, with sublevel intervals at 30 m spacing. The mine has been divided into seven mining horizons to allow for several simultaneously-active mining fronts.

As of October 2018, ramp development reaches a depth of approximately 1,130 m from surface while production had started in Horizon 5, on the 980 m Level.

The main infrastructure, including the production shaft, is located in the orebody hanging wall. There are four access points, consisting of the surface portal with an internal ramp, and three level accesses from the production shaft on the 400, 650 and 1140 m Levels.

Each level has electrical bays, sumps, ventilation accesses, backfill accesses, a refuge station and dumping bays. The main haulage drifts are located in the orebody hanging wall and are positioned 30 m from the expected ore contours. Ore access points (i.e. drawpoints) are situated about 100 m apart and each has a backslash at the intersection with the main haulage drift to allow for efficient truck loading.

The ramp is driven at a maximum gradient of -17% and is positioned to cross predicted faults in a perpendicular manner.

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.

Production is currently taking place from five different horizons. Horizons 1 to 4 are mature, and Horizon 5 is in the early production stages. Horizon 2 is linked to Horizon 3 via ore passes. Material from the 290 m Level and up is transported to surface using trucks. Below the 320 m Level a mix of ore passes and trucking is being used to send material to the 650 m Level. This material is subsequently hoisted to surface via the production shaft.

An average production rate of 1,050 t/d per stope is used throughout the mine. Currently, rates are between 800 and 2,500 t/d per horizon, excluding panel sequence beginnings and ends. The material handling system and producing horizons are capable of meeting an average 6,600 t/d production rate.

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 seven metres.

The following stope dimensions are used for mine planning:
- Stope width = minimum 2.5 m
- Stope height = 30 m (floor to floor);
- Stope strike length = designed as 25 m. Where stopes are mined-out, lengths are kept on the superposed stopes till the stopes under the sill. The maximum stope length is 45 m.

Material can be hoisted to surface via the production shaft on the 690 m Level or 1140 m Level. Material can also be trucked to surface via the ramp.

Two ore passes are operational, linking the 320 m Level to the 650 m Level in the centre of the deposit, and the 350 m Level to the 650 m Level in the north. Truck chutes are installed on this level, allowing ore to be transferred to the shaft via trucking to the grizzlies (with rockbreakers) over the storage bins on the 650 m Level.

A new material handling system is in development on the 1090 m Level, and will be connected to the 1140 m Level with storage waste and ore bins at a capacity of 3,000 t each. On the 1090 m Level, a rock-breaking system will be located over the bins to break oversized rock. The main bins feed the rock onto a conveyor that transports the material to a measuring loading box on the 1140 m Level. At that point, the rock will be automatically loaded into the skip.

The mobile diesel equipment fleet consists of 9.5 yd3 and 15.2 yd3 loaders, 45 t, 55 t and 60 t dump trucks, mine service and personnel vehicles, fully automatic jumbo drills, bolting platforms, scissor lifts, forklifts, boom trucks, and utility diameter holes in trucks. Top hammer drills are used to drill 102 mm diameter holes in the stope.

Production Shaft
Production Shaft The production shaft is circular with an inside diameter of 7 m. The shaft is lined with concrete to a final depth of 1,190 m and is equipped with two 23 t skips (payload), has a service cage with two cables, and a Maryann auxiliary cage.
The production shaft is rated to have a hoisting capacity of 8,500 t/d (combined ore and waste). At peak capacity, skipping will be required at a speed of 3,000 ft/ min (15.24 m/s).

A service cage is installed to transport personnel and material to the working levels. An auxiliary Maryann cage is also installed in the production shaft for personnel and emergency situations.

Three shaft stations are excavated from the production shaft, at the 400 m Level, 650 m Level and 1140 m Level. Two shaft loading stations are at depths of 690 m Level and in development on the 1140 m Level.

Surface Ramp
The portal is located approximately 800 m from the orebody. The first part of the ramp is 7 m wide by 5 m high and has a grade of 15% (8.4°). At the connection with the 400 m Level, the ramp dimension reduces to 5.8 m wide and a grade of 17%. Currently the internal ramp is located in the orebody hanging wall and extends from surface to the 1130 m Level.

Fresh Air System
Fresh air enters the mine through the two shafts. The Gaumond shaft was initially used for hoisting at the beginning of the operations; however, the shaft infrastructure has been dismantled to reduce air resistance. On top of this shaft, two parallel 750 hp fans push fresh air through this dedicated ventilation shaft. Fresh air is discharged on the 400 m and 650 m Levels.

Backfill
Where possible, unconsolidated backfill is used to fill empty stopes, to avoid costs incurred by hoisting waste rock to surface.

Consolidated backfill is used to avoid pillars between stopes. Paste fill, mill tailings and binder have been incorporated in the backfill. 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 (15%) can be added, so the percentage of the mill tailings in the backfill can decreased to 55%.

The surface backfill plant is equipped with the option to add crushed waste rock into the paste-fill circuit so that the surface waste rock pad area can be reduced by the end of the mine life. The paste plant was designed to provide paste to two different lines at the same time and has provision for the supply to be of two different paste compositions.

Crushing Circuit
The crushing plant is designed to process 8,500 t/d of material in 16 hours of operation or less per day (7,000 t of ore and 1,500 t of waste). Material is first passed through grizzly screen with 356 mm x 356 mm openings. Oversize material is broken using a hydraulic rock hammer. The material is then fed by a variable-speed apron feeder to a 1,200 mm wide conveyor that discharges into the primary crushing feed hopper. From there, a vibrating grizzly feeder feeds the coarser material to the primary crusher, which is a 1,250 mm x 950 mm jaw crusher, while the finer material falls through the feeder “fingers” and by-passes the primary crusher.

The grizzly feeder undersize and the jaw crusher product are collected on a common conveyor that transfers the material to the secondary crushing surge bin, from which the material is fed to a double deck vibrating screen (76 mm and 22 mm openings). The oversize discharges to the secondary cone crusher, which is a standard head, 450kW HP6 cone crusher equipped with a standard/fine cavity bowl. The secondary crusher product and the secondary crusher screen undersize are collected onto a common conveyor with the tertiary crusher product and transferred to the tertiary crusher double deck vibrating screens (32 mm and 10 mm openings).

The screen oversize is collected by a conveyor and loaded into a surge bin with two retractable variable speed belt feeders. The feeders feed the two tertiary cone crushers, which are short head, 450 kW HP6 cone crushers operating in parallel. The tertiary crusher product is recycled back to the tertiary crusher screens. Tertiary crusher screen undersize product, at -10 mm, is conveyed and stored in two 3,500 t “live’’ fine ore bins or into the 2,000 t waste bin which is enclosed to prevent freezing. These bins are located at the process plant and provide more than 24 hours of storage capacity.

Grinding Circuit
The ore stored in the fine ore bins is reclaimed via two variable speed belt feeders and loaded at a controlled feed rate into a 6.40 m x 11.9 m, 9,000 kW ball mill. This mill is operated in closed circuit with nineteen 400 mm diameter hydrocyclones which are used as particle size classifiers. The hydrocyclones are designed for 65 µm P80 product size and eight to 10 hydrocyclones are typically in operation while the others are standby. Hydrocyclone overflow is sent to the next stage of the process while the coarser underflow is recycled back to the ball mill for further grinding.

The IsaMill (M5000 with a 1,500 kW motor) receives the flotation concentrate thickener underflow. Grinding media is added as required in the IsaMill feed pump box to keep the power input constant to the regrind mill. The flotation concentrate is reground to a P80 of 10 to15 µm before being discharged into a second pumpbox where dilution water, recycled from the concentrate CIP thickener overflow, and process water is added to reduce the leach feed density to 30% solids. The IsaMill product is then pumped to the first of two pre-aeration tanks to pre-condition the slurry for leaching through three flotation concentrate leaching tanks (7.9 m diameter x 8.4 m).

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

The main process infrastructure consists of a crushing plant, ore storage bins, a grinding and gravity gold recovery circuit, a flotation circuit, a flotation tails cyanidation and CIP circuit, a flotation concentrate regrinding, cyanidation and CIP circuit, a Zadra stripping circuit, a gold refinery, concentrate and tailings dewatering circuits and a paste backfill system.

The crushing area is designed for a capacity of 8,500 t/d, including waste crushing (1,500 t/d), while the other plant areas are designed for a processing capacity of 7,000 t/d at 95% availability.

Comminution consists of conventional three-stage crushing circuit followed by a single stage of closed-circuit ball milling, to a P80 of approximately 65 µm. Within the ball milling circuit, a gravity concentration circuit consisting of two Knelson concentrators recovers coarse liberated g ........