Both MacLellan and Gordon deposits can be considered as belonging to the class of gold deposits referred to as orogenic.

Gold and silver mineralization can be geochemically anomalous to economic at the MacLellan site, Gordon area as well as the Burnt Timber – Linkwood areas of the southern belt. Gold is usually associated with pyrrhotite-pyrite mineralization and often with minor chalcopyrite, sphalerite, galena and arsenopyrite. Gold mineralization is often associated with narrow quartz and quartz carbonate veins and within semi-massive sulphide lenses 1 to 20 cm thick. Gold is usually very fine grained and is rarely visible and appears to be structurally controlled. The structures, usually quartz veins, are eastwest trending.

At MacLellan and Burnt Timber gold-bearing structures dip steeply to the north and are hosted in mafic flows and sediments. Gold seems to be associated with carbonate and silica alteration.

With respect to MacLellan, the high-strain-zone and accompanying hydrothermal alteration localized to the picrite flows and minor intercalated sediments, coupled with its chemical trapping characteristics created favourable conditions for gold mineralization. Hastie (2014) emphasizes the importance of brittle D4 structures, with supporting evidence for a second hydrothermal fluid event. The first gold-silver mineralizing episode, during ductile D2 shearing and alteration, is characterized by biotite ± quartz ± sulphide alteration and shows goldpyrrhotite-pyrite mineralization. The second episode of gold- silver mineralization exhibits fracture-fill Au, arsenopyrite, galena, and sphalerite, associated with D4 faulting and hydrothermal fluids with Cr- clinochlore + carbonate ± hornblende + quartz alteration. A significant increase in gold-silver mineralization near the intersections of D2 shear zones and D4 faults is noted throughout the MacLellan deposit.

At Gordon, gold is often associated with quartz veins cutting folded and contorted Iron Formation, trending east-west and dipping shallowly to the south. Au mineralization is normally trapped in sulfide replacement zones averaging 2.4 m wide, associated with thin, centimetrescale quartz- sulfide veins and breccia veins. In places, coarse gold flecks are observed within these quartz veins and in iron-carbonate altered fragments within breccia veins. Strong ironcarbonate – chlorite – amphibole alteration is related to some high grade veins.

Both the Gordon and MacLellan deposits will be developed using conventional shovel/truck open pit mining methods with owner mining assumed within the Feasibility Study. The Gordon and MacLellan deposits are expected to operate concurrently for the first six years of operation, with Gordon to be depleted first given its higher grades and lower stripping ratio. As the Gordon pit nears depletion, mining equipment will be transferred to MacLellan and utilized over the remainder of its mine life.

Following a one year pre-production period at Gordon and two-year pre-production period at MacLellan, combined mining rates are expected to range between 20.5 and 27.0 Mt of material per year over the first seven years. This includes peak mining rates of 13 Mt at Gordon and 24.7 Mt at MacLellan.

Loading of ore and waste rock is planned to be carried out with two 300 t class hydraulic shovels and two front end loaders, paired primarily with 144 t capacity mine trucks. Ore from MacLellan will be hauled to the primary crusher (located to the south of the pit). All ore from Gordon will be transported approximately 55 km to the process facility at MacLellan via a fleet of 23 highway trucks, each with a capacity of approximately 30 t.

Lynn Lake’s process plant has been designed as a conventional milling operation with a nominal capacity of 7,000 tpd.

Crushing and Stockpile
ROM ore from both MacLellan and Gordon open pits is discharged to the ROM ore hopper by front end loaders (FEL) or, haul trucks or highway trucks. The ROM ore hopper incorporates a horizontal static grizzly with 800 mm x 800 mm aperture to screen out lump oversize. The static grizzly oversize is reclaimed by a front end loader and stockpiled for rock breaking. The static grizzly undersize discharges into the ROM ore hopper. Ore is reclaimed at a controlled rate by an apron feeder and discharged onto a vibrating grizzly screen.

The oversize from the vibrating grizzly enters the single toggle 490 t/h (design) Metso C130 51” x 40” primary jaw crusher powered by a 160 kW motor. The jaw crusher close size setting (CSS) is 130 mm. The vibrating grizzly undersize, jaw crusher product and apron feeder fines combine and discharge onto the primary crusher transfer conveyor. A tramp magnet removes steel trash from the primary crushed ore as it transfers by conveyor to the secondary crusher.

The secondary crusher is a 490 t/h (design) cone crusher with CSS of 35 mm. The crusher is powered by a 450 kW motor. It is located inside the main process plant building, in the grinding area. A surge bin with ten minutes retention time, located above the crusher, ensures choke feed conditions. A pan feeder extracts ore from the surge bin to feed the secondary crusher via a conveyor. The fine ore product of P80 of 40 mm is conveyed by a stockpile feed conveyor to the fine ore stockpile (FOS). A weightometer measures the fine ore rate produced from the crushing circuit.

The FOS has a live volume of 5,300 t, providing 16 hours of mill feed. Two variable speed reclaim apron feeders provide two live draw-down pockets. The feeders provide duty/duty mill feed service whereby either one can handle nominal mill feed demand if the other unit is off line.

Grinding and classification
The grinding circuit consists of one single pinion 7.3 m x 3.6 m SAG mill followed by one single pinion 5.8 m x 8.7 m ball mill. The ball mill operates in closed circuit with a hydrocyclone cluster. The final product from the grinding circuit (cyclone overflow) has a target P80 75 µm. The SAG mill is equipped with a single 3.1 MW low speed synchronous motor with variable frequency drive (VFD) to operate between 61% and 79% of critical speed. The ball mill is equipped with a single 5.1 MW low speed synchronous motor to operate at 75% of critical speed.

The reclaimed fine ore is conveyed by a covered SAG mill feed conveyor from the two FOS reclaim feeders under the stockpile to the SAG mill feed chute. The recycled pebbles from the SAG mill trammel oversize chute are re-introduced to the SAG mill via a high angle pebble conveyor that discharges onto the SAG mill feed conveyor. A weightometer, after the stockpile reclaim, measures the amount of fresh mill feed ore entering the SAG mill and a second weightometer to the SAG mill, after the recycled pebbles and lime addition points onto the conveyor, measures the total feed. The pebble recirculating load is a maximum of 15% by weight. Both, or either of the variable speed duty/duty reclaim feeders can supply the mill demand. Quick lime is metered to the SAG mill feed conveyor using a screw feeder. For both mills, process water is added at a controlled rate into the feed chutes to achieve a nominal pulp density of 71% solids.

The SAG mill is fitted with 20 mm discharge grates to allow slurry to pass through the mill and prevent pebble build-up in the mill. The SAG mill discharge product is screened on the SAG mill trommel with 10 mm aperture. Oversize from the SAG mill trommel is conveyed back to the SAG mill feed conveyor using a series of pebble conveyors. A provision is made in the layout to accommodate a future pebble crusher. SAG mill trommel undersize gravitates to the cyclone feed pumpbox, where it is combined with the ball mill discharge slurry from the ball mill trommel undersize.

Ball mill slurry discharge overflows onto a rubber lined trommel screen with trommel oversize discharging to a bunker for regular collection and disposal by a skid steer loader. The trommel undersize gravitates to the cyclone feed hopper where the slurry is diluted with process water and pumped with a single duty cyclone feed pump to the cyclone cluster. A density meter monitors and controls the amount of process water required to produce a target density to the cyclones. The cluster consists of eight cyclones: six operating and two standby.

SAG and ball mill grinding media (steel balls) supplied in trucks are unloaded into three ball storage compartments, each holding a specific diameter steel ball. A ball loading magnet (moving through an overhead ball bin crane) attracts and transports a collection of balls from the compartments to individual storage bins. From each storage bin the balls are discharged into a dedicated 1 t ball kibble, which in turn discharges to the mills to maintain the desired ball loads and power draw. The ball kibble is lifted by a 50 t bridge-crane and emptied into the mill ball discharge indexer.

The cyclones produce a ground overflow product of P80 75 µm which is sampled and then gravitates to the linear trash screen. Oversize debris is removed and falls to a trash bin at
ground level. The trash screen underflow gravitates to the pre-leach thickener feed box outside the west wall of the building.

The proposed plant design is based on leach/carbon in pulp (“CIP”), and will consist of crushing, grinding, thickening, pre-aeration and leaching, CIP, cyanide detoxification, carbon elution and regeneration, and gold smelting.

The flow sheet incorporates the following major process operations:
-Two-stage crushing and stockpile,
-Semi-autogenous grinding (SAG),
-Ball mill grinding and classification,
-Leaching and CIP adsorption,
-Desorption and gold room,
-Tailings detoxification and disposal,
-Fresh and reclaim water supply, and
-Reagent preparation and distribution

Leach and Adsorption
Trash screen undersize is thickened from 33% to 55% solids in a 31 m diameter high rate preleach thickener in preparation for downstream pre-aeration, leaching, and carbon-in-pulp (CIP). Hydrated lime slurry is added to the ground ore slurry in the feed box to raise the pH to 10.5. Flocculant is metered to the thickener feedwell.
........