Mining activities are conducted in and about the municipality of Red Lake (population approximately 4,670), which consists of six distinct communities, Red Lake, Balmertown, Cochenour, Madsen, McKenzie Island, and Starratt-Olsen.

The operations comprise the former Campbell and Red Lake underground mines, which are now integrated and operated as a single entity by Red Lake Gold Mines Ltd., a Goldcorp subsidiary. For the purposes of this Report, the shafts and mill at Red Lake are collectively termed the Red Lake Complex; those at Campbell are termed the Campbell Complex. The combined mine area is also referred to as the Red Lake–Campbell Complex.

The Cochenour Complex covers mineralization discovered at the Western Discovery Zone deposit and the former Cochenour–Willans mine. It also includes the former Eagle Mines Joint Venture property.

The Red Lake–Campbell Complex has approximate deposit dimensions of 2.2 km north–south, 3.2 km east–west, and remains open down-dip. Mine workings extend to 2,360 m depth (52 Level), with the deepest drill intercept currently at around 2,600 m depth.

The Red Lake–Campbell Complex is underlain mainly by tholeiitic to komatiitic basalts and minor interflow iron formations of the Balmer Assemblage, with lesser amounts of younger peridotitic, felsic and gabbroic intrusive rocks. These rocks have been folded and fault offset with bedding now steeply-dipping to the south–southwest. Unconformably overlying the Balmer Assemblage are the chemical sedimentary rocks of the Bruce Channel Assemblage, succeeded by the conglomeratic, clastic and felsic volcaniclastic rocks of the Confederation Assemblage. The apparent anticlinal fold structure enclosing the deposit is defined by this unconformable contact between the Balmer Assemblage and the overlying sedimentary rocks, and is partially erosional and partly structural in nature. This apparent fold is oriented along a 135º trend and plunges moderately at 45º to the southwest.

The Cochenour Complex comprises the Main, Inco, Upper Main, Iron Formation, Footwall and Western Discovery zones. The Main and Inco zones form part of the original Cochenour Mine, while the remainder are located on ground acquired from Gold Eagle Mines Ltd. The Western Discovery Zone mineralization is located on McKenzie Island, approximately 1.5 km due west of the Cochenour mine site.

Mineralization is primarily localized within the tholeiitic mafic rocks and shows strong structural control along broad to discrete shear structures running along a 135º trend in the east, refracting to a 120º trend in the west. Other significant mineralized zones occur along discordant brittle structures which most commonly appear as a conjugates system generally oriented east-west (110º azimuth) and north–south (160º azimuth). Competency and permeability contrasts between adjacent lithologies is also important as seen by the strong association of higher-grade mineralization when basalt comes in contact with ultramafic rocks.

Mineralized zones are cut by post-mineralization feldspar porphyry dykes and two generations of lamprophyre dykes. The generally east–west trending feldspar porphyry dykes are important since they are not mineralized, but are affected by D2 deformation, thus providing a minimum age date for mineralization occurring during the later stages of the D2 event (ca. 2.714 Ga). One set of lamprophyre dykes is typically steep-dipping and follows the mine-trend foliation (ranging from 120º to 135º azimuth). The second set is shallow-dipping (20º to 40º) to the west to southwest.

There are generally three styles of mineralization in the Red Lake–Campbell Complex: vein replacement mineralization, replacement mineralization, and sulphide mineralization. Vein replacement ore involves intense silica replacement of precursor ankerite veins often accompanied by abundant visible gold and minor sulphides. This is the dominant mineralization type found in zones like the Red Lake High Grade Zone and the Campbell G and L zones. Vein replacement zones occur along narrow discrete shears and along brittle high-angle structures, averaging widths of 1–2 m in width and extending over strike lengths ranging from 30–300 m.

Replacement mineralization involved the intense silica replacement of sheared mafic rocks accompanied by abundant arsenopyrite and pyrrhotite ± biotite. This style of mineralization commonly envelops vein replacement mineralization, but can occur elsewhere.

Sulphide mineralization is typically found within broad zones of strongly sheared mafic rocks and consists of fine disseminated pyrrhotite (as much as 30%) accompanied by biotite alteration. This mineralization generally runs lower grade, 0.25–0.50 oz/t Au (8.6–17.2 g/t) but can run higher grade if accompanied by notable amounts of arsenopyrite and vein replacement mineralization. Sulphide zones vary from 3–12 m in width and extend over a strike length of 120–180 m, though a few zones on the Red Lake side are continuous along an 800 m strike length.

Recent exploration has focused on an area northwest of the Red Lake Operations area immediately to the west of the old HG Young mine site area. The structural framework of this area is significantly different that the Red Lake gold mines, with the stratigraphy and mineralization hosting shear structure generally oriented north–south (more accurately along a 160º trend dipping moderately to the west). Although it is still early in the drill delineation phase, mineralization appears to be most consistently associated with narrow shear zones developed along the contact of carbonatized basaltic komatiites and tholeiitic basalts. The mineralization style also appears to be different in the HG Young area, with most of the mineralization associated primarily with glassy quartz veins, containing significant scheelite, minor sulphides, and locally, visible gold.

The operations comprise the former Campbell and Red Lake underground mines, which are now integrated and operated as a single entity by Red Lake Gold Mines Ltd., a Goldcorp subsidiary. For the purposes of this Report, the shafts and mill at Red Lake are collectively termed the Red Lake Complex; those at Campbell are termed the Campbell Complex. The combined mine area is also referred to as the Red Lake–Campbell Complex.

The Red Lake Complex is serviced by three shafts. The historic Red Lake Complex head frame is set over the #1 Shaft which extends to a depth of 1,023 m and serves the mine from 1 level to 23 level (the Upper Mine area). The Lower Red Lake mine is accessed from the #3 Shaft. Since #3 Shaft completion, #2 Shaft is on care and maintenance.

Mining is carried out using a combination of long hole and mechanized underhand or overhand cut-and-fill techniques, which allow maximum ore extraction while reducing dilution. Stope sequencing is carefully analyzed and adapted to surrounding conditions to alleviate seismic activity induced by mining. Stope sequencing is based on an amalgamation of elastic/plastic stress modelling, seismic system data analysis and underground observations.

Once mining blocks or lifts are completed, waste rock fill, paste fill, or a combination of both, is employed to fill the open excavation. This not only helps to stabilize the excavation and prevent unraveling but it also reduces surface storage requirements.

The seismic system for the mine consists of about 200 macro and/or micro seismic sensors dispersed through the mine, providing 15–200 ft (7.6–61 m) accuracy in event localization.

Broken muck is dumped into passes located near the ore zones by trucks and load–-haul–dump (LHD) equipment. Broken rock above 42 level is carried to the shaft by ore and waste passes. Broken rock below and on 42 level is carried to the shaft by LHD units or trucks. All skipping at the Red Lake Complex is currently accomplished through #3 Shaft and #1 Shaft. The #1 Shaft is in the process of being decommissioned.

The high-grade mineralization and complex geometry of the ore lenses require operating under tight geological and grade control.

Conventional percussive drills, long-hole drills, and “jumbo” drilling rigs are used for drilling ore and waste. Mucking machines or LHD units ranging in size from 1 yd3 to 4.0 yd3 capacity (ore width determines the size of the LHD units used for mucking stopes), are used in conjunction with trains or haulage trucks to move the broken rock. There are currently three tele-remote LHDs operated from surface.

Additional equipment includes ventilation fans, pumps, rock-breakers, rail-mounted vehicles, jumbo face drills, bolters, mine service and transport vehicles, and a variety of utility vehicles.

Campbell Complex.
Longhole panel mining is performed on 15 m sublevel intervals with typical widths of 2.4 m to 6 m and typical strike lengths from 15 m to 21 m. Larger stopes may be mined transversely through the use of draw points on 15 m intervals. For long hole mining, block spans are minimized, blast size is kept small and paste fill is placed as required. Ore is hoisted to surface via the Reid Shaft and crushed.

The seismic system for the mine consists of about 150 macro and/or micro seismic sensors dispersed through the mine, providing 30–50 ft (9.1–15 m) accuracy in event localization.

Campbell infrastructure is also being used for accessing and mining the Red Lake Complex orebodies, as well as providing access for the exploration projects at the Cochenour Complex and H.G. Young.

The operation is supported by two mill processing facilities (Red Lake and Campbell mills), providing a total milling capacity of 3,100 tonnes per day, including crushing, processing and pastefill plants.

Red Lake Processing Complex.
The crushing plant is a two-stage process which reduces underground ore from about 30 cm to 1 cm. Underground ore from a coarse ore bin is fed to a jaw crusher and sizing screen. Screen oversize is crushed in a cone crusher and screen undersize is conveyed into a fine ore bin as plant feed material.

Unit operations in the processing plant include grinding, gravity concentrating, cyanidation, carbon-in-pulp, carbon elution and reactivation, electrowinning, bullion smelting/refining, cyanide destruction, flotation, and concentrate handling. Three types of gold occur in the Red Lake Mine ore requiring these various unit operations.

Coarse gold is recovered from the ore via the gravity concentrating circuit. A portion of the ground slurry from the ball mill is fed to two Knelson concentrators which produce a gravity concentrate that is upgraded on a Diester table to a concentration of approximately 75% gold, and directly smelted into bullion. Bullion is then shipped to a refinery for later sale into the spot market.

There is an additional Knelson concentrator operating from a portion of the verti-mill product. The verti-mill was installed in 2007 to increase the grinding capacity of the mill. During 2010, the gravity circuit recovered 51% (265,641 ounces) of the gold from the processing plant feed.

Finer-grained gold is dissolved in the cyanidation or leach circuit in which sodium cyanide is introduced to the process stream. The leach circuit consists of four tanks each overflowing from one to the next. In the leach tanks the gold is dissolved from a solid state into solution. Gold is removed from solution and onto granular carbon particles in the carbon-in-pulp (CIP) tanks. Values from the carbon are removed in the carbon strip plant, in which a high-grade gold-bearing solution (loaded eluate) is generated. This loaded eluate, or pregnant solution, reports to two electrowinning cells where, under an applied voltage and current density, gold precipitates out of solution and back into its solid state as “cathode sludge”. This sludge is also directly smelted into bullion for subsequent shipment to the refinery.

The pulp discharging from the CIP circuit is pumped to the detox or Inco SO2 circuit for cyanide destruction. The circuit consists of two tanks with mechanical agitation where air, copper sulphate and sulphur dioxide are added to rapidly oxidize the cyanide and convert it to a non-toxic cyanate that hydrolyses to ammonia. Only one tank is in use at any one time.

The refractory component of the ore is gold that is extremely fine and locked in arsenopyrite and pyrite minerals (sulphides). Conventional milling methods are not capable of recovering this type of gold. The Red Lake Complex processing plant employs a typical sulphide flotation circuit generating a bulk sulphide concentrate. This concentrate is pumped as a slurry to the Campbell Complex for processing in the autoclave.

The process stream (tailings) reports to the paste fill plant where most of the water is removed and the pulp is stored in a large stock tank. This material is either discharged to the tailings management area or sent underground for use as backfill. The paste fill plant is a semi-batch process, which implies that all aspects of the plant are continuous with the exception of the discharge of paste to the underground distribution system. In the paste fill plant a tailings filter cake is generated, binder (cement and fly ash) and water is added and mixing occurs. Once the proper consistency is achieved, the paste is discharged underground to flow by gravity to mined-out areas.

The Campbell Complex mill was designed to treat free-milling and refractory gold ore at a rate of 360 t/d in 1949. The throughput has been gradually increased over the years to the current 1,800 t/d.

Conventional crushing and grinding is followed by gravity concentration to recover free milling gold. Refractory gold, finely disseminated in the arsenopyrite and pyrite matrix, is recovered by flotation followed by pressure oxidation, neutralization and carbon-in-leach (CIL). This stream joins the non-refractory flotation tails and is recovered by cyanidation/CIP processing.

The ore is hoisted from the Reid Shaft to a 1,500 t coarse ore bin. From there, it is transferred to a 250 t coarse ore bin located in the Campbell Mine head frame. The crushing plant consists of two Ross feeders, jaw crusher, standard cone crusher, short head cone crusher, Tyler double deck screen, variable speed short feeder belt, and six conveyors.

A 19 mm product is produced in three stages of crushing at an average rate of 140 t/hr. A jaw and standard cone crusher operates in open circuit and a short head cone crusher operates in closed circuit with an 18 mm vibrating screen. The closed side setting of the standard and short head cone crusher is approximately 19 mm and 15 mm, respectively.

Fine ore is conveyed to the mill by inclined conveyor discharging, via a conveyor, to a 3,100 t fine ore bin.

Grinding is achieved in a two-stage rod/ball mill circuit. The ore from the fine ore bin is fed to the rod mill via two slot feeders and a conveyor. The grinding circuit consists of a 2.74 m x 3.8 m rod mill and 3.8 m x 4.7 m ball mill discharging, through trommel screens, into a common primary pump box.

The grinding circuit produces flotation feed with an average p80 size of 65 µm (84% passing 200 mesh) and pulp density of 35% solids by weight. Shaking table concentration is carried out on the Knelson concentrate. The final gravity concentrate assaying 72–75% gold by weight is refined into bullion.

The cyclone overflow is pumped to a conditioner tank. The slurry reports to a seven cell bank of Denver DR-500 rougher/scavenger cells. Concentrate reports to a four cell bank of Denver DR-100 cleaner cells. Cleaner tails are recycled back to the DR 500 cells and the final concentrate assays approximately 15% sulphur and is pumped to a 9 m concentrate thickener. The overflow from the concentrate thickener is recycled to the conditioner. The flotation tailing is transferred to a 27 m diameter thickener with the underflow sent to the flotation tails leaching circuit and the overflow to the process water tank. The reagents are stage added to the conditioner and junction box. A Courier 30XP on-stream analyzer is used to monitor and control the flotation performance.

Carbonate destruction prior to pressure oxidation improves the oxygen utilization in the autoclave. The thickened flotation concentrate (at 55% solids) is contacted with acidic solution (recycled first counter-current decant (CCD) wash thickener overflow) in the pre-treatment circuit consisting of six pre-treatment tanks with a total retention time of six hours. The recycled acid is generated by the oxidation of sulphides and reacts with the carbonates in the concentrate, evolving carbon dioxide. Fresh acid, 93% concentration by weight, can be added as required to maintain a discharge pH of not higher than 3.0.

Cyanidation and carbon adsorption of the oxidised concentrate takes place in two CIL tanks with a retention time of 48 hrs each. The slurry is in contact with carbon at a concentration of 35 g/L. The leaching and carbon adsorption are not completed in this single stage circuit therefore the tails of the second CIL tank is combined with the flotation leach and CIP circuit.

Thickened flotation tailing (50% solids) is leached for 20–28 hrs. The leached slurry, a combination of oxide and flotation tails, is pumped into a train of six CIP tanks; each has a slurry retention time of 50 min.