Overview
The Red Lake Gold Mine is composed of two operating complexes: the Red Lake Complex and the Campbell Complex. Red Lake Gold mine is Canada?s largest gold mine, and in 2009 produced 623k ounces at a cash cost of $288/oz. It is also one of the world?s richest gold mines and lowest cost producers.
In May 2006 Goldcorp acquired the Placer Dome Canadian operations, which saw the combination of two major Canadian gold mining operations. The new Red Lake Gold mines now consists of the Red Lake Complex and the Campbell Complex.
Following the discovery of a high grade ore zone and subsequent expansion of mine facilities, the Red Lake Complex was revitalized and achieved full production on January 1, 2001. Mining is carried out using underground cut and fill techniques allowing maximum ore extraction and minimal dilution. The high-grade, narrow vein system is being mined at the rate of 635 tonnes per day with an average grade of over 68 g/t. The high-grade mineralization and complex geometry of the ore body require operating under unique circumstances. Various mining cut and fill methods are currently in use.
The implementation of innovative mining techniques, as well as improvements and refinements to other areas of the operation, has been key to the success of the Red Lake Complex. Goldcorp has implemented the use of Virtual Reality (VR) technology for mine design and planning purposes, and has recently built a state-of-the-art VR studio on site.
Location
Red Lake Gold Mines are located in the Canadian Shield of Northwestern Ontario, Canada, 180 kilometres north of Dryden. They cover approximately 2,335 hectares within the District of Kenora in Northwestern Ontario.
The area is accessible by Highway 105, which joins the Trans Canada Highway at Vermilion Bay, east of Kenora. Commercial air services from Thunder Bay and Winnipeg are available with several flights daily to each community.
Geology
The Red Lake Gold Mines property is underlain mainly by tholeiitic basalt and locally by komatiitic basalt of the Balmer assemblage. The mine sequence is completed by peridotitc komatiite, rhyolite and associated mafic intrusions of the Balmer assemblage. The steeply plunging south-southwest folded package is overlain by felsic volcaniclastics, clastic and chemical sedimentary rocks of the Bruce Channel assemblage defining an enveloping syncline anticline couplet based on younging directions, with the synform hinge located on the north side of the Campbell Complex, east of the HG Young shaft underneath Balmer Lake and the anticlinal hinge in the south central portion of the former partywall boundary and east at the Red Lake Complex. The prominent fabric at the site is the S2 cleavage, trending northwest-southeast, axial planar of the F2 folding, plunging steeply to the south-southwest.
The major mineralized zones are associated with a central ultramafic unit, which is a highly carbonatized and altered unit, believed to be either volcanic or plutonic in origin.
The Red Lake Gold Mines mineralized system is a wedge-shaped zone above roughly the 27 level which widens upwards and is constrained by bounding fault structures on the northeast and southwest flanks. This wedge is defined by steeply south-dipping and South-southwestern plunging litho-structural packages of ultramafic and rhyolitic bodies, enveloped mainly by metabasalts.
Mining & Operations
Red Lake Complex The primary mining methods utilized are overhand and underhand cut and fill, pillar recovery and longhole. These methods where chosen: (a) to selectively mine highly variable and complex ore structures, allowing for full production geology control of each ore blast; (b) to reduce dilution in order to make the most of the limited available hoisting capacity by optimizing the grade of the ore hoisted; (c) to mitigate the potential for and damage from seismic events by controlling the open mining span, providing better control of teh mining sequence and minimizing the creation of sill pillars; (d) to maximize ore recovery; and (e) to develop methods that could be applied to future mine expansion at depth.
Jacklegs, stopers, longtoms, two boom air jumbos, and single boom electric/hydraulic jumbos are used for drilling ore and waste. Mucking machines and trains, scooptrams ranging in size from 1 yard to 3.5 yard capacity, and 16 ton trucks are used to move the broken rock. The most common explosive used in blasting is ANFO. Ground support consists of various combinations of rebar bolts, swellex bolts, and screen, depending on the requirements of the heading being driven. Blasting is carried twice a day when all workers are out of the mine, and is initiated by an electrical central blasting system. On-shift blasting is heavily restricted, and only permitted with proper guarding procedures in place. Broken muck is dumped into passes located near the ore zones by trucks and scooptrams. The muck is pulled from chutes on 37 Level and 34 Level, and hauled by train to passes near #2 Shaft, which feed the loading pocket on 38 Level. At the loading pocket, muck is loaded into the 6 ton skips, and hoisted up #2 Shaft, and dumped into bins on 23 Level. A 36 ton train is used to transfer the muck across 23 Level to passes that feed another loading pocket at the bottom of #1 Shaft. From that loading pocket, muck is loaded onto 4 ton skips and hoisted up #1 Shaft, and dumped into bins on surface that either feed the process plant or the trucks that haul to the waste dump.
Processing
Red Lake Complex
The processing facilities consist of three separate plants: the Crushing Plant, Processing Plant, and Pastefill Plant.
The Crushing Plant consists of a two stage process which reduces underground ore size (12 inches to 3/8 inch). The ore is fed to the jaw crusher and then the sizing screen. The screen oversize is crushed in the cone crusher which reports back to the screen, and screen undersize is conveyed to the Processing Plant for gold extraction. Separate operations in the Processing Plant consist of grinding, gravity concentrating, leaching, carbon-in- pulp (CIP), 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.
The mined material goes through a primary crusher that reduces it to a maximum size of 150mm. Approximately 2,500 tonnes of ore are dumped into the primary crusher each hour. The secondary crusher's product is conveyed to the primary stockpile, which has a capacity of 10,000 tonnes.
Grinding consists of a ball mill (11.5 feet by 16 feet) in closed circuit with sizing cyclones. Coarse gold is recovered from grinding using two Knelson Concentrators. This gold is upgraded on a Deister Table and smelted into bullion on site. During 2005, the gravity circuit recovered over 55% of the gold fed to the processing plant.
Following grinding, thickened slurry is pumped to four leach tanks where gold is dissolved using a weak cyanide solution. The slurry, with the gold now in solution, flows to six CIP tanks that contain granular carbon particles that adsorb the gold. The adsorbed gold is stripped from the carbon using a heated mild caustic solution that is pumped to two electrowinning cells.
Under applied voltage and current density, the gold is electrically plated onto stainless steel cathodes in the cells. The gold is washed off and smelted into bullion on site. During 2005, the leach circuit recovered over 34% of the gold fed to the Processing Plant. After exiting the CIP tanks, all remaining cyanide in solution is destroyed. This is accomplished using the INCO SO2 treatment process which oxidizes the cyanide component of the slurry and precipitates heavy metals. After the cyanide is destroyed, the slurry flows to the flotation circuit where a concentrate of sulphides, which encapsulates the remaining recoverable gold, is separated from the rest of the slurry stream. In the flotation circuit, chemicals are added to help the gold bearing sulphide minerals adhere to tiny bubbles of air that are added in small agitated tanks. The bubbles rise to the surface and collect in a froth layer which is removed from the surface with paddles. The concentrate is collected and excess water is removed with a thickener and then a drum vacuum filter. The gold-bearing concentrate is trucked from site for treatment in an autoclave, either at Placer Dome?s Campbell Mine, also in Balmertown, or at Barrick?s
Goldstrike Mine in Nevada.
The tailings from the flotation circuit are directed to the Pastefill Plant from where the slurry is either discharged to the Tailings Management Area or mixed and sent underground for use as backfill. Slurry sent underground is first filtered before adding cement and water to form a paste. Once the proper consistency is achieved, the paste is discharged underground to flow by gravity to the mined out areas.
In 2006 good progress was made in developing the new Balmer shaft which will provide improved access to reserves at deeper levels of the mine.
Campbell Complex
The processing consists of crushing, grinding, gravity recovery, flotation, pressure oxidation, cyanide leach, CIL, CIP recovery and pastefill.
The crushing plant is a 3 stage process which reduces underground ore size to approximately ½? in size. The ore is fed to a jaw crusher, then to a standard cone crusher, then to a sizing screen. Screen oversize is then fed to a short head cone crusher, which then reports back to the screen. Screen undersize is conveyed on to the grinding circuit. The grinding circuit is a 2 stage process, with an open circuit rod mill (9 feet by 12.5 feet) followed by a ball mill (12.5 feet by 15.5 feet) in closed circuit with sizing cyclones. Coarse gold is recovered from grinding using a Knelson Concentrator. The gold is upgraded on a Deister Table, and smelted into bullion on site.
Following grinding, the slurry is fed to the flotation circuit, where a sulphide concentrate is produced. In the flotation circuit, chemicals are added to help the gold bearing sulphide minerals adhere to tiny bubbles of air that are added to the bottom of small agitated tanks. The bubbles rise to the surface and collect in a froth layer which is removed from the surface with paddles. The concentrate is collected and excess water is removed with a thickener. This concentrate is then mixed with concentrate from the Red Lake Mine, and passes into the pressure oxidation circuit. The flotation tails pass on to the cyanide leach circuit.
In the cyanide leach circuit, thickened slurry is fed through five leach tanks where gold is dissolved using a weak cyanide solution. The slurry, with the gold now in solution, flows to six CIP tanks that contain granular carbon particles that adsorb the gold from solution. The carbon, along with the gold adsorbed onto it, is then fed into the "CIL tanks"
