Wawa is a small town located about 250km north of Sault Ste. Marie, Ontario. It’s right at the junction of provincial highways 101 and 17, Canadian National and Algoma Railways service the area, and Lake Superior is just about 50km to the west.
As small towns go, Wawa has a lot to offer and until the late 1980s, the forest industry considered it to be one of the prime locations in Ontario to set up shop and to draw from many of the town’s 2950 residents to work in the surrounding forests and mills.
When much of the industry decided to pull up roots (sorry for the pun), unemployment skyrocketed and it wasn’t until the mining industry came to the rescue when the focus moved from forestry to developing the area’s vast mineral resources.
Wawa is in the heart of the mineral-rich Michpicoten greenstone belt and contains a host of ores, including a series of sub-parallel lenses containing gold mineralization within deformed rocks under Goudreau Lake, located about an hour’s drive northeast of the town.
Finding minerals under a lake is not unusual, but what makes this discovery interesting is that it caught the attention of Richmont Mines Inc. from Rouyn- Noranda in neighbouring Quebec.
Richmont Mines was founded in 1981 by Jean-Guy Rivard who focused on the exploration and development of underground gold deposits. Since then, the company has been instrumental in the development of the Francoeur, Beaufor and East Amphi mines in Quebec, plus the Nugget Pond and Hammerdown mines in Newfoundland.
And since 2005, the company has also been working about 83km northeast of Wawa on its Island Gold Mine property (named appropriately because of its location under an island on Goudreau Lake), a site containing 251,572 tonnes (Proven Reserves) and 48,086 ounces of gold at 5.95 g/t, and 481,775 tonnes (Probable Reserves) and 95,419 ounces of gold at 6.16 g/t.
In addition, Measured Resources are 28,087 tonnes and 5,031 ounces of gold at 5.57 g/t, Indicated Resources are 255,600 tonnes and 59,402 ounces of gold at 7.23 g/t while Inferred Resources are 362,858 tonnes and 82,744 ounces of gold at 7.09 g/t.
The Island Gold property is stratigraphically positioned in the area composed by intermediate felsic volcanic rocks capped by pyrite-bearing iron formations containing gold. The veins containing gold have been found roughly at the -100m and -500m levels.
Nearly 100,000m of drilling were completed underground at the Island Gold Mine, including about 62,000m for continuing exploration, 20,000m of definition drilling and 18,000m of exploration in other areas of the mine.
From the end of 2011 and throughout 2012, Richmont completed extensive exploration drilling below the Island Gold Mine infrastructure. Using a total of 117 surface and underground holes, the company modeled and established a mineral resource estimate for the deep extension below the mine of 1.5 million tonnes and 508,000 ounces at 10.73 g/t in February 2013.
Additional drilling expanded this resource base to its current estimate of Indicated Resource of 456,013 tonnes and 168,897 ounces of gold at 11.52 g/t and additional Inferred Resource of 3,196,114 tonnes and 954,583 ounces of gold at 9.29 g/t.
Because of where the gold is located, mining in the current operations is done via a ramp, and is predominantly done using the longitudinal long-hole retreat method on levels that are approximately 22m apart vertically.
Mining consists of drilling downwards in a series of vertical holes from one level to the next and blasting in vertical slices. The broken ore then ends up in the bottom of ore drift and is hauled out with scoop trams to the on-site mill.
Broken ore is extracted before another slice is blasted to ensure a maximum recovery of ore should any unplanned caving occur. Once the stope is completed, waste rock is dumped in the hole as non-cemented rock fill.
To get space to blast the second stope of the same horizontal sublevel, a void is pulled as a primary opening. The second stope is then blasted, mucked and backfilled, and so on and so on, until all sublevels are mined out.
The recovery process involves bringing the ore to the surface and to a mill located approximately 0.8km from the portal of the mine’s ramp.
Current mining operations extend to an approximate vertical depth of 450m, but the company has been extending the ramp at depth in order to access the higher-grade established resource below the mine’s infrastructure.
The ramp reached a vertical depth of 620m at the end of June, 46m below its depth of 574m at the end of 2013.
The ramp is 4.5m x 4.5m and there are four main ventilation fans on surface (two 54-inch diameter Joy units each with a 200 hp motor, and two 60-inch Hurley fans each with 350 hp motors) to provide a total volume of 366,000 cfm of fresh air.
There are also four propane burners producing 43 million BTU for air heating and six compressors producing 8,000 cfm. A 750-cfm diesel compressor is also on-site in case of emergency, either for surface or underground needs.
About 750 tonnes per day is being delivered to the mill, with 65 per cent of it coming from stopes and the remaining tonneage from ore development.
The Island Gold Mine’s Kremzar Mill uses a conventional gold milling approach using the carbon-in-pulp (C.I.P.) process. The plant consists of a crushing circuit (primary and secondary crusher) followed by a ball mill for size reduction, then thickening of the ground slurry ahead of cyanization and C.I.P. processing. Gold is recovered using an electrowinning cell fitted with stainless steel mesh cathodes.
Before all of that, however, ore from the mine is delivered directly into the crusher feed hopper or deposited in a nearby stockpile area.
The crushing plant consists of a fixed grizzly with a rock breaker, feed storage
hopper, vibrating grizzly feeder, jaw crusher followed by a cone crusher installed in closed circuit with a vibrating screen.
The jaw crusher (30″ x 42″), is operated with approximately 75mm closed-side setting to help ensure that the final crushed product size will be 80 per cent passing 100mm. Undersize products are sent to a vibrating screen in closed circuit with a 4 ¼ short head cone crusher. The cone crusher is operated with an approximate 25mm closed-side setting to help ensure that the final screen undersize product will be 80 per cent passing 16mm. At this stage, the undersize product is dropped into a fine-ore bin storage of 500 ton live capacity.
The mine’s grinding circuit is composed of two grinding mills in series and is fed directly from the fine-ore bin to grind to 80 per cent passing 75 microns with only one ball mill, operated in closed circuit with cyclones.
Like all mines, tailings are a major consideration in the operation of the Island Gold Mine and Richmont Mines has taken every precaution to help ensure that minimal harm comes to the surrounding environment.
Tailings discharge point is located about 750m from the mill where they are pumped through a pipeline and discharged into a massive holding area where part of the discharged water is pumped back (800m3/day) to the mill and then treated and recycled.
The remaining water follows a small creek before reaching a clear-water pond. At this point, an impervious dam controls the water discharge into the environment.
In addition to water treatment through a primary tailings and secondary settling pond, the Island Gold Mine site includes the mill, ramp and portal, plus a 15-km gravel mine access road to the nearby town of Dubreuilville where bunkhouses are located for mine personnel.
The site also features a hydro-electric power supply, an office, core-logging and storage facilities, and a warehouse.
Since the start of commercial production in October 2007, Richmont’s 100 per cent-owned Island Gold Mine has produced more than 256,000 ounces of gold and in 2014, the company is targeting approximately 35,000 to 40,000 ounces of production.
With a million-ounce gold resource at depth, the Island Gold Mine is an asset that has the potential to transition into a longer-life, higher-grade and lower-cost operation and is proof that gold mining in Canada is in good hands thanks to companies like Richmont Mines Inc. from Rouyn-Noranda, Quebec.