ENGINEERING A BETTER CANADA AWARD & AWARD OF EXCELLENCE Detour Lake Gold Mne

On February 18, 2013, Detour Gold Corporation announced the pouring of the first four gold bars, consisting of approximately 2,000 ounces of gold, from its Detour Lake Gold Mine in northern Ontario. The event was a remarkable milestone in the company’s transition from a young exploration company to an innovative, leading gold producer. Today, the mine is the largest regional employer, creating sustainable opportunities for the local communities and the region.

Detour Gold Corporation acquired the property in 2007. It is the site of a former open-pit/underground mine (operating 1983-1999), located 185 kilometres northeast of Cochrane.

After completing a feasibility study for the client, BBA helped to guide the development of this low-grade, high tonnage gold operation. BBA completed the detailed engineering, equipment purchasing and technical support for the open pit mine and new processing plant for on-site gold recovery. Standard mining practices had to be adapted and innovative techniques used in order to develop a robust design that met the production goals and extends the mine’s operational life.

The project also had to respect Aboriginal communities, provide regional social and economic benefits, and minimize the environmental footprint. This whole initiative was a tall order, but BBA forged a clear path forward.

Innovations boost production

The project included mining service buildings, waste tailings decantation and pumping, processing facilities and a 230-kV high voltage transmission line. In the processing plant crushing and grinding circuits feed ore at a nominal rate of 55,000 tonnes per day. This objective has been exceeded, with a record day at 63,700 tonnes on November 16, 2013.

BBA implemented innovations that enabled the mine to surpass the typical capacity of similar operations. The innovations include the use of:

• four 1,000 hp crushers (two pebble and two pre-crushing units) in order to reduce the milling energy consumption, increase the mill productivity and reduce grinding ball consumption:

• the latest pump cell technology for carbon in pulp gold recovery from solution;

• oxygen in leaching to reduce residence time, improve kinetics and eliminate the use of lead nitrate in the process;

• waste heat recovery of process equipment, mill drives and motors for building heat;

• heating of mine service facilities using waste oil from trucks;

• tight water balancing and water recycling to minimize the use of fresh water, which eliminated the need to build a pipeline from a nearby river.

Worker housing and infrastructure

A major complexity was the significant muskeg and sensitive wetlands of the area. BBA used construction innovations and completed the early work infrastructure including building a remote camp to house 1,400 workers, 12 months ahead of the required construction schedule. For the worker housing, modular units were acquired from the 2010 G7 Summit. The site services include power supply, emergency services (e.g. first aid, ambulances and firefighters), communications, permanent housing, parking and recreational facilities.

Respect for local communities and the environment

Four agreements with Aboriginal groups define how they participate in the environmental management of the project and how they will benefit through training, jobs and contracting. To date, local Aboriginal people account for approximately 24% of the corporation’s workforce, and over 53% of the workforce is from the Cochrane area. The broader community has benefited from the infrastructure investments, such as offices, lay-down yards and housing. The project has significantly reduced the regional unemployment rate. Local businesses are growing and new jobs have been created. For example, the new testing laboratory in Cochrane created 35 new jobs.

In deciding to rehabilitate a shut-down mine the company took on a whole new set of environmental challenges, as well as risks. Comprehensive environmental assessments and studies were conducted to meet the provincial and federal requirements for responsible development.

Prior to construction tours of the old mine site were arranged for key stakeholders to help them understand how the closed mine could be revitalized. As well, all environmental information was publicly posted in the regional municipal offices and libraries, and multiple open houses and community meetings were held to seek input on the proposed environmental mitigation. Meetings were held with chiefs, mayors, municipal councils, emergency responders and social service agencies to ensure they were prepared for Cochrane’s imminent economic growth and to inform them of any environmental issues as they arose.

During each stage of the project, every effort was made to reduce the environmental impact, including recycling process water to provide zero discharge to the environment. Power lines were installed only during winter to mitigate the impacts on muskegs and local wildlife, and the power lines were installed before construction to avoid using diesel generators. cce

Name of project: Detour Lake

gold mining project, Northern Ontario

Award-winning firm (feasibility study, EPCM early site preparation, detailed engineering, equipment procurement, technical site supervision): BBA, Mont-St-Hilaire, Quebec (André Allaire, ing., Patrice Live, ing., Guy Décoste, ing., Jean Lavoie, P.Eng., Nathalie Blackburn, P.Eng., Jean-Guy Quenneville, ing., José De Andrade, ing., André Goyette, ing., Jorge Torrealba, ing., Langis Charron, ing.)

Owner: Detour Gold Corporation

Other key players: AMEC Mines & Metals (overall project & construction management); AMEC E & I (environmental studies, tailings); Walters (steel structure, detailing); Kiewit (high-voltage power); Promec; Moreau; Blais (mechanical, piping, electrical)