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Q&A with Bruce Armitage from Lake Shore Gold: Energy efficiency in gold mining

We chatted with Bruce Armitage, Energy Manager at Lake Shore Gold. Among the many awards to his name, Bruce received the title of IAP-CIPEC Energy Manager of the Year in 2018. He initiated an energy conservation program that educates and rewards employees while making the company more efficient and sustainable.

Bruce Armitage (in the middle) pictured with Metso people.

Lake Shore Gold realized $1.5 million annually in energy savings while increasing production nearly 30% with the help of Metso’s liner and grate solutions. This project was the cornerstone that allowed Armitage and Lake Shore Gold to save $12 million and more energy than any other organization in Ontario in 2018.

Q1. Can you tell us a little bit about Lake Shore Gold?

A division of Tahoe Resources*, Lake Shore Gold is a Canadian-based gold producer with operations in Timmins, Ontario. We mine gold from our two underground mines, Timmins West and Bell Creek. All ore is processed at a central milling facility located at Bell Creek, which runs 24 hours a day, 7 days a week.

At Lake Shore Gold, energy efficiency considerations are included in all aspects of our business planning and operations, along with sound business management practices and our responsibilities as a corporate citizen. Being a low gram per tonne operation, we are committed to reducing our energy costs, which gives us a competitive advantage in the industry. 

Q2. What are the characteristics of your production?

The Bell Creek Mill is a conventional gold mill circuit, involving crushing and grinding, gravity, and leaching, followed by carbon-in-leach (CIL) and carbon-in-pulp (CIP) processes for gold recovery. Most gold mills (approximately 90%) worldwide use conventional methods for gold extraction. I would say that conventional methods for gold extraction are very energy intensive, and the industry struggles to reduce its energy consumption.

Q3. Could you share how you have addressed energy efficiency?

When I started at Lake Shore Gold, the energy program was in its very early stages.  Through hard work and dedication by our energy team, we took the program from its infancy to industry leader in less than a year.

We have established a program that addresses sustainability, environmental stewardship (water, waste management, biodiversity, climate change, land use), recycling, government funded programs, energy monitoring, measurement, and verification plans. It includes an energy incentive program that rewards the workforce for submitting suggestions that help Lake Shore Gold meet its energy conservation targets.

Our approach is holistic, and the program has its own symbol and slogan. We want to demonstrate the importance of environmental stewardship as well as the struggle, understanding, and acceptance that as a mine advances, it will inevitably require more energy resources (ventilation, dewatering, etc.) to extract the reserves. We educate and remind our workforce of the benefits of an energy efficient mining operation.

Q4. How has Metso been involved in the energy program?

A well-recognized issue with low-aspect, single-stage SAG mills is the phenomenon of slurry pooling, or excessive accumulation of slurry in the mill. Impact grinding is reduced considerably since the falling material splashes into a slurry pool instead of making contact with the solid toe of the charge region. Essentially, inefficient grinding is the result.

More power was being consumed by the SAG mill than was needed to process the ore, which increased the cost. Under the direction of the Senior Mineral Processing Engineer, Metso assisted with the grinding circuit’s mass balance to find a solution and proposed a new grate design with more holes to increase the open area and a wider taper angle to eliminate plugging.

These measures resulted in the SAG mill saving $1.5 million in electricity alone. This project has allowed nearly a 30% increase in production, from 170 tonnes per hour (tph) to 225 tph. The Metso team, in particular our Account Manager Mark Wagner, is dedicated, driven, and timely. Metso has been a dependable partner that we can always count on.

Q5. What is your view on the future of the mining industry?

With the views and beliefs of the world heavily shifting towards the environment and climate change, technologies in all industries will have to become more efficient. A large emphasis will be placed on renewables and technological advances in the future which will consume less energy and produce less emissions. This will change the way mines operate in the future. 

Newer mines will look to design the underground environment using electric battery technology, thus reducing diesel emissions and saving the considerable quantities of electricity which were previously required to power the ventilation fans used to dissipate the diesel emissions. Operating mines will need to be more inventive and invest in renewable technology, but this will be heavily influenced by the life of the mine.

*Tahoe Resources Inc. has been part of Pan American Silver Corp. since February 2019


Efficiency in comminution
In the first piece of our series "How to ensure energy efficiency in mining", we focus on comminution circuit design.

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