Sudbury Mining Solutions Journal is a magazine that showcases the mining expertise of North Bay, Timmins and Sudbury. This article is from the December, 2013 issue.
Water, emissions priorities for mine design
More stringent environmental oversight of new mine development means more work. But instead of a challenge, it’s actually made the process easier at Totten Mine because it allows Vale to meet industry expectations and be creative in its approach, said senior environmental specialist Allison Merla.
“There’s the opportunity here to do it right, right away,” said Merla, who acted as the environmental co-ordinator for the mine, ensuring Vale’s permits and requirements met current industry standards.
“If you’re looking at a legacy site that has always done something a certain way for years, and they’re working on some of the older permits or legislative requirements, it takes a while to instill that change. Here, we’ve built it right and we’re going to do it right.”
Every aspect of Totten was designed with the environment in mind, starting with its overall footprint. The headframe and main operations have been laid out on top of previous mine workings, while the Victoria Creek pumphouse, from which Vale gets its domestic water, has been retrofitted and upgraded to meet today’s standards.
This effort will not only minimize the environmental impact of the mine, but also assist with the eventual closure process, Merla said.
“The design was to build where there was already impact, so when we go to remove infrastructure from this site we’ll be cleaning up the previous site operations as well,” she said.
Unique to Totten are the enclosed material-handling operations. The bin house, where materials are hoisted and loaded onto trucks, the material storage area and the fuel-delivery system are all enclosed to minimize dust and other fugitive emissions that could impact the environment.
At other mines, the material that isn’t ready to be shipped is typically dumped in piles in the mine yard. At Totten, even the material-handling area, where waste ore and rock can be stored prior to shipment for milling, is encased in a protective shell.
Three large bays, built to store 2,000 tonnes of ore or 500 tonnes of waste rock, have been constructed inside a building, into which transports can drive to receive their loads. A carbon monoxide monitoring system ensures the air remains safe.
“It fits with Totten’s design that there is no waste stockpiled, so there aren’t going to be material piles outside, and there isn’t going to be material handling out in the open where it’s subject to wind, erosion and rain,” Merla said. “All those are minimized by having material handling done inside enclosed buildings.”
A sophisticated water treatment system, which includes three water treatment plants, is at the heart of the Totten operation, which does not have access to a municipal water source. A mix of chemicals is used to treat mine water, removing the metals and filtering particles before being pumped back out to Victoria Creek or recycled for mine usage.
Everything within the plant is automated to monitor for oversight, Merla said. If the pH levels don’t meet required standards, for example, the water is returned to the system for reprocessing, rather than sent back into the environment.
“There is a tight water balance to manage, and we don’t want to be impacting the creek in any negative way, so we’re only taking as much as we need,” Merla said.
The original mine operation, dating back to the 1920s, had been left untouched since a cave-in took place in 1927, leaving the area resembling an open pit, Merla said. In the mid-2000s, Vale’s environmental department went in and partially reclaimed the area, removing waste rock material and seeding it.
Now, waste rock that would normally be sent to Copper Cliff will be used to backfill the cave-in area.
“That’s going to provide a safe place to put waste rock,” Merla said. “It’s reducing truck traffic, potential for spillage of mine waste, and it’s also afforded more stability to the cave zone.”
Eventually, Merla said, Vale will reclaim the entire site, bringing it as close to its original, natural state as possible. If Vale is successful, passers-by won’t know the site had ever hosted a mine cave-in, or any mining operations at all.