INNOVATION July-August 2013

it becomes easier to go after solutions that could yield even higher capture rates but be more expensive to implement. “That is really about a decade out,” he says. A Game Changer Which laboratory test project stands the best chance of going forward into the field for testing is still an open question at this stage. But, the work carried out by the UBC team today could even change the way that future ore extraction is planned. “It could impact how you design your pit,” observes Dipple, as overburden rock could be mined to a cost-advantage to earn GHG offset credits. It also has the ability to change the perception of mining if mines could offset the carbon emissions of other industries. The team’s current research is being funded by Carbon Management Canada (CMC-NCE), a national research network that has committed $22 million to 44 Canadian research projects all focused, in one way or another, on reducing carbon emissions in the fossil energy industry and from other large scale emitters. Says Richard Adamson, the organization’s managing director: “Canada has a lot of rock and the mining industry is offering a lot of opportunity. We are really only scratching the surface.” He speaks optimistically of the project: “It has the potential to turn hard-rock mining in many situations into net negative emitters. If a mine can absorb more CO 2 than it produces in the mining process, then that is a major step forward.”

Quantifying Potential Greg Dipple began his own investigation into tailings carbon sequestration in 2001, alongside team member Ulrich Mayer, P.Eng., but was prompted by the concern over climate change rather than mine economics; “We have looked at mines, both active and abandoned, in BC, Quebec, the Yukon and Australia.” By examining old tailings piles at mine sites, he found they were naturally sequestering carbon under varying conditions and his team was able to quantify how much the rock had absorbed since it was milled and placed in the tailings piles. The ability to measure the absorption of the tailings showed the tremendous potential that existed. Dipple’s team, for example, found that tailings from one of the world’s largest nickel mines naturally absorb up to 50,000 tonnes of CO 2 per year—15% of the mine’s annual GHG emissions. “If we can increase that tenfold, the mine is going to be more than GHG neutral,” states Dipple. Like Hitch’s research, it boiled down to speeding up the mineral carbonization. Dipple has been running his own laboratory experiments. His group is not working with olivine, but serpentinite, another magnesium silicate derivative. Some serpentinites react quite aggressively with carbon dioxide, absorbing it rapidly. During the past two years, modeling in the department’s lab has been carried out using one-metre high columns of these tailings. CO 2 is injected at the column’s base with the focus on the rate of its absorption throughout the column as it rises to the top and the remaining gas exits. Again, the lab simulation is attempting to mimic what might be possible in the field. “At a mine site where there is a large- scale power plant producing CO 2 —

Clearing the Path to Success

especially if diesel is used—you may deliver the emissions to the tailing pile,” he explains, or route emissions through a tailings pond. Another viable solution might lie in utilizing wetlands, where microbial activity can speed up carbon capture through photosynthesis. The test project that eventually goes into the field in as short a time frame as two years will go after easy captures with rates of 20-40% targeted, according to Dipple. “We are going after the low- hanging fruit first,” he says and anticipates they will involve the serpentinite rock “to show the concept will work.” The test project would provide both technical and economic feedback. Once there is a demonstrated net gain to the mine from the technology,

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