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West coast team aims for speedy CO2 trap in mine rocks

EcoLog, 11/23/2012 2:29:00 PM

A west coast Canadian geologist says it’s time for mining companies to start putting dollar values on mine waste because it can be used to trap greenhouse gases (GHG).

Dr. Michael Hitch of the University of British Columbia’s (UBC’s) Norman B. Keevil Institute of Mining Engineering studies the value of mine waste rock for its potential to trap CO2. He says that mining companies typically use just one per cent of the materials from a mining pit, when they could also be getting value and promoting sustainability by using the mines’ non-commodity rock.

Mine waste rock is rich in mineral magnesium silicate, which can chemically fix CO2 in place as magnesium carbonate, Hitch explains.

“All of a sudden this material starts having value, and this material starts taking on a position in the company’s cash flow as a byproduct,” Hitch said in a written statement released through Carbon Management Canada, which helped fund the rock research. “It really kind of changes the dynamics of the mining operation.”

Hitch and his colleagues note that the capacity for CO2 fixation can be five to 10 times greater than total GHG production from some mine operations such as nickel, diamond, copper and chromite. Larger mines, the researchers say, could fix 5 million tonnes or more of CO2 per year.

Hitch says that within 25 years mining companies could be using the mine waste rock to offset carbon emissions from mining projects.

Eventually, he says, companies could even sell carbon credits.

Hitch’s team says it has already observed how CO2 attaches quite quickly in rock tailings from a mine. They propose this is due to the large surface area exposed after rocks are crushed into small particles.

The main goal for Hitch’s team is to measure how fast the CO2 fixes to the mine rock tailings in a lab setting, and then determine how to speed up the process.

As the global price of carbon emissions credits continues to rise, the mining waste rock could become valuable. However, in order to achieve noteworthy CO2 sequestration in the rock, the rather slow chemical reactions that naturally fix CO2 would require a jumpstart.

Hitch is working on finding the key to the jumpstart alongside researchers Greg Dipple, team lead, and Ulrich Mayer, both part of UBC's Department of Earth, Ocean and Atmospheric Sciences. They work with Gordon Southam of the University of Western Ontario's Department of Earth Science.

“None of this (work) is done in isolation,” notes Hitch, adding that carbon management is not an easy solution. “It requires lots of different perspectives and lots of different skill sets,” Hitch says.

“I don’t like waste,” Hitch adds. “I like to see efficient use of the resources.”

Carbon Management Canada funds research to produce the technology, knowledge, and human capacity that will reduce carbon emissions in the fossil energy industry and in other large-scale emitters.

The collaborating researchers hope to move to field trials in five years.

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