Natural Elements, NRCan's Monthly Newsletter

Green Mines-Green Energy

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Field trials are set to begin this summer for an exciting research project led by Natural Resources Canada. The Green Mines–Green Energy initiative promises both environmental and economic benefits. NRCan and its partners plan to transform mine waste sites called tailings ponds into productive land for growing “energy” crops.

A tailings pond, long considered the scourge of the mining industry, contains water and waste material from the processing of ores. Depending on the type of ore mined, a tailings pond may become very acidic because the tailings rust when exposed to oxygen, so very little can live or grow at the site.

Here’s the basic idea behind the Green Mines–Green Energy project. Researchers will cover mine tailings with organic wastes from paper mills and municipalities. This material will generate alkalinity near the surface of the tailings, which helps to neutralize the acidic tailings. In addition, the material will provide essential nutrients for crop growth. Approximately one metre of material will be added, then the site will be used to grow energy crops (such as corn, canola or soy) that can be harvested to make biodiesel or ethanol.

“We’re trying to use organic wastes from one industry to rehabilitate another’s waste site ─ then we’re using the reclaimed land to grow crops to produce bioenergy,” says Bryan Tisch, Project Manager, CANMET Mining and Mineral Sciences Laboratories. “So there’s a big upside if we’re successful.”

The production of bioenergy from reclaimed tailings areas would be a substantial achievement for the mining sector and Canada, in terms of both environmental responsibility and addressing climate change. Although mining companies are unlikely to make much money from the sale of such crops, any revenue generated could help offset ongoing mine rehabilitation costs.

Field trials are planned for this summer at three Ontario mines ─ CVRD Inco’s Copper Cliff tailings near Sudbury, Goldcorp’s Delnite tailings near Timmins and Xstrata Nickel’s Strathcona tailings in Onaping (west of Sudbury).

Other partners in the Green Mines–Green Energy project include Laurentian University/MIRARCO, the City of Greater Sudbury, St. Mary’s Paper, Domtar Inc., Abitibi Consolidated, Highland Valley Copper, BHP Billiton, Alberta Research Council, GSI Environment Inc., Ontario Ministry of Agriculture and Food, and Agriculture and Agri-Food Canada.

Will the Green Mines–Green Energy processes completely rehabilitate a mine tailings pond?

“We know that covering the pond with organic material helps keep water and oxygen out of the tailings. This makes the site more stable. But we still need to examine the interaction between the biosolids and tailings to determine if there are concerns about drainage, metal mobility or toxicity,” says Bryan.

The Green Mines–Green Energy initiative advances the Government of Canada’s commitment to taking clear, decisive steps to protect our environment.