Suncor Energy Inc. looks to clean up tailings ponds
A new process speeds the drying time of tailings by as much as 80 per cent
Suncor expects to spend $450 million in 2010 on tailings reduction operations
Suncor Energy Inc. has the eldest oil sands plant, so it would only seem natural for the 43-year-old mining and upgrading complex to dig up a philosopher’s stone to solve one of the most pernicious – and visible – Alberta industrial problems. The philosopher’s stone was the alchemist’s dream. It could turn base metal into gold. The 21st-century version would turn northern oil sands tailings ponds back into pristine wilderness.
Since their birth when the Suncor plant started up under the name of Great Canadian Oil Sands, tailings ponds have theoretically been the temporary resting place for leftover particles, water and other unwanted byproducts after bitumen is separated from the shallow ore deposits north of Fort McMurray. The problem is that, effectively, they never go away. The more bitumen the plants extract, the bigger and deeper the ponds grow. Today, the yogurt-like waste materials fill about 130 square kilometers of ponds dotting the landscape – an unnatural feature that industry critics claim is so large it can be seen from outer space.
But Suncor thinks it has an answer. And the preliminary claims made by the company for its idea are so impressive they won a rare, though modest, crumb of praise from the Pembina Institute, an environmental group that has spent years calling for a halt to bitumen belt development and is one of the coiners of the disparaging term “dirty oil.”
Suncor calls its invention tailings reduction operations, or TRO. The process is supposed to reduce the drying time of a tailings pond by as much as 80 per cent, down to between seven and 10 years from the current snail’s pace of four decades or longer, reports Suncor representative Sneh Seetal.
Tailings are part of every mining method. Naturally occurring substances are pumped into holding ponds to enable them to settle out from the water. But in the oil sands, the waste particles are tiny, extremely light and shaped like miniature boat hulls. It takes nearly half a century for the stuff to settle, dry and compact solidly enough to hold the heavy equipment used for reclamation. “Dry enough to drive on,” is the industry standard.
Bitumen tailings include sand as the largest component (about 35 per cent), residual traces of hydrocarbons, almost microscopically small clay bits known as mature fine tailings, or MFT for short, and, of course, water. In the 1990s, Suncor pioneered a technology called consolidated tailings. Known as CT, the approach added sand and gypsum as a coagulating agent to the tailings. It cut the waiting down to 40 years from forever.
“But with the implementation of TRO, we expect to see, in a much shorter time, the reclamation. We expect to see a reclaimable surface after 10 years,” Seetal says.
TRO is not complicated. It adapts, for the oil sands, technology that’s been used in civic wastewater treatment for years.
Dwayne Edwards, tailings reduction operations supervisor, is in charge of the TRO physical process. “What we’re actually doing is pumping mature fine tailings from the bottom of a pond with a dredge,” he reports.
The material is piped to a processing building where a polymer flocculent is added. Tufts of wool or down, with great capacity to absorb water, are natural versions. To visualize the polymer or plastic-like synthetic variety, think of fluffy nylon or shellac.
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