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Handling leftover sand is relatively easy; it can be dredged and used safely as fill to reclaim old mine pits. But the problem of mature fine tailings implied the construction of and maintaining for at least three decades each ever more ponds as production expands. However, Suncor researchers have developed a new tailings reduction operation (TRO) that enables the company to solidify and recycle the fine tailings in just a few years.
To demonstrate the new technology, Suncor lab director Adrian Revington took a beaker of mature fine tailings and added a tiny amount of a polyacrylamide flocculant [PDF] commonly used in water treatment that then precipitated out the suspended clay particles. At the industrial scale, the mature fine particles are dredged, treated with flocculant, and piped to 220 acres of sloped drying beaches where the water drains away to be recycled at the mine. This process takes three weeks or so and leaves behind rock hard clay that is used as fill for reclaiming old mine pits and tailings ponds, or to build dikes and roads. Because of this new TRO process, Suncor has cancelled plans to build five additional tailings ponds. The company believes that it will now need only one tailings pond in the future, enabling it to close and reclaim all of its current ponds.
Next, the bus took us over to the upgrading plant, which produces 310,000 barrels of synthetic oil per day. The oil is piped to the Athabasca Tank Terminal for further pipeline distribution to refineries in Canada and the United States. Bitumen is a mixture of very heavy hydrocarbons such as asphaltene that contains not only carbon and hydrogen, but also nitrogen and sulfur. The upgrading plant removes these substances and transforms the bitumen into lighter hydrocarbons. The sulfur is sold to fertilizer plants. Suncor plans to add capacity for upgrading 200,000 more barrels per day.
Our Suncor tour ended with a visit to what is now called Wapisiw Lookout, formerly known as Pond #1. Reclamation specialist Lelaynia Cox joined us on the bus as we circumnavigated the site. She explained that Wapisiw is the first tailings pond in the history of oil sands mining to be reclaimed. The process started in 2007 and was completed in 2010. In this case, the mature fine tailings were dredged out and the pond was filled with leftover sand from which the bitumen had been removed. The landscape was contoured with hummocks and swales and covered with the muskeg topsoil that had been removed and stored years ago. The site was then planted with 600,000 trees, including jack pine, aspen, white birch, and white spruce, all grown from local seeds. In northern Alberta’s cold climate it takes it takes trees seven to ten years to grow to the height of an average person. The pond site reclaimed measures just over a square mile. As we drove around, we saw a fox, several white-tailed deer, and spooked a couple of coveys of sharp-tailed grouse. Some of my more sharp-sighted compatriots claimed to have seen a black bear in the distance.
The bus brought us back to our motel for a buffet dinner with some Canadian oil sheikhs. More on that and a visit to ConocoPhillips’ SAGD facility in my next dispatch tomorrow.
Ronald Bailey is Reason's science correspondent. His book Liberation Biology: The Scientific and Moral Case for the Biotech Revolution is now available from Prometheus Books.
Disclosure: My travel expenses to visit Alberta’s oil sands were covered by the American Petroleum Institute. The API did not ask for nor does it have any editorial control over my reporting of this trip.