Tailings are a mixture of water, sand, clay and residual bitumen, and are the by-product of the hot water treatment process used to separate the oil from the sand and clay. Tailings are stored in large engineered dam and dyke systems called tailings ponds, designed to settle out the solid particles from the water.
Water is continuously recycled from the tailings ponds back into the extraction process, reducing new withdrawals of fresh water from the Athabasca River and other sources. Although sand separates quickly from the tailings, smaller particles of clay and silt remain in suspension and form fluid tailings which in the past could take up to 30 years to separate.
New technologies are accelerating the separation process. Over the past several years, Suncor’s holistic Tailings Reduction Operations (TRO™) approach has allowed us to:
- reclaim a tailings pond, Wapisiw Lookout
- make another one trafficable through the use of coke capping technology
- convert a third tailings pond to a fluid tailings treatment area
- start increasing our fluid tailings treatment capacity in 2018, to begin draining another tailings pond to remove it from the landscape
As our mining operations have expanded, the volume of fluid tailings have increased. However, with the implementation of TRO™ in 2010, fluid tailings volumes at site have remained steady and we’re now working to decrease the inventory of fluid tailings on site. Suncor currently has about 300 million cubic metres of fluid tailings.
Fort Hills, operated by Suncor, ramped up earlier than anticipated and is targeting 90% average production by the fourth quarter of 2018. Suncor is treating fluid tailings from the start of operations with extraction thickeners and tailings sand-placement activities to reduce the amount of fluid tailings and minimize further treatment requirements.
Tailings operations feature an out-of-pit tailings area with plans to transition to below-grade tailings treatment once space is made available in the first mining area. The peak fluid tailings inventory at Fort Hills is expected to be below 130 million cubic metres. This represents a step change in fluid tailings management compared to industry demonstrated inventories.
To ensure fluid tailings volumes are managed appropriately, the Government of Alberta released the Tailings Management Framework in 2015, which is intended to ensure fluid tailings are in a ready-to-reclaim state within 10 years of the end-of-mine life.
And last year, the Alberta Energy Regulator (AER) finalized a new oil sands directive called the Fluid Tailings Management for Oil Sands Mining Projects (Directive 085). This regulation includes tailings management plan application and tailings performance reporting requirements aligned with the government’s Tailings Management Framework.
In 2015 and 2016, Suncor was invited to work with Aboriginal communities, the AER and other stakeholders to support the development of Directive 085.
To meet the new requirements, Suncor requested permission and received approval in 2017 to add treatment capacity to our TRO™ operations at our Base plant. Meanwhile, Fort Hills has applied for amendments to update its tailings management plan, to align with new requirements in Directive 085, under the Tailings Management Framework policy. Both updated plans are based on what we’ve learned through our implementation of TRO™ and from members of Canada’s Oil Sands Innovation Alliance (COSIA).
Raising the bar: tailings collaboration
As a member of COSIA, Suncor is sharing details of our tailings technologies with other member companies. In return, we are given access to technologies that others are using to manage their tailings. Highlights in 2017 included:
- 13 new projects started
- 178 contributed technologies
- 78 active projects, with a cost of approximately $280 million
Through shared research, experience, expertise and financial commitments, we are able to investigate new tailings technologies faster. We anticipate this resource-sharing through COSIA will improve tailings management now and at future oil sands mine operations.
Coke capping technology
Thanks to breakthroughs that have come from research and development, Suncor continues to make progress in tailings management. Following the surface reclamation of Pond 1 (now known as Wapisiw Lookout) in 2010, we began creating a trafficable surface on Pond 5, with a reclamation technique called coke capping. Thanks to teamwork and dedication, Pond 5 can now support heavy equipment – more than two years ahead of what we had planned.
The coke capping technology we developed and commercially deployed at Pond 5 involves placing a geofabric/geogrid on a tailings pond and then placing petroleum coke (a byproduct of upgraded bitumen) to create a solid surface. Giant straws, called vertical strip drains, are added to dewater the fluid tailings. In the future, we will spread sand over the coke to allow placement of a soil cover and vegetation (trees and shrubs).This is the first full-scale soft tailings cap of its kind in the industry.
Originally, Suncor anticipated completing the cap on Pond 5 in 2019. However, based on how well the dewatering had already progressed, an opportunity to mobilize a team to install the rest of the cap allowed for the pond to be fully trafficable late last year.
Now that the cap is complete, settlement will continue and Suncor will work to understand how to apply this technology to further improve our operations. In addition, we will share our lessons learned with other oil sands operators through COSIA.