Oil sands tailings
Since oil sands mining began more than four decades ago, oil sands tailings management has been a perplexing challenge for the industry.
The fact is all forms of mining produce tailings — and operators must determine how to safely and effectively dispose of this byproduct. With mining operations on the scale of the oil sands, the challenge is all the more daunting.
Oil sands tailings are a mixture of water, clay, sand and residual hydrocarbons produced during the mine extraction process (in situ drilling of oil sands bitumen does not produce tailings; this is becoming a far more common industry practice as approximately 80% of the proven oil sands reserves are buried too deep to be reached by mining).
The standard industry practice until now has been to pump oil sands tailings into large engineered settling ponds, called tailings points, which are often discontinued mine areas. There, the heaviest material — mostly sand — settles to the bottom, separating from the top layer of water, which can be recycled. A middle layer forms, known as mature fine tailings (MFT), which is comprised of about 70% water and 30% fine clay. Left on its own, the MFT could take centuries to solidify sufficiently for reclamation.
As mining operations expanded, it became necessary to build more and larger tailings ponds. Suncor currently has eight oil sands tailings ponds covering a total of approximately 3,000 hectares and containing about 200 million cubic metres of mature fine tailings. These ponds account for about 14% of the approximately 20,000 hectares of land that Suncor has disturbed through oil sands mining. So finding a way to get the MFT to quickly solidify and be suitable for reclaiming is critical to improving Suncor’s overall reclamation performance.
Oil sands tailings management and the TROTM process
Suncor has pioneered development of new technologies, including the TROTM process, it allows us to dry our mine tailings into a material solid enough to be reclaimed in a fraction of the time that earlier technologies require. This should, in turn, greatly accelerate our overall mine reclamation efforts. With the new drying process in place, we expect to reduce the time it takes from initial land disturbance to having a reclaimable surface to about 10 years — a third of what is now the industry standard.
Read more about the TROTM process
As of 2012, Suncor has spent more than $1.3 billion to research, develop and implement its TROTM process across our operations. We expect our TROTM method to help us rapidly reduce our existing inventory of oil sands tailings and the need for future oil sands tailings storage ponds.
The technology has already enabled Suncor to cancel plans for five additional tailings ponds at its existing mine operations in addition to two ponds contemplated for the new North Steepbank extension. In the years ahead, Suncor also expects to reduce the number of tailings ponds at its present mine from the current eight to just two — shrinking the total land area covered by the ponds by approximately 80%.
Read more about tailings management
Raising the bar: tailings collaboration
In 2010, Suncor co-founded the Oil Sands Tailing Consortium (OSTC) along with six other oil sands companies. Each company committed to sharing its existing tailings research and technology and removing barriers to collaborating on future tailings research and development. Suncor waived certain rights to its TROTM process in order to share process details with other consortium members.
During 2012, the OSTC transitioned into Canada's Oil Sands Innovation Alliance (COSIA), which has 14 member companies representing almost 90% of the oil sands production in Canada. COSIA was part of the Tailings Technology Roadmap and Action Plan project, a major industry/government collaboration to improve tailings management across the entire industry.
Read more about the Tailings Technology Roadmap and Action Plan in OSQAR
Coke capping technology
Suncor is also accelerating tailings pond reclamation by using petroleum coke, a byproduct of upgraded bitumen, to help create a solid surface on the company’s Pond 5. The coke capping layer is light enough to float on the surface of the pond and yet strong enough to allow trucks to drive over the pond surface. Wicking drains in the coke cap, which act like straws, remove the water and potentially separate tailings and reclamation material.
The Pond 5 coke capping project is one of the largest field trials of a tailings technology anywhere in the world. The required consolidation is expected to be complete by 2019; at that point, sand will be spread over the coke until tailings can support vegetation and further reclamation.
Read more about coke capping in OSQAR
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