Shell Canada has started to use a technique called Atmospheric Fines Drying on a commercial scale at its Muskeg River Mine in Canada to demonstrate its effectiveness in managing tailings from oil sands operations.
Atmospheric Fines Drying was initially tested at Shell’s tailings pilot plant at the Muskeg River Mine and this commercial-scale demonstration is the next stage of development for the technology. It is hoped that this project will demonstrate the ability of Atmospheric Fines Drying to be one of a number of technologies that can be brought to bear on the challenge of managing tailings.
Tailings themselves are a mixture of fine clay, sand, water and residual bitumen produced through oil-sands extraction. When tailings are released to a pond, the heaviest material − mostly sand − settles to the bottom, while water rises to the top. But the middle layer, often called mature fine tailings, is made up of fine clay particles that can remain suspended in water for long periods of time.
Atmospheric Fines Drying involves using a large barge to collect the mature fine tailings from the tailings pond and transfer them to a drying area. The mature fine tailings are mixed with flocculants − chemical agents that help bring the fine clay particles in the MFT together − and placed on a sloped surface to help speed up the release of water from the clay. The released water runs down the sloped surface to a collection area and is returned to the external tailings facility for re-use in the extraction process. What remains are deposits that are then further dried.
Shell is working with a number of others in the industry, as well as research institutes, to advance the technique and plans to share what it learns from the demonstration project with industry players, academia, regulators and others interested in working on tailings solutions.
Shell Canada Energy is the 60-per-cent owner of the Athabasca Oil Sands Project (AOSP), which includes the Muskeg River Mine. The other 40 per cent is jointly shared between Chevron Canada and Marathon Oil Sands.
It’s the biggest petroleum reserve on the planet, but also the dirtiest. Can technology clean up the oil sands industry? Click here to read more (subscription required).