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Shell technology tackles oil sands tailings challenge


August 26, 2010
by PLANT STAFF

CALGARY: Shell Canada has started-up its commercial-scale Atmospheric Fines Drying field demonstration for managing tailings from its oil sands operations.

The demonstration project, which received Energy Resources Conservation Board Aug. 6, is located at Shell’s Muskeg River Mine and occupies more than 75 acres.

Tailings are a mixture of fine clay, sand, water and residual bitumen produced through oil sands extraction. When they’re released into a pond, the heaviest material (mostly sand) settles to the bottom and the water rises to the top. But the middle layer of fine clay particles stay suspended in the water for years.

Shell’s new technology is intended to speed up the process, which will reduce the need to find new tailings facilities.

Its Atmospheric Fines Drying process involves collecting mature fine tailings (MFTs) using a large barge and transferring them to a drying area where they are mixed with flocculants (chemical agents) that help bring the particles together and placed on a sloped surface to help speed up the release of the water.

Shell says the released water runs down the sloped surface to a collection area and is returned to the external tailings facility for reuse in the extraction process. Remaining deposits are further dried to meet strength and reclamation requirements.

The project received approval on Aug. 6 from the Energy Resources Conservation Board (ERCB). Its Directive-074 requires a 50% reduction of particles by 2013.
John Abbott, executive vice-president, for Shell’s Heavy Oil business said the technology could result in a fine tailings deposit that releases water and gains strength “in weeks rather than decades.”

Abbott also said Shell is working to promote broader industry collaboration in tailings remediation.

“Shell will openly share the outcome of this demonstration project with industry players, academia, regulators and others interested in working on tailings solutions,” he said.

It’s expected to deliver a final deposit of some 250,000 tonnes.

Shell said the technology could be applied to tailings from both its Muskeg River Mine and future Jackpine Mine operations.

Oil sands tailings ponds attracted global attention in April 2008 when 1,600 ducks died in one of Syncrude’s huge oil sands tailings ponds.