Partially Hydrophobic and Natural Graft Polymers for the Efficient Treatment of Mature Fine Tailings

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Today, more than 50 years after the Clark Hot Water Extraction Process was first used to extract bitumen from oil sands, the oil sands industry is still dealing with vast volumes of water trapped in tailing ponds. Tailings, a mixture of about 30% clays and 70% water are a undesired by-product of the oil sands extraction process.In July 2016, the Alberta Energy Regulator issued Directive 085 implementing the Tailings Management Framework. Directive 085 mandates that oil sands tailings must be continually treated during their project lifetime so that the land occupied by tailing ponds is ready to be reclaimed within 10 years of the end of the mine lifetime. Existing chemical (coagulants and flocculants) and mechanical (centrifugation, thin lift drying, deep deposits) methods currently used to treat tailings have limited effectiveness. Consequently, significant advances in these methods are needed to meet the land reclamation targets for the oil sands industry. Polyacrylamide flocculants are typically used to treat tailings, but their application is limited by the high viscosity of their solutions, which makes them difficult to dose and handle. Flocs generated with this technology may also break when they are pumped through pipelines from the treatment station to the deposition site. In addition, polyacrylamide retains substantial amounts of water in the treated tailings, which do not get dry enough to allow for land reclamation. The current research proposal will address the limitations of polyacrylamide flocculants using two different, yet complementary, approaches: 1) modified natural polymers, and 2) partially hydrophobic (which do not retain water in the tailing sediments) polymers. We will also combine the advantages of these two approaches in what we call hybrid polymers in this proposal.