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The impact of fabric and surface characteristics on the engineering behavior of polymer-amended mature fine tailings

University of British Columbia

Management and reclamation of large inventories of legacy and fresh mature fine tailings (MFT) represent a continuing and significant challenge to surface mine operators in the Alberta Oil Sands because of the complex chemical and physical behavior of these tailings. Suncor’s tailings recovery operations (TRO™) and Shell Canada’s atmospheric fines drying (AFD) use anionic polymers to flocculate MFT to remove fine tailings solids from aqueous suspension. Addition of anionic polyacrylamide polymer to MFT results in the creation of a complex synthetic material, polymer-amended MFT (PA-MFT). This research investigates the fundamental properties and characteristics governing PA-MFT dewatering in an effort to better understand how these factors contribute to overall material behavior including strength development and consolidation. This work confirms that the addition of anionic polyacrylamide polymer does little to change the zeta potential of the input raw MFT as the resulting material is colloidally stable. The work also indicates how residual bitumen and fabric act independently and in combination to reduce the permeability of PA-MFT and enable retention of water within the material’s fabric especially when it is stored in lifts that exceed the depth at which the combination of evaporative drying and underdrainage are effective. It is concluded that PA-MFT fabric includes abundant micropores with tortuous flow paths with little connectivity between pores. The size and configuration of the pores effectively traps water within the PA-MFT fabric. Residual bitumen may also block pore throats or form a hydrophobic barrier that limits both the effectiveness of evaporation for material deposited below a depth of 15 cm in thick lift deposits. Residual bitumen may also prevent diffusion of trapped water upward through deposited material and contributes to the plasticity and compressibility exhibited by PA-MFT when it is deposited in lifts thicker than 20 cm.

Text

2016-04-01

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/57392

Mining Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/