Conventional practice limits sand-cap placement to tailings that have already achieved trafficable strengths. Most fine tailings deposits in the oil sands industry will not achieve this strength until they have consolidated and dewatered for some time. Sand-cap or sand-layer placement using hydraulic delivery methods offers great potential as a cost-effective, technically feasible capping method for treated fine tailings of the oil sands industry. However, hydraulic placement is a novel technique for cap placement that requires study to determine the range of conditions where it is feasible.
As part of a collaborative project funded by the Institute for Oil Sands Innovation and Canada’s Oil Sands Innovation Alliance, Barr and Deltares evaluated the conditions needed to successfully place a cap on treated fine tailings deposits. The scope involved geomechanical numerical modelling (using FLAC 2D) of both subaerial and subaqueous hydraulic placement of sand and coke caps on a fine tailings deposit. Physical modelling of the subaerial sand capping was also conducted to help validate the modelling and develop important factors for scaling to commercial applications. The work is an important step in establishing a foundation for an engineering and design approach for sand cap placement.