Fisseha, BT, Wilson, GW & Fredlund, DG 2023, 'Assessment on consolidation behaviours of treated fluid fine tailings using applied suction method', in GW Wilson, NA Beier, DC Sego, AB Fourie & D Reid (eds), Paste 2023: Proceedings of the 25th International Conference on Paste, Thickened and Filtered Tailings, University of Alberta, Edmonton, and Australian Centre for Geomechanics, Perth, pp. 510-525, https://doi.org/10.36487/ACG_repo/2355_38
(https://papers.acg.uwa.edu.au/p/2355_38_Fisseha/)
Abstract: Large volumes of fluid tailings have been produced by the oil sands mining operations in Northern Alberta using bitumen extraction processes. The produced tailings pose a challenge to the operators due to low compressibility behaviour of materials in the tailing pond as a result of the low hydraulic conductivity and high thixotropic strength. Deposited tailings that are ready to be reclaimed require being consolidated and have adequate strength. Consolidated and developed strength of the deposited tailings need to provide adequate bearing capacity, which is pivotal in establishing the basis for reclamation work such as the capacity to carry the machinery that carry out the reclamation work. Field trials display formation of both unsaturated and saturated zones within the deposited tailings following the deposition of fully saturated tailings. The development of the unsaturated zone requires the removal of moisture from freshly deposited slurry materials. The unsaturated zone development can be attained during design stage by using various dewatering technologies. The presence of the unsaturated zone significantly enhances consolidation properties of the deposited tailings due to dewatering of tailings using the applied suction method. This paper will present results of laboratory experiments carried out to assess consolidation behaviours of freshly deposited treated fluid fine tailings using the applied suction method. The laboratory experiment was conducted using a meso-scale column made of Plexiglas and a PVC base with a high air-entry value ceramic disc with dimensions of 300 mm diameter and 500 mm height. Consolidation of fluid fine tailings obtained using column tests were assessed using standard large-strain compressibility curves and predicted using unsaturated engineering properties. Results were checked and consistent with fundamental principles of unsaturated soil mechanics. Experimental test results from the meso-scale test were compared with standard engineering property testing methods and discussed.

Keywords: consolidation of tailings, applied suction, unsaturated properties of tailings