Feasibility study of using bench-scale centrifugation for segregation and consolidation behaviour of oil sands tailings products

Abstract

Fluid fine tailings (FFT) are a by-product of the process used to extract bitumen from surface-mined oil sands in Alberta, Canada. One of the FFT reclamation techniques involves mixing centrifuged FFT with coarse sand tailings to form non-segregating tailings (NST). While NST provides a means to achieve mine closure and reclamation objectives, the self-weight consolidation of NST takes years to complete in full-scale testing. This paper examines the use of bench-scale centrifugation for physical modelling of the consolidation of NST under centrifuge loading. A series of bench-scale centrifuge tests is conducted on NST specimens reconstituted at different sand–fines ratios (SFRs), along with conventional oedometer and standpipe tests. Micro-computed tomography technique with high resolution is used to quantify the internal structure of the centrifuged specimens, and to infer the segregation and consolidation behaviour of NST specimens under 1-g and centrifuge loading. No segregation is detected in NST specimens under 1-g loading, while segregation occurs in NST specimens with low SFRs under centrifugal loading. Thus, only consolidation behaviour of NST specimens without segregation is investigated and compared to those determined from conventional oedometer tests. Limitations on use of bench-scale centrifuge in physical modelling of consolidation behaviour of oil sands tailings are addressed.