Consolidation and unsaturated properties of in-line flocculated fluid fine tailings and centrifuged tailings from oil sands mines

Abstract

Canadian government regulatory and closure commitments for oil sands mines and tailings ponds compel oil sands companies to dewater and reclaim the fluid fine tailings (FFT) in the tailings ponds. As a result, extensive research is underway by several organisations to develop methods to understand the reasons for the slow consolidation of FFT and to design treatment methods for mine closure. The most promising technologies for oil sands tailings dewatering are thickening and centrifugation. In this research, large strain consolidation (LSC) and modified Tempe cell, using axis translation technique with shear strength tests, were conducted on in-line flocculated fluid fine tailings and centrifuged cake tailings samples. These tests determine the treated tailings' consolidation, geotechnical properties, unsaturated characteristics and shear strength. The results of the tests provided several useful engineering functions relating matric suction and effective stress to shear strength, solids contents, and water contents. The modified Tempe cell technique, however, yielded results four times faster than the LSC test technique. The methods and evaluations of the engineering functions are discussed.