Journal Published Online: 12 January 2017
Volume 40, Issue 2

Drying Behavior of Mature Fine Tailings Pre-Dewatered With Super-Absorbent Polymer (SAP): Column Experiments



Laboratory column experiments were conducted to investigate the effect of super-absorbent polymer (SAP) on the drying behavior (e.g., dewatering, strength, suction, settlement) of mature fine tailing (MFT). Four experimental columns filled in two different stages with dewatered MFT of 1 wt. % SAP were subjected to atmospheric drying. Moreover, four additional columns (control columns) filled with raw MFT (not pre-dewatered with SAP) were also subjected to drying. The rate of evaporation, drainage, settlement and evolution of suction, strength and void ratio were monitored or determined in a 30-day period. Promising results have been obtained. The results show that the rate of evaporation for SAP pre-dewatered samples was lower than that of raw MFT. Cumulative water lost via evaporation decreased from 13 kg for raw MFT to 7.2 kg for pre-dewatered MFT, which is because of the lower water content of the pre-dewatered MFT. Water drainage for pre-dewatered MFT showed 82 % reduction in comparison with raw MFT within the test period. This finding suggests that the use of SAP pre-dewatered method could considerably reduce the seepage of toxic water from the tailings and MFT impoundments. Developed suction in the first lift showed a sharp reduction by loading the second lift because of redistribution of pore water but this effect was temporary and developed suction in the second lift gained strength. Vane shear strength of pre-dewatered MFT after 30 days was around 3.6 kPa and 7.3 kPa for 5-cm (bottom) and 15-cm heights, respectively, and the strength of the upper parts reached 2.3 MPa. SAP pre-dewatered MFT had a much higher strength increase rate at early ages than the raw MFT. After 10 days of drying, the undrained shear strength at all column heights exceeded or was close to the 1-year value (5 kPa) required by environmental regulations set by the Energy Resources Conservation Board (ERCB). This could have significant practical implication with respect to accelerating the dewatering process and consolidation of MFT, thus increasing the pace of reclamation, reducing the cost of the tailing management and reducing the environmental footprint of heavy oil operations.

Author Information

Roshani, A.
Univ. of Ottawa, Dept. of Civil Engineering, Ottawa, Ontario, CA
Fall, M.
Univ. of Ottawa, Dept. of Civil Engineering, Ottawa, Ontario, CA
Kennedy, K.
Univ. of Ottawa, Dept. of Civil Engineering, Ottawa, Ontario, CA
Pages: 11
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Stock #: GTJ20160034
ISSN: 0149-6115
DOI: 10.1520/GTJ20160034