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Geotechnical News • June 2014
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THESIS ABSTRACTS
framework and implemented in the numerical model for
inclined flows. The model performs well in capturing the
extended framework and flow profiles of dense granular
inclined flows on flat-frictional and rough bases.
Supervisor: D. Chan, Geotechnical and Geoenvironmental Group,
Department of Civil & Environmental Engineering, University
of Alberta, 3-133 Markin/CNRL Natural Resources Engineering
Facility, Edmonton, Alberta T6G 2G7, Tel: 780-492-2176,
Fax: 780-492-8198
Application of Dewatering Technologies in
Production of Robust Non-Segregating
Tailings
Reza Moussavi Nik
Reza Moussavi Nik, Shell Canada Energy, 400 4
th
. Avenue S.W.,
PO Box 100 Station M, Calgary, AB T2P 2H5,
email: reza.nik@shell.com
One of the current technologies used by the oil sands
industry to reduce the volume of fluid fine tailings and cre-
ate a dry landscape is production of CT (Composite Tail-
ings) and NST (NonSegregating Tailings). CT and NST are
engineered tailings streams obtained by recombination of
fines (MFT or TT) and coarse tailings (sand) plus a chemi-
cal amendment. If produced on-spec, the main advantage
of CT/NST would be its improved dewatering behavior and
rapid release of relatively clear water during the hindered
settling and selfweight consolidation, while a majority of the
fine particles are entrapped within the matrix of its coarser
fraction (sand).
Production of a robust CT/NST at a commercial scale has
been a challenge for the industry. While CT/NST has been
expected to be non-segregating when discharged, partial
segregation and release and re-suspension of the fines has
been observed following deposition. To produce a robust
CT/NST and reduce its susceptibility to segregation, the
yield stress of the carrier fluid (i.e. fines + water) must be
enhanced. This can be achieved by increasing the solids
content of CT/NST).
The present research reviewed the different methods of
solid-liquid separation and experimentally investigated the
possible application of some of these methods for improv-
ing the quality of CT/NST. A major part of this research was
focused on dewatering of MFT and using it as a component
for making CT/NST. A batch filtering centrifuge was uti-
lized to dewater MFT samples received from three different
operators and the major factors affecting the process of cen-
trifugal filtration were investigated. The resultant dewatered
MFT samples were mixed with a mixture of sand and pond
water to produce CT/NST with higher solids content. The
depositional behavior and robustness of the produced CT/
NST samples were investigated using a flume apparatus.
The flow profile and variations of solids content and SFR
(Sand to Fines Ratio) were identified for each deposition
test, also the yield stress of the CT/NST samples was evalu-
ated using a strain-controlled viscometer and vane spindles.
The results of this study indicate that using dewatered MFT
promotes production or robust CT/NST streams achieved
with lower dosage of chemical additives.
Supervisor: D.C. Sego & N.R. Morgenstern, Geotechnical and
Geoenvironmental Group, Department of Civil & Environmental
Engineering, University of Alberta, 3-133 Markin/CNRL Natu-
ral Resources Engineering Facility, Edmonton, Alberta T6G 2G7,
Tel: 780-492-2176, Fax: 780-492-8198
Stabilization of Oil Sands Tailings Using
Vacuum Consolidation
Ehsan Abazari Torghebeh
Ehsan Abazari Torghebeh, Coffey Inc., 20 Meteor Drive,
Etobicoke, ON, Cell: 647-879-8470, email: abazarit@ualberta.ca
This research is an experimental design and numerical
analysis of a novel technique of the vacuum consolida-
tion of Mature Fine Tailings (MFT). A meso-scale test was
conducted to examine the feasibility of the MFT dewatering
process. Vacuum consolidation involves applying a nega-
tive water pressure to the coke layer overlain by a saturated
sand layer and underlain by MFT. Numerical modeling was
conducted using the finite element program SoilVision to
model the meso-scale experiment. Unsaturated behavior of
Suncor coke, Suncor sand and MFT was investigated using
Tempe pressure cell and capillary rise in an open tube prior
to commencement of tests. Results indicate that a flux of
water flows from the MFT layer into the coke layer, which
is indicative of the MFT dewatering. The modeling analysis
indicates that suction has little effect on the settlement while
the overburden has the significant effect on consolidation.
This thesis also illustrates the importance of recalibrating
TDR probes for different materials. The three layered sys-
tem testing of MFT, Suncor coke and Suncor sand indicates
that applying suction causing MFT to dewater, can set the
stage for a four layered system in which another layer of
MFT is placed on top of the sand layer. The suction applied
to the coke layer causes the double-drained MFT to dewater
faster.
Supervisor: D.C. Sego & G.W. Wilson, Geotechnical and Geoen-
vironmental Group, Department of Civil & Environmental
Engineering, University of Alberta, 3-133 Markin/CNRL Natu-
ral Resources Engineering Facility, Edmonton, Alberta T6G 2G7,
Tel: 780-492-2176, Fax: 780-492-8198
Re-Visitation of Actual Evaporation Theories
Dat Tien Quoc Tran
Dat Tien Quoc Tran, Thurber Engineering Ltd., 180, 7330 Fisher
Street S.E. Calgary, AB T2H 2H8, Tel: 403-253-9217 ext 155,
email: dattienq@ualberta.ca or dtran@thurber.ca
Evaporation from a deposit of thickened or paste tailings or
cover system is increasingly becoming a big challenge for
geotechnical engineers. Accurate calculation of the actual
evaporation from a saturated-unsaturated surface requires