Phase 1 (2013-2019)

Project 1.1: Measure and Predict De-watering Performance

Iman Entezari, PhD: Applications of remote hyperspectral sensing in the characterization of Alberta's oil sands tailings

Water removal from saturated tailings is the first step in densifying and consolidating tailings. The separation of water from mature fine tailings (MFT) is thus an operational and environmental challenge of tailings management. Remote estimation of moisture content, evaporation rate, and total suction would help operators to assess the drying process, determine when the deposit has stopped drying, and decide when the next lift should be deposited. Therefore, our work provides low-risk, cost-effective quick surveys to the tailings operators to manage their large volume of tailings and thus accelerates the process of converting tailings to reclaimable landscapes.

Janeen Ogloza, MSc: Measuring Actual Evaporation Rates from a Tailings Pond

By having accurate and actual evaporation rates, oil sands operators would know when the tailings surface has reached its driest state and new tailings can be placed on the surface. As different tailings volumes (lift thicknesses) dry at different rates, the optimum point where the most tailings is placed to dry for the least amount of time could be determined. This would ensure that the tailings pond is consolidated to its maximum potential, which would aid in the reclamation of these massive tailings ponds.

Nicolas Olmedo, PhD: Tailings characterization using an unmanned ground robot

The development of autonomous systems for environmental studies is generally applicable to tailings operators and will support the efforts for reclamation of tailings impoundments. These systems can be used to obtain in situ tailings properties from treated fluid fine tailings deposits that not trafficable. The new technologies will enable characterization of deposits that are not available using conventional geotechnical tooling. This new information will aid in the understanding of the how tailings change over time, which is very important to the oil sands operators as well as the decision-making on process control and post-deposition work; and are of direct economic benefit to the oil sands industry and Canada’s economy.

Project 1.2: Determination of properties for high volume change materials

Feixia Zhang, PhD: Unsaturated Soil Property Functions for High Volume Change Materials

The coefficient of permeability function and the water storage function are two important hydraulic properties required in the numerical modeling of geotechnical problems such as transient seepage or contaminant transport that occurs during mine waste or tailings disposal. The inaccurate estimation of the hydraulic properties will cause erroneous numerical modeling results, which will then cause engineers to make inappropriate decisions concerning a project. Existing estimation techniques, such as the van Genuchten-Burdine (1980) equation, the van Genuchten-Mualem (1980) equation and the Fredlund, Xing and Huang (1994) permeability function, produce reasonable results when estimating the coefficient of permeability function and the water storage function for unsaturated soils with low compressibility such as sands or silts, but the analysis protocols require changes when predicting the coefficient of permeability and the water storage for materials that undergo volume change as soil suction changes (e.g. oil sands tailings slurry). The revised theory could be applied in the numerical modelling to facilitate a proper design of tailings disposal, reducing potential engineering costs that could have been caused by decisions based on misinformation.

Project 1.3: Assessment of Shear Strength

Bereket Fisseha, PhD: Undrained shear strength of amended oil sand tailings

The research focused on investigating fundamental soil mechanics such as stress–strain relationships and the engineering properties of FFT under saturated/unsaturated conditions. These fundamental principles will be used to predict the behaviours of FFT as accurately as possible by incorporating them into available numerical modeling softwares. Subsequently the software will be used as a tool for analysis during engineering designing at various stages such as bearing capacity earth fill structures that will be used as containment. The research program will provide a laboratory data set and analysis that leads towards narrowing the existing knowledge gap and contribute towards resolving challenges facing mine operators.

Project 1.4: Modelling of pore fluid in the computation of actual evaporation

Prempeh Owusu, MEng: Laboratory study of the effects of repeated freeze-thaw cycles on the suction behavior of centrifuged tailings

The research work focused on establishing and enhancing understanding of the influence of the effects of freeze-thaw cycles on the suction behaviour of centrifuged tailings. Knowledge of the development of osmotic suction and electrical conductivity through freeze-thaw cycles is required to evaluate potential capping and reclamation schemes in the design and construction of cover systems on centrifuged tailings.

Project 2.1: Observations and Analysis for a 30-Year Large-Scale Consolidation Experiment on Oil Sands Mature Fine Tailings

and

Project 2.2: Theory and Computer Modelling of Sedimentation, Consolidation and Creep of MFT

Elena Zabolotnii, MEng: Observations and analysis for a 30-year, 10-m column consolidation experiment on oil sands mature fine tailings

These research projects focused on sedimentation and consolidation processes governing the transition of mature fine tailings to a soil state, as well as fundamental processes for consolidation and creep in MFT. The goal was to understand and describe, both qualitatively and quantitatively, the processes at work in MFT consolidation for the advancement of our understanding of soft soil behaviour. The immediate benefits of the research include assessing an innovative approach to removing residual bitumen from MFTs without the use of chemicals in terms of its effects on the time rate of its consolidation; and understanding the effect of the presence of residual bitumen in MFTs.

Project 2.3: Modelling MFT Consolidation with a Geotechnical Centrifuge

Taylor Hall, MSc

This research provides the opportunity to improve understanding of the consolidation behaviour of oil sands tailings through testing in a geotechnical centrifuge. Results obtained from this research project will also guide future experimental design for the testing of oil sands tailings using the geotechnical centrifuge. Understanding the consolidation behaviour and correct interpretation of test results is crucial to the prediction and modelling of the long term behaviour of the tailings deposits as required by the regulator.

Project 3.1: Deep Fines-Dominated (Cohesive) Deposits

Umme Rima

The research aims to establish an enhanced understanding of the volume change and engineering behaviour of deep tailings deposits exposed to surficial seasonal weathering. Understanding the development of a surficial crust is required to evaluate potential capping and reclamation scenarios and ultimately to guide the design and construction of reclamation cover systems on deep tailings deposits. This work will provide design criteria and data that will aid in the design of closure landforms for tailings deposits.

Project 3.2: Co-deposition and Blending of FFT with Overburden

Ralph Burden

Dewatering of MFT remains a significant, largely unresolved challenge, and represents a barrier to reclamation and closure. Whilst most approaches currently in use or development aim to increase the solids content of the FFT by removing water, essentially here we are increasing the solids content by adding solids. This has great potential because of the high water demand of the overburden material. The Clearwater formation often has natural water contents below the plastic limit. Upon mixing, water is rapidly transferred from the MFT to the shale. Early indications have shown that this can create a stable material with shear strengths in excess of 5 kPa, eliminating the need for containment and having the potential to create dry post-closure landscapes.

Project 4.1: Assessment and simulation of tailings dewatering methods

Nam Pham, PhD: Developing a numerical tool to predict freeze-thaw desiccation and large strain consolidation of tailings

This project aimed to develop a computer program to simulate the dewatering of thickened tailings using natural processes, including freeze-thaw, consolidation and desiccation, which are relevant to the oil sands industry in the Fort McMurray region. The code developed under this program, FTCD (Freeze-Thaw-Consolidation-Desiccation), is currently being trialed in industry.

Tony Zheng, MSc: Development of a tailings simulation model using System Dynamics

The integrated model provides a quick method to test hypotheses and gain insights into the interaction between capping material and tailings substrate over long term. It can be used by regulators and producers as a high-level analytical tool for due diligence and regulatory audits; builds a common qualitative language for interdisciplinary collaboration; and fosters the culture of participatory modelling across disciplinary boundaries and among non-technical stakeholders. This model also brings transparency and flexibility to the modelling process (as opposed to the black-box commercial models).

Project 4.2: Influence of chemical amendments and dewatering processes on the geotechnical behaviour of oil sand tailings fines

Jordan Elias, MSc: Measurement of Floc Size and the Influence of Size Distribution on Geotechnical Properties of Oil Sands Fluid Fine Tailings

This research builds toward technologies and processes that remove water from saturated tailings to assist in densifying and consolidating tailings. The ultimate goal is for oil sands operators to manage the dewatering of tailings prior to deposition in tailings dams, which require more intensive reclamation technologies. This research contributes to industry’s goals of accelerating the process of converting tailings to reclaimable landscapes.

Kelsey Stienwand

This research provides the opportunity to further understand the long-term strength behaviour of amended tailings deposits. Currently available correlations of strength to material characteristics such as clay to water content or void ratio may not account for changes in strength with time (thixotropy) or sensitivity. A good understanding of the transient nature of the strength of tailings deposits is required for the design of the capping and reclamation. This information will ultimately guide the design and construction of a cover system on flocculated/dewatered tailings deposits in the oil sands.

Project 4.3: Freezing Characteristics of FFT and their Relation to Unsaturated Soil Properties

Haley Schafer, MSc: Freezing Characteristics of Mine Waste Tailings and their Relation to Unsaturated Soil Properties

The soil-water characteristic curve (SWCC) is time-consuming and challenging to attain. A single test can take anywhere from weeks to months to attain. The soil-freezing characteristic curve (SFCC) test takes approximately two days to perform. This is a great advantage over the SWCC. Ultimately, this method would provide an alternative to a time-consuming test which is advantageous as the SWCC is needed to predict the rate of dewatering and magnitude of strength gain during desiccation dewatering. Overall, the experimental method produced repeatable and reliable results. The results showed that the SWCC could be estimated from the SFCC for tailings from metal mines (gold tailings and copper tailings) with a high portion of sand and a small amount of clay. The SFCC was not able to estimate the SWCC for oil sands tailings. Regardless, this method is highly promising as a screening tool to rapidly test a wide variety of tailings to determine which should have additional traditional SWCC testing.

Project 4.4: Landscape architecture and engineering design for mined earth structures and reclamation

Neeltje Slingerland, PhD: Geomorphic landform design and long-term assessment of tailings storage facilities in the Athabasca oil sands

Erosion of oil sand tailings dams has been a known concern since the 1970s, but has not been studied in detail or evaluated to determine cause, characteristics, or quantity such that the risk is fully understood. This erosion quantification work provides evidence of the geomorphic processes actively taking place on above ground tailings dams in the oil sands such that industry may be better prepared to reclaim and identify problems post-closure. Given the size of the oil sands mining region, post-closure monitoring is expected to be a grandiose undertaking in terms of effort and cost. The remote methods tested in this project provide a cost-effective tool to aid regulators and oil sand companies in evaluating landscape performance during active and passive reclamation stages.

The IRC program partnered with colleagues at the University of Alberta and from other universities and industry to provide additional expertise, collaboration and HQP supervision.

Department of Civil & Environmental Engineering, University of Alberta

Dr. N.A. Beier: Advanced soil/slurry freezing and thawing behaviour, Numerical modelling

Dr. R.J. Chalaturnyk: Centrifuge experimentation

Dr. C.D. Martin: Mine Waste Laboratory Testing

Dr. N.R. Morgenstern: A principal contributor to the Technical Guide for Fluid Fine Tailings Management

Dr. J.D. Scott: Consolidation and creep behaviour of MFT

Dr. D.C. Sego: Cold regions engineering advanced soil/slurry freezing and thawing behaviour

Dr. L. Perez-Estrada: Bitumen removal work for the 10-m column experiments

Department of Mechanical Engineering, University of Alberta

Dr. M. Lipsett: Advanced rover technology

Department of Earth and Atmospheric Sciences, University of Alberta

Dr. B. Rivard: Remote sensing and hyperspectral imaging

Dr. A. Sanchez-Azofeifa: Measuring evaporation for tailings through ECV

Department of Civil Engineering, University of Saskatchewan

Dr. D. Fredlund: Unsaturated soil mechanicals and technology development

Department of Civil Engineering, University of Carleton, Canada

Dr. P. Simms, : In-situ monitoring and instrumentation of fines-dominated deposits, Field evaporation from tailings deposition

School of Civil Engineering, University of Queensland, Australia

Dr. D. Williams: Physical characterization of mine tailings deposition; co-disposal of mine tailings and coarse-grained mine wastes; dewatering and densification of mine tailings

Argila Enterprises Inc. and Lunar Geotechnical Institute Inc.

Dr. D. Carrier III: Accelerated dewatering of fines-dominated deposits

SoilVision Systems Ltd.

Dr. M. Fredlund: Numerical modelling and simulation of in situ fines-dominated deposits