Shear behvaiour of oil sand fine tailings in simple shear and triaxial devices

Gholami, Masoumeh

doi:10.22215/etd/2014-10929

Cited by 2 publications

(4 citation statements)

References 26 publications

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“…Creep compression occurs at practically constant effective stress (Robinson, 1999). In high void ratio materials such as tailings, hydraulic conductivity-void ratio relationship is the property that dictates the rate and magnitude of settlement during primary consolidation (Suthaker and Scott, 1994;Gholami, 2014). While the excess pore water pressure dissipates, the tailings increase in effective stress and subsequently go through a deformation, and therefore, the void ratio changes.…”

Section: Creep In Natural Clay Depositsmentioning

confidence: 99%

“…The rearrangement of the particles prompts a volume change and this volume change leads to the compression, and subsequently, to the settlement of the fine-grained particles. The rate of volume change reflects the rate at which pore water moves out, which again depends on the hydraulic conductivity or permeability of the material (Gholami, 2014;Bajwa, 2015).…”

Section: Sedimentation and Consolidationmentioning

confidence: 99%

“…They are used to solve the governing equation, where the derivatives of effective stress and hydraulic conductivity need constitutive relationships to reduce the unknowns and solve for void ratios (Jeeravipoolvarn, 2010). Void ratio-hydraulic conductivity relationship affects the completion of tailings densification over time and void ratio-effective stress relationship influences the densification progress within the consolidation process (Gholami, 2014).…”

Section: Consolidation Theories and Modelsmentioning

confidence: 99%

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Effects of Polymers on short-and long-term dewatering of oil sands tailings

Salam¹

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Each year, while extracting bitumen from the oil sands ores, the oil sands industry generates a large volume of tailings. Although the polymers have been found to improve the release of water from the tailings and accelerate the dewatering and settling processes in the shortterm, longer-term dewatering processes such as consolidation are crucial for making the tailings deposits safe and strong enough for reclamation. Unamended tailings have been found to demonstrate time-dependent creep and thixotropic behaviour. However, whether such behaviour influences the long-term dewatering and consolidation performance of polymer amended/flocculated tailings deposits is unknown. This research investigated the creep, thixotropy, and structuration in polymer amended tailings from an experimental perspective using different polymer dosages, mixing methods, and boundary conditions. Flocculated tailings developed a thixotropic strength and also a higher preconsolidation pressure and reduced compressibility, which was clearly a structuration effect that impeded the self-weight consolidation in longer-term by limiting the creep compression. Similar experiments performed on the Leda clay showed that the structuration effect observed in flocculated tailings is not atypical of the structuration effect observed in natural clays. The potential of the UV-vis spectrophotometry and torque rheometry techniques for determining the optimum polymer dosage was investigated. The results indicated that the techniques could determine the optimum polymer dosage and help to minimize the operational costs and improve the dewaterability in the short-term. Longer-term column dewatering tests showed that the choice of polymer dosage could influence the dewatering and settlement behaviour of tailings in the long-term. Different polymer dosages resulted in different degrees of structuration with the higher dosages showing a relatively prominent iii structuration behaviour but also a suboptimal dewaterability. Hence, if the structuration effect is considered, the optimum polymer dosage for the long-term dewatering mechanisms may not be the same as the polymer dosage that produces optimum dewatering performance in the short-term. Based on the experimental findings, an empirical method was proposed for predicting the degree of structuration in a particular tailings-polymer mixture; such a method would allow the operators to minimize the negative effects of structuration through the selection of an appropriate polymer dosage or deposition management plan.

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Section: Creep In Natural Clay Depositsmentioning

confidence: 99%

Section: Sedimentation and Consolidationmentioning

confidence: 99%

Section: Consolidation Theories and Modelsmentioning

confidence: 99%

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Effects of Polymers on short-and long-term dewatering of oil sands tailings

Salam¹

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“…Creep compression generally occurs at practically constant effective stresses (R. Robinson, 1999). Hydraulic conductivity-void ratio relationship dictates the rate and magnitude of settlement during primary consolidation for soils with high initial void ratios (Gholami, 2014;Nagula Naguleswary Suthaker, 1995). At the end of this process, soil goes through deformation while the excess pore water pressures dissipate and effective stresses in the soil increase.…”

Section: Creep Compressionmentioning

confidence: 99%

Rapid Measurement and Estimation of Saturated Hydraulic Conductivity of Mineral Slurries

Babaoglu¹

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Large strain consolidation (LSC) behaviour of mineral slurries regulates the performance of tailings management and reclamation plans. The hydraulic conductivity-void ratio relationship primarily influences this behaviour, dominating the long-term performance of fine-grained slurries with higher initial water contents. However, the determination of this function can be very challenging and time-consuming, considering the long duration of the conventional tests and significant variation in hydraulic conductivity values with the wide range of void ratios.This study focuses on identifying or creating a rapid method to evaluate the large strain consolidation parameters, especially the k-e relationship, of fine-grained soils by (i) establishing a relationship between the consolidation parameters and more easily measured properties and (ii) designing a self-weight consolidation setup to evaluate the k-e relationship using Instantaneous Profiling Method (IPM). For part (i), a total of 79 k-e data sets of fine-grained soils are examined. Using some of the above innovations, equations are found that require only a single measurement of hydraulic conductivity at a single void ratio. When applying these new equations to the k-e data set, 94% of the predicted k values are within an order of magnitude of the measured data points. This is likely sufficient for this method to be used as a screening tool for tailings treatments. For part ii), the design of a prototype consolidometer is introduced, and the consolidation behaviours of various finegrained soils are evaluated. The prototype is designed as an alternative experimental setup to conventional laboratory tests and aims to rapidly assess the k-e equation for fine-grained soils. The test column was instrumented with tensiometers and capacitance-based sensors c 

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Shear behvaiour of oil sand fine tailings in simple shear and triaxial devices

Cited by 2 publications

References 26 publications

Effects of Polymers on short-and long-term dewatering of oil sands tailings

Effects of Polymers on short-and long-term dewatering of oil sands tailings

Rapid Measurement and Estimation of Saturated Hydraulic Conductivity of Mineral Slurries

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