Filtration tests on PVD filter jackets in fine oil sands tailings

Yao, Yao; Tol, A van; Everts, B; Mulder, A.

doi:10.1201/b10569-45

Cited by 5 publications

(7 citation statements)

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“…The SWCC plot using degrees of saturation was generated from the SWCC using gravimetric water content and the SCs. The SWCC air-entry value (AEV) is shown as 200-300 kPa for both flocculated FFT and FCTC compared to 100 kPa and 200 kPa as reported by Yao (2016)…”

Section: Unsaturated Engineering Properties (Swcc and Sc)mentioning

confidence: 72%

Assessment on consolidation behaviours of treated fluid fine tailings using applied suction method

Fisseha¹,

Wilson²,

Fredlund³

2023

Paste 2023: 25th International Conference on Paste, Thickened and Filtered Tailings

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Large volumes of fluid tailings have been produced by the oil sands mining operations in Northern Alberta using bitumen extraction processes. The produced tailings pose a challenge to the operators due to low compressibility behaviour of materials in the tailing pond as a result of the low hydraulic conductivity and high thixotropic strength. Deposited tailings that are ready to be reclaimed require being consolidated and have adequate strength. Consolidated and developed strength of the deposited tailings need to provide adequate bearing capacity, which is pivotal in establishing the basis for reclamation work such as the capacity to carry the machinery that carry out the reclamation work. Field trials display formation of both unsaturated and saturated zones within the deposited tailings following the deposition of fully saturated tailings. The development of the unsaturated zone requires the removal of moisture from freshly deposited slurry materials. The unsaturated zone development can be attained during design stage by using various dewatering technologies. The presence of the unsaturated zone significantly enhances consolidation properties of the deposited tailings due to dewatering of tailings using the applied suction method. This paper will present results of laboratory experiments carried out to assess consolidation behaviours of freshly deposited treated fluid fine tailings using the applied suction method. The laboratory experiment was conducted using a meso-scale column made of Plexiglas and a PVC base with a high air-entry value ceramic disc with dimensions of 300 mm diameter and 500 mm height. Consolidation of fluid fine tailings obtained using column tests were assessed using standard large-strain compressibility curves and predicted using unsaturated engineering properties. Results were checked and consistent with fundamental principles of unsaturated soil mechanics. Experimental test results from the meso-scale test were compared with standard engineering property testing methods and discussed.

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Section: Unsaturated Engineering Properties (Swcc and Sc)mentioning

confidence: 72%

Assessment on consolidation behaviours of treated fluid fine tailings using applied suction method

Fisseha¹,

Wilson²,

Fredlund³

2023

Paste 2023: 25th International Conference on Paste, Thickened and Filtered Tailings

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“…Flocculation refers to the process by which high molecular weight polymers help the colloidal-sized fine particles to aggregate from dispersions into larger flocs through the formation of bridges between those particles or by charge neutralization (Vajihinejad and Soares, 2018;. The larger aggregates or flocs settle more quickly than the individual fine particles that would not normally settle within an economically reasonable time frame (Yao, 2016). Hence, polymer-assisted flocculation is often deemed an important pretreatment step in the dewatering of tailings streams containing significant quantities of very fine particles (<44 μm) and the efficiency of the flocculation step ultimately governs the performance of the dewatering system (Hogg, 2000).…”

Section: Flocculation and Flocculantsmentioning

confidence: 99%

“…However, in the under-dosed or the overdosed condition, the amount of free water released by the FFT was relatively smaller (Wells et al, 2011). Although it is necessary to apply adequate mixing energy to the FFT-polymer mixture for a specific period of time in order to disperse the polymers into the FFT materials and produce a well-flocculated FFT with good dewaterability potential, if the mixing is continued at high intensity for a period longer than the necessary, the larger aggregates or flocs resulting from the flocculation process may disintegrate into smaller flocs and result in poor dewaterability and strength (Yao, 2016). Hence, the buildup of yield stress in the fFFT material was found to be a function of the shear energy applied to the FFT-polymer mixture (Wells et al, 2011).…”

Section: Polymer Optimization For Tailings Dewateringmentioning

confidence: 99%

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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“…The current approach of concentrated storage increases the concentration of tailings to 60%-70% in which a deep cone thickener is used, which directly discharges the water and steams the tailings dry. The ensuing problems include the poor permeability of the discharge and the difficulty of consolidation (Yao et al, 2012;Yan et al, 2019). The concentration problem restricts the curing and storage of tailings (Indraratna, 1994) attempted to alter the mechanics of fine tailings by mixing coarse and fine tailings and improved the utilization of fine tailings.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of triaxial shear features of concentrated full tailings considering the effect of curing age

et al. 2023

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The strength evolution law of concentrated full tailings is closely related to the storage construction method, especially the growth law of shear strength with curing age. This study aims to investigate the influence of curing materials on the shear strength of full tailings and reveal the change law of the shear strength of concentrated full tailings with the curing age. Therefore, we carried out a comparative triaxial shear test between pure full tailings and concentrated full tailings with different curing ages. The test results show that concentrated full tailings had a 70.7% higher cohesion and a 10% larger internal friction angle (IFA) than that of pure full tailings at the age of 0 days. Moreover, the concentrated full tailings cured for 3 days had a 170.2% higher cohesion and a 12.1% larger IFA than that cured for 0 days. In addition, the concentrated full tailings cured for 7 days had a 149.4% higher cohesion and a 12.1% larger IFA than that cured for 0 days. The stress-strain curve exhibits that the shear strength of full tailings is significantly influenced by the curing material and curing age. The stress-strain curve gradually moved from strain hardening to strain softening as the curing age increased, and the failure curve had two steps. This indicates that the specimen still has a certain shear capacity despite having a shear zone. The entire specimen instantly fails when the strain exceeds that capacity. The results of this study can be used as scientific bases for the design and construction of the surface storage structures of concentrated full tailings.

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Filtration tests on PVD filter jackets in fine oil sands tailings

Cited by 5 publications

References 1 publication

Assessment on consolidation behaviours of treated fluid fine tailings using applied suction method

Assessment on consolidation behaviours of treated fluid fine tailings using applied suction method

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

Experimental study of triaxial shear features of concentrated full tailings considering the effect of curing age

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