Microstructure and macroscopic behaviour of polymer amended oil sands mature fine tailings

Bajwa, Tariq Mahmood

doi:10.22215/etd/2015-10922

Cited by 2 publications

(25 citation statements)

References 65 publications

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“…A continuous 'hindered settling' of the solid particles results in the formation of a 'sediment bed', where effective stress does not exist. However, when the hindered sedimentation approaches an end, the particles in the sediment bed starts to exhibit grain-to-grain interactions (Bajwa, 2015). At the initial stage, the pore water carries the self-weight, which gives rise to the development of excess pore water pressure.…”

Section: Sedimentation and Consolidationmentioning

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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Section: Sedimentation and Consolidationmentioning

confidence: 99%

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

Salam¹

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“…Previously, there has been some analysis done regarding the qualitative analysis using SEM images for polymer amended tailings (Salam et al 2017, Bajwa 2015, Mizani 2016. Until now no research has been reported using Digital image processing techniques for optical microscope images and scanning electron microscope images for quantitative fabric analysis of polymer amended tailings.…”

Section: Novelty Of This Research Workmentioning

confidence: 99%

“…The SEM device has the ability to adjust the vacuum for a wide range, it has the potential to generate a difference in the pressure with a successive reduction in the pressure and work under controlled environmental condition. (Bajwa 2015).…”

Section: Operation Of Sem Testsmentioning

confidence: 99%

“…General approach to prepare sample like those generated in a field application of in-line flocculation To create field representative samples, a similar procedure used for the preparation of stock solution were optimized from a baseline procedure developed by Shell Canada in 2010, to prepare laboratory generated FFT similar in field properties to field generated FFT. The procedure was optimized by Bajwa (2015) and Mizani (2016) based on yield stress, capillary suction time, and 48-hour dewatering potential. Figure 16 shows yield stress measured on samples obtained from field trials and those measured on laboratory prepared samples.…”

Section: Procedures For Preparation Of Stock Solutionmentioning

confidence: 99%

“…The corresponding ImageJ path is Analyze> analyze particles in Figure 70 till Binarized Images were analyzed using the particle analyzer section built into the Image J software. The analysis was performed on the entire image, not on the specific area selected in Image as reported in (Bajwa 2015) and (Mizani 2016). This tool scans the entire selected image or choice until it finds the edge of objects.…”

Section: Binarization Stepmentioning

confidence: 99%

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Microstructural Quantitative Analysis of Polymer amended Fluid Fine Tailing’s Using Digital Image Processing Techinques

Khattak¹

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Understanding long-term dewatering behavior of oil sands tailings is significant to the success and optimization of tailings reclamation plans. Long-term dewatering of tailings is somewhat complex due to mechanical creep, structuration drove by electrochemical forces between clay particle and other potential mechanisms such as cementation. To modernize conceptual models of tailings dewatering, the fabric evolution of tailings over months has been studied using low vacuum SEM as well as optical microscopy methods.Morphological information is extracted from different images using a sequence of image processing techniques, designed by trial and error to produce repeatable information for the studied material, flocculated fluid fine tailings (FFT). The designed image processing method produces binary images defining pore-space and solid particles (solid grains or flocs). The binary images are then analyzed using a software, primarily "Fiji-Image J"for quantitative analysis of the image for tends in pore and particle size distributions. The samples that were imaged were obtained from amended FFT dewatering experiments, comprising many replicates of 0.10 m high columns that were sampled over months. The tailings were dosed with a high molecular anionic polymer at two doses (600 and 800 ppm polymer per dry tailings). Columns either had one way or two-way drainage. Repeatable trends were found for all samples for both image processing techniques. The most dramatic observation was the increase in floc size over 48 hours using optical microscopy.iii DedicationThe thesis is dedicated to my wonderful parents, Retd. Prof.

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Microstructure and macroscopic behaviour of polymer amended oil sands mature fine tailings

Cited by 2 publications

References 65 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

Microstructural Quantitative Analysis of Polymer amended Fluid Fine Tailing’s Using Digital Image Processing Techinques

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