Impact of chemical and physical treatments on freeze-thaw dewatering of fluid fine tailings

Li, Yunhui; Kaminsky, Heather; Sadighian, Ardalan; Sun, Yijia; Murphy, Fergus; Gong, Xue Yuki; Ghuzi, Mohammed; Rima, Umme Salma

doi:10.1016/j.coldregions.2021.103385

Cited by 2 publications

(4 citation statements)

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“…The alum and PAM doses were approximately 875 mg/L of porewater and 2.43 g/kg of solids, respectively. NAIT's flocculation procedure (see Li et al 2021a) and conveyance test (see Li et al 2021bLi et al , 2022) mimic Suncor's PASS treatment process and the subsequent mechanical shearing that occurs during pipeline transport of the PASS-treated FFT to a disposal area.…”

Section: Sample Collection and Treatmentmentioning

confidence: 99%

Evaluating the long-term behaviour and viability of an oil sands tailings management and reclamation strategy

Cossey¹,

Kaminsky²,

Ulrich³

2022

Mine Closure 2022: 15th Conference on Mine Closure

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Surface mining of oil sands ore in Alberta, Canada, has generated over a billion cubic metres of waste, known as fluid fine tailings (FFT). FFT are a mixture of fine-grained solids (silt and clay), water, dissolved salts, and organic compounds. Eventually, FFT must be reclaimed and integrated into mine closure landscapes. One proposed method of FFT management and reclamation is through end pit lakes (EPLs), which are engineered water bodies that consist of a thick layer of FFT capped with water. FFT deposited in EPLs may also be treated with a coagulant (alum) and polymer flocculant (polyacrylamide, PAM) to improve tailings dewatering and cap water quality. Theoretically, EPLs are a suitable reclamation strategy because the water cap develops into habitat for an aquatic ecosystem while the FFT slowly dewaters over time. However, successful use of EPLs in the oil sands has not been demonstrated, and knowledge gaps exist surrounding the long-term behaviour of EPLs and their viability as an FFT management and reclamation strategy. Uncertainties surrounding EPL behaviour include the flux of salts and organics into the water cap, biogeochemical cycling processes, which can generate sulfide species and greenhouse gases, and the environmental fate of PAM. To address these knowledge gaps, aging experiments are being performed in 1 L and 19 L EPL columns containing untreated or treated (with alum and PAM) FFT and a water cap. Aging is simulated in the columns through higher temperature and carbon amendments. Results to date show that fluxes of salts into the water caps are generally consistent with consolidation trends and are similar in columns containing either untreated or treated FFT. Compared to untreated FFT, treated FFT has undergone more extensive sulfur cycling, as evidenced by higher sulfate reduction rates and higher sulfide species concentrations.

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Section: Sample Collection and Treatmentmentioning

confidence: 99%

Evaluating the long-term behaviour and viability of an oil sands tailings management and reclamation strategy

Cossey¹,

Kaminsky²,

Ulrich³

2022

Mine Closure 2022: 15th Conference on Mine Closure

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“…Two-hundred and fifty grams of the flocculated sample was transferred to a test cell containing a 90-mm-diameter Whatman 50 filter paper diameter (2.7 µm pore). The test cell, including the airtight piston described in Li et al [34], was assembled and fixed to an OFITE Multi-Unit filter press. A 500-mL baffled beaker was placed on a balance below the test cell and tared.…”

Section: Flocculation Of Undiluted Mftmentioning

confidence: 99%

“…As the main goal of the modifications is to improve the water release after degradation to increase the speed of consolidation, the modified SRF test was used to evaluate the speed of water released from a 250-g MFT sample under a pressure consistent to an applied load of a sand cap. This method provides a description of the relative dewatering rates of MFT in less than 48 h [34] and is suitable for evaluating the degradable flocculant, as its potential benefits are expected to become more evident over time. The base case result for the SRF test is untreated MFT.…”

Section: Flocculation-filtration Of Undiluted Mftmentioning

confidence: 99%

“…The filtration of high-solid MFTs following flocculation has been demonstrated to accelerate dewatering compared to filtration alone [29], and researchers are exploring methods of improving the process by using flocculants to first bridge the particles [30][31][32]. Pressure filtration has been successfully employed to characterize the filterability of various flocculants by examining the net water release (NWR) or specific resistance to filtration (SRF) of flocculated MFT [33] and, when modified with an airtight piston, is a method for estimating the long-term settling performance of flocculants in a compressed time frame [34]. The information from these testing methodologies can be combined to provide a more complete assessment of the expected field performance of poly(PLA 4 ChMA).…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of a Novel Polymeric Flocculant for Enhanced Water Recovery of Mature Fine Tailings

2020

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The novel cationic flocculant, poly(lactic acid) choline iodide ester methacrylate (poly(PLA4ChMA)), has been shown to provide improved flocculation of 5.0 wt.% mature fine tailings (MFT) diluted in deionized water compared to commercial anionic polymers, with continued dewatering of the sediment occurring as the polymer undergoes partial hydrolytic degradation. However, the elevated dosages (10,000 ppm) required would make the polymer costly to implement on an industrial scale. With this motivation, the impact of MFT loading and the use of process water is explored while comparing the settling performance of poly(PLA4ChMA) to available commercial alternatives such as anionic FLOPAM A3338. Improved consolidation of 5.0 wt.% MFT diluted with process water could be achieved at reduced dosages (500 ppm) with poly(PLA4ChMA). However, the final compaction levels after polymer degradation were similar to those achieved with the nondegradable commercial flocculants. Flocculation-filtration experiments with undiluted MFT are also conducted to compare the performance of the polymers. Significantly faster rates of water release were observed with the cationic flocculants compared to FLOPAM A3338, but no improvement in the overall tailings compaction was found either before or after poly(PLA4ChMA) degradation. Thus, the improved dewatering observed with poly(PLA4ChMA) in dilute MFT suspensions does not extend to conditions that would be encountered in the field.

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Impact of chemical and physical treatments on freeze-thaw dewatering of fluid fine tailings

Cited by 2 publications

References 18 publications

Evaluating the long-term behaviour and viability of an oil sands tailings management and reclamation strategy

Evaluating the long-term behaviour and viability of an oil sands tailings management and reclamation strategy

Evaluation of a Novel Polymeric Flocculant for Enhanced Water Recovery of Mature Fine Tailings

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