scholarly journals Effects of Calcium and Aluminum on Particle Settling in an Oil Sands End Pit Lake

2021 ◽  
Author(s):  
Kai Wei ◽  
Heidi L. Cossey ◽  
Ania C. Ulrich
Keyword(s):  
Surface Water ◽  
Oil Sands ◽  
Surface Mining ◽  
Pit Lake ◽  
Particle Settling ◽  
Pit Lakes ◽  
Fine Tailings ◽  
High Turbidity ◽  
Fluid Fine Tailings ◽  
Al Treatment

AbstractSurface mining of oil sands ore in Alberta, Canada has generated fluid fine tailings (FFT) that must be reclaimed. End pit lakes (EPLs), which consist of thick deposits of FFT capped with water, have been proposed for FFT reclamation, and Base Mine Lake (BML) is the first full-scale demonstration EPL. However, FFT particle settling and resuspension contributes to high turbidity in the BML water cap, which may be detrimental to the development of an aquatic ecosystem. This study investigated the effect of Ca and Al treatments on turbidity mitigation. The initial turbidity was reduced from 20 NTU to less than 2 NTU in BML surface water treated with 54 mg/L of Ca or 1.1 mg/L of Al. At a concentration of 1.1 mg/L, Al reduced the initial turbidity to a greater extent, and in a shorter time, than 54 mg/L of Ca. Further, resuspended Al-treated FFT particles were 100–700 nm larger in diameter, and thus resettled faster than the resuspended untreated or Ca-treated FFT particles. The final turbidity values 21 days after resuspension of untreated and 1.7 mg/L Al-treated FFT particles in fresh BML surface water were 20.5 NTU and 2.5 NTU, respectively. Thus, Al treatment may be effective in mitigating turbidity in BML through both Al-induced coagulation and self-weight settling of the resuspended Al-treated FFT particles.

scholarly journals Suspended solids in an end pit lake: potential mixing mechanisms

2016 ◽  
Vol 43 (3) ◽  
pp. 211-217 ◽  
Author(s):  
Gregory A. Lawrence ◽  
Edmund W. Tedford ◽  
Roger Pieters
Keyword(s):  
Oil Sands ◽  
Suspended Solids ◽  
Salt Water ◽  
Wind Waves ◽  
Vertical Mixing ◽  
Pit Lake ◽  
Surface Cooling ◽  
Activity Data ◽  
Fine Tailings ◽  
Fluid Fine Tailings

The production of crude oil from the Canadian oil sands has generated tailings ponds that contain oil sands process-affected water and oil sands fluid fine tailings (FFT). One remediation strategy is to backfill a mined out pit with FFT and cap this with a mix of oil sands process-affected water and fresh water to form a lake, called an end pit lake. Here we discuss various mechanisms governing the vertical mixing of suspended solids in an end pit lake. Depending on the depth of the water cap, wind waves can cause mixing between the water cap and the FFT. Other potential mixing mechanisms include: convection due to salt-water exclusion during ice formation, penetrative convection due to surface cooling, gas emission from the FFT, and internal wave activity. Data collected at Syncrude Canada Limited’s Base Mine Lake in 2013 and 2014 are used to demonstrate the effects of some of these processes.

Chemical mass transport between fluid fine tailings and the overlying water cover of an oil sands end pit lake

2017 ◽  
Vol 53 (6) ◽  
pp. 4725-4740 ◽  
Author(s):  
Kathryn A. Dompierre ◽  
S. Lee Barbour ◽  
Rebecca L. North ◽  
Sean K. Carey ◽  
Matthew B. J. Lindsay
Keyword(s):  
Mass Transport ◽  
Oil Sands ◽  
Pit Lake ◽  
Overlying Water ◽  
Fine Tailings ◽  
Fluid Fine Tailings ◽  
Water Cover

Capping dewatered oil sands fluid fine tailings with salvaged reclamation soils at varying depths to grow woody plants

2020 ◽  
Vol 100 (4) ◽  
pp. 546-557
Author(s):  
Ryan S. Lalonde ◽  
Bradley D. Pinno ◽  
M. Derek MacKenzie ◽  
Nicholas Utting
Keyword(s):  
Plant Growth ◽  
Populus Tremuloides ◽  
Oil Sands ◽  
Land Reclamation ◽  
Surface Mining ◽  
High Water ◽  
High Water Content ◽  
Trembling Aspen ◽  
Fine Tailings ◽  
Fluid Fine Tailings

Managing fluid fine tailings (FFT) present a major cause of industrial and environmental concerns in oil sands surface mining production. A potential management solution is to dewater and cap the FFT solids for use in land reclamation. A 16 wk greenhouse study was conducted to assess whether FFT centrifuge cake with caps of various reclamation soil mixes (forest floor mineral mix, peat mineral mix, and a mixture of both) and depths (0, 5, 10, and 20 cm) would support growth of trembling aspen (Populus tremuloides — native broadleaf tree) and beaked willow (Salix bebbiana — native broadleaf shrub). Beaked willow had a much greater survival rate (100%) when grown directly in FFT cake compared with trembling aspen (16.7%). Plants grown directly in FFT cake were negatively impacted by high water content, low nitrate supply rates, and high metal concentrations with beaked willow seedlings having 10 times higher foliar concentrations of Al, Cr, and Ti compared with any other treatments. Adding soil caps substantially increased aboveground biomass for both species, but differences among soil cap types and depths did not have as significant of an effect on plant growth. Results from this study show that capping FFT substantially improves woody plant growth, and S. bebbiana and P. tremuloides are potentially suitable species for tailings reclamation.

Initial geochemical characteristics of fluid fine tailings in an oil sands end pit lake

2016 ◽  
Vol 556 ◽  
pp. 196-206 ◽  
Author(s):  
Kathryn A. Dompierre ◽  
Matthew B.J. Lindsay ◽  
Pablo Cruz-Hernández ◽  
Geoffrey M. Halferdahl
Keyword(s):  
Oil Sands ◽  
Geochemical Characteristics ◽  
Pit Lake ◽  
Fine Tailings ◽  
Fluid Fine Tailings

scholarly journals Biofilms for Turbidity Mitigation in Oil Sands End Pit Lakes

2021 ◽  
Vol 9 (7) ◽  
pp. 1443
Author(s):  
Heidi L. Cossey ◽  
Mian Nabeel Anwar ◽  
Petr V. Kuznetsov ◽  
Ania C. Ulrich
Keyword(s):  
Microbial Communities ◽  
Oil Sands ◽  
Threshold Velocity ◽  
Water Turbidity ◽  
Mixing Speed ◽  
Fine Grained ◽  
Pit Lakes ◽  
Fine Tailings ◽  
Fluid Fine Tailings ◽  
The Impact

End pit lakes (EPLs) have been proposed as a method of reclaiming oil sands fluid fine tailings (FFT), which consist primarily of process-affected water and clay- and silt-sized particles. Base Mine Lake (BML) is the first full-scale demonstration EPL and contains thick deposits of FFT capped with water. Because of the fine-grained nature of FFT, turbidity generation and mitigation in BML are issues that may be detrimental to the development of an aquatic ecosystem in the water cap. Laboratory mixing experiments were conducted to investigate the effect of mudline biofilms made up of microbial communities indigenous to FFT on mitigating turbidity in EPLs. Four mixing speeds were tested (80, 120, 160, and 200 rpm), all of which are above the threshold velocity required to initiate erosion of FFT in BML. These mixing speeds were selected to evaluate (i) the effectiveness of biofilms in mitigating turbidity and (ii) the mixing speed required to ‘break’ the biofilms. The impact of biofilm age (10 weeks versus 20 weeks old) on turbidity mitigation was also evaluated. Diverse microbial communities in the biofilms included photoautotrophs, namely cyanobacteria and Chlorophyta (green algae), as well as a number of heterotrophs such as Gammaproteobacteria, Desulfobulbia, and Anaerolineae. Biofilms reduced surface water turbidity by up to 99%, depending on the biofilm age and mixing speed. Lifting and layering in the older biofilms resulted in weaker attachment to the FFT; as such, younger biofilms performed better than older biofilms. However, older biofilms still reduced turbidity by 69% to 95%, depending on the mixing speed. These results indicate that biostabilization is a promising mechanism for turbidity mitigation in EPLs.

scholarly journals Using Specified Risk Materials-Based Peptides for Oil Sands Fluid Fine Tailings Management

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1582
Author(s):  
Yeling Zhu ◽  
Yuki Gong ◽  
Heather Kaminsky ◽  
Michael Chae ◽  
Paolo Mussone ◽  
...  
Keyword(s):  
Oil Sands ◽  
Colloidal Stability ◽  
Free Water ◽  
Value Added ◽  
Settling Rate ◽  
Test Range ◽  
Tailings Management ◽  
Fine Tailings ◽  
Fluid Fine Tailings ◽  
Hydrolyzed Polyacrylamide

Fluid fine tailings are produced in huge quantities by Canada’s mined oil sands industry. Due to the high colloidal stability of the contained fine solids, settling of fluid fine tailings can take hundreds of years, making the entrapped water unavailable and posing challenges to public health and the environment. This study focuses on developing value-added aggregation agents from specified risk materials (SRM), a waste protein stream from slaughterhouse industries, to achieve an improved separation of fluid fine tailings into free water and solids. Settling results using synthetic kaolinite slurries demonstrated that, though not as effective as hydrolyzed polyacrylamide, a commercial flocculant, the use of SRM-derived peptides enabled a 2-3-fold faster initial settling rate than the blank control. The pH of synthetic kaolinite tailings was observed to be slightly reduced with increasing peptides dosage in the test range (10–50 kg/ton). The experiments on diluted fluid fine tailings (as a representation of real oil sands tailings) demonstrated an optimum peptides dosage of 14 kg/ton, which resulted in a 4-fold faster initial settling rate compared to the untreated tailings. Overall, this study demonstrates the novelty and feasibility of using SRM-peptides to address intractable oil sands fluid tailings.

Impact of flocculation-based dewatering on the shear strength of oil sands fine tailings

2013 ◽  
Vol 50 (9) ◽  
pp. 1001-1007 ◽  
Author(s):  
Nicholas Beier ◽  
Ward Wilson ◽  
Adedeji Dunmola ◽  
David Sego
Keyword(s):  
Oil Sands ◽  
Material Handling ◽  
Performance Criteria ◽  
Regulatory Requirements ◽  
Strength Performance ◽  
Tailings Management ◽  
Fine Tailings ◽  
Fluid Fine Tailings ◽  
Management Techniques ◽  
Reported Data

The oil sands in northern Alberta have been mined to produce bitumen over the past five decades. Since the 1980s, technical advances have been made in mining, material handling, and bitumen extraction. However, acquiring practical methods to control and reduce the fluid fine tailings build-up has been an ongoing challenge. Recent regulatory changes have driven the industry to review current tailings-management techniques and investigate numerous alternative technologies and processes to manage and reclaim fine tailings. Many of these fine tailings–management techniques involve some form of polymer or chemical addition to promote dewatering and strength gain to meet the regulatory requirements. Based on the reported data, the chemically amended fine tailings deposits have the characteristics of sensitive, metastable deposits, necessitating additional mitigative measures by oil sands operators beyond the regulatory requirements. This paper explores the geotechnical aspects of meeting regulatory strength performance criteria by employing flocculation-based dewatering of fluid fine tailings.

Addition of Tubifex accelerates dewatering of oil sands tailings

2016 ◽  
Vol 43 (12) ◽  
pp. 1025-1033 ◽  
Author(s):  
Xiaojuan Yang ◽  
Miguel de Lucas Pardo ◽  
Maria Ibanez ◽  
Lijun Deng ◽  
Luca Sittoni ◽  
...  
Keyword(s):  
Oil Sands ◽  
Land Reclamation ◽  
Test Results ◽  
Anionic Polymer ◽  
Fine Tailings ◽  
Fluid Fine Tailings ◽  
Oil Sands Tailings ◽  
Set Up ◽  
Solids Content

Accelerating dewatering of fluid fine tailings (FFT) to facilitate land reclamation is a major challenge to the oil sands industry in Canada. A new method was tested, addition of Tubifex to FFT. Tubifex is an indigenous earthworm in Canada. The survival rate tests showed that Tubifex can survive in oil sands tailings and penetrate to 42 cm depth (maximum depth tested). Columns (5 L of FFT) were set-up with tailings alone, Tubifex treated tailings and polymer-Tubifex treated tailings. Test results showed that (a) the final mud–water interface of tailings alone was 26% higher than that of Tubifex treated tailings; (b) solids content of Tubifex treated tailings was 21% more than that of tailings alone; (c) Tubifex was capable to accelerate the dewatering process of both cationic and anionic polymer treated tailings; (d) anionic polymer was superior in facilitating long-term dewatering and its coupled effects with Tubifex were better than the cationic polymer.

Effect of various treatments on consolidation of oil sands fluid fine tailings

2018 ◽  
Vol 55 (8) ◽  
pp. 1059-1066 ◽  
Author(s):  
G. Ward Wilson ◽  
Louis K. Kabwe ◽  
Nicholas A. Beier ◽  
J. Don Scott
Keyword(s):  
Shear Strength ◽  
Oil Sands ◽  
Large Strain ◽  
Regulatory Requirements ◽  
Freeze Thaw ◽  
Treatment Processes ◽  
Fine Tailings ◽  
Fluid Fine Tailings ◽  
Solids Content ◽  
And Storage

Regulatory policy and regulations in Alberta require oil sands companies to reduce their production and storage of fluid fine tailings by creating deposits that can be reclaimed in a timely manner. To meet the regulatory requirements, some companies are adding flocculants to the fluid fine tailings and then using thickeners, inline flocculation or centrifuges to increase the solids content. Freeze–thaw and drying processes are then used to further dewater the tailings. The effects of flocculating, thickening, and freeze–thaw treatments were investigated by performing large-strain consolidation and shear strength tests on these treated fluid fine tailings. The consolidation and shear strength results were then compared with those of untreated fluid fine tailings. All of the treatments increased the hydraulic conductivity of the fluid fine tailings to some degree, but had little to no effect on the compressibility and shear strength. The effects of the treatment processes are discussed and evaluated.

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