10 m standpipe tests on oil sands tailings: long-term experimental results and prediction

2009 ◽  
Vol 46 (8) ◽  
pp. 875-888 ◽  
Author(s):  
S. Jeeravipoolvarn ◽  
J. D. Scott ◽  
R. J. Chalaturnyk
Keyword(s):  
Effective Stress ◽  
Oil Sands ◽  
Large Scale ◽  
Material Behavior ◽  
Compression Behavior ◽  
University Of Alberta ◽  
Fine Tailings ◽  
Oil Sands Tailings ◽  
Set Up ◽  
Conventional Behavior

Three large 10 m high standpipe tests were set up at the University of Alberta in 1982 to simulate large-scale compression behavior of oil sands tailings in a controlled environment. The objectives of the tests were to study material behavior and to provide consolidation performance for theoretical verification. Three tailings materials (fine tailings and two mixes of fine tailings and sand) were used. Test results showed that the fine tailings, standpipe 1, strained more than 30% over a 25 year monitoring period by self-weight with very little to no effective stress developing, while the mix of fine tailings and sand, standpipe 3, compressed with a significant effective stress development. The tailings in standpipe 1 can be regarded as a class of material where a reduction in volume is not governed by a unique relationship between effective stress and void ratio, whereas the tailings in standpipe 3 can be categorized as slurry with conventional behavior. To investigate the capability of the finite strain consolidation theory on these tailings, a numerical model with appropriate material constitutive relationships was developed and used to make predictions. Numerical results, compared with the performance of the standpipe tests, indicated that the theory overestimated the compression behavior of the standpipe 1 material, but it could predict the standpipe 3 consolidation behavior.

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.

Effective stress-strain relations for two-dimensional cellular sandwich cores: Homogenization, material models, and properties

2001 ◽  
Vol 55 (1) ◽  
pp. 61-87 ◽  
Author(s):  
Jo¨rg Hohe and ◽  
Wilfried Becker
Keyword(s):  
Effective Stress ◽  
Large Scale ◽  
Material Behavior ◽  
Core Material ◽  
Two Dimensional ◽  
Stress Strain ◽  
Material Models ◽  
Sandwich Construction ◽  
Specific Effects ◽  
Nonlinear Elastic

The theory of sandwich construction has been an active field of research for more than five decades. Aim of the present article is to review the work dedicated to the theoretical determination of the effective stress-strain material behavior of two-dimensional cellular materials with large-scale cells used as core material of structural sandwich panels. Both, the applied homogenization schemes and the applied material models are considered. Explicit expressions for the linear properties of a variety of basic cell geometries are presented, as well as schemes for the analysis of more general cases. In addition, the incorporation of specific effects such as cell wall imperfections or core face sheet constraints and the analysis of nonlinear elastic and elastic-plastic effective material response are reviewed. This review article includes 148 references.

Linking hydrocarbon biodegradation to greenhouse gas emissions from oil sands tailings and its impact on tailings management

2020 ◽  
Vol 100 (4) ◽  
pp. 537-545
Author(s):  
Tariq Siddique ◽  
Alsu Kuznetsova
Keyword(s):  
Oil Sands ◽  
Solid Phase ◽  
Extraction Process ◽  
Hydrocarbon Biodegradation ◽  
Soil Productivity ◽  
Main Research ◽  
Fine Tailings ◽  
Oil Sands Tailings ◽  
Tailings Ponds ◽  
Bitumen Extraction

Microbial research for maintaining soil productivity, health, and environment as well as for ecosystem function has been one of the main research focuses in the Department of Renewable Resources (formerly Department of Soil Science) during the last 100 yr. In recent years, microbial research has been expanded to effectively reclaim disturbed land, remediate contaminated sites, and manage soft sediments such as huge volumes of oil sands tailings. This article highlights the microbial processes in tailings ponds that can affect strategies to manage growing inventory of oil sands tailings and reduce associated environmental footprint. Enormous volumes of fluid fine tailings produced during bitumen extraction from oil sands are retained in tailings ponds. Some tailings streams contain residual labile hydrocarbons originated from the hydrocarbon solvents used in the extraction process. Indigenous microorganisms acclimated to the pond environment metabolize certain fractions of the fugitive labile hydrocarbons into biogenic greenhouse gases (GHG) such as methane (CH4) and carbon dioxide (CO2). Long-term (1–7 yr) biodegradation studies conducted using mature fine tailings (MFT) collected from different tailings ponds reveal that the microorganisms sequentially and preferentially biodegrade hydrocarbons under methanogenic conditions. The stoichiometric mathematical model developed on these biodegradation studies can predict GHG emissions from tailings ponds. Production of biogenic gases also affects the porewater and solid-phase chemistry of MFT and accelerates their de-watering and consolidation during active methanogenesis, which is beneficial for recovery of porewater for reuse in the bitumen extraction process and for effective reclamation of consolidated material.

scholarly journals Methanogenic Biodegradation of iso-Alkanes by Indigenous Microbes from Two Different Oil Sands Tailings Ponds

2021 ◽  
Vol 9 (8) ◽  
pp. 1569
Author(s):  
Mohd Faidz Mohamad Shahimin ◽  
Julia M. Foght ◽  
Tariq Siddique
Keyword(s):  
Oil Sands ◽  
Carbon Chain ◽  
Lag Phase ◽  
Carbon Chain Length ◽  
Oil Sand ◽  
Degradation Pattern ◽  
Fine Tailings ◽  
Oil Sands Tailings ◽  
Tailings Ponds ◽  
Oil Sands Tailings Ponds

iso-Alkanes, a major fraction of the solvents used in bitumen extraction from oil sand ores, are slow to biodegrade in anaerobic tailings ponds. We investigated methanogenic biodegradation of iso-alkane mixtures comprising either three (2-methylbutane, 2-methylpentane, 3-methylpentane) or five (2-methylbutane, 2-methylpentane, 2-methylhexane, 2-methylheptane, 2-methyloctane) iso-alkanes representing paraffinic and naphtha solvents, respectively. Mature fine tailings (MFT) collected from two tailings ponds, having different residual solvents (paraffinic solvent in Canadian Natural Upgrading Limited (CNUL) and naphtha in Canadian Natural Resources Limited (CNRL)), were amended separately with the two mixtures and incubated in microcosms for ~1600 d. The indigenous microbes in CNUL MFT produced methane from the three-iso-alkane mixture after a lag of ~200 d, completely depleting 2-methylpentane while partially depleting 2-methylbutane and 3-methylpentane. CNRL MFT exhibited a similar degradation pattern for the three iso-alkanes after a lag phase of ~700 d, but required 1200 d before beginning to produce methane from the five-iso-alkane mixture, preferentially depleting components in the order of decreasing carbon chain length. Peptococcaceae members were key iso-alkane-degraders in both CNUL and CNRL MFT but were associated with different archaeal partners. Co-dominance of acetoclastic (Methanosaeta) and hydrogenotrophic (Methanolinea and Methanoregula) methanogens was observed in CNUL MFT during biodegradation of three-iso-alkanes whereas CNRL MFT was enriched in Methanoregula during biodegradation of three-iso-alkanes and in Methanosaeta with five-iso-alkanes. This study highlights the different responses of indigenous methanogenic microbial communities in different oil sands tailings ponds to iso-alkanes.

Platelet Anti-Aggregating Activity and Tolerance of Clopidogrel in Atherosclerotic Patients

1996 ◽  
Vol 76 (06) ◽  
pp. 0939-0943 ◽  
Author(s):  
B Boneu ◽  
G Destelle ◽  
Keyword(s):  
Platelet Aggregation ◽  
Large Scale ◽  
Bleeding Time ◽  
Antithrombotic Activity ◽  
Ambulatory Patients ◽  
Patients At Risk ◽  
Set Up ◽  
Ischemic Events ◽  
Large Scale Clinical Trial ◽  
Selection Of

SummaryThe anti-aggregating activity of five rising doses of clopidogrel has been compared to that of ticlopidine in atherosclerotic patients. The aim of this study was to determine the dose of clopidogrel which should be tested in a large scale clinical trial of secondary prevention of ischemic events in patients suffering from vascular manifestations of atherosclerosis [CAPRIE (Clopidogrel vs Aspirin in Patients at Risk of Ischemic Events) trial]. A multicenter study involving 9 haematological laboratories and 29 clinical centers was set up. One hundred and fifty ambulatory patients were randomized into one of the seven following groups: clopidogrel at doses of 10, 25, 50,75 or 100 mg OD, ticlopidine 250 mg BID or placebo. ADP and collagen-induced platelet aggregation tests were performed before starting treatment and after 7 and 28 days. Bleeding time was performed on days 0 and 28. Patients were seen on days 0, 7 and 28 to check the clinical and biological tolerability of the treatment. Clopidogrel exerted a dose-related inhibition of ADP-induced platelet aggregation and bleeding time prolongation. In the presence of ADP (5 \lM) this inhibition ranged between 29% and 44% in comparison to pretreatment values. The bleeding times were prolonged by 1.5 to 1.7 times. These effects were non significantly different from those produced by ticlopidine. The clinical tolerability was good or fair in 97.5% of the patients. No haematological adverse events were recorded. These results allowed the selection of 75 mg once a day to evaluate and compare the antithrombotic activity of clopidogrel to that of aspirin in the CAPRIE trial.

MODELING THE SOUTH ATLANTIC OCEAN FROM MEDIUM TO HIGH RESOLUTION

2014 ◽  
Vol 31 (2) ◽  
Author(s):  
Mariela Gabioux ◽  
Vladimir Santos da Costa ◽  
Joao Marcos Azevedo Correia de Souza ◽  
Bruna Faria de Oliveira ◽  
Afonso De Moraes Paiva
Keyword(s):  
High Resolution ◽  
Atlantic Ocean ◽  
Large Scale ◽  
South Atlantic ◽  
Surface Relaxation ◽  
The South ◽  
Small Surface ◽  
Basic Model ◽  
Basic Set ◽  
Set Up

Results of the basic model configuration of the REMO project, a Brazilian approach towards operational oceanography, are discussed. This configuration consists basically of a high-resolution eddy-resolving, 1/12 degree model for the Metarea V, nested in a medium-resolution eddy-permitting, 1/4 degree model of the Atlantic Ocean. These simulations performed with HYCOM model, aim for: a) creating a basic set-up for implementation of assimilation techniques leading to ocean prediction; b) the development of hydrodynamics bases for environmental studies; c) providing boundary conditions for regional domains with increased resolution. The 1/4 degree simulation was able to simulate realistic equatorial and south Atlantic large scale circulation, both the wind-driven and the thermohaline components. The high resolution simulation was able to generate mesoscale and represent well the variability pattern within the Metarea V domain. The BC mean transport values were well represented in the southwestern region (between Vitória-Trinidade sea mount and 29S), in contrast to higher latitudes (higher than 30S) where it was slightly underestimated. Important issues for the simulation of the South Atlantic with high resolution are discussed, like the ideal place for boundaries, improvements in the bathymetric representation and the control of bias SST, by the introducing of a small surface relaxation. In order to make a preliminary assessment of the model behavior when submitted to data assimilation, the Cooper & Haines (1996) method was used to extrapolate SSH anomalies fields to deeper layers every 7 days, with encouraging results.

Evaluation of the flocculation and dewatering performance of dual polymers for treating oil sands tailings

2021 ◽  
Author(s):  
Xiaoxiao Li ◽  
Yang Shen ◽  
Raymond S. Farinato ◽  
Ponisseril Somasundaran ◽  
Yuejun Zhang
Keyword(s):  
Oil Sands ◽  
Oil Sands Tailings

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

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