Aggregate structures formed by hyperbranched functionalized polyethylene (HB<i>f</i>PE) treatment of oil sands tailings

Costine, Allan; Vajihinejad, Vahid; Botha, Linda; Fawell, Phillip D.; Soares, João B. P.

doi:10.1002/cjce.23287

Cited by 7 publications

(11 citation statements)

References 11 publications

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“…Microscopic flocculation assessment includes the measurement of aggregate structure peculiarities such as size, shape, density, and strength that determine the final solids‐water separation efficiency as measured by the so‐called indirect metrics discussed in Section 5.2.1. For example, the implications of developing polymer flocculants that are able to form dense aggregates are i) a denser aggregate hold less water, thus helping with dewatering efficiency of sediments; ii) with the same size, the denser aggregates offer faster settling velocities reducing the size of the treatment unit; and iii) the denser aggregates occupy less effective volume in suspension, allowing for the lower solids dilution before polymer flocculation . The last feature is more useful in the context of high solids effluents such as oil sands tailings.…”

Section: Performance Assessment Of Flocculantsmentioning

confidence: 99%

“…Their method may not give the true density of aggregates, but it serves to be a good quantitative measure to relate the apparent aggregate density of polymer flocculated slurries to the process conditions and polymer properties. The full description of their method can be found elsewhere, but simply put: aggregates are diluted down to 0.1–0.5 wt% freely falling down a cylindrical graduated vessel (no interaction with other aggregates), where their settling velocity and size are captured by a high resolution camera. The vertical and horizontal diameters of the smallest ellipse encompassing the aggregate, a and b , respectively, are measured from the recorder photos, and then the following equation is used to find the diameter of a sphere with the equivalent Stokes settling velocity, d st , as

d_{st} = ([], 0.8248 normal + normal 0.168 (\frac{a}{b}) + 1.033 normal \times 10^{- 2} {(\frac{a}{b})}^{2} - 1.264 normal \times 10^{- 3} {(\frac{a}{b})}^{3} + 3.728 normal \times normal 10^{- 5} {(\frac{a}{b})}^{4}) b, 0.1 \leq \frac{a}{b} \leq 20

…”

Section: Performance Assessment Of Flocculantsmentioning

confidence: 99%

“…For example, the implications of developing polymer flocculants that are able to form dense aggregates are i) a denser aggregate hold less water, thus helping with dewatering efficiency of sediments; ii) with the same size, the denser aggregates offer faster settling velocities reducing the size of the treatment unit; and iii) the denser aggregates occupy less effective volume in suspension, allowing for the lower solids dilution before polymer flocculation. [231] The last feature is more useful in the context of high solids effluents such as oil sands tailings. Fractal Dimension: Aggregates formed by polymer flocculation are characterized as a permeable cluster of particles often having irregular (fractal) shape as one shown in Figure 44.…”

Section: Aggregates Characterizationmentioning

confidence: 99%

“…• The implication of using flocculants that give high density aggregates in industrial applications are requiring lower dilution prior to flocculation in high solids and easier dewatering primarily because inter-aggregate liquor is easy to be removed than intra-aggregate liquor. [231,250] • A good measure of impact of flocculant properties on the structure of aggregates. [231] Macromol.…”

Section: Imagingmentioning

confidence: 99%

“…[231,250] • A good measure of impact of flocculant properties on the structure of aggregates. [231] Macromol. Mater.…”

Section: Imagingmentioning

confidence: 99%

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Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

Vajihinejad

Gumfekar

Bazoubandi

et al. 2018

Macro Materials & Eng

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142

108

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Water soluble polymer flocculants are important constituents of solid–liquid separation units for the treatment of a variety of process‐affected effluents. The systematic development of a flocculant relies on a good understanding of flocculation process, polymer synthesis, polymer characterization, and, not the least, flocculation performance assessment as desired for a particular treatment process, all of which are essential to establish meaningful relationships between flocculant microstructure and flocculation efficiency. The aim of this article is to communicate the bigger picture of this research area to the readers. The recent advances in the application of bio/natural, synthetic, and stimuli‐responsive flocculants are reviewed. Then, the basic polymer reaction engineering tools to control the microstructure of flocculants are provided and the techniques for the quantification of flocculant microstructure are concisely discussed. This is followed by a review of the methods used for the characterization of particle‐polymer force measurement, and flocculation/dewatering assessment with attention to the characterization of aggregate structures.

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Section: Performance Assessment Of Flocculantsmentioning

confidence: 99%

d_{st} = ([], 0.8248 normal + normal 0.168 (\frac{a}{b}) + 1.033 normal \times 10^{- 2} {(\frac{a}{b})}^{2} - 1.264 normal \times 10^{- 3} {(\frac{a}{b})}^{3} + 3.728 normal \times normal 10^{- 5} {(\frac{a}{b})}^{4}) b, 0.1 \leq \frac{a}{b} \leq 20

…”

Section: Performance Assessment Of Flocculantsmentioning

confidence: 99%

Section: Aggregates Characterizationmentioning

confidence: 99%

Section: Imagingmentioning

confidence: 99%

“…[231,250] • A good measure of impact of flocculant properties on the structure of aggregates. [231] Macromol. Mater.…”

Section: Imagingmentioning

confidence: 99%

See 3 more Smart Citations

Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

Vajihinejad

Gumfekar

Bazoubandi

et al. 2018

Macro Materials & Eng

Self Cite

142

108

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Polymeric flocculation of oil sands tailings: Unveiling rheological indicators and dynamics of bitumen release

Sasar,

Johnston,

Santagata

2024

Can J Chem Eng

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Polymeric flocculation is widely used to accelerate the dewatering and consolidation of oil sands fluid fine tailings (FFTs). Optimizing flocculation requires a fundamental understanding of the changes to the internal structure of the material with polymer addition. Key challenges include sensitivity of flocculation to polymer dose, mixing conditions, and composition of individual FFTs. Moreover, despite the environmental implications, little is known of the effects of flocculation on the mobility of the residual organics present in the tailings. In this paper, advanced rheological tests are used to probe the formation and development of the polymer–clay structure during flocculation in near‐real time. This is achieved through a novel setup for controlled delivery of the polymer directly into the measuring cell of a rheometer. This enables continuous monitoring of the rheological parameters during the flocculation process and yields consistent and reproducible samples. An optical monitoring system is used to relate rheological measurements to water release and to changes in the surface accumulation of the residual bitumen. The water‐release polymer dose is found to be associated with a distinct rheological response highlighting the potential use of rheometry for polymer dosing/mixing optimization in real time and on a continuous basis in thickeners and inline flocculation systems.

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Advanced Polymer Flocculants for Solid–Liquid Separation in Oil Sands Tailings

Gumfekar

Vajihinejad

Soares

2018

Macromol. Rapid Commun.

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volume of tailings is projected to reach two billion cubic meters in 2034 if tailings management procedures remain the same. [3] When fresh tailings consolidate for a few years after their transfer to tailings ponds, gravitational forces cause the coarse components (sands) to settle, releasing a limited amount of the water to the surface. The bottom part of the remaining suspension is called mature fine tailings (MFT). Typically, MFT contains negatively charged clays (≈30-35 wt%), water (≈65 wt%), and residual bitumen (3-5 wt%). [4] Compared to fresh tailings, which still contain coarse particles that consolidate over time, MFT is a gel-like suspension that consolidates extremely slowly. Clays in MFT contain mainly kaolinite, illite, and mixedlayer clays such as interstratified illitesmectite and kaolinite-smectite. [5] Fine clays are mostly responsible for the water retained in MFT due to their high surface area. Additionally, fugitive bitumen binds clay particles, constricting interparticle pathways and trapping water. Colloidal Stability of Tailings and Challenges in DewateringSince MFT contains a mixture of negatively charged clays, it shows strong negative zeta potential that causes colloidal stabilization. Generally, clays contain hydroxyl and oxide functional groups that make their particles negatively charged at neutral pH (pH = 7) and even more negative as pH increases. Thus, the stability of clays in MFT increases with increase in pH. Current bitumen extraction processes use caustic additives to liberate bitumen from oil sands, generating alkaline tailings with pH of approximately 8.5. This alkaline medium increases the electrostatic repulsive forces between clays and significantly increases MFT stability. Surface charges also arise when ions from the neighboring solution adsorb on an initially neutral solid surface. Another source of surface charges is the dissociation of surface groups. The silica surface of clays can react with water to form silicic acid, which can then dissociate to form a silicic anion, as shown below. SiOHO HSiO (HSiO ) H 2 S 2 2 3 S 3 S ( ) ( ) + ↔ ↔ + − +(1) Multifunctional FlocculantsThe generation of tailings as a by product of the bitumen extraction process is one of the largest environmental footprints of oil sands operations. Most of the tailings treatment technologies use polymer flocculants to induce solid-liquid separation. However, due to the complex composition of tailings, conventional flocculants cannot reach the same performance achieved in other wastewater treatments. Over the last couple of decades, the oil sands industry has used acrylamide-based flocculants to treat tailings, achieving major progress in process optimization and integration with mechanical operations, but they still could not reach the required land reclamation targets. Over the last 5 years, the group designed, synthesized, and tested several novel polymer flocculants tailored for oil sands tailings treatment. This feature article communicates recent developments in these innovative polymers. Th...

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Aggregate structures formed by hyperbranched functionalized polyethylene (HBfPE) treatment of oil sands tailings

Cited by 7 publications

References 11 publications

Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

Polymeric flocculation of oil sands tailings: Unveiling rheological indicators and dynamics of bitumen release

Advanced Polymer Flocculants for Solid–Liquid Separation in Oil Sands Tailings

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