Investigation on the flocculation of oil sands mature fine tailings with alkoxysilanes

Thompson, Dominic K; Motta, Fernanda Lopes; Soares, João B. P.

doi:10.1016/j.mineng.2017.06.008

Cited by 24 publications

(14 citation statements)

References 17 publications

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“…Concentrations of major ions in MFT were measured by atomic adsorption spectroscopy (Varian 220FS), as shown in Table . The MFT used in flocculation tests in this work was the same as that characterized by Thompson et al…”

Section: Methodsmentioning

confidence: 99%

Water soluble polymeric nanofibres for rapid flocculation and enhanced dewatering of mature fine tailings

2019

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Water‐soluble polymer flocculants have been used to efficiently release entrapped water in oil sands tailings by bridging fine particles to create large heavier flocs which can then settle faster and release water more efficiently. Due to their initial interaction with the fine particles suspended in tailings, polymer nanofibres may perform better than their parent polymers because of the entire surface of the nanofibres being fully accessible to the fine particles. In this work, commercially available poly(acrylamide‐co‐diallyl dimethylammonium chloride) was chosen as a basis for this study. Initial settling rate, supernatant turbidity, water recovery, capillary suction time, and solids content were measured to determine the effect of polymer nanofibres on solid‐liquid separation. The solid forms of the polymer (either as nanofibre or powder) perform better than the polymer solution in each test, with optimum dosages of 5 wt% mature fine tailings (MFT) loading. Nanofibres could achieve settling rates of 60 m/h, while the other forms were only able to achieve 42 m/h. Additionally, the turbidity of the supernatant obtained after flocculation with nanofibres was 15 nephelometric turbidity units (NTU), while the polymer solution and powder produced turbidites of 162 NTU and 70 NTU, respectively. In addition, polymer nanofibres and powders generated larger flocs compared to the polymer solution, which produced small, homogenized flocs.

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Section: Methodsmentioning

confidence: 99%

Water soluble polymeric nanofibres for rapid flocculation and enhanced dewatering of mature fine tailings

2019

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“…Thompson et al. adopted a unique approach of using alkoxysilanes to induce the flocculation in MFT . They hypothesized that alkoxysilanes can form oligomers or polymers after sequential hydrolysis and condensation reactions in aqueous alcoholic solution.…”

Section: Other Tailings Remediation Strategiesmentioning

confidence: 99%

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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“…11 Several performance metrics are adopted to assess MFT flocculation and dewatering behavior: (i) sediment volume reduction, determined by measuring the normalized mudline height and initial settling rate (ISR); (ii) ease of further dewatering, quantified by capillary suction time (CST) and specific resistance to filtration (SRF); (iii) quality of supernatant, assessed by measuring supernatant turbidity and (iv) yield strength, which is related to the solids content of the sediments; while thixotropic and temporary viscosity effects may affect apparent yield strength, solids content is an absolute measurement of consolidation. 12 Mudline height (the interface between the supernatant and sediments) and total fluid level are measured using a graduated cylinder, and used to calculate the normalized mudline height, given as the ratio: mudline height/total fluid level. The ISR is calculated by measuring the slope of the linear portion of the mudline height versus time curve.…”

Section: Potential Alternative Polymer Flocculants For Mft Dewateringmentioning

confidence: 99%

Using Polymer Reaction Engineering Principles to Help the Environment: The Case of the Canadian Oil Sands Tailings

Soares¹,

Motta²

2018

J. Braz. Chem. Soc.

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Investigation on the flocculation of oil sands mature fine tailings with alkoxysilanes

Cited by 24 publications

References 17 publications

Water soluble polymeric nanofibres for rapid flocculation and enhanced dewatering of mature fine tailings

Water soluble polymeric nanofibres for rapid flocculation and enhanced dewatering of mature fine tailings

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

Using Polymer Reaction Engineering Principles to Help the Environment: The Case of the Canadian Oil Sands Tailings

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