LAPSE:2020.1008
Published Article
LAPSE:2020.1008
Development of Test Procedures Based on Chaotic Advection for Assessing Polymer Performance in High-Solids Tailings Applications
Allan Costine, Phillip Fawell, Andrew Chryss, Stuart Dahl, John Bellwood
September 23, 2020
Post-thickener polymer addition to initiate rapid tailings dewatering has gained considerable interest for tailings storage facility (TSF) management. However, the highly viscous and non-Newtonian rheology of dense suspensions presents unique challenges for mixing with polymer solutions. Such mixing is highly inefficient, often resulting in polymer overdosing and wide variations in deposited tailings characteristics, with the potential to significantly compromise TSF performance. In this study, a new type of mixer based on the principles of chaotic advection was used for treating kaolin suspensions with high molecular weight (MW) anionic copolymer solutions. Chaotic advection imparts efficient mixing by gently stretching and folding flows in a controlled manner, as opposed to random, high-shear flows associated with turbulent mixing, and this lower shear stress allows for the controlled formation of larger aggregate structures with vastly improved dewatering characteristics. A pre-conditioning pipe reactor prior to this mixer can also be advantageous in terms of providing a short burst of high shear for initial polymer distribution. Seven acrylamide/acrylate copolymers of a fixed anionic charge density (30%) spanning a distinct MW range, as characterized by intrinsic viscosity, were applied at elevated dosages to high-solids (20−30 wt %) kaolin suspensions in continuous flow through the chaotic mixer described above. Medium-to-high MW polymers were generally preferred, with further increases in MW resulting in significantly diminished dewatering outcomes. Direct analysis of polymer solution properties through oscillatory rheology gave a better indication of a polymer’s potential performance compared with intrinsic viscosity, offering a more robust basis for polymer selection. This represented the first systematic study into the effects of polymer properties on deposition behavior after dosing at high solids, which was only possible through the ability to apply controlled shear across the entire suspension during sample preparation.
Keywords
compressive yield stress, consolidation, dewatering, flocculants, inline flocculation, polyacrylamides
Subject
Suggested Citation
Costine A, Fawell P, Chryss A, Dahl S, Bellwood J. Development of Test Procedures Based on Chaotic Advection for Assessing Polymer Performance in High-Solids Tailings Applications. (2020). LAPSE:2020.1008
Author Affiliations
Costine A: CSIRO Mineral Resources, Waterford, WA 6152, Australia
Fawell P: CSIRO Mineral Resources, Waterford, WA 6152, Australia
Chryss A: CSIRO Mineral Resources, Clayton, VIC 3169, Australia
Dahl S: CSIRO Mineral Resources, Waterford, WA 6152, Australia
Bellwood J: BASF plc, Hub 26, Charlesworth House, Hunsworth Lane, Cleckheaton BD19 4LN, UK
Journal Name
Processes
Volume
8
Issue
6
Article Number
E731
Year
2020
Publication Date
2020-06-24
Published Version
ISSN
2227-9717
Version Comments
Original Submission
Other Meta
PII: pr8060731, Publication Type: Journal Article
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LAPSE:2020.1008
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doi:10.3390/pr8060731
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Sep 23, 2020
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CC BY 4.0
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Sep 23, 2020
 
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Sep 23, 2020
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https://psecommunity.org/LAPSE:2020.1008
 
Original Submitter
Calvin Tsay
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