The Role of Micromechanics

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The Role of Micromechanics in Oil Sands Research
Tony Yeung and Kevin Moran NSERC Industrial
Research Chair in Oil Sands Engineering Departmen
t of Chemical and Materials Engineering University
of Alberta Edmonton Alberta
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• General Problem
• Removal (through coalescence / aggregation)
• of small droplets from suspension
• Here, small microns in size
• Relation to Oil Sands Extraction
• coalescence of bitumen drops to form froth
• coalescence / aggregation of water droplets
• during Froth Treatment
• In both cases, it is the smallest droplets
• that present the biggest challenges.

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Structures at droplet surfaces are the culprits
? study bitumen-water interfaces Question Ar
e these interfacial structures homogeneous and
therefore scale-independent ?
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• Micromechanics
• A means of studying oil-water interfaces
• on the micron scale
• Method involves
• visualization (light microscopy)
• stress-strain experimentation on
• individual emulsion drops
• a wealth of micron-scale information
• inaccessible through bench-scale
• methods

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Measuring IFT directly at Droplet Surface
10 mm
Minimum pressure to draw in the droplet is
where ? is the interfacial tension (IFT)
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Gibbs Adsorption Relation surface coverage ?
slope of IFT vs log (conc.)
zero coverage regime
saturated regime
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• Surprises
• IFTs are different from those quantified
• using bench-scale techniques
• Droplets are stable in both the
• saturated and zero coverage regimes
• Upon compression, interface exhibits
• ? 2-D solid properties in
• zero coverage regime
• ? 2-D liquid properties in
• saturated regime

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Squeezed-out structures determined by
higher-order bending effects
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Zero Coverage Regime interface is 2-D solid
Saturated Regime interface is 2-D liquid
Small water droplets spawning off interface
upon compression
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Similar phenomenon in biology same physics in
both cases?
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• Other Surprises
• uneven charge distributions
• on bitumen-water interfaces
• (micron-sized patches ?)
• complex surface properties
• of bitumen drops under
• certain conditions

profound effects on bitumen recovery
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• Future Plans
• refine techniques to study
• surface rheological properties of
• bitumen / water drops
• (piezoelectric controls)
• thermo-mechanical properties of
• single emulsion drops
• develop microelectrodes for probing
• charge distributions on bitumen-water
• interfaces