Rate of Bitumen Film Transfer from a Quartz Surface to an Air Bubble as Observed by Optical Microscopy
The rate of bitumen transfer from a bitumen-coated quartz plate to a gas bubble surface in aqueous alkaline solutions was recorded photographically. During bitumen spreading, a bulk layer followed the formation of thin bitumen films (precursor films). The bulk layer spread at the bubble surface with a velocity of about one order of magnitude less than the velocity of the precursor film. The energy of activation for spreading of the bulk layer varied from about 66 to 123 kJ/mol depending on the stage of bitumen spreading but remained constant at about 105 kJ/mol for the precursor film. Results are discussed with respect to fundamental issues associated with flo t a t i o n r e c o v e ry of heavy oils.
Water-based bitumen recovery from diluent-conditioned oil sands
Important process development aspects leading to more efficient bitumen recovery from diluent-conditioned oil sands by water-based methods are discussed. Bitumen viscosity of 0.5–2 Pa·s is required at the processing temperature and can be reduced to this level by bitumen dilution with an organic solvent. Oil sand porosity, however, poses a restriction on the amount of diluent that can be accepted by the oil sand. Also oil sand-diluent conditioning time is an important process parameter and can vary from a few minutes for oil sands with low-viscosity bitumen to several hours if viscosity of the bitumen is high. Additionally, the bitumen separation efficiency during digestion and flotation can be enhanced by reducing the bitumen/water interfacial tension through addition, for example, of tripolyphosphate to the aqueous phase. 
 
 
 
On a examine d'importants aspects du developpement de procedes conduisant a une meilleure recuperation de bitumes de sables bitumineux conditionnes par des diluants a l'aide de methodes basees sur l'eau. Une viscosite de bitume de 0,5-2 Pa.s est requise a la temperature de procede et peut etre reduite a ce niveau par la dilution du bitume avec un solvant organique. Cependant, la porosite du sable bitumineux impose une restriction pour la quantite de diluant qui peut etre acceptee par le sable bitumineux. En outre, le temps de conditionnement sables bitumineux-diluant est un parametre important et peut varier de quelques minutes pour des sables bitumineux dont le bitume est de faible viscosite a plusieurs heures si la viscosite du bitume est elevee. Enfin, l'efficacite de separation des bitumes lors de la digestion et de la flottation peut etre amelioree en reduisant la tension interfaciale bitume/eau par l'ajout, par exemple, de tripolyphosphate dans la phase aqueuse.
Particle Collection in Columns—Gas Rate and Bubble Size Effects
AbstractThe collection first-order rate constant is governed by three parameters: gas rate, bubble size and bubble collection efficiency. Their interrelationship in flotation columns is analysed using a two-phase flow model and a fundamental model of particle collection by gas bubbles. One of the conclusions demonstrated is that generation of very small gas bubbles (less than about 0.08cm diameter) will not always yield higher rate constants in conventional column operation. As well, the existence of an optimum gas rate for particle collection is rationalized.