Bitumen droplet size distribution

The packing density of aerated bitumen droplets at the froth interface is a function of droplet size distribution, the flux of material imping-... 

In this section, we discuss the effects of solids addition on the rheology of oil-in-water emulsions, in particular, the effects of solids size (size distribution) and shape (spherical versus irregular). Because the type of the oil used to form an emulsion is important in determining the viscosity of the oil-in-water emulsion, the rheology of the emulsion-solids mixtures is also influenced by the type of oil. Thus, two distinct emulsion systems with added solids will be discussed (1) synthetic (Bayol-35) oil-in-water emulsions 21, 57) and (2) bitumen-in-water emulsions (58). The synthetic oil has a viscosity of 2.4 mPa s, whereas the bitumen has a viscosity of 306,000 mPa s at 25 C. The Sauter mean diameter of the oil droplets is 10 xm for synthetic oil, and 6 xm for bitumen-in-water emulsions. The synthetic OAV emulsions are fairly shear-thinning, whereas the bitumen OAV emulsions are fairly Newtonian. 

The critical size ratio above which emulsions can be regarded as a continuous phase toward solids is not a unique value for the following reasons. First, the size distributions of the solids and the oil droplets are most likely to be different from one system to another. Second, the viscosity of the oil used to form the emulsions also affects this critical size ratio. Evidence of this dependence on oil viscosity is the fact that in the bitumen (viscosity 306 Pa s)-in-water emulsions, the solids do not see the emulsions as a continuous phase even at a size ratio of 6. If solids are regarded as having an infinite viscosity, Farris (35) found that the critical size ratio is about 10 for a bimodal solids suspension. 

Figure 11. Size distributions of bitumen droplets formed when processing an average quality oil sand (broken curve) and a poor quality oil sand (solid curve). The particle sizes reported are for two-phase droplets consisting of a bitumen layer around a gas bubble. (Reproduced from reference 62, from Syncrude Canada Ltd.)...

Figure 14.33. Particle size distribution of bitumen emulsion droplets...

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