  Asphaltene precipitation is a crucial phase separation phenomenon in the oil
industry, especially in paraffinic froth treatment to extract bitumen from oil
sands ores. This work reveals the formation of particles at 0.2 to 0.4 um in
radius, defined as a primary sub-micron particle (PSMP), which is ubiquitous
from diffusive mixing between asphaltene solution and any of 23 types of
precipitants examined in our experiments. The yield and quantity of asphaltene
particles are affected not only by the Hildebrand solubility parameter of the
precipitants but also by the diffusion coefficients of the asphaltene solution
and the precipitant. The Population Balance Model (PBM) with the Hildebrand
solubility parameter has been used to model particle size distribution. Good
agreement has been achieved between numerical predictions and the experimental
data. It indicates that the colloid theory can describe the size distribution
of PSMP and larger aggregates. Therefore, this study provides new insight into
the mechanism for the dependence of yield and size distribution of the
precipitated asphaltene particles on the composition of precipitants and adding
inhibitors. Controlling of asphaltene yield and size distribution may be
applied to the process of hydrocarbon separation or asphaltene precipitation
prevention.
