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Chapter 5

5. Separation of diluted bitumen emulsion

This chapter mainly presents the methods and procedures that are focused
on the brine in diluted bitumen emulsions with demulsifier, silicate and pH control.

5.1. Introduction

In chapter 3, PRs is chosen as optimal demulsifier for diluted bitumen
emulsion. But a rag layer develops in the middle of the sample and prevents the
complete separation of oil, water and clay solids. In the rag layer, clay solids are
associated with oil components (e.g. asphaltenes) in diluted bitumen ^t13'^t5ξ which
will stabilize water-in-oil emulsions ^[1] '^[3]. To break the rag layer and get complete
separation, associated oil should be separated from clay solids. Experiments
show that a coated bitumen film can be separated from glass surface when
contacting with water at high pH (pH 11) ^[6]. Contact angle of bitumen on glass
surface increases with increase of pH, which reveals glass surface is more
water-wet with increase of pH ^[6]. Sodium meta-silicate (Na2SiO3) can enhance the
dispersion of clay solids and minimize bitumen-clay coagulation ^[7]. In chapter 4,
increasing pH with silicate was shown to make kaolinite more water-wet.
Increasing pH can also convert naphthenic acids in the oil to soaps, which can
emulsify and separate oil from clay solids and form an oil-in-water emulsion.
Hereby optimal demulsifier, silicate and pH control are used to break diluted

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