Separating

The second step in transforming the oil sands into commercial petroleum products is separating the bitumen from the sand. In this step, raw oil sand enters the plant and is broken apart into bitumen, which is saved, and sand tailings, which are discarded.

There is more than one way to separate oil sand into its component parts. However, the only method ever used at Bitumount is the hot water separation process. Basically, it consists of the following steps:

1. transforming the sand into a slurry, or pulp, by breaking up any lumps, removing impurities such as rocks and twigs, and adding hot water to dilute the sand
2. agitating the slurry to separate the oil and the sand, and adding it to a hot water bath where an oil froth can rise to the surface and sand can sink to the bottom
3. skimming the oil froth off the water, and reprocessing the separated sand to capture any additional oil
4. removing excess water from the separated oil by heating it and adding a diluent

A number of technical problems complicate the process.

1. The oil sands are not a simple mixture of oil and sand. Rather, the grains of sand are coated with a layer of water that has minute particles of silt, clay and minerals in it, which is in turn covered by a film of oil. The spaces between the coated sand grains may be filled with more water, or with air or natural gas. When oil and sand are separated, the minute particles in the water layer can settle out, but they can also remain suspended in the water or become bonded with the oil. Thus, even once the sand and oil are separated, there is the secondary problem of removing the particles from the oil and the water.
2. The bitumen in the oil sands is actually heavier than water, and does not float to the top on its own when mixed with water.

3. The composition of the oil sands varies from place to place, and even within individual deposits. The amount of oil in the sand is not constant. Some deposits are more acidic, some have more impurities and some are more viscous than others. All these factors require that variations be made in the separation process.
4. The oil sands have chemical and physical properties that can be very hard on components of the separation plant. The plant needs to be very durable and adjustable in order to avoid having to halt the processing while parts are cleaned, repaired or replaced.

Two hot water separation plants were constructed at Bitumount. Robert Fitzsimmons was responsible for the first plant. Initially, it was based on publicly-available information about hot water separation. Over time it evolved, with Fitzsimmons, who had no background in scientific research or the oil business, making alterations based on practical considerations and as his budget allowed.

In its final stages, Fitzsimmons engaged the services of petroleum engineers, with mixed results. The second plant, on the other hand, was built all at once, with the benefit of input from professional researchers and engineers, and with a budget that increased to cover costs. Interestingly, this plant also saw its share of on-the-spot adjustments and alterations.