The McClave Process

James Mason McClave, the chief engineer of Abasand Oils Ltd., designed the separation process used at the Abasand plant that came into operation in September 1936. In October of that year, McClave and A.J. Smith, an American petroleum engineer and vice-president of Abasand Oils Ltd., gave a presentation to the 18^th Annual Western Meeting of the Canadian Institute of Mining and Metallurgy, in which they described the process:

The separation plant, as built, is rated at 250 tons per day of 24 hours, and consists of the following equipment.

1. Pulper: The sand after mining is discharged to a machine which has been designed to serve as a combined wet ore bin, disintegrator and feeder…At the lower end is a large hopper partially filled with water…There the sand is disintegrated and passed along by the pug blades and discharged at the upper end of the chamber.
2. Pug Mill: The second machine is a pug mill…In this unit the breaking of the oil films from the sand grains, which is commenced in the pulper, is completed. The effect of the warm water, heat, mild abrasion and the slight alkalinity of the water tending to lower the surface tension of the oil films on the sand grains so that they leave the grains and become particles of oil disseminated through the remaining pulp of water, sand and oil.
   Interposed between the pulper and the pug mill is a vibrating screen to prevent any large foreign bodies in the sand from getting into the pug mill.

3. Q.Z. Flotation Cell: The next principal machine is the quiet zone flotation cell. Here the pulp from the pug mill is discharged. This machine [has its] sides built up to provide a deep water bed at the lower end. The machine is set at an angle upward and is steam-jacketed. The mechanical raking mechanism is a double flight conveyor. The conveyor moves the sand through the cell and discharges it at the upper end, and in so doing stirs the sand and permits the oil particles to float out…At the top of the water bed are placed large rollers, which revolve slowly, thereby skimming the fine oil froth which adheres to them. The froth is removed from the rollers by fixed scrapers.
4. Classifier: The other principal machine in the separation plant proper is [a] classifier…The tailings from the Q.Z. flotation cell enter this machine. The dewatered sand…goes to the tailings pile near the separation plant. The water recovered from the tailings in the classifier returns to the circuit for reuse.

The thick oil separated in the Q.Z. flotation cell still contained a certain amount of water, sand and smaller mineral particles. The addition of a lighter form of hydrocarbon, such as kerosene, served to dilute the oil, allowing it to float on the water and the minerals to settle out. The diluent was subsequently returned to the separation plant for reuse when the oil was refined.