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Method for Separating Bituminous Sands

Dr. Karl Clark is strongly associated with the hot water separation of bituminous sands and while he did not invent the procedure, he improved upon it by utilizing chemical reagents and fine-tuning the process, resulting in the cleanest bitumen achieved at that time. patent record for this invention

In 1920, Clark considered the heavy, viscous oil coming from the tar sands as a potential ingredient in road surfacing. At the time, the dirt roads of the Prairies were vulnerable to moisture, and Clark thought a bituminous emulsion would be useful to in stabilizing the earth, fixing the roads so they could stand up to wet weather.

In the 1920s, standard techniques of emulsifying paving material made use of a soap reagent. Clark found, however, that when he tried this process with the Northern Alberta sands, the sand and the oil (bitumen) separated; the sand sank to the bottom, with the bitumen settling above it. Unfortunately, bitumen is heavier than water, and so the water involved in the procedure came out on top. As such, it was impossible to recover the bitumen without mixing it with sand again.

Clark explained his discovery in a letter to Dr. H. M. Tory, President of the University of Alberta. Within weeks, Clark was hired to Tory’s Research Department, the precursor to the Alberta Research Council (ARC), in order to study the separation process further. Bituminous sand as a paving material was soon abandoned as uneconomical, Clark’s focus shifting to cleaning the bitumen as much as possible in order to process it.

Clark began experiments with hot water, an idea pioneered by others such as Sidney Ells, an engineer for the Federal Department of Mines. Tar sands frothed when dispersed in hot water. After months of tests, Clark found that if he created a pulp of tar sand in hot water, a froth of oil would form once more hot water was introduced. This froth then floated to the surface, while the sand sank to the bottom, allowing the froth to be easily collected from the surface.

With some minor adjustments, this method of separating bituminous sands was patented in 1929, though it would be decades of experimenting with new techniques in oil refinement before the oilsands yielded more valuable petroleum products.

Clark continued with his research, and in the early 1930s, discovered what the role of the reagent was in separation. At this time, Clark was working with sand coming from a quarry to the north of the previous quarries with which he had worked. He noticed the sands from this location were not separating the way he expected them to.

It turned out the sands from this quarry were different from those mined from others in that there was a considerable amount of soluble salts present in them. This caused a high level of acidity, which was causing the difficulty in separation. To separate them, the sands had to be neutralized by an alkaline substance, such as soap reagent.

Clark further discovered that certain neutralizing agents worked better than others. While lime and caustic soda did not work well, soda ash worked perfectly. In his 1931 report to the Alberta Research Council, Clark states, "generally speaking, if bituminous sand as found in Northern Alberta is mixed and heated with a solution of soda ash till all its acidity is neutralized and then washed in hot water, practically one hundred percent of the bitumen content of the same will be recovered."

Hot water separation plant Clark continued his research, and was granted one more patent (Clark wasn’t terribly interested in patents), in 1948. The process patented improved upon previous separation techniques by identifying the role of air bubbles in separation. Air bubbles occur naturally in the oilsands, and are necessary for the separation of the bitumen. Bitumen particles attach to the air bubbles and float to the surface.

If there is too much air, however, sand will start attaching to the oil bubbles, causing excessive sand to be present with the bitumen. The patent makes it clear that the amount of air used must be controlled in order for the process to work efficiently. Though Clark discovered this principle over 50 years ago, it is still employed today.

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