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.
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 Torys
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, Clarks focus
shifting to cleaning the bitumen as much as possible in order to process
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
Clark continued his research, and was granted one more patent (Clark
wasnt 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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