Separating Sand

The last annual report recorded the success achieved in the operation of a semi-commercial plant in the North under the practical conditions at the bituminous sand deposits. The report also dealt with preliminary studies of some unexpected difficulties encountered in the North and predicted that progress following from these differences was likely to be more valuable than the substantial success of the large plant. Further studies have amply confirmed this prediction.

Chance has played an interesting part in bringing about the progress, which has been achieved. The Federal Department of Mines located its bituminous sand quarry, beside which the Research Council of Alberta agreed to build and operate a separation plant, at what it considered the most convenient place available. It did not know that the bituminous sand beds at this place were in any sense extraordinary. Yet they were. Ground water working through them from the clay overburden above had carried into them unusual quantities of soluble salts. The presence of these salts caused a very considerable amount of trouble in the separation plant. But in doing so they "gave away" the secret of bituminous sand separation. The Research Council has been trying for years to get its finger on the fundamental principle underlying this process. Its workers were well prepared to take advantage of the chance encounter with an abnormal condition at the northern bituminous sand quarry and turn it rapidly into concrete knowledge.

The secret of bituminous sand separation by hot water turns out to be very simple. In the first place all bituminous sand contains acid. Sometimes there is very little and other times, due to the presence of iron salts, there is a very considerable amount. This acid must be neutralized by mixing the bituminous sand with an alkali before the sand will separate satisfactorily on washing with hot water. In the second place, lime in the bituminous sand must be avoided for it is a veritable poison for the separation process. Consequently lime cannot be used to neutralize the acidity of bituminous sand. Further, there is danger in using another common alkali, namely, caustic soda, for this will generate lime from calcium slats that may be present in the bituminous sand. Soda ash is the proper chemical to use. 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.

Alberta Research Council. [1931] Annual Report. With permission from the Alberta Research Council.