Tailings sands, waste sand from the processing of the Athabasca Oil Sands, average 95 to 98 percent silica (SiO2) in the raw bulk samples. These sands, together with other high quartz sands in the Fort McMurray area including McMurray Formation sands where the formation is not impregnated with bitumen, alluvial (bedrock channel) sands from the Clearwater River valley, and dune sands, were studied for their potential as a source of silica sand for glass manufacture and other uses.
The main contaminants of the tailings sands are the residual oil film, the "fines", the iron content, and mica. After beneficiation, the tailings sands analyzed 98 to 99 percent silica (SiO2), with iron contents of 0.02 to 0.04 percent Fe203 well within range for high quality glass manufacture. Mica is present in minor amounts but may not have to be removed.
There should be few constraints in the exploitability of this otherwise wasted "byproduct". The little or no mining costs, easy access, and unlimited quantities should more than compensate for the costs of beneficiation.
alluvial (bedrock channel) sands, located within easy access of Fort McMurray, are also a good potential source of high quality silica sand. After beneficiation, silica (SiO2) is over 98 percent and iron content (Fe203) is 0.03 to 0.05 percent. Iron is the main contaminant; mica is not present. These sands are well sorted and within the specified size range for glass and glass fibre manufacture.
In some ways the alluvial sands are superior in quality to the oil sand tailings. However, they do lack the ready availability of the tailings sands, in that exploitation would involve dredging, and thus there could be environmental constraints.
Most of the dune sands tested are well sorted, fine- to medium-grained, and generally of better quality than dune sands elsewhere in the province. One dune sand sampled in the Clearwater River valley has a silica content of over 98 percent SiO2 and an iron content of 0.04 to 0.05 percent Fe203 after beneficiation. However, this deposit is far from Fort McMurray, with difficult access, so it is of purely academic interest at this time. Other dunes of lesser quality are located near Fort McMurray and could be considered as sources of sand for industrial or construction uses.
The non bitumen-saturated McMurray Formation sands are very high in quartz, ranging from 97 to 98 percent SiO2, and have iron contents as low as 0.01 percent Fe203 after beneficiation. Mica is a major problem and would have to be removed to bring these sands to glass grade quality. Exploitation is uncertain as overburden is thick in many localities, and access difficult. Overall, the unsaturated McMurray Formation sands are not considered a potential source of silica sand.
McLaws, I.J. (1980): Silica sands in the Fort McMurray area, Alberta; Alberta Research Council, ARC/AGS Economic Geology Report 6, 61 p.