What is Coal?
Coal is a
complex combination of materials, and the combination can greatly differ from
one formation or deposit to another. These differences result from the varying
types of vegetation from which the coal originated; the depths of burial, and
the temperatures and pressures at those depths; as well as the length of time
the coal has been forming in the deposit. The varying amount of minerals in
a coal deposit may also have a significant effect on its properties and
classification. In addition to carbon, coals contain hydrogen, oxygen, nitrogen
and varying amounts of sulphur. High-rank coals are high in carbon and heat
value, but low in hydrogen and oxygen. Low-rank coals are low in carbon but high
in hydrogen and oxygen content. Anthracite is the highest carbon content,
followed by bituminous, sub-bituminous and lignite coal, which has the lowest
carbon content. Sub-bituminous, bituminous metallurgical, and bituminous thermal
coals are the three types that are produced in Alberta. Regardless of their
rank, however, Alberta coals are comparatively low in sulphur, ranging from 0.2
to 0.7 percent.
The most abundant type of coal in Alberta is
sub-bituminous coal, found east of the mountains. Although its heating value is
lower than some other coals (it is better than lignite), it is useful in electricity generating stations.
Bituminous metallurgical coal has a higher heating value than lignite or
sub-bituminous coal. Because of its higher
heating value, it is used in making coke. Coke is in turn used in making iron
and steel. Bituminous metallurgical coal is found in the mountain region.
Like bituminous metallurgical coal, bituminous thermal coal also has a high
heating value. This coal is found mostly in the foothills.