Minerals composed of iron oxides are the main source for iron
mining. Pure metallic iron is too rare within the Earth's crust to act as the
main supply for iron mining companies.
There are two popular types of mineral form iron oxides used to
excavate iron. These ores are hematite and magnetite. A third common iron ore
is known as taconite, which is a variant of magnetite ores.
Taconites are a type of sedimentary rock containing fine traces of
magnetite, as well as quartz, chert and carbonate. Taconites are occasionally
also described as banded iron formations.
Banded iron formations, or BIFs, are also a type of sedimentary
rock from which iron is derived. BIFs are known to be millions of years old,
with data illustrating these rocks to be part of the Proterozoic Eon. Both
hematite and magnetite are commonly found within BIFs and are also interlaced
with layers of an assortment of mineral quartz, such as chert and silica. BIFs
are readily available around the world and are the first source of iron
deposits within the iron mining industry.
Both hematite and magnetite ores have iron grades of approximately
70 per cent
Fe. Prior to beneficiation processes, taconite ores only carry about a 30 per cent
iron grade. Hematite ores are ideal due to the ease of excavation and
separation from gangue, when compared to other iron ores.
Within the iron mining industry, hematite ores are often referred
to as DSO, which stands for direct shipping ore. Hematites are given this title
because in comparison to the other types of iron deposit, hematites provide a
significantly more efficient mining and beneficiation procedure. Therefore,
hematite ore forms are almost directly ready to be shipped to manufacturers
once being excavated, hence the term DSO.
Magnetite and taconite ores experience a longer, more effortful
separation process. To extract the desired materials from magnetite and
taconite ores, the deposits must go through a process involving:
Depending on the desired outcome, some iron deposits may
experience further separation processes, as seen with iron pellets.
Although magnetites and taconites require a more time consuming
beneficiation process, and thereby require more money spent by the mining
company, the final products have significantly fewer impurities than the
products of hematite ores.
DSO's like hematite ores may be advantageous to mining companies
as it saves time and money. However, hematite ores produce a high level of
impurities that manufacturing companies must deal with. The receiving firms
must provide the time and money to eliminate impurities, often by running blast
furnaces for an extended period of time. Therefore, depending on the point of
view, DSO's are an advantage while simultaneously being a disadvantage.
Furthermore, while taconite ores may begin with poor iron grade levels, once
enduring beneficiation, taconite products assume iron grade levels averaging 65
Fe. Therefore, in place of immediacy, magnetite ores and taconite ores supply
manufacturers with better quality iron products.
Hematite, magnetite, and taconite ores all result in products rich
in iron grade levels. Depending on factors like time and money, each ore
provide a variety of advantages and disadvantages.