Page 59 - New Trends In Coal Conversion

Coal 27

have shifted energy away from coal to natural gas. Despite this, it is expected that coal
plays an important role on the energy supply if the global energy demand continues to
rise in the near future.
Considering that the steel industry is largely iron-based through the blast furnace
route and the lack of satisfactory material that can replace coke either fully or partially
in its physical role, the coking coal will continue to be essential for its transformation
into high-quality coke. By this reason, the demand for these commoditiesdcoking
coal and cokedin the near future will be determined predominantly by the demand
of the steel industry. The quality of coke depends on the formulation of blends
with coking coals of different qualities, additives (if any), and coking conditions
applied. Each coal type in the blend formulation has its own role to give a porous
and highly carbon material with a high strength and a moderate reactivity to carbon
dioxide. As a priority throughout the overall history of cokemaking, there has been
a great interest in the increase of the blending ratio of low-quality coals, the use of
other materials containing carbon, the decrease of the quantity of coke required to
feed the blast furnace, the reduction of emissions, and the development of alternative
cokemaking technologies. This overall trend has been motivated by the progressive
depletion of high-quality coking coal resources, the advances in blast furnace technol-
ogy, and the fact that coke is the most expensive feed material employed in the blast
furnace ironmaking. It obviously helps to safeguard good coking coals and to reduce
costs in cokemaking and then in iron and steel final products. However, there are some
less positive aspects that need to be solved for increasing the current ratio of low-
quality or marginal coals because, at the same time, the requirements of coke quality
should be maintained. In the coming years, the priority targets in cokemaking will also
be linked to the production of high-quality coke at low cost, the safeguarding of good
coking coals, and energy saving, together with the minimization of wastes and fugi-
tive emissions.

1.8 Concluding remarks

Coal is a non-renewable natural resource and because it is the world’s most abundant,
cheapest, and most widely distributed fossil fuel used today, it is still considered a pri-
mary energy source and an essential feedstock for other industrial processes such as
cokemaking, the cement industry, and the production of chemicals.
The major coal deposits started to develop during the Carboniferous, and its distri-
bution worldwide is uneven as a result of the formation of peat at different times in the
geological record in predominantly tropical latitudes and the subsequent drift of the
continents to their present-day positions. The major regions with coal deposits are
located in the Northern Hemisphere, whereas those in the Southern Hemisphere,
with the exception of Australia, are relatively deficient in this type of resource.
According to various coal associations, there are an estimated 1.1 trillion tonnes of
proven coal reserves worldwide. Therefore there are sufficient coal reserves for the
next 150 years at current production rates. Of the total existing coal reserves, 71.6%
correspond to anthracite and those of bituminous coal rank, while subbituminous