India's largest coal handling agency - Mjunction

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steel was estimated at around 66 mt in 2009-10. Coke is the
crucial raw material for production of steel through the blast
furnace route. At present the country is producing around
22-26 mt of coke and importing another around 2.5 mt from
countries like Colombia, Russia, and China.
It is envisaged that India’s steel production will go up to
around 110 million tons per annum (mtpa) by 2011-12 and
further to around 200 mtpa by 2020. To achieve this production
of steel, the country will need huge amount of coking coal to
make coke that can be charged in blast furnaces.
Going by this assumption, as per a conservative estimate
the country will need around 100 mt of coking coal and around
70 mt of LAM coke by 2011-12 and around 150 mt of coking
coal and around 120 mt of coke by 2020.
From the facts available, it is clear that the country will
depend immensely on imported coking coal as well as LAM
coke to produce the planned quantity of steel.
The current global situation indicates that the country’s
planned steel production capacities might face severe
challenges largely due to non-availability of coking coal
as well as coke. Rumours are also rife in certain quarters
that India may not achieve the planned steel production
capacities due to limited availability of coking coal in the
world market.
Global situation
Global metallurgical coke production currently hovers around
500 million tons (mt) per year, 90 percent of which is used in
the steel industry. A significant proportion of this global trade
All about met coke
Coal Insights Bureau
Metallurgical coke, also known as “Met” coke,
is a carbon material manufactured by the
“destructive distillation” of various blends
of bituminous coal (coking coal or metallurgical coal).
Bituminous coal is a soft, medium grade coal that contains
a high percentage of volatile components.
Destructive distillation is performed in “coke
batteries” which are banks of large enclosed kilns. Once
the kilns are loaded, they are heated to approximately
1000 degree Celcius in the absence of air.
During the heat cycle the volatile components of
the coal are released and the solid coal goes through a
partial melt and subsequent re-solidification to a nonmelting
carbon. Volatile components include coal tar,
ammonia, and literally dozens of other “products of
decomposition”. Most volatile components are reclaimed
or recycled. The final solid is a non-melting carbon called
metallurgical coke. As a result of the loss of volatile gases
and of partial melting, Met coke has an open, porous
morphology and may appear glassy in some specimens.
As a result of the heat treatment process Met coke
has a very low volatile content. However, the “ash”
constituents, that were part of the original bituminous
coal feedstock, remain encapsulated in the resultant coke.
Met coke feedstocks are available in a wide range of sizes
from fine powder to basketball-sized lumps. Typical
purities range from 88 to 92 percent fixed carbon.
Commercial grades are available in sizes from
30-micrometer powders up to 20 cm lumps. Metallurgical
coke is used where a high quality, tough, resilient,
wearing carbon is required. Applications include but
are not limited to conductive flooring, friction materials,
foundry coatings, foundry carbon raiser, corrosion
materials, drilling applications, reducing agents, heattreatment,
ceramic packing media, electrolytic processes,
and oxygen exclusion.
Coke is made by destructive distillation of a blend
of selected bituminous coals (called Coking coal or
Metallurgical coal) in special high temperature ovens in
the absence of oxygen until a greater part of the volatile
matter is driven off. The resulting product, Coke, consists
principally of Carbon.
Traditionally, chemistry, size & strength (both cold
as well as hot) have been considered the most important
properties for use in the blast furnace. The quality of the
constituent coals determines the characteristics of the
resultant coke.
Coke is primarily used to smelt iron ore and other
bearing materials in blast furnaces, acting both as a source
of heat and as a chemical reducing agent to produce pig
iron or hot metal. Coke, iron ore and limestone are fed into
blast furnace, which runs continuously. Hot air blown
into the furnace burns the coke, which serves as source of
heat and as an oxygen reducing agent to produce metallic
iron. Limestone acts as a flux and also combines with
impurities to form slag. Coke also serves as a structural
material to support the deep bed of coke/iron oxide/
limestone that makes up much of the furnace volume.
It is in this last role that its properties are crucial. It
is important that it does not degrade (e.g. break up into
small particles) during its descent through the oxidizing
hot gases passing through the stock region of the furnace.
To produce high quality blast furnace coke, high
quality coal must be used. High quality coals are those
coals that when coked together produce the highest
stability and CSR (Coke Strength after Reactivity) to
support the blast furnace burden and allow maximum
production.
COAL INSIGHTS 32 October 2010