Raw Material In Iron Making

Dear Readers,
In this presentation, I have tried to explain main raw material sources of iron making process. Also, with my experience, I have tried to give a concept about the plant engineering related to raw material. I hope that, this presentation will be helpful for young engineers. With this presentation they will get a broad idea about the raw material, based on which they can study more on the subject.
Regards,
Nirjhar.

1. A
Nirjhar Chakravorti
Presentation

2. RAW MATERIAL PLANT
FOR IRON MAKING

3. Nirjhar Chakravorti
Nirjhar, a Mechanical Engineer by
profession, has completed engineering in
the year 2000, from Jalpaiguri Government
Engineering College, India.
Nirjhar has experience in design,
development, project and plant
engineering.
As an engineering professional Nirjhar has
worked at different industries.
Nirjhar’s interest is to know different
technology and process engineering.

4. Where from iron produced?
Raw iron is found in earth’s crust,
as an ore.
Iron ore mostly found as Fe
2O
3 (the
form of iron oxide found as the
mineral hematite).

5. Where from iron produced?
At present, blast furnace is most commonly
used furnace to produce iron.
The Blast furnace iron making process
basically consists of the conversion of iron
oxide to iron in liquid form . This requires
reductant for reduction of iron oxide and
heat for the above reduction reaction to
take place. The primary source to fulfill
both these requirements is carbon (in the
form of coke).

6. Where from iron produced?
The blast furnace is a vertical
counter-current heat exchanger as
well as a chemical reactor in which
burden material charged from the top
descend downward and the gasses
generated at the tuyere level ascend
upward.

7. Raw Material Section in iron making
Broadly a raw material section in iron
making plant has the following
sections:
a. Iron Ore Handling System
b. Coke & Coal Handling System
c. Lime & Other Material Handling
System
d. Sinter Plant

8. Flow Diagram
Blast
Furnace
Iron
Ore

9. Iron Ore Section
Ore crushed &
Transported from
mine to plant
Steel Plant
Blast
Furnace
Iron
Ore
Mine
Stack
Yard
Material
Handling
System

10. Iron Ore Section
Iron ore chunks dugs from the earth and
taken to process plant.
Chunks are crushed to small fractions, and
impurities are removed by magnetic
separator or other means. The small iron
fractions are formed into marble sized
pellets in forming drums and discs. Then
the pellets are transported to stack yard of
steel plant.

11. Iron Ore Section
Iron ore is collected from mines and crushed

12. Iron Ore Section
Stack Yard
Processed iron ore are dumped at stack yard

13. Iron Ore Section
Iron ore are transported through belt conveyor
Belt Conveyor

14. Iron Ore Section
Material
Handling
System
Raw Materials are
Stored and
transported
inside steel plant
and fed into
Blast Furnace
through material
handling system

15. Flow Diagram
Blast
Furnace
Iron
Ore
Coal
Coke
Oven
Plant
Coke

16. Coal & Coke Section
Processed &
Transported from
mine to plant
Steel Plant
Blast
Furnace
Coal
Mine
Stack
Yard
Coke
Oven
Plant
Transportation by
Material Handling
System
Coke
Stack
Material
Handling
System

17. Coal & Coke Section
Coal are collected from mines. Then
they are washed & crushed to pieces.
After that coal is transported to stack
yard of steel plant. From stack
through material handling section,
they are transported to coke oven
section, where coal is baked and
converted into coke.

18. Coal & Coke Section
Coal is collected from mines

19. Coal & Coke Section
Coal is processed, washed and crushed and then
transported into stack yard of steel plant

20. Coal & Coke Section
Processed coal is dumped at stack yard and transported
to coke oven plant by material handling system

21. Coal & Coke Section: Coke
Oven Plant
Coke is source of thermal energy
inside the Blast Furnace, which burns
and the converted heat melts the iron
ore.

22. Coal & Coke Section: Coke
Oven Plant
Conventional coke making is done in
a coke oven battery. Inside oven
battery coal is sandwiched between
heating walls. They are carbonized
(at a temperature around
1000
o
-1100
o
C) upto a certain degree
of de-volatization to produce
metallurgical coke of desired
mechanical and thermo-chemical
properties.

23. Coal & Coke Section: Coke
Oven Plant
Coke Stack
Storage Bunker
(Coal Tower)
Stamp
Charging Car
Coke Oven
Battery
Quenching
Car
Water
Sprayed
Material
Handling
System
Coke Bridge
Waste
Coke lump collected
under ground,
Crushed & Stacked
Coal Pushed in
Coke
Pushed out
Liquid Chemical
Off gas
used as fuel
Waste Volatile
Substance

24. Coal & Coke Section: Coke
Oven Plant



Schematic View of Coke Oven battery. Here instead of
collecting coal at stamp charging car, loose coal is
directly fed into the oven from top.

25. Coal & Coke Section: Coke
Oven Plant
Stamp Charging of Coal :
Stamp charging involves formation of a
stable coal cake with finely crushed coal
(88-90% - 3mm) by mechanically stamping
outside the oven and pushing the cake thus
formed inside the oven for carbonisation.
Coal moisture is maintained at 8-10% for
the formation of cake. Due to stamping,
bulk density of charge increases by 30-35%
causing significant improvement of coke.
Oven productivity increases by 10-12% &
there is a possibility of using inferior coking
coals to the extent of about 20%.

26. Coal & Coke Section: Coke
Oven Plant
Stamp Charging Machine: Erection Stage

27. Coal & Coke Section: Coke
Oven Plant
Stamped Coal cake ready for charging into the oven

28. Coal & Coke Section: Coke
Oven Plant
Pictorial View
Pusher and Charging Car travels & stops in front of the oven, where
coal cake needs to be pushed
Coke Oven
Oven Door
Coal cake box
front door
Coal cake
box
Coal
cake
Charging
plate
Coal
pusher
plate
Coal pusher
Plate drive
Coal
Charging
Car
Pusher and
Charging Car
Rail

29. Coal & Coke Section: Coke
Oven Plant
Stamped Coal cake pushed into the oven

30. Coal & Coke Section: Coke
Oven Plant
Pictorial View
Charging (i.e. pushing) the coal cake inside the oven
Oven door in
semi open condition
Coal cake box
Front door in
Open position
Quenching Car Side
Stamping & Charging Car Side

31. Coal & Coke Section: Coke
Oven Plant
Coke Oven :
During carbonization, coals undergo transformation
into plastic state at around 350
o
-400
o
C, swell and
then re-solidify at around 500
o
-550
o
C to give semi-
coke and then coke. In coke ovens, after coal is
charged inside the oven, plastic layers are formed
adjacent to the heating walls, and gradually the plastic
layers move towards the centre of oven from either
side and ultimately meet each other at the centre.
The quality and quantity of plastic layer is of extreme
importance and it determines the inherent strength of
coke matrix. For producing coke of good quality, coals
should have certain degree of maturity, good
properties and wide range of fluidity.

32. Coal & Coke Section: Coke
Oven Plant
Pictorial View
Coal cake is pushed inside the oven and charging plate is pulling back
Coal pusher plate holds back the coal
cake inside the oven, while pulling
back the charging plate

33. Coal & Coke Section: Coke
Oven Plant
Coke inside oven ready for push out from oven

34. Coal & Coke Section: Coke
Oven Plant
Hot Coke pushed out from oven

35. Coal & Coke Section: Coke
Oven Plant
Quenching of hot coke :
Red hot coke formed inside oven
pushed out by pusher car, and
collected on quenching car.

36. Coal & Coke Section: Coke
Oven Plant
Hot coke being pushed from an oven into a quench car.
Quenching
Car
Locomotive
engine of
quenching car
Coke collected
on quenching
car
Coke Oven

37. Coal & Coke Section: Coke
Oven Plant
The Quenching car travels and placed below the quench tower. The
coke is treated to high-pressure water jets to cool the coke while still
in the quench car. The coke is discharged from car and crushed into
pieces and stacked.
Quench
Tower
Quenching Car
with coke

38. Flow Diagram
Blast
Furnace
Iron
Ore
Coal
Coke
Oven
Plant
Coke
Flux

39. Flux Section
Flux crushed &
Transported from
source to plant
Steel Plant
Blast
Furnace
Material
Handling
System
Flux
Stack
Yard

40. Flux Section
Flux is added in the blast furnace to
remove impurities, by producing slag.
Lime is the most commonly used flux
material. Lime may be used as a flux
in the form of CaO, limestone
(CaCO3), dolomite (magnesium
calcium carbonate) or dolomitic lime
(product obtained from burning or
roasting of dolomite).

41. Flux Section
Lime is used as a flux in solid,
particulate form and reacts with
impurities in the charge to form a
slag.
It is important that the slag be kept
fluid, not only to increase its ability to
scavenge impurities from molten
metal, but also to permit the slag to
be readily removed from the furnace.

42. Flux Section
Formation of slag has a adverse effect also.
Lime in reaction with silica or silicates
present in the ore forms dicalcium silicate,
which has 3800
0
C melting point. It form a
coating on lime particles and prevent it
from further reaction.
Auxiliary flux is used for the purpose of
facilitating the reaction between lime and
silica or silicates. Fluorspar is a example of
auxiliary flux.

43. Flow Diagram
Blast
Furnace
Iron
Ore
Coal
Coke
Oven
Plant
Coke
Flux
Sinter
Fines
from
different
sources

44. Sinter Plant Section
In order to enhance the productivity of
blast furnaces, a high percentage of sinter
charge is a prerequisite.
Sinter is an agglomeration of iron ore fines,
coke and limestone in the form of cakes.
To ensure sinter burden in the blast
furnaces at 75 per cent, a total of 3 million
tonnes of sinter was envisaged for a
production of about 2 million tonnes of hot
metal.

45. Sinter Plant Section
Sinter Plant

46. Sinter Plant Section
Sinter Plant

47. Sinter Plant Section
Simple Flow Diagram of Sinter Plant

48. Sinter Plant Section
The raw materials used are as follows -
Iron ore fines (-10 mm), coke breeze (-3
mm), Lime stone & dolomite fines (-3mm)
and other metallurgical wastes. The
proportioned raw materials are mixed and
moistened in a mixing drum. The mix is
loaded on sinter machine through a feeder
onto a moving grate (pallet) and then the
mix is rolled through segregation plate so
that the coarse materials settle at the
bottom and fines onto the top.

49. Sinter Plant Section
The top surface of the mix is ignited
through stationary burners at 1200
o
C. As
the pallet moves forward, the air is sucked
through wind box situated under the grate.
A high temperature combustion zone is
created in the charge -bed due to
combustion of solid fuel of the mix and
regeneration of heat of incandescent sinter
and outgoing gases. Due to forward
movement of pallet , the sintering process
travels vertically down. The different zones
created on a sinter-bed are shown in the
simple flow diagram of sinter plant.

50. Sinter Plant Section
Sinter is produced as a combined result of
locally limited melting , grain boundary
diffusion and recrystallization of iron
oxides.
On the completion of sintering process,
finished sinter cake is crushed and cooled.
The cooled sinter is screened and + 6 mm
fraction is dispatched to blast furnace
through material handling system and -6
mm is re-circulated as return sinter.

51. Blast Furnace
All the raw material is charged into
the blast furnace, from top, through
variable throat armour or any other
means.
The purpose of a blast furnace is to
chemically reduce and physically
convert iron oxides into liquid iron
called "hot metal".

52. Blast Furnace
The blast furnace is a huge, steel stack
lined with refractory brick, where iron ore,
coke and limestone are dumped into the
top, and preheated air is blown into the
bottom.
The raw materials require 6 to 8 hours to
descend to the bottom of the furnace where
they become the final product of liquid slag
and liquid iron. These liquid products are
drained from the furnace at regular
intervals.

53. Blast Furnace
The hot air that was blown into the
bottom of the furnace ascends to the
top in 6 to 8 seconds after going
through numerous chemical
reactions. Once a blast furnace is
started it will continuously run for
four to ten years with only short
stops to perform planned
maintenance.

54. Blast Furnace

55. Blast Furnace

56. Thank You
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