The document discusses the sintering process used at the Rourkela Steel Plant in India. It describes how iron ore fines, limestone, dolomite and other raw materials are blended and formed into nodules. These nodules are then processed through a sintering machine, where combustion of coke forms sintered agglomerates. The sinter is cooled, crushed, and screened before use as a raw material input for blast furnaces. Key aspects of the sinter plant like the mixer, nodulizer, sinter machine, cooler and screens are explained. Parameters that affect sintering quality like raw material chemistry and size, moisture content, and suction pressure are also summarized.

1. Sintering process in steel plant
Core Industry Internship and Colloquium (IPP201)
IIT ROPAR
AASHISH KUMAR KHOLIYA

2. About SAIL RSP
• Rourkela Steel Plant (RSP) is the first of the three integrated steel
plants set up by Government of India in 1959.
• The first Steel Industry set up under Hindustan Steel limited on 19th
January 1954 which paved way for laying up of infrastructure for rapid
industrialization of the country.
• It is also the first steel plant in SAIL and the only one presently, where
100% of the slabs rolled are produced through the cost effective and
quality centered continuous casting route.

3. Flow Chart

4. Raw Material
• The fully mechanized captive mines under Raw Material Division
(RMD).
• a unit of SAIL meet the bulk requirements of Iron ore, Limestone,
Dolomite, Manganese, Quartzite and coal as raw materials of RSP.

5. Raw material
a) Iron Ore: Captive Mines at Barsua, Kalta, Meghathatuburu,
Kiriburu
b) Limestone: - Purnapani , Kuteshwar ,Jaisalmer and Katni
c) Dolomite: - Biramitrapur and Sonakhan,Bilha, Baraduar and Katni
d) Manganese : Purchased from Barajamda and Koira
e) Ferro Manganese and Silico Manganese: Maharashtra
Electrosmelt Limited (MEL)
f) Quartzite: Purchased from Local areas
g) Coal: Prime Coking Coal (PCC) and Medium Coking Coal (MCC)
from Indian Sources Imported Coking Coal (ICC) – Hard
and Soft from Australia, Canada, USA and China

6. Product mix and application of product

7. Product mix and application of product

8. Departments
• Ore Bedding and Blending Plant
RSP’s Ore Bedding & Blending Plant (OBBP) has a base mix
preparation system with on-ground bedding, blending and conveying
facilities
• Coke Oven
RSP has five 4.7-metre-tall coke oven batteries (COBs) that
produce coke as the input for blast furnaces.

9. Departments
• Sintering Plant
This has facilitated the increased usage of sinter in blast furnace
burden.
• Blast furnaces
The Five blast furnaces of RSP, with a combined capacity of 4.5
MTPA, produce hot molten metal for steel production.
• SMS

10. Departments
• Plate Mill
RSP’s 3.1 meter wide, 4 high reversing mill is equipped with
online thickness measurement facilities.
• Hot Strip Mill
• Cold Rolling Mill
• Silicon Steel Mills
• Pipe Plants
• Traffic & Raw Material

11. Sinter Plant
• Due to increased mechanisation in the mines, lot of fines are
generated which cannot be charged into the Blast Furnaces directly.

12. Sinter Plant
• In order to conserve these, otherwise waste material, they are
compacted together and made into lumps by a process known as
sintering.
• Sintering is defined as the agglomeration of the fine mineral particles
into a compact lumpy mass by incipient fusion caused by the heat
produced during the combustion of the solid fuel within the moving
bed of loosely particles.

13. Sinter making facility in RSP
Sinter Plant-I
Sinter Plant-II
Sinter Plant-III
•1.50 MT
•1.57 MT
•3.70 MT
InstalledCapacity

14. Definition of Sintering
• Sintering is a process of agglomeration of fine mineral particles into a
porous and lumpy mass by incipient fusion caused by heat produced
by combustion of solid fuel within the mass itself.

15. Why there is need of sintering?
• To utilize the fines generated during the mining operation.
• To utilize different additives like mill scale, flue dust, hearth slag etc.
in an integrated steel plant.
• The need for charging prepared burden in Blast Furnaces to increase
productivity and lower fuel rate.

16. Advantages of sintering
• Agglomeration of fines into hard, strong and irregular porous lumps which
gives better bed permeability.
• Elimination of 60 - 70 % of sulphur and Arsenic (if present) during sintering.
• Elimination of moisture, hydrated water and other volatiles on the sinter
strand with a cheaper fuel.
• As the calculation of flux takes place in sinter strand, super-fluxing saves
much more coke in the furnace.
• It increases the Blast Furnace productivity.
• Increase of sinter percentage in Blast Furnace burden, increases the
permeability, hence reduction and heating rate or burden increases, so the
productivity also.
• Utilization of solid wastes generate within steel works

17. Mechanism of sintering

18. Specific consumption of raw material per unit ton
of sinter
85%
5%
6%
1%
1%
1%
1%
Kg/Ton of sinter
Iron Fine Ores
Limestone(HS)
Limestone(LS)
Lime
LD slag
Mill Scale
Flue Dust

19. Chemistry of sinter
Fe%, 55
Feo%, 8
SiO2 %, 5
Al2O3 %, 2
CaO %, 9
MgO %, 3

20. Sintering Process

21. Raw Material
• Volume of bunkers different
for each material depending
upon their percentage
composition in sinter.

22. Mixer
• It prepare homogeneous mixer of all components.
• In mixer lime CaO uses as binder with water for bind the
base mix, limestone and coke.
• In this process temperature of mixer increase due to
exothermic reaction between lime and raw material it is
about few degree centigrade depends upon how much lime
added.
• About 60% of water added in Mixer of charge before sinter
machine.

23. Sintering Process

24. Mixer

25. Mixer

26. Mixer
• Continuously Raw
materials send to mixer
at connecting piece,
calcined lime added and
water added by venture
scrubber shown in
figure.

27. Mixer

28. Mixer
• Density of mixed material is 2 ton/m3, particle size is less than 10 mm
and moisture content less than 7%.
• Rated capacity of mixer is 714.9 Ton/hour and designed capacity is
900 Ton/hour.
• Mixing pan drive motor power rating is 90kW and angular velocity of
mixing pan is 6.3 RPM and Rotor motor power rating is 200kW and
speed of rotor tool is 180 RPM.

29. Nodulizer
• After mixing, mixture is send to nodulizer
• Nodulizer creates spherical lumps or nodules.
• As a result of nodulizing, mechanical strength is increased, and the
ore acquires a porous structure.

30. Sintering Process

31. Nodulizer
• Construction and
specification of nodulizer
are identical to above
Intensive Mixer.

32. Nodulizer
• Nodules increase permeability of
sinter mix. and heat transfer
through suction is increase.
• It increase sinter machine
efficiency.

33. Sinter Machine
• Sintering is the process of compacting and forming a solid mass of
material by heat and/or pressure without melting it to the point of
liquefaction.
• The atoms in the materials diffuse across the boundaries of the
particles, fusing the particles together and creating one solid piece.
• Sinter machine creates large particle size sinter which can be allow in
blast furnace .till now particle size around 3mm after sintering nodule
become size of 3- 200 mm.

34. Sintering Process

35. Sinter Machine

36. Sinter Machine

37. Sinter Machine
• Sinter machine is a pallet car which rotates with a sprocket driven by
motor. And grates are placed at the bottom of pallet car. Below there
are two series of wind man connected with each 21 wind boxes.

38. Sinter Machine
Figure.1 show wind boxes
connected with bottom of sinter
machine ;
Figure.2 show just below wind
boxes wind man connected to it.

39. Sinter Machine
• Hearth Layer is placed at bottom of pallet car to increase permeability
of sinter.
• It is necessary that large size particles of
base mix should go to bottom first to
increase permeability. For this to
happen segregation belt is introduced
after the roller shown in figure.

40. Sinter Machine

41. Circular Cooler
• Crushed sinter temperature is about 1000 oC. For further screening
sinter is cooled by a circular cooler to a lower temperature about
100oC which is suitable to operate.

42. Sintering Process

43. Crushing and Screening
• Sinter is crushed by single roll crusher then
for reduce size further by double roll
crusher.
• This size less than 50mm sinter divided in
two portion as required by plant necessity.
Some portion of it used in making hearth
layer for sinter machine and another large
portion send to blast furnace and rest then
stored in sinter plant.
• Both portion send to screen 15mm/25mm.

44. Crushing and screening
• Sinter less than 15mm again screened by 5mm screen where less
5mm sinter send to return fine bunker.

45. Sintering Process

46. Parameters affecting sintering
Iron ore size:
The granulometry of iron ore fines, used in sintering, has a great influence
on sinter plant performance. Laboratory Experiments were conducted with
different granulometry of iron ore fines to assess its influence on sinter quality
and productivity. when we reduce iron ore size then productivity increase
(ton/m2/hr).
 Iron ore fines chemistry
lower Fe grade (< 62% Fe) SFCA (SiO2-Fe2O3-CaO-Al2O3)
Medium grade (62-65% Fe) SFCA and SFCA-1..
High grade (65-68% Fe) SFCA-1.
The SFCA-1 phase is the most desirable bonding phase in iron ore sinter, since
microstructures composed entirely of SFCA-1 show higher physical strength and
higher reducibility than microstructures composed predominantly of SFCA.

47. Parameters affecting sintering
Coke breeze
The required coke breeze granulometry for efficient sintering is:
+5 mm < 5 % - 3 mm = 85-90 % -0.5 mm < 15 %
Presence of higher % of +5 mm slows down the coke breeze burning
rate and thus reducing sintering rate. For reducing the micro-fines
generation during crushing, -3 mm should be screened out before the
crusher.

48. Parameters affecting sintering
Calcined Lime
Calcined lime is one of the best intensifier of sintering process.
It preheats the sinter mix enhances balling phenomena Replaces raw
lime stone Calcined lime addition @ 20kg/t was found to be optimum
for SAIL sinter plants.
Moisture
As is known, faster the rate of air flow through the bed faster is
the rate of sintering. The rate of flow of the air through the bed is
controlled by the vacuum under the bed and the permeability of the
bed.

49. Parameters affecting sintering
Under-grate Suction
The rate of flow of the air through the bed is controlled by the
vacuum under the bed and the permeability of the bed. The
optimization of the gas dynamics parameters of the sinter machines
enables one to achieve higher under grate suction and thus substantial
improvements in the techno-economic parameters of the sinter
production.

50. Parameters affecting sintering
Preheating of sinter mix
Pre-heating of sinter mix helps in reducing the ill effects of Re-
condensation of moisture.
Pre-heating of sinter mix can be done by:
1. Addition of hot water in balling drum
2. Addition of steam in balling drum or raw mix hopper
3. Installing gas burners inside the balling drum
4. Adding hot return fines
5. Addition of calcined lime

51. Thank You

52. References
• Improvement in performance of sinter plant by Dr. M T Raju, Deputy
General Manager, RDCIS
• SAIL.
• Permeability optimization by DR. M.T.RAJU ,Deputy General Manager
RDCIS, SAIL, RANCHI.
• Raw material quality for sinter making byA Sengupta, DGM, RCL.