In this presentation, I try to explain the whole concept of sinter.

1. BY:
VIKAS KUMAR
vikasalluri2012@gmail.com
1

2. ➢ Introduction of sintering technology
➢ History of sintering technology
➢ Flow chart of sintering process
➢ Equipment in sinter plant
➢ Phase in sintering process
➢ Sintering process
➢ Raw material used for sintering
➢ Raw materials per unit ton of sinter
2

3. ➢Chemical composition of flux materials
➢Mechanism of sintering
➢Sinter quality requirement by B.F
➢Need of sintering
➢Advantage of sinter in B.F
➢Factors affecting sinter quality
➢Sinter process control parameters
➢Important key for sinter
3

4. ➢Important formula in sintering process
➢Cost Calculation
➢References
4

5. ➢SINTER: It is an agglomerate
➢What is Agglomerate ?
➢An agglomerate is a porous lump,
Reducible, Hard mass.
5

6. ➢ What is Sintering ?
➢Sintering is a process of agglomeration
of iron ore fines, flux fines with coke
fines at high temperature, during high
temperature all material fuse together
and create a product that can be used in
blast furnace, and that product is called
sinter.
6

7. ➢There are basically the following three
types of sinters.
➢Non flux or acid sinter:-In these sinter no
flux is added to the iron ore in preparing
the sinter mix. Non flux sinters are very
rarely being produced these days.
➢Self flux or basic sinter:-When flux
addition in sinter is just enough to take
care of flux required for sinter percentage
7

8. in blast furnace burden it is called self flux
sinter
➢Super flux sinters:-When flux addition in
sinter is extra enough to take care of total
flux requirement in BF it is called super
flux sinter.
8

9. ➢First time Iron ore sintering technology
was developed in the middle of 19th
century in Germany.
➢In Germany(1892) first pot type Iron ore
sintering machine with upward draught
was installed.
➢Almost after ten years two no.pot type
(upward draught) sinter machine was
installed in USA for commercial
production.
9

10. ➢Upward draught sinter machines have
many constraints like high dust emission,
high iron loss, high maintenance cost and
ignition was very difficult.
➢The upward draught sintering machine
problem solved in1908 with downward
draught by Dwight and Lloyd of
Germany. So it is called Dwight and
Lloyd sinter machine.
10

11. Dwight and Lloyd S/M
HORIZONTAL TRAY
MACHINE
STRAIGHT LINE
SINTER MACHINE
Circular rotary table Straight type
Fixed ignition furnace and
charging equipment
Fixed ignition furnace and
charging equipment
Mainly used for 25 to 40
Sq.mtr
Mainly used for 50 to 600
Sq.mtr.
11

12. FLOW CHART:-
Proportion
ing section
Raw mix
hopper
Drum
feeder
Sinter m/c
Segregation
plate
pallets
SRC
YARD
Furnace
12

13. ➢Raw material bunker
➢Weigh feeder
➢Conveyor belt for receiving and
discharging the raw material.
➢Mixing and nodulizing drum i.e (PMD,
SMD) with water system
➢Mix bin hopper
➢Drum feeder, Segregation plate, Leveler
➢Ignition furnace with burner
13

14. ➢Pallets with grate bars
➢Compress air fan
➢Single horn crusher
➢Pneumatic actuator and valve
➢Wind box
➢Cold screen system
➢ESP (Electrostatic precipitators)
➢LT and HT motor
14

15. Phases:-
1. Wet zone 2.Dry zone 3.Combus
tion zone
4.Hard
sinter
5.Soft sinter
6.Shrinkge
Time
B
e
d
h
e
i
g
h
t
Furnace
Grate
Top of sinter zone
15

16. The following steps required to form sinter:-
➢ All raw materials are stocked in
proportioning bunkers.
➢ Raw materials comes through weigh
feeder and puts on conveyor belt layer by
layer.
➢ Raw materials comes to PMD where only
20% water is added, remaining 75% water
is added on SMD.
16

17. ➢From SMD raw materials comes in the
form of micro ball formation and
delivered to mix bin bunker.
➢Above process is called green mix.
➢From mix bin bunker, green mix comes
to pallet, where pallets divided into two
layer.
➢30 to 40mm laid with hearth layer and it
size should be 5 to 10mm.
17

18. ➢Remaining pallets laid with green mix.
➢When pallets enters into furnace area
where number of row of burner are
installed, top layer coke ignited.
➢Blast furnace gas is used as ignition fuel
for preparing sinter.
➢Due to down ward draught (suction
pressure) range (-1500mm) heat from
burning coke travel downward.
18

19. ➢Slowly pallets move horizontally and
flames travels downward by the time
materials fuse and stick together.
➢This phenomena occur from top to
bottom layer on horizontally moving
pallets.
➢By the time pallets reach at last wind
box, fuse materials start cooling and coke
totally burn from top to bottom .
19

20. ➢This is called burn through point (BTP)
and the total process is called sintering.
➢BTP is determined by highest temp. of
wind box.
➢Generally sintering speed is 1200 to 1300
mm/hrs (20 to 22mm/min)
➢After sintering cooling take place and
falls at machine discharge end due to
return travels of pallets.
20

21. ➢Sinter is broken into pieces (below
150mm in size) by single horn
crusher(SRC).
➢When sinter broke from SRC, it divided
into three ranges.
➢-5mm to 5mm :- Return fines
➢ 5 to 10mm :- Hearth layer
➢ 10mm and more :- For BF use.
21

22. ➢Iron ore fines
➢Lime Stone
➢Dolomite
➢Coke fines
➢Mill scale
➢Flue dust.
➢Internal Return fines.
22

23. 1.Iron Ore Fines:-The required iron ore
fines granulometry for efficient sintering.
Chemical
Specification
Iron ore size
T.FE – 63% Min +8mm : 5% Max
AL2O3 – 2% Max -3mm : 60 to 65% Max
SIO2 – 3% Max -0.15mm : 15% Max
AL2O3/SIO2 – 0.4 to
0.6
MPS : 2.5 to 3.25mm
23

24. ➢Iron ore fines are four types:-
➢Hematite(Fe2o3), Magnetite(Fe3o4),
Limonite (Feo(OH).n(H2O),
Goethite(Feo(OH).
Principles for good sinter from iron fines:-
➢Size should be less than 8mm
➢FE contains should be more than 62%
➢Sio2 and Al2o3 as low as possible.
24

25. Effects of feo:-
➢If feo is more, sinter will become more
brittle, causing more fines generation and
cause for continuous furnace hanging
and increase coke rate in blast furnace.
➢If feo is less, sinter will weak, causing
more fines generation and cause for
continuous furnace hanging.
➢Feo should be always optimum (8 to 9)%
25

26. 2.LIME STONES:- The required lime
fines granulometry for efficient sintering:
CHEMICAL
SPECIFICATION
LIME STONE
SIZES
Cao - 50% Min +40mm : 5% Max
Al2o3 - -5mm : 5% Max
Sio2 – 2% Max Moist : 2.5% Max
Mgo – 2.5% Max After crushing ( 0 to -
3mm) : 90% Max
26

27. 2.LIME STONES:- Lime stones are used
as flux materials ( 10mm to 40mm)
which will be crushed and used in
process where fraction of 1mm to 5mm
should bé 80 to 85% always.
Use of lime stones in sinters:
➢Preheats the sinter mix.
➢Inhances balling phenomena.
27

28. Effects of Cao:-
➢The main function of Cao is used to
remove the gangue particles (Al2o3, Sio2
etc) which is present in iron ore fines.
➢By removing the gangue particles, Sinter
becomes strong.
28

29. 3.Dolomite:- The required dolomite
granulometry for efficient sintering:-
Chemical
Specification
Quick lime sizes
Mgo – 20% Min +40mm : 5% Max
Cao – 30% Min -5mm : 5% Max
Al2o3 -NIL Moist : 2.5% Max
Sio2 – 2% Max After crushing ( 0 to -
3mm) : 90% Max
29

30. 3.Dolomite:- Dolomite are used as flux
materials ( 10mm to 40mm) which will
be crushed and used in process where
fraction of 1mm to 5mm should bé 80 to
85% always.
➢Effects of Mgo:-Mgo provides for an
optimum blast furnace slag condition in
terms of both good flowability and
desulphurisation.
30

31. 4.Coke fines:-The required coke fines
granulometry for efficient sintering is:
Chemical
specification
Coke sizes
Fixed carbon - 80% min +5mm : 5% Max
Ash – 20% Max Moisture : 10% Max
V.M – 2% Max After crushing (-3mm) :
90% Min
31

32. ➢If sizes of coke fines (+5mm) are
presence in higher % than slow down the
coke breeze burning rate and reducing
sinter rate.
➢Coke fines playing a fuel role in making
sinter, which distribute the heat
throughout the sinter bed effectively
which help us in making good quality
sinter
32

33. ➢Productivity and quality are determined
by coke consumption behaviour during
sintering process.
➢Suction temp will inc. with inc. in coke
fines up to certain limit whereas suction
temp. will decrease with inc. in coke
fines, from this sticker type sinter
formation will occur.
33

34. 5.Flue Dust & Mill scale:-The required
flue dust & mill scale granulometry for
efficient sintering is:
Tfe Sio2 C Mgo Al203 Feo Sizes
Flue
dust
30% 6% 45% 0.8% 4% - 0 to 3
mm
Mill
scale
70%
Min
- - - 1 %
Max
50%
Min
0 to
5mm
34

35. Flue Dust :- Generally it generate from
Blast furnace.
Mill Scale:- Generally it generate from
rolling mill.
➢Mill scale is costlier than Iron ore fines.
➢While using mill scale, it form like chip
type due to this it create problem in
suction and fines will generate more.
35

36. 6.Internal Return fines :-
➢Return fines mixed while making sinter
because melting of sinter becomes fast
and sintering speed increase while
without mixing return fines it take more
time for melting.
➢It improves the permeability and more
even distribution and transfer of heat are
attained. So heat losses decreases, &
shrinkage of mixture is lowered.
36

37. Specific Consumption of raw materials per
unit ton of sinter.
Iron ore fines
Lime stone(HS)
Lime stone(LS)
Lime
LD slag
Mill scale
Flue Dust
85%
5%
6%
Remaining all are 1%
37

38. TFE FEO Cao Mgo Sio2 Al2o3 s Loi
LIME
STONE
- - 50%
min
2.5%
max
2%
max
- - 40%
DOLOM
ITE
- - 30%
min
20%
min
2%
max
- - 45%
QUICK
LIME
- - 90%
min
2.5%
max
2%
max
- - 17%
38

39. During sintering of 600mm layer of charge
following reaction will take place:
➢ C + O2
➢ Fe2o3 + Co
➢ Fe3o4 + Co
Co + Co2
Fe3o4 + Co2
Feo + Co2
39

40. Mechanism:-
Heating
Heating
Cooling
Fe2o3
Single lump
+
2Feo3Cao at 1200°©
Calcium ferrite
2Fe2O3
40

41. ➢ 2fe2o3.Cao + Al2o3.Sio2 2Fe2o3Cao .
Al2o3.Sio2
(SFCA)
2Fe2o3 2Fe2o3
2Fe2o3
Slag bond
Silico ferrite of calcium and aluminium
41

42. CHEMICAL SPECIFICATION EXPECTED RANGE
FE(T) 54 To 56 %
FEO 8 To 9 %
SIO2 4.5 To 6 %
AL2O3 2.5 % Max
AL2O3/SIO2 0.4 To 0.6 %
CAO 9 To 11 %
MGO 2.5 To 3 %
CAO/SIO2 1.8 To 2.0 %
T.I 71 to 75 %
R.D.I 20 To 30 %
R.I 65 % Min
42

43. ➢ To utilize fines generated during the
mining operation.
➢ To utilize different additive like mill
scale, flue dust, hearth slag etc in an
integrated steel plant.
➢ Need for charging prepared burden in
blast furnace to increases productivity
and lower fuel rate.
43

44. ➢Sinter increases the blast furnace
productivity .
➢Increase sinter percentage in blast
furnace burden, increases the
permeability, hence reduction and
heating rate and burden increases , so
productivity also increases.
➢Iron ore fines is easily available at much
cheaper rate than lump ore.
44

45. ➢Sinter is pre fluxed so reducibility of
sinter is better than lump ore.
➢Size of sinter is narrower so heat zone
distribution inside furnace is better and
stable.
➢Blast furnace operation becomes more
smooth and stable with sinter.
45

46. ➢Size of raw materials:-The strength of
sinter is directly related to the size of
charge of raw materials. If size is large,
contact area will less and strength of
sinter will low where as size is small,
contact area will large and strength of
sinter will high.
46

47. ➢Fuel Content :- Variation in fuel content,
it affect the peak temperature affected
during sintering process because of this
poor bed permeability, sinter will weak
and fines will generate more.
➢Moisture:-It maintain proper
permeability in bed during sintering
process. Moisture should maintain 6.5 to
7 % of charge
47

48. ➢Mean particle size of charge should be
2.5 to 3.25mm
➢Alumina to silica ratio in sinter
(Al2o3/Sio2) between 0.4 to 0.6 gives
better slag chemistry in BF.
➢Charge level in mix bin should be
maintain at 30 to 50%. This give better
horizontal segregation of particulates.
48

49. ➢BTP temperature should maintain 300 to
325 degree centigrade at 13th wind box.
➢Maintain ignition temperature in ignition
furnace at 1100 to 1200°©
➢High FC coke gives better sinter quality
than low FC coke because of this
temperature is directly proportional to
quality of sinter.
49

50. ➢If(Sio2+Feo+Cao+Al2o3)/T.Fe is
between 0.48 to 0.55, TI will be better.
➢Total gangue materials in sinter
(Sio2+Cao+Al2o3+Mgo+Tio2) should
18 to 19% give better TI and RDI.
➢Al2o3+Mgo+Tio2 in sinter should not
more than 4% .
50

51. ➢Fe in sinter comes mainly from sintering
iron ore fines and mill scale.
➢Cao in sinter comes mainly from
sintering of Lime stone and lime and
little from dolomite.
➢Mgo in sinter comes mainly from
sintering of Dolomite and little from
Lime stone.
➢Sio2 in sinter comes mainly from
sintering of Iron ore fines and little from
Flux and coke.
51

52. ➢ Al2O3 in sinter comes mainly from
sintering of Iron ore fines and little from
Flux and coke.
➢ Effects of Sio2:- Higher Sio2 in sinter will
induce the formation of glassy phases in
sinter and reduce the strength of sinter.
➢ Effects of Cao/Sio2 :- It is required for
better reducibility of sinter as well as good
slag chemistry and fluidity of slag in B.F.
52

53. ➢Effects of Al203 :- An increase in Al2o3
% by 1 % increase the RDI value by 10
%.
➢Effects of L.O.I :- The higher LOI of iron
ore fines has a detrimental effect on
sinter quality and productivity.
➢Effects of Hearth layer :- Hearth layer is
placed at bottom of pallets to increase
permeability of sinter.
53

54. ➢ Reduction Degradation index :- Fe is
mostly in the form of Fe2o3, when
reduction of sinter start at 400 to
600°©, Fe2o3 reduce to Fe3o4. Sinter
volume increase by 25% and crack will
occur in sinter and sinter will break into
pieces, called disintegration. Because of
small pieces it will create problem in
suction (reduce permeability).
54

55. ➢Reducibility index (RI) :- Reducibility is
an important characteristic of sinter
which measures the ability to transfer
oxygen during reduction in the blast
furnace stack, giving an idea of fuel
consumption needs in the furnace.
55

56. ➢Tumbler index (TI) :- Increase in sinter
basicity, Sinter productivity and RDI
decrease and tumbler index increase for
both low and high sinter.
➢Method to improve Feo in sinter:-
➢Reduce +5mm size of particles in
charging.
➢Increase coke feed ratio.
➢Increase in balling index.
56

57. How to control return fines ?
➢Increase feo of sinter.
➢Increase bed height.
➢Increase in coke and flux.
➢Improve in balling index.
➢Reduce sintering speed.
57

58. ➢Loss of Ignition:-
Dry weight of material- Weight after ignition
Dry weight of materials
*100
➢ 500gm of dry material is heated at 900°©
for 1 hrs.
58

59. ➢Dry weight of materials:-
➢ Natural weight of materials – Moisture in
matreials
➢ Moisture in materials:-
Natural weight of materials – Dry weight of materials
Natural weight of materials
* 100
59

60. ➢ To calculate dry weight 500gm materials is
heated at 500°© for 2hrs
➢ Balling Index :-
+3mm after SMD.
+3mm after PMD
It should be 1.6 minimum
60

61. ➢ (Total Raw materials consumed in 24hrs
+ handling loss) * unit cost of raw
materials + handling cost + cost of
electric consumed + cost of gas
consumed + cost of water consumed +
spare consumed + consumables
consumed + cost of repair and
maintenance + cost of man power +
administrative and over head cost.
61

62. ➢Per ton sinter cost :-
Total cost as above in 24hrs
Sinter produced in 24hrs
62

63. ➢R.P Bhagat “Fundamental of iron ore
sintering”.
➢Aashish kumar kholiya “Sintering
process in steel plant”
➢Raj kumar goel “Sinter plant”.
➢Goutam bose “Sinter making”.
➢Shukdeo prasad “Sintering technology”.
63

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