sintering plant at a glance - copy

8/12/2019 Sintering Plant at a Glance - Copy

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SINTERING PLANT


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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.


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TYPES OF SINTER

NON FLUX SINTER

FLUXED SINTER

SELF FLUXED SINTER

SUPER FLUXED SINTER


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SCHEMATIC DISTRIBUTION OF THE ZONES IN CHARGE DURING SINTERING

ON THE SINTER STRAND

ZONE OF SINTERING

ZONE OF

CONDENSATION

OF MOISTURE


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RAW MATERIALS USED FOR SINTERING

1. Iron ore fines

2. Flux ( lime stone & dolomite )

3. Coke breeze

4. Waste Materials:a). Flue dust ( From Blast Furnace but added in RMHP )

b). Mill scale ( From Slabbing Mill, H.S.M.&CCS)

c). L.D.Slag (From S.M.S.)

d). Lime dust ( From R.M.P.)5. Sinter return ( Own generation)


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MAIN SECTIONS OF SINTERING PLANT

1. RAW MATERIAL SECTION.( For crushing of coke and flux )

2. STOCK BINS AND PROPORTIONING SECTION

( For storing,proportioning & mixing )

3. SINTER MACHINE SECTION

( For sinter making )


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COKE CRUSHING BY FOUR ROLL CRUSHERS( 08 Nos. CAPACITY 16 T/Hr. EACH )

MIX COKE FROM C.O. COKE RETURN FROM B.F.

( - 15mm ) ( - 25mm )

+ 15 mm TO B.F.

MIXED WITH SINTER

-15 mm TO FUEL

STORAGE

- 15 mm

- 3 mm-3 mm TO STOCK BINS

6 mm

2 mm

(NUT COKE SCREEN)


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STOCK BINS AND PROPORTIONING SECTION

A. TO STOCK RAW MATERIALS :

There are three similar series of over head bunker andconveyors to feed three sinter machines at a time. Each series

contains 23 bunkers . Materials are stored in the bunkers in

following order :

BUNKER No. TOTAL BUNKER MATERIAL1 6 06 Iron ore fines

7 13 07 Crushed flux ( - 3 mm )

14 17 04 Crushed coke ( - 3 mm )

18 01 Waste materials

19 20 02 Cold sinter return

21 01 Hot sinter return

22 23 02 Lime dust


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B. FIXING OF FEED RATE :

For sending raw mix to sinter machine for sintering, fixation of

feed rate of materials is done considering capacity of the sinter

machine and quality requirement of blast furnace.

Feed rate fixed is :

Iron ore fines 250 T/hr.Flux 75 T/hr.

( Feeding of Flux depends on available lime in sinter required

in blast furnace.Available lime means CaO SiO2in sinter.)

Coke 20 T/hr.

Waste materials 20 T/hr.

Sinter return 60 T/hr.

Lime dust 02 T/hr.


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PROPORTIONING OF CHARGE

ELECTRONICCONVEYOR SCALES

ELECTRONIC

FEEDER

VIBRO FEEDER

O/F FLUX COKE W/M S/R L/D

A 1

CONV.

TO

S/M -1

A 3

CONV.

TO

S/M -2

A 5

CONV.

TO

S/M -3

PRIMARY

MIXING

DRUM


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RAW MIX

SRC

D/C

D/F C/S

SHAKER GATE

RAW MIX BUNKERS

ELECTRONIC FEEDERS

BALLING DRUMS

SHUTTLE DISTRIBUTOR

FURNACE

CHARGE HOPPER

DRUM

FEEDER

SINTER MACHINE

WIND BOXES

1 2 25 26

MAIN GAS COLLECTOR

TO EXH.

TO EXH.DUST POCKETS

(36Nos.)

WATERDRUM

COOLER

-5mm

+8mm TO BF

-8mm

TO STOCK BINS

-5mm TO STOCK BINS (HOT SINTER RETURN)

SINGLE ROLL CRUSHER

HOT SCREEN

COLD SCREEN

DISC FEEDER

SINTER MACHINE PROCESS FLOW

WATERWATER

H/S

RAW MIX


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Sinter Machine Specification for each machine

There are three Sintering machines

Length - 78 M

No. of pallets - 130

Sintering area

252M2Bed height - 480mm

Exhauster - 02 Nos.

Aspirator - 02 Nos.

Cooler Blower- 06 Nos.

Balling Drum - 02 Nos.

Drum Cooler - 01 No.

Straight line Cooler - 01 No.


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CRANES Location & Capacity

Name Location Tons

G/Crane Fuel Storage 10

C/Crane C/Crane Building 05

H/Crane H/Crane Building 10

S/B S/B Tops 05

A1/A2 A1/A2 Area 15

B/Drum B/Drum Area 50

Exh. Exh Buld. 50

Sinter Machine Machine Build. 30

Bay 1,4& 5 ARS 15

Bay 6 ARS 03

MDP MDP 05

JN 12 S/B Top 15

Other then these 46 nos. of Telphers are also there.


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WHAT IS

AGGLOMERATION Agglomeration is defined as the process to

prepare a suitable Blast furnace feed forsmooth, proper and efficient running of theBlast furnace operation.The process of agglomeration can be classifiedas follows:i) Briquetting.

ii) Nodulising.

Iii)Vacuum Extrusion process.iv) Sinteringv) Pelletizing.


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ADAVANTAGES OF

AGGLOMERATION Ability to use all kinds of Raw Materials- like iron ore

fines, iron bearing waste products, flue dust, Steel plantreverts.

It can be produced into any shapes and sizes. It can be cured to adequate strength suiting Blast

Furnace needs.

Process designed to suitable small batch operations andlarge scale operations.

Excellent blast Furnace charge material in place oflump ore, reduces the cost of smelting of ore, increasesFurnace permeability there by increasing BFproductivity and lowering cost in terms of lower fuelrate.


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WHAT IS SINTER

Sintering is the process of agglomeration of

iron ore fines into a porous mass by

incipient fusion heat generated within themass itself.


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TYPES OF SINTER

Depending upon weather bases have been incorporated in the Sinter mix,sinters are divided into three broad classes: -

(i) Non Fluxed OR ACID SINTERS: - Those where no flux is present or isadded in the ore.

(ii) BASIC SINTER OR Self Fluxing SINTER: - Those where sufficientflux has been added in the sinter mix to provide a basicity that is desiredin the final slag, taking into consideration only the burden acids. An extraflux is added to the BF burden, to take care of coke ash acids.

(iii) SUPER BASIC OR SUPER FLUXED SINTER: - In these type of

sinters an additional flux is added to the mix to provide for the desiredfinal slag basicity, taking into account the acids content of both ore as wellas the coke ash.


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THE NEED FOR SINTER

(i) To utilize the fines generated during the miningoperation.

(ii) To utilize different additives like mill scale, fluedust, hearth slag etc. in an integrated steel plant.

(iii) The need for charging prepared burden in Blast

Furnaces to increase productivity and lower fuel rate.


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ADVANTAGE OF SINTER i) Agglomeration of fines into hard, strong and irregular porous lumps which givesbetter bed permeability.

ii) Elimination of 60 - 70 % of sulphur and Arsenic (if present) during sintering.

iii) Elimination of moisture, hydrated water and other volatiles on the sinter strand witha cheaper fuel.

iv) Increased the softening temperature and narrowing down of the softening range.

v) As the calculation of flux takes place in sinter strand, super-fluxing saves much morecoke in the furnace.

vi) It increases the Blast Furnace productivity.

vii) Lime rich bosh slag hinders reduction of silica, absorbs vaporized silicon and

sulphur to produce low- Si, low-S iron.

viii) Increase of sinter percentage in Blast Furnace burden, increases the permeability,hence reduction and heating rate or burden increases, so the productivity also.

ix) Utilization of solid wastes generate within steel works


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TYPES OF SINTER MAKING

PROCESS Huntington and

Heberlein Pot Process-fpr non-Ferrous metal

Industry. Batch Sintering-

Greenwalt Single PanProcess

Allmanns IngenoirsBryans Multi PanProcess

Dwight-LloydContinuous SinteringProcess

Pelletizing Process- Thisconsists of suboperations likepreparation of ore feed,balling, hardening. Shaft

furnaces are used forproducing smalltonnages. MultipleShafts handle largerproduction level.


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23Huntington & Heberlein Blast roasting Pot Vacuum Extrusion Process


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24Green walt Single Pan Sinter Machine Pelletizing Process


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PRINCIPLE OF THE SINTER

MAKING PROCESS Iron one sintering is carried out by putting GREEN MIX after Mixing and Nodulizing drum (a

mixture of Base mode with iron ore fines, mixed with flux, coke breeze as a solid fuel, otheradditions, sinter return fines, lime, moisture) over a traveling gate in form of permeable bedand permeable bed.

The top layer of this sinter bed is heated to the sintering temp. (1200C-1300C) inside a Ignition

Hood furnace. In the ignition hood the air is drawn downwards, through the grate with the helpof exhaust blowers (Waste Gas Fan) connected by means of Waste gas main.

The narrow combustion zone developed initially at the top layer by layer to the sintering level.The cold blast drawn through the bed cools the already sintered layer the thereby gets itselfheated. The heat contained in the blast is utilized in drying and preheating the lower layers inthe bed. In advance of combustion therefore each layer gets dried and preheated by the heattransferred from the upper combustion zones. The lower portion of the bed absorbs much ofthe heat in the gases.

In the combustion zone, bonding takes place between the grains and a strong and porousaggregate is formed. The process is over when the combustion zone has reached the lowestlayer of the bed. The sinter cake is thus tipped from the grate in hot condition . It is thenbroken, cooled in sinter cooler cold sized and sent to the Blast furnace.


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MECHANISM OF SINTERING

2Fe2O3.CaO + Al2O3.SiO2 2Fe2O3 CaO.Al2O3.SiO2

(SFCA)

SILICO FERRITE OF CALCIUM

AND ALUMINIUM

2Fe2O3

SLAG BOND

2Fe2O3

2Fe2O3

Heating Cooling

Singlelump

Heating2Fe2O3

2Fe2O3

+ CaO 2Fe2O3CaO at 12000CCALCIUM FERRITE


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GENERAL ARRANGEMENT OF

A SINTER PLANT Raw material receiving and

proportioning system

Mixing and Nodulizing-moisture addition

Charging Station-laying ofGreen mix on the strand

Ignition

Sintering Process

Sinter Discharging and Hotbreaking

Cooling of sinter in SinterCooler

Treatment of Sinter in termsof Cold crushing and sizing.

Conveying to BF stock-house

Dust treatment and Waste

Gas system with Waste GasFan and De-dusting Fan


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EQUIPMENTS IN SINTER

PLANTS RAW MATERIAL BINS AND

WEIGH FEEDERS

MIXING AND NODULIZINGDRUM WITH WATERINJECTION SYSTEM

SURGE BIN-SECTOR GATESWITH SERVO DRIVES ANDFEED DRUM

IGNITION HOOD FURNACEWITH BURNERS

SINTER MACHINE-PALLETS

with GRATE BARS WINDBOXES WITH WASTE

GAS MAIN

SPIKE CRUSHER-WITHCRASH DECK

DOUBLE ROLL CRUSHER

VIBRATORY COLD SCREENFOR HEARTH LAYER

VIBRATORY SCREEN FORRETURN FINES

CONVEYORS, RECEIVINGCHUTES AND TRANSFERCHUTES FOR RAWMATERIAL AND SINTER

WASTE GAS FAN WITH LCIDRIVE

DEDUSTING FAN FOR PLANT

DEDUSTING ESPs

LT and HT DRIVES

PNUEMATIC ACTUATORS &VALVES


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SINTER PLANT FACILITIES AT

TATA STEEL

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DIFFERENT UNITS OF SINTER PLANT

RAW MATERIAL BEDDING AND BLENDING PLANT

SINTER PLANT 1

SINTER PLANT 2

RAW MATERIAL BEDDING AND BLENDING ( NEW )

SINTER PLANT 3


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FUNCTIONS OF RMBB

Stacking of Raw materials

Bedding and Blending of various rawmaterials and other constituents of Sintermix through proportioning

Homogenizing the mix components forachieving consistent Sinter chemistry

R M B B PLANT LAYOUT


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R.M.B.B.PLANT LAYOUT

WAGO

NT/H

C/S

TGH

P

R

O

P

B

U

I

L

D

I

N

G

ROD MILLS

CRUSHER

H/M

COKE SCREEN

FLUX

SCEEN

WOB#2

WOB#1

TBS#1

TBS#2

SP1/SP2

B/R (L&T)

B/R

(ELECON)

P

Y

RD

U

N

Ld

Slg.

Ret. Sinter fines From G.Fce.

I

O

F

LS

F

R

P

D

F


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Material Flow at Sinter Plant


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Hot Return

Fines

Hearth

Layer

SINTER

STORAGE

Sinter

Screening

Proportioning

Bins

Mixer

Water

Sinter

Machine

Sinter

Cooler

Waste Gas

Fan Waste Gas

Esp.

BF HIGH

LINE

Raw

MaterialsReturn Fines Lime

Dust

Hearth

Layer

Hot Air

Combustion Air

Cold Return

Fines

Ignition Hood

Spike

CrusherCooler Fan

Segregati

on

Chute

Doubl

eRoll

Crusher

Cold

screen

SINTER PLANT

OVER VIEW OF SP#3-a typical DWL Sinter


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OVER VIEW OF SP#3-a typical DWL Sinter

Machine


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FEDDING SYSTEM


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BED

HEIGHT

LEVEL SENSOR

FLAPGATES

IGNITION

HOOD

FEED ROLL

HEARTH LAYER

GREEN-MIX

BIN

GREEN MIX

SHUTTLE CONVEYOR

THERMO-VISION

CAMERA

PROBES

HEAT TREAT

MENT HOOD

HEARTH

LAYER

BIN

CUT-OFF

PLATE


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QUALITY ASPECT OF SINTER-

WITH RESPECT TO BLAST

FURNACES PERFORMANCE CHEMICAL

1. Fe% in Sinter

2. CaO % in Sinter

3. SiO2 % in Sinter

4. MgO% in Sinter

5. Al2O3 % in Sinter

6. FeO % in Sinter

7. K2O % in Sinter

PHYSICAL

1. SINTER SIZEANALYSIS in terms ofCum+10mm and -5mm

2. TUMBLER INDEX

3. SHATTER INDEX

4. RDI (ReducibilityDegradation Index)

5. RI (Reducibility Index)

6. Softening and MeltingTest (S-M)


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FACTORS AFFECTING SINTER

QUALITY

(1) Size of The Charge Mix: The strength of sinter is directly related to the sizedistribution of the charge mix. If size is large, the contact area will be less and thestrength of the sinter will be low and conversely if size is too small the contact area ofparticles will be large and the strength will be high.

Ideal size of ore Fines -10 mm to + 100 meshCoke breeze -3.2 mm 85%Flux - - 3.2 mm 85%

(2) Fuel content: - Variation in Fuel content in Charge Mix affect the peak Temperatureattained during sintering, the combustion zone will not be uniform leading to poor bedpermeability, This increases return fines generation

(3) Moisture: - The presence of moisture in the Charge mix has several advantages. Itmaintains proper permeability in the bed during sintering. This is beneficial from thepoint of view of heat transfer during sintering.

(4) Re-circulating load or Return fines addition:- For higher output of the sinter strandthe circulating load should be low. A low circulating load however, reduces thepermeability of the bed. An optimum-circulating load is established for maximumoutput of the acceptable sinter to the Blast Furnaces.


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Parameters Controlling Sintering

Process Fuel content for heat input

Ignition intensity-Temperature of Ignition

Hood Furnace

Moisture content of mix tocontrol its permeability.

Machine speed control to

obtain complete Burnthrough

Return Fines Addition

Waste Gas Temperature

Sintering Temperature orBurn through Temperature

Pressure drop across theSinter Bed- Main Suction

Bed Height

Calcined Lime addition- toimprove bed Permeability.


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IMPROVEMENT IN PERFORMANCE OF

SINTER PLANTS

BYINTENSIFICATION OF SINTERING

PROCESS

By

Dr M T Raju

Deputy General ManagerRDCIS

SAIL


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Managing the existing technologies to reach

designed/rated performance

Incorporation of innovations to surpass rated

capacity


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Reaching rated capacity:

1. MEN (WOMEN)

2. MATERIAL3. MONEY

4. MINUTES


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Surpassing rated capacity:

Creative (Innovative) solutions can only

enable to surpass.Five elements of creativity.

1. FLUENCY

2. FLEXIBILITY

3. ORIGINALITY

4. AWARENESS

5. DRIVE


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INTENSIFICATION OF SINTERING

PROCESS

Sinter as a prepared burden material

continues to hold its prominent position in

world due to its very good metallurgicalproperties such as tumbling strength,

reduction degradation index, reducibility

index, high softening temperature and low

range of softening range

PRINCIPAL STEPS OF IRON ORE


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PRINCIPAL STEPS OF IRON ORE

SINTERING TECHNOLOGY The iron ore fines , lime stone fines, dolomite

fines, lime dust, metallurgical wastes and cokebreeze are proportioned based on charge

calculations.

Then this mix is mixed and balled in mixing and

balling drums with the addition of water and thenloaded onto the pallet.

The sinter mix undergoes ignition as well as

suction is applied under the bed.

The top layer gets ignited and sintering proceeds

down wards till the end .

The hot sinter is screened and crushed.

The hot sinter is then cooled on a cooler

The cooled sinter is screened to remove -5mm

fraction and then transported to blast furnace.


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Need of Intensification of

sintering process

Why?

Intensification of sintering process is required

to enhance the production capacity of existingsinter machines.

How?

Without sacrificing the quality aspects.


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What is meant by intensification?

Accelerating sintering process for achieving higherproduction without deterioration in quality.

Production = k*A*B*V*Yk = Constant

A = Sintering Area

B = Bulk Density of mix

V = Vertical sintering speedY = Yield


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Methodology of Intensification of

sintering process

Factors that influence sintering

1) MEN2) MATERIALS

3) PROCESS PARAMETERS.


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MATERIALS1) Iron ore fines size

2) Iron ore fines chemistry

3) Coke breeze

4) Calcined Lime


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.

The granulometry of iron ore fines, used in

sintering, has a great influence on sinter plant

performance.

Laboratory Experiments were conducted withdifferent granulometry of iron ore fines to assess its

influence on sinter quality and productivity.

The upper size of the iron ore fines was reduced ineach of the experiments.

GRANULOMETRY OF IRON ORE FINES


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EFFECT OF IRON ORE FINES SIZE ON

SINTERING

Sl.No Size Lime %yield VSS Prod. T.I(mm) (Kg/t) (+5mm) mm/min t/m2/h %

1 0-15 0.0 70.6 18.6 1.182 69.3

2 0-8 0.0 76.5 19.6 1.272 68.3

3 0-8 20.0 75.6 20.1 1.326 67.2

4 0-6 20.0 80.3 20.3 1.418 67.3

5 0-5 20.0 81.0 21.6 1.489 66.7


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Chemical Quality

EFFECT OF TOTAL Fe

Results show that lower Fe grade (< 62% Fe) ores and

concentrates will typically form SFCA (SiO2-Fe2O3-

CaO-Al2O3) as part of the final assemblage.

Medium grade (62-65% Fe) ores will form a mixture of

SFCA and SFCA-1..

High grade (65-68% Fe) ores will form largely SFCA-1.

The SFCA-1 phase is the most desirable bonding phase in

iron ore sinter, since microstructures composed entirely ofSFCA-1 show higher physical strength and higher

reducibility than microstructures composed predominantly

of SFCA


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LOSS ON IGNITION

The higher LOI of iron ore fines has a detrimental

effect on sinter quality and productivity

EFFECT OF Al2O3

An increase in Al2O3 % by 1 % increases the RDI

value by 10%

EFFECT OF SiO2

Higher SiO2 in sinter will induce the formation of

glassy phases in sinter and reduce the strength ofsinter.


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COKE BREEZE SIZE

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.


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PROCESS PARAMETERS

Mixing and Balling

Segregation of mix

Moisture

Ignition

Under-grate Suction

Preheating of sinter mix

Use of hot air in ignition hood

cooling


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MIXING AND BALLING REGIMES

Generally most of the sinter plants are provided

with separate mixing and balling drums. But the

latest generation of sinter plants are provided with

a combined mixing and balling drums.

The main purpose of mixing drum is to

homogenize the sinter mix . The diameter of the

drum , the RPM and the space factor play a major

role in achieving higher degree of mixing.


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The balling drum (Nodulising drum) ensures that

fines are coated on the nuclei particles, thus

produce higher size balls. This facilitates in

improving the mean size of sinter mix and hencethe permeability of mix. Here again the diameter ,

RPM and space factor play a major role in

achieving higher degree of balling.

Very little water is added in mixing drum and

major quantity of water is added in the balling

drum

The amount of water added and the method ofwater addition in the balling drum also control the

degree of balling and hence the permeability of

sinter mix.

Laboratory model of high speed agitating mixer


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A

Laboratory model of high speed agitating mixer

Lab study at RDCIS showed improvement of strength

index with reference to conventional mixer


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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.


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SUCTION UNDER-GRATE

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 ofthe sinter production.

IMPROVING IN SM PRODUCTVITY PER 10 AS


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IMPROVING IN SM PRODUCTVITY PER 10 mmwc AS

A FUNCTION OF SUCTION UNDER GRATE

500 600 700 800 900 1000 110 1200 1300 1400 1500

1.2

1.0

0.8

0.6

0.4

SUCTION, mmwc

IN

CR

E

A

SI

N

G

IN

P

R

O

D

U

C

TI

VIT

Y,

%

IGNITION


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IGNITION

To provide the required free oxygen potential in thezones for faster burning of the fuel and also early

starting of sintering.

Oxygen enrichment in ignition hood

To produce a strong sinter in the upper part of the

layer;

PRE HEATING OF SINTER MIX


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PRE-HEATING 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:

* Addition of hot water in balling drum* Addition of steam in balling drum or raw mix hopper

* Installing gas burners inside the balling drum

* Adding hot return fines

* Addition of calcined lime


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HOT AIR IN IGNITION HOOD

Hot air recovered from sinter cooler could be used in

the ignition hood.

This will help in not only saving gaseous fuel, but alsoincreases the free oxygen potential.

COOLING OF SINTER


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COOLING OF SINTER

Efficient cooling of sinter will help in improving sinterstrength

Installation of proper waste heat recovery system of

cooler will help in adding hot air in ignition hood


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Rate

Size

BTP

Temp

Sinter Quality

Temp

Free O2

Potential

Top layer

Starting of

sintering

Productivity

Rate

Method of

Addition

Balling

Permeability

Re-condensation

Under

Ignition hood

Rest of

machine

Coke

Water

Under grate

suction

Ignition

RECENT TRENDS OF INTENSIFICATION OF


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RECENT TRENDS OF INTENSIFICATION OF

SINTERING

High Fe, low Al2O3iron ore fines Serpentine replacing dolomite

Good quality and quantity of lime addition

High Intensity mixer

Divided coke addition Polymer addition in balling drum

Pre-heating of sinter mix

New sinter mix charging system

New ignition furnaces

Taller bed operation Higher under grate suction

Taller bed circular coolers

Process control models


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