200085263 project-report

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COMPARISON OF BLAST FURNACE PARAMETERS
DURING DIFFERENT SINTER PERCENTAGES
A PROJECT SUBMITTED BY
C.SIVA (080114801045),
V.VIGNESH (080114801057),
J.VINOTH (080114801058).
1

Bachelor of Engineering
In
Metallurgical Engineering,
Government College of Engineering,
Salem-11.
COMPARISON OF BLAST FURNACE PARAMETERS
DURING DIFFERENT SINTER PERCENTAGES
A PROJECT SUBMITTED BY
C.SIVA (080114801045),
V.VIGNESH (080114801057),
J.VINOTH (080114801058).
2

Bachelor of Engineering
In
Metallurgical Engineering
Government College of Engineering
Salem-11
UNDER GUIDANCE OF
MR. SUDHARSAN
SENIOR MANAGER (BF OPERATION)
JSW, SALEM WORKS.
ACKNOWLEDGEMENT
The success of any project work depends upon team work and cooperation
of many people. We would like to take this opportunity to express our gratitude to
the people who supported and guided us in this project.
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We would like to express our deep sense of gratitude to
Prof.P.M.KAVIMANI, M.E., Principal, Government College of Engineering,
Salem, for his encouragement in this project work.
We should like to express our immense gratitude to
Dr.P.G.VENKATAKRISHNAN, M.E., Head of the Department, Department of
Metallurgical Engineering for his earnest guidance and invaluable suggestions.
We wish to extend our gratitude to our guide
Mr.SUDHARSAN, Sr Manager (BF Operation) JSW, for his dexterous esteemed
guidance, persistent encouragement and do involvement in fruitful discussion
through our project work.
We are also very thankful to our faculty members and non-teaching staff
members for giving us the timely suggestions and necessary help.
Table of Contents
1. Abstract……………………………………............... 6
2. Introduction………………………………………… 6
2.1. JSW Steel Ltd………………………................... 7
3. Salem Works ………………………………….......... 8
3.1. Plant Details…………………………………….. 9
4

3.2. Production Details……………………………… 13
4. Sinter Plant………………………………………….. 15
4.1. JSW Sinter Plant………………………………... 16
4.2. Sintering………………....................................... 17
4.3. Types of sinter……………………….…………. 19
4.4. Bonding…………………………………………. 20
4.5. Quality of Sinter……………………………….... 21
4.6. Parameters affecting Sinter quality …………….. 22
4.6.1. Alumina content.................….............….. 22
4.6.2. FeO content………………….………….. 23
4.6.3. Tumbler index……………………….….. 23
4.7. Advantages of sinter…………………………… 24
5. Blast Furnace…………………………………………... 25
5.1. Blast furnace Construction……………………... … 27
5.2. Blast furnace Process……………………………… 33
5.3. Blast furnace Reactions…………………………… 37
5.3.1. Reactions in the Upper zone ………………. 38
5.3.2. Reactions in the Middle zone………………. 39
5.3.3. Reactions in the Lower zone………………. 40
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6. Raw materials used in Blast Furnace……………….... 41
6.1. Quality of charge material ……………………….... 41
6.2. Iron Ores……………………………………........... 41
6.2.1. Magnetite………………………………….. 42
6.2.2. Hematite…………………………………... 42
6.2.3. Limonite………………………………….... 42
6.2.4. Siderite…………………………………….. 43
6.3. Manganese Ores…………………………………... 43
6.4. Fluxes ………………………………………... 43
7. Result and Discussions……………………………….... 44
8. Conclusions...................................................................... 52
9. References…………………………………………….... 53
1. ABSTRACT:
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Since the inception of blast furnace method of iron making, technology itself has
either undergone a rapid change or has innovated techniques with suitable
alteration and modification. The principle remaining the same, the changes aim
at lowering energy consumption and achieving higher productivity. The
increased use of sinters as iron burden in most blast furnaces is a true pointer to
this claim. However, the pre-evaluation of this burden for its suitability as blast
furnace feed is of dire need. Jindal South West(JSW) Steel Works has two blast
furnaces and they have a target of increasing productivity with decrease in fuel
rate, blast rate and iron ore consumption rate with respect to increase in %
sinter. JSW has taken the challenge to fulfill this requirement. The present
paper deals with the various factors which contribute towards economical
profit via increasing %sinter. Strategies are also described in the paper.
2. INTRODUCTION:
The performance of a blast furnace is generally evaluated by the level of its
productivity, fuel rate and the quality of the hot metal. Usage of sinter in blast
furnace lead to the decrease of fuel rate and blast with increase in productivity. So
it is essential to increase the percentage of sinter in blast furnace from economical
point of view. JSW Salem Steel Works concentrates on it and it has taken every
step to increase sinter consumption. Our project deals with the parameters which
get affected by increase in percentage of sinter.
2.1. JSW STEEL Ltd:
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JSW Steel is an Integrated Steel Plant owned by the JSW Group based in
Mumbai, Maharashtra. The Group set up its first steel plant in 1982 at Vasind near
Mumbai. Soon after, it acquired Piramal Steel Ltd., which operated a mini steel
mill at Tarapur in Maharashtra. The Jindals, who had wide experience in the steel
industry, renamed it as Jindal Iron and Steel Co. Ltd. (JISCO). In 1994, in order to
achieve the vision of moving up the value chain and building a strong, resilient
company, Jindal Vijayanagar Steel Ltd. (JVSL) was setup, with its plant located at
Toranagallu in the Bellary-Hospet area of Karnataka, the heart of the high-grade
iron ore belt and spread over 3,700 acres of land. It is just 340 kms from
Bangalore, and is well connected with both the Goa and Chennai ports. In 2005,
JISCO and JVSL merged to form JSW Steel Ltd. In the year 2004, SISCOL which
was under LMW group was acquired and was merged with JSW Group.
JSW Steel is among India's largest steel producers, with a capacity of
7.8 MT as on 2010. JSW Steel is one of the low cost steel producers in the world.
JSW Steel offers the entire gamut of steel products – Hot Rolled, Cold
Rolled, Galvanized, Galvalume, Pre-painted Galvanised, Pre-painted Galvalume,
TMT Rebars, Wire Rods & Special Steel Bars, Rounds & Blooms. JSW Steel has
manufacturing facilities at Toranagallu in Karnataka, Vasind & Tarapur in
Maharashtra and Salem in Tamil Nadu.
By 2020, the Company aims to produce 34 million tons of steel annually
with Greenfield integrated steel plants coming up in West Bengal and Jharkhand.
JSW Steel Limited has the largest galvanizing and colour coating production
capacity in the country and is the largest exporter of galvanized products with
presence in over 74 countries across five continents.
3. SALEM WORKS
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JSW group acquired the Company and took over the Management from
November 2004. Salem Works is the only integrated steel plant in Tamil Nadu and
is located at Pottaneri /M. Kalipatti villages and at about 35 kms from Salem.
As part of the JSW group, the plant underwent a dramatic transformation
and started making profits from the first year onwards. Today, it has become the
first 1 MTPA integrated steel plant in Tamil Nadu. It is also the highest Alloy Steel
Maker in the Country.
The Company is having facilities for production of Pig Iron, Steel, Billet and
Rolled Steel products in the long product category. The present capacity is being
expanded to one million tones per annum. It has adopted the Sinter plant – Blast
furnace – Energy Optimizing Furnace – Ladle Furnace, Vacuum Degassing
Continuous Casting Machine – bar and rod mill route with iron ore as the basic
input material. It also has plants for generation of power and production of oxygen.
Salem Works is highly environment conscious and the process and
technology is designed for reusing and recycling the process waste. We have an
expanding green belt to provide a green environment.
Products of Salem Works have the hallmark of quality and combined with
competitive pricing, they are highly preferred in automobile and construction
sectors.
3.1. PLANT DETAILS:
9

COKE OVEN:
JSW Steel Limited, Salem Works has one coke oven of capacity 0.5 MTPA
under the technology of MECC, China. This coke oven supplies enough coke for
the requirement of this plant.
IRON COMPLEX >>SINTER PLANT:
JSW Steel Limited, Salem Works has two Sinter Plants 1 and 2. The Sinter
Plant 1 is of 20 m 2
grate area, supplied by M/s Lurgi India Company Limited. The
capacity of the plant is 0.2 MTPA. The Sinter Plant 2 is of 90 m 2
grate area. . The
capacity of the plant is 1.1 MTPA. Sinter is an input material for Blast Furnace and
is partial/full replacement of lump iron ore. Sinter is produced by using coke fines,
iron ore fines, limestone fines, dolomite, EOF slag & flew dust.
Besides fulfilling the twin objectives of improving the productivity of Blast
Furnace and reducing the coke rate, the usage of sinter at Blast Furnace addresses
larger environmental aspects by waste utilization in the plant.
IRON COMPLEX >>BLAST FURNACE:
JSW Steel Limited, Salem Works has two Blast Furnaces. The Mini Blast
Furnace 1 is of 402 m3
useful volume and Mini Blast Furnace 2 is of 550 m3
useful
volumes. The technology was supplied by CERIS, China. The capacity of the BF-1
is 0.4 MTPA. The capacity of the BF-2 is 0.6 MTPA. Iron is produced at Blast
Furnace in the liquid state, which is called Hot Metal. This is either transferred to
Steel Melting Shop (SMS) for converting into liquid steel and then billets or to the
Pig Casting Machine (PCM) to be cast into pigs. Granulated slag is the by-product
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from Iron Complex. It is used as a raw material in cement manufacturing
industries.
STEEL MAKING SHOP >>ENERGY OPTIMIZING FURNACE:
JSW Steel Limited, Salem Works has a 0.4 MTPA capacity Energy
Optimizing Furnace (EOF), the technology of which was developed by KORF
Technological Services (KTS) Brazil and supplied by M/s Tata KORF Engineering
Services Limited. Now it has another Energy Optimizing Furnace i.e. EOF 2 with a
capacity 0.6 MTPA, the technology of which was developed by MINITEC Brazil.
At the EOF, hot metal from Blast Furnace and sold metallic charges, generated as
well as purchased, are charged and refined into liquid steel by using oxygen and
fluxes. This solid charge percentage can be up to 30% maximum.
STEEL MAKING SHOP >>LADLE FURNACE:
JSW Steel Limited, Salem Works has 4 Ladle Furnace (LF) of 45T, 65T,
65T and 65T capacity respectively. LF 1 which was developed by the technology
of ABB. LF 2 & 3 which was developed by the technology of DANIELI, Italy. LF
4 which was developed by the technology of EASTERN METEC, Kolkata. The LF
facilitates further refining of steel by addition of Ferro alloys and purging with
nitrogen / argon to achieve the chemical composition of the targeted grades of
steel. It also raises and maintains the liquid steel temperature to match the working
regimes of EOF and Continuous Casting Machine.
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STEEL MAKING SHOP >>VACUUM DEGASSING:
JSW Steel Limited, Salem Works has a vacuum degassing plant. This is
present in the SMS region. Salem Works has two Vacuum degassing (VD). The
capacity of the both VD 1& 2 is 65T. VD 1 which was developed by the
technology of DANIELI, Italy. VD 2 was developed by the technology of
EASTERN METEC, Kolkata. This facilitates in the complete removal of gaseous
products from the hot steel metal.
STEEL MAKING SHOP >> CONTINUOUS CASTING MACHINE:
JSW Steel Limited, Salem Works has two Continuous Casting Machine
(CCM). CCM 1 has a capacity of 0.4 MTPA is supplied by M/s CONCAST India
Ltd. with double radius of 9/16 meters and with a capability of casting billets /
blooms in the sizes ranging of 100, 130 and 160 Squares.
CCM 2 has a capacity of 0.6 MTPA, the technology of which was developed
by DANIELI, Italy. With double radius of 12 / 16.5 / 30 Meters radius bloom
caster capable of casting 160mm to 340x400 mm.
BAR AND ROD MILL:
The Bar and Rod Mill (BRM) is highly versatile and consists of 22 stand
continuous mill preceded by a 3 - high roughing stand with a capability of
producing 0.4 MTPA bars and rods in the sizes of 6 mm to 55 mm. BRM which
was developed by the technology of DEMAG / Morgan.
The following facilities are provided at BRM, the material flow being in the
sequence as described.
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 0.45 Million Tonnes per annum Bar & Rod Mill
 2 no.s 45 T / hour – Walking hearth Re-heating Furnaces
 18 Stand Horizontal – Vertical Configuration.
 Cooling bed line for bars / Flats.
OTHERS >> AIR SEPARATION PLANT:
JSW Steel Limited, Salem Works has two Air Separation Plant. The Air
Separation Plant (ASP 1) has a capacity of 150 TPD. It’s supplied by M/s Kaifeng
Air Separation Factory Limited, China. The Air Separation Plant (ASP 2) has a
capacity of 450 TPD. It’s supplied by AIR LIQUIDE HYD. Oxygen, Nitrogen and
Argon is produced by cryogenic process based on the principles of different
liquefying and boiling points of gases. The production can be in gaseous and liquid
modes. Presently, oxygen and nitrogen with a purity of above 99.5% and 99.95%
respectively are being generated. The plant has been provided with a most modern
Distributed Control System (DCS) for operation of plant and online control of
parameters including gas analysis. The gases are consumed in the plant excess gas
generated is marketed.
OTHERS >> POWER PLANT:
JSW Steel Limited, Salem Works has three Power Plants. The Power Plant 1
has a capacity of 7.7 MW, consisting of 2 boilers, 2 Turbo Blowers (one at use plus
one as stand-by) and 2 Turbo Generators. The Power Plant 2 is of capacity 30 MW
and is a coal based one. The Power Plant 3 is also of capacity 30 MW, whereas
here the plant is based on BF gas and Coke Oven Flue gas.
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3.2. PRODUCTION DETAILS:
JSW STEEL LIMITED, SALEM WORKS is a modern plant with
technologies and infrastructure for producing One Million tons. They have
produced 762650 MT steel in 2009-10 and 786542 MT of Hot metal. The
technology and machinery have been sourced from leading suppliers in the world.
Pig Iron Complex consists of a two number of Blast Furnaces with the
production capacity of 1.0 Million TPA. Two number of Sinter Plants with
the production capacity of 1.30 Million TPA and 2 Strand Pig Casting
Machines. JSW Steel Limited, Salem Works is one of the plants in INDIA to
introduce Energy Optimizing Furnace. Recently the billets in the size of 100x100,
130x130, 160x160, 250x250 & 340x400 mm – Billets / Blooms 160, 200, 220, 310
mm - Rounds are being produced. The standard length of the billet is 6 meter.
The Grades produced are,
1. Mild steel,
2. Cold heating quality,
3. High carbon steel,
4. Medium carbon steel,
5. Electrode quality,
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6. Low alloy and forging steel.
Products from JSW STEEL LIMITED, SALEM WORKS are,
Types Size
Wire Rods and Rounds 6mm-55mm
Hexagons and Squares 12mm-56.5mm
Flats(Spring steel) Width up to 125mm
GRADES AND ITS SPECIFICATION:
Grades specification
Electrode Quality Wire Rods All Types
Low Carbon Wire Rods (General / Special)All Types
High Carbon Wire Rods All Types
Cold Heating Quality Rounds AISI - 1010, 1541 & 4140
High Tensile Bars IS 961 ST 58 HT ST 55 HT
Stainless Steel AISI 304/316
4. SINTER PLANT:
15

The function of the Sinter Plant is to supply the blast furnaces with sinter, a
combination of blended ores, fluxes and coke which is partially ‘cooked’ or
sintered. In this form, the materials combine efficiently in the blast furnace and
allow for more consistent and controllable iron manufacture. Figure 1 shows a
simplified diagram of a sinter plant.
Materials enter the sinter plant from storage bins. They are mixed in
the correct proportions using weigh hoppers, one per storage bin, except for the
return fines for which an impact meter is used instead. Weighing is continuous, as
is the whole sintering process. The weighed materials pass along a conveyor to the
mixing drum where water is added either manually or as a calculated percentage of
the weight of material entering the drum.
The moisture content of the coke is measured in the strand roll feed hopper
and used to trim the secondary water flow rate. The mix permeability is also
measured and used to modify the amount of water required.
The mix material is fed onto the strand from the hopper by a roll feeder. The
bed depth is set and kept constant by adjusting the cut-off plate which is fitted with
probes to sense the depth of material and automatically vary the roll feeder speed.
The quantity of material in the feed hopper itself is held constant by automatic
adjustment of the feed rates from the individual raw material bins. .
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4.1. JSW SINTER PLANT:
There are two sinter plants with a capacity of 1.25 million TPA. Sintering is
essentially a process of heating of fine particles to the stage of incipient fusion
(temperature little below the melting point) for the purpose of agglomerating them
into lumps. In Iron ore sintering it produces strong but porous agglomerate from
uncompacted mass. Besides fulfilling the twin objectives of improving the
productivity of Blast Furnace and reducing the coke rate, the usage of sinter at
Blast Furnace addresses larger environmental aspects by utilization of wastes
generated in the plant. Sintering of iron ore fines is carried out on travelling grate
machines running on a continuous basis. The top layer of sinter bed is heated to
temperature of 1050 to 1150°C by using BFG burners. Finally cooling of sinter is
carried out with the aid of circular cooler.
The raw materials for sinter are,
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1. Iron ore fines
2. Limestone fines
3. Dolomite fines
4. Coke breeze
5. Flue dust, GCP sludge, mill scale
6. Return fines.
4.2. SINTERING:
Sintering is a method for making objects from powder, by heating the
material in a sintering furnace below its melting point (solid state sintering) until
its particles adhere to each other. Sintering is traditionally used for manufacturing
ceramic objects, and has also found uses in such fields as powder metallurgy.
Agglomeration by sintering is achieved by the application of heat which
results in the conversion of ore fines into large, hard, porous lumps. The formation
of such lumps is caused by:
(a) An incipient fusion of ore particles at the contact surface which binds them
together;
(b) Formation of diffusion bonds through recrystallization and crystal growth of
hematite and magnetite which keep the particles together without melting.
 Combustion of small sized coke breeze which are intimately mixed
with moistened ore fines.
 Due to complete combustion of carbon, a temperature of 1300-1400
deg.C is easily attained.
 This process is performed commonly Dwight-Lloyd type continuous
travelling grate machines.
18

 Before charging the mix the grates are initially covered with 4-5 cm
thick layer of coke free return sinter of size -10, +8mm in order to
prevent leakage as well as to protect the grates from overheating.
 Sinter mix usually contains other materials like flue dust, return fines,
limestone/dolomite.etc.
 About 4-8 percent coke breeze in the sinter mix should suffice to raise
the temperature to 1400 deg.C
 The preheating of layers below the combustion zone results in the
evaporation of moisture and hydrated water and dissociation of
carbonates.
 The rate of sintering is very fast and depending upon the permeability
and thickness of the bed it takes 15-20 minutes for completion.
 For attaining optimum permeability the water content of the sinter mix
may range from 5 – 20 percent, the content increasing with increasing
degree of fineness.
 For adequate voidage and heat transfer the ore size should not exceed
6 mm and coke and limestone 3 mm.
 For a given fuel rate if the coke size is too large, a local overheating,
excessive liquid formation and reduction of iron oxides to difficulty
reducible fayalite can occur.
 The optimum coke rate varies between 4 -8 percent to give at least 65
– 70 percent of +12 mm fraction in the finished sinter.
19

 The amount of limestone added depends upon the basicity,
reducibility and strength of the sinter desired.
 It is much cheaper to calcine limestone in the sinter strand with low
cost fuel than in the blast furnace.
4.3. TYPES OF SINTER:
Sinters are divided into two broad classes:
1. NON – FLUXED OR ACID SINTER:
Those where no flux is present in the ore or is added
2. FLUXED SINTER:
Those where sufficient flux has been added or is present in the ore.
Depending upon the relative amounts of bases and acids, these are further
categorized into two sub-classes according to basicity:
(a). SELF-FLUXING SINTER:
Those where sufficient flux has been added in the sinter mix to provided a
basicity that is desired in the final slag, taking into consideration only the burden
acids. An extra flux is added in the burden while charging to cater to coke ash
acids.
(b). SUPER-FLUXED SINTER:
In such sinters, an additional flux is added to the mix to provide for the
desired final slag basicity, taking into account the acids content of both the ore as
20

well as coke ash. If any flux is naturally present in the ores, then they are called
self-fluxing ores.
4.4. BONDING:
1. SLAG OR FUSION BOND:
Partial or complete embedding of crystalline constituents in the matrix of a
fused glassy melt, the extent depending upon the volume and wettability of the
liquid face. The bond strength depends upon the amount of glass and the amounts
and types of the constituents. This depends upon the fuel rate and impurities SiO2,
CaO, MgO and Al2O3, added present.
2. DIFFUSION BOND:
Recrystallisation and crystal growth of Hematite (and Magnetite). Hematite
diffusion plays an important role, especially above 1250-1300 Deg.C, because of
surface mobility at high temperature. Diffusion bonded sinters are more porous,
accessible to reducible gases and hence easily reducible.
SINTER HANDLING:
After the end of the strand, the sinter passes through a spiked roll crusher
and the hot screens to the rotating circular cooler. A number of fans are usually
used for cooling, and the speed of the cooler is determined by:
 Strand speed
 Bed depth
The fines removed by the hot screens are conveyed to the return fines bin.
After cooling, the sinter is passed into the discharge bunker. At this stage,
the level is controlled by varying the outlet feed rate (usually vibro feeders).
21

The sinter then passes to the cold screening area, where it is passed through
crushers and screens to produce particles in a specific size range. Sinter below the
required size passes over a belt weigher and returns with the hot fines to the return
fines bin.
4.5. QUALITY OF SINTER:
The aim of sintering is to agglomerate the iron ore fines. Once the beneficial
effects of sinter as a blast furnace burden were realized, the physical properties and
chemical constitution of sinter came to be examined more closely. The
understanding of the ideal blast furnace properties of burden and the possibilities
of achieving these in the sinter developed hand in hand.
The objective of sintering therefore enlarged and these are now:
1. To increase the size of ore fines to a level acceptable to the blast furnace.
2. To form a strong agglomerate with high bulk reducibility.
3. To remove volatiles like CO2 form carbonates, H2O from hydroxides or sulphur
from sulphides type of ore fines along with their agglomeration.
4. To incorporate flux in the burden.
Out of the above four aims first one is must. The extent to which the second
object is met will very much depend on the nature of the ore and other economics
consideration of carrying out the process of sintering. The removal of volatiles is
only incidental. The main attention is therefore focused on to the extent to which
flux can be incorporated in the sinter mix without in any way, jeopardizing other
properties of the resultant sinter. Incorporation of flux in the burden in this way
rather than its addition as a separate charge material greatly improves the blast
furnace performance, since the formation of slag then becomes relatively easy and
it forms at the correct level in the blast furnace.
The main natural fluxes used for iron making in blast furnace are limestone
and dolomite. These fluxes are charged either in the blast furnace in lump form or
through sinter. In the later case the fluxes calcined during sintering and enter the
blast furnace in a combined form along with the oxide burden. This reduces the
thermal load in the blast furnace as a result of prior calcinations outside the furnace
22

and thus reduces the coke rate. Limestone is composed mainly of calcium
carbonate and dolomite is a double carbonate of calcium and magnesium.
i.e. CaCo3 and MgCo3.
4.6. SINTER QUALITY AFFECTING BLAST FURNACE
PROCESS
4.6.1. ALUMINA CONTENT:
The extent of alumina content should be maintained to the optimum level to
control the quality of sinter. Excess alumina content adversely affects the sinter
quality. As a result it also influence on the productivity of the blast furnace too.
Alumina content in the range of 1-2% is desired. Excess alumina leads to makes
the slag more refractory and this problem is overcome by increasing the basicity
(Cao/SiO2). It leads to increase the slag volume, decreases productivity, increase
the coke rate
Alumina content is the major concern in JSW STEEL LIMITED, SALEM
WORKS sinter plant. To control the alumina content addition of coke breeze is
minimized. The other controlling measures which are used are given below
1. Imported lime stone is used. (Which has low lime content),
2. Coke breeze consumption was reduced by increasing the fixed carbon content,
3. Alumina content in Fe ore fines is also restricted to max 3.5%.
4.6.2. FeO CONTENT:
23

The quality of sinter in terms of FeO content significantly affects the
composition of the hot metal delivered from the blast furnace. The main source of
FeO in sinter is iron ore fines, mill scales. The FeO content of the raw materials
have a significant impact on the burn through point and tumbler index. Burn
through temperature and tumbler index would increases with increasing amount of
FeO content in the sinter raw material.
In JSW STEEL LIMITED, SALEM WORKS it aimed at the range of 8 –
11% of FeO content.
4.6.3. TUMBLER INDEX:
This is one of the most important variables to determine the strength of the
sinter. The tumbler index of the sinter is estimated by using tumbling test. The test
essentially consists of tumbling a standard weight of a sinter of certain size in a
standard drum; tumbling is carried out at a standard speed for a fixed number of
revolutions. The percentage material passing through or retained on a certain sieve
is the index. A suitable tumbler index can be specified to ensure tolerable
minimum degradation of the sinter during the handling. In general higher is the
tumbler index the better the sinter will stand during handling. Generally pelletized
iron ore fines has high tumbler index compared sintered iron ore.
In JSW STEEL LIMITED, SALEM WORKS the tumbler index is calculated
in the XRF laboratory. One sample of sinter is taken for analysis of tumbler index
every day. The target for tumbler index is +70%.
4.7. ADVANTAGES OF SINTERING:
ACID SINTER:
24

i. Agglomeration of fines into hard, strong and irregular porous lumps which
give good bed permeability.
ii. Elimination of 60-70 percent of ore sulphur and arscenic during sintering.
iii. Elimination of moisture, hydrated water and other volatiles.
iv. Increase in softening temperature and narrowing down of the softening
range.
FLUXED SINTER:
i. Calcination of limestone inside the blast furnace is very expensive of
carbon. Approximately 60-7- Kg C/100 Kg of Co2 (230 Kg.CaCo3) are
saved by transferring the calcinations to sinter strand.
ii. Lime increases the activity coefficient of FeO in the silicate and increases
sinter reducibility.
iii. Super-fluxing saves much more coke in the blast furnace.
iv. Lime in sinter stabilizes the liquidus temperature of the primary FeO-
Al2O3-SiO2 slag the melting point of which would otherwise rise steeply as
the FeO is reduced in the bosh.
v. Lime-rich bosh slag hinders reduction of silica, absorbs vaporized silicon
and sulphur to produce low-Si,low-S iron.
vi. Primary slag formed from fluxed sinter possesses lower viscosity and
liquidus temperature and more uniform composition and hence permits
smoother furnace operation.
vii. Sintering rate is higher than in acid sinters.
viii. High blast furnace productivity, better than even with pellets.
5. BLAST FURNACE:
25

A blast furnace is a type of metallurgical furnace used for smelting to
produce industrial metals, generally iron.
In a blast furnace, fuel and ore are continuously supplied through the top of
the furnace, while air (with oxygen enrichment) is blown into the bottom of the
chamber, so that the chemical reactions take place throughout the furnace as the
material moves downward. The end products are usually molten metal and slag
phases tapped from the bottom, and flue gases exiting from the top of the furnace.
Blast furnaces are to be contrasted with air furnaces, which were naturally
aspirated, usually by the convection of hot gases in a chimney flue. According to
this broad definition, bloomeries for iron, blowing houses for tin, and smelt mills
for lead, would be classified as blast furnaces. However, the term has usually been
limited to those used for smelting iron ore to produce pig iron, an intermediate
material used in the production of commercial iron and steel.
The blast furnace remains an important part of modern iron production.
Blast furnaces are highly efficient, including Cowper stoves to pre-heat the blast
air and employ recovery systems to extract the heat from the hot gases exiting the
furnace. Competition in industry drives higher production rates. The largest blast
furnaces have a volume around 5580 m3
(190,000 cu ft) and can produce around
80,000 tonnes (88,000 short tons) of iron per week.
This is a great increase from the typical 18th-century furnaces, which averaged
about 360 tonnes (400 short tonnes) per year. Variations of the blast furnace,
such as the Swedish electric blast furnace, have been developed in countries
which have no native coal resources.
26

The purpose of a blast furnace is to chemically reduce and physically
convert iron oxides into liquid iron called "hot metal". 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. 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.
5.1. BLAST FURNACE CONSTRUCTION:
27

A modern blast furnace is nearly a 30m (about 100 feet) tall welded plate
construction with circular cross section of varying sizes at different levels. It is
illustrated in fig. to show the essential metallurgical design features and various
important parts of furnace. The cross-the sectional area increases from the top or
28

downwards, a maximum being at bosh level (mantle) it decreases downwards
thereafter. The structure of the furnace essentially consists of a massi9ve
foundation, the hearth, the bosh, the mantle and columns, the stack, the raw
material hauling and charging facilities and the top as shown in fig..
The outer welded steel shell is lined from inside with refractory lining to
stand the smelting conditions during its operation. Previously the furnace was
supported by a box-cage like structure, but now it freely stands only on its
foundation without lateral support.
1. FOUNDATIONS:
It is a massive steel reinforced concrete mass partially embedded below the
ground level. It may be about 15 m in dia and 6-8 m thick upon which is placed the
furnace bottom consisting about 4-5 m thick of fire bricks.
2. HEARTH:
It is a receptacle to collect the liquid slag and metal and is also referred to as
a crucible. The old practice of using fire bricks for hearth construction is almost
universally replaced by carbon blocks. Water cooled copper or steel plates are laid
in the side walls to protect the lining. The carbon may be more than a meter of
uniform thickness or a stadium type construction. In the hearth wall are located a
tap hole for iron,12-15 cm in dia and .3-.6 m above the hearth bottom level, and a
slag notch 1.2-1.6 m above the tap hole level, but staggered through a right angle
in the horizontal plane. These holes are closed with clay when not in use and are
29

opened for tapping slag and metal as and when necessary. At the top level of the
hearth are located tuyeres uniformly distributed over the entire cross-section.
3. BOSH:
The top of the bosh has the maximum dia of furnace and it is the zone of
intense heat. It is a stadium-type construction with steel reinforcement. Water
cooled copper or steel plates are inserted at regular intervals in the furnace lining in
this zone to effect protection against high temperature. The intensive cooling of a
thin walled bosh forms a layer of solidified slag mixed graphite on the lining which
in reality protects the brickwork from molten metal and slag.
4. MANTLE AND COLUMNS:
The furnace structure above the bosh level is supported on a heavily braced
steel ring encircling the furnace at the top of the bosh. This is called the mantle
which is supported by uniformly spaced upright heavy columns, which are firmly
anchored in concrete foundation at the bottom.
5. STACK:
It is frustum of a huge cone mounted on the mantle and extends to the top of
the furnace. The furnace top that is bell, the charging arrangement, the gas off-
takes, etc.are mounted on top of the stack. The stack is welded steel plate
30

construction lined from inside to a thickness of about a meter of hard firebricks.
Flat water cooled plates are inserted in the part of the stack lining. The top 2-3 m
height, which is stackline, is protected from abrasion caused by the falling charge
by providing armour plates on the inner surface of lining.
6. TUYERE AND BUSTLE PIPE:
Immediately above the hearth are located the tuyeres through which hot air
blast is blown for fuel combustion see fig..The number tuyeres with the various of
size of furnace. Usually it is any even number between 10-20 and is uniformly
spaced all over the periphery.
Air from hot blast stoves is supplied to a huge circular pipe encircling the
furnace at the bosh level. This is called the bustle pipe. The individual tuyeres are
connected to the bustle pipe which, by virtue of its enormous size, equalizes the
pressure of the blast at all the tuyeres. It is in fact its very purpose.
7. BELL AND HOPPER:
A bell and the hopper or the cup and cone arrangement, is called, was
commonly used in blast furnaces for charging the solid charge. It allowed smooth
charging without the off-gas leaking out into open. The off-gas, which has some
fuel value by virtue of its CO content and, which is available in large amount could
thus be collected , cleaned and utilized as a by-product fuel, for pre-heating the
blast and the still leftover part, elsewhere in the plant. This design lasted for a
longtime, with or without some additional facilities to improve upon the charge
distribution chute known as PAUL WURTH DISTRIBUTOR, slowly replaced the
31

traditional double bell arrangement since the 1980’s and the replacement was
nearly total by the beginning of twenty first century, except some exceptional or
the small furnace. This improved the burden distribution inside the furnace and
thereby improved the blast furnace efficiency considerably.
Towards the latter half of the first decade of the twenty-first century a still
better modified and more efficient top has been designed and put into use. This is
known as gamble top, which has been designed open by the Siemens-Voest-Alpine
group. New blast furnaces or those being modernized have started adopting it as a
better alternative. The C-furnace of Tata steel is going to adopt it during its design
modifications to be carried out in 2007-08.
When high pressure was introduced several complex seals had to be used on
the top with double bell arrangement. The Paul-worth bell-less top proved very
effective from this point of view as well. The gamble-top is claimed to be still
more efficient from the point of view of adopting high top pressure. It is claimed to
be more effective for far better charge distribution and easier mechanical
maintenance.
8. OFF-TAKE:
There are four exhaust pipes which are connected to the furnace top evenly
at four points. These rise vertically up above the furnace top and then join to a
bigger single pipe known as the down comer which delivers the gas to the gas
cleaning system i.e. dust catcher.
32

9. HOT BLAST STOVE:
Air blast is preheated to a temperature of 700-1300 C in Cowper regenerator
stoves. A set of three or four regenerators is provided for each furnace. The stove is
about 6-9 m in dia and 30-35 m in height. Special thin walled bricks are4 used to
construct the checker work in the stove. During one stove is ‘on-blast’, heating it,
while the remaining two or three are ‘on-gas’ that is getting themselves heated by
burning the cleaned blast furnace gas. The earlier stove had nearly 5000m2
as the
checker surface area for heat exchange but the modern one may have about five
times this much. The thermal efficiency o2 such a stove is around 80-90%.Several
valves are provided on the stove assembly to carry out the changeover from gas to
air and vice versa smoothly.
Steam driven centrifugal blowers are generally employed to supply blast at a
uniform rate to the furnace. These are lo0cated in the blower house near the
furnace.
5.2. BLAST FURNACE PROCESS:
Iron oxides can come to the blast furnace plant in the form of raw ore,
pellets or sinter. The raw ore is removed from the earth and sized into pieces that
range from 0.5 to 1.5 inches. This ore is either Hematite (Fe2O3) or Magnetite
(Fe3O4) and the iron content ranges from 50% to 70%. This iron rich ore can be
33

charged directly into a blast furnace without any further processing. Iron ore that
contains a lower iron content must be processed or beneficiated to increase its iron
content. Pellets are produced from this lower iron content ore. This ore is crushed
and ground into a powder so the waste material called gangue can be removed. The
remaining iron-rich powder is rolled into balls and fired in a furnace to produce
strong, marble-sized pellets that contain 60% to 65% iron. Sinter is produced from
fine raw ore, small coke, sand-sized limestone and numerous other steel plant
waste materials that contain some iron. These fine materials are proportioned to
obtain desired product chemistry then mixed together. This raw material mix is
then placed on a sintering strand, which is similar to a steel conveyor belt, where it
is ignited by gas fired furnace and fused by the heat from the coke fines into larger
size pieces that are from 0.5 to 2.0 inches. The iron ore, pellets and sinter then
become the liquid iron produced in the blast furnace with any of their remaining
impurities going to the liquid slag.
The coke is produced from a mixture of coals. The coal is crushed and
ground into a powder and then charged into an oven. As the oven is heated the coal
is cooked so most of the volatile matter such as oil and tar are removed. The
cooked coal, called coke, is removed from the oven after 18 to 24 hours of reaction
time. The coke is cooled and screened into pieces ranging from one inch to four
inches. The coke contains 90 to 93% carbon, some ash and sulfur but compared to
raw coal is very strong. The strong pieces of coke with a high energy value provide
permeability, heat and gases which are required to reduce and melt the iron ore,
pellets and sinter.
The final raw material in the iron making process is limestone. The
limestone is removed from the earth by blasting with explosives. It is then crushed
and screened to a size that ranges from 0.5 inch to 1.5 inch to become blast furnace
34

flux. This flux can be pure high calcium limestone, dolomitic limestone containing
magnesia or a blend of the two types of limestone.
The iron ore, pellets and sinter are reduced which simply means the oxygen
in the iron oxides is removed by a series of chemical reactions. These reactions
occur as follows:
 Begins at 850° F
3 Fe2O3 + CO = CO2 +2 Fe3O4
Fe3O4 + CO = CO2 + 3 FeO
FeO + CO = CO2 + Fe or
FeO + C = CO + Fe
At the same time the iron oxides are going through these purifying reactions,
they are also beginning to soften then melt and finally trickle as liquid iron through
the coke to the bottom of the furnace.
The coke descends to the bottom of the furnace to the level where the
preheated air or hot blast enters the blast furnace. The coke is ignited by this hot
blast and immediately reacts to generate heat s follows:
C + O2 = CO2 + Heat
35

Since the reaction takes place in the presence of excess carbon at a high
temperature the carbon dioxide is reduced to carbon monoxide as follows:
C O2+ C = 2CO
The product of this reaction, carbon monoxide, is necessary to reduce the
iron ore as seen in the previous iron oxide reactions.
The limestone descends in the blast furnace and remains a solid while going
through its first reaction s follows:
CaCO3 = CaO + CO2
This reaction requires energy and starts at about 1600°F. The CaO formed
from this reaction is used to remove sulfur from the iron which is necessary before
the hot metal becomes steel. This sulfur removing reaction is:
FeS + CaO + C = CaS + FeO + CO
The CaS becomes part of the slag. The slag is also formed from any
remaining Silica (SiO2), Alumina (Al2O3), Magnesia (MgO) or Calcia (CaO) that
entered with the iron ore, pellets, sinter or coke. The liquid slag then trickles
through the coke bed to the bottom of the furnace where it floats on top of the iquid
iron since it is less dense.
Another product of the iron making process, in addition to molten iron and
slag, is hot dirty gases. These gases exit the top of the blast furnace and proceed
through gas cleaning equipment where particulate matter is removed from the gas
and the gas is cooled. This gas has a considerable energy value so it is burned as a
36

fuel in the "hot blast stoves" which are used to preheat the air entering the blast
furnace to become "hot blast".
The blast furnace is a counter-current realtor where solids descend and gases
ascend. In this reactor there are numerous chemical and physical reactions that
produce the desired final product which is hot metal.
Typical hot metal chemistry follows:
Iron (Fe) = 93.5 - 95.0%
Silicon (Si) = 0.30 - 0.90%
Sulphur (S) = 0.025 - 0.050%
Manganese (Mn) = 0.55 - 0.75%
Phosphorus (P) = 0.03 - 0.09%
Titanium (Ti) = 0.02 - 0.06%
Carbon (C) = 4.1 - 4.4%
37

5.3. BLAST FURNACE REACTIONS:
The reduction and smelting of iron ore is done mainly in the iron blast
furnace. The burden charged at the top of the furnace consists primarily of iron ore,
flux and coke. The reducing gas carbon monoxide and the heat required for the
smelting of the ore are generated at the bottom of the furnace by blowing preheated
air into the coke bed. The slag and metal accumulate as two liquid layers at the
bottom of the furnace. In order that efficient conversions of reactants to products
occur, there is an overall chemical stiochimetry, which must be met. In addition,
specific thermal requirements must also be satisfied to permit the endothermic
reactions to proceed and the products brought to their final temperatures. The blast
furnace can be conveniently divided into three zones for a study of the physical
and chemical reactions occurring therein. These zones are as follows:
o The upper or preheating or preparation zone
o The middle or indirect reduction or thermal reserve or isothermal zone
o The lower or processing or melting or direct reduction zone
5.3.1. REACTIONS IN THE UPPER ZONE:
The reactions of primary concern in the iron blast furnaces are the reduction
reactions of iron oxides. The formation of product layers during the reduction of
iron ore is well known. The greater the driving forces for the reduction and the
38

faster the rate of chemical reaction, the more pronounced is the formation of the
product layers.
3 Fe2O3 + CO = CO2+ 2 Fe3O4 + 10.22kcal (1)
Fe33O4 + CO = CO2 + 3FeO- 8.75kcal (2)
FeO + CO = CO2 + Fe+ 3.99 kcal (3)
At the same time the iron oxides are going through these purifying reactions,
they are also beginning to soften, then melt and finally trickle down as liquid iron
through the coke to the bottom of the furnace. Magnetite is reduced to wustite
mainly at 700-900°C, thermodynamically carbon deposition from CO by the
reaction
2CO = CO2 + C + 41.21 kcal (4)
The deposition occurs predominantly in a narrow temperature range 440-
600° C, the presence of iron and its oxides catalyses the reaction. It is also possible
for CO to reduce H2O in the upper furnace to a certain extent.
CO + H2O = C02 + H2+ 9.68 kcal (5)
The decomposition of carbonates other than those of calcium occurs at a
relatively low temperature around 400° C. they are of very little importance
because modern furnaces are using pellets or sinter and these carbonates are
calcined outside.
39

5.3.2. REACTIONS IN THE MIDDLE ZONE:
It is a moderate temperature zone where the temperature ranges between
800-1000° C. most of the indirect reduction of wustite(Eq. 3) occurs in the zone.
The CO/CO2 ratio of the inactive zone is about 2.3, a value exhibiting equilibrium
with Fe-FeO (Eq.3). The larger the height of the 800-1000° C temperature zone,
the longer the gas- solid contact time at these temperatures and the greater the
degree of indirect reduction. Similarly, the higher the reducibility of the ore, the
more rapid is the reduction. In short, the rate of reduction of ore in the middle zone
must not be a restriction for the attainment of optimum coke rate.
5.3.3. REACTIONS IN THE LOWER ZONE:
The temperature of the lower zone is 900-1000° C. a variety of physical and
chemical processes occurs in this zone. Most of the unreduced iron oxides descend
into the lower zone as fayalite, calcium ferrites or intermixed in the primary slag.
Direct reduction of iron oxide proceeds at temperature above 1000 °C according
to:
FeO + CO = Fe + CO2 (6)
C + CO2 = 2CO (7)
The reduction of Si and Ti require very high temperatures while the oxides
of Ca, Mg and Al are so stable that they are reduced to a very negligible extent.
The reduction of Mn from its monoxide is much more difficult and occurs at a still
40

higher temperature. The extent of reduction varies with temperature and slag
basicity. Cr and V behave in the same way as Mn.
MnO + C = Mn + CO (8)
SiO2 + 2C = Si+ 2CO (9)
S + CaO + C = CaS + CO (10)
A major portion of P is present as tri- or tetra- phosphate of Ca. Silica helps
in breaking phosphate bond.
3CaO.P2O5 + 3SiO2 = 3(CaO.SiO2) + P2O5 (11)
P2O5 + 5C = 2P + 5CO (12)
6. RAW MATERIALS USED IN A BLAST FURNACE
Iron ore or Hematite (Fe3O2), Carbon in the form of 'Coke', and Limestone
(Calcium Carbonate 'CaCO3') are all used in the blast furnace. Iron Ore is melted
down with coke, the coke burns heat into the furnace. Oxygen gas is blasted in
from the sides. The carbon (C) and oxygen (O2) react to form carbon dioxide gas
(CO2). At higher temperatures more carbon (C) is reacted with the carbon dioxide
(CO2) to create carbon monoxide (2CO). The carbon monoxide 'steals' the oxygen
from the iron oxide (Fe3O2), reducing the iron oxide to iron. Due to the impurities
in the iron, it is called 'pig iron'. Limestone (CaCO3) is added to remove the
impurities from the iron. The limestone (CaCO3) reacts with mainly silicate in the
iron, and becomes calcium silicate (CaSiO3) and carbon dioxide (CO2). Calcium
silicate is known as 'slag' and is used for construction.
6.1. QUALITY OF CHARGE MATERIAL:
A blast furnace charge consists of coke, ore or sinter, and limestone. These
41

materials must be in lumps of a certain size (40-60 mm). Larger lumps prolong the
process of reduction and fluxing. Smaller lumps block the flue-gas passages and
prevent a uniform descent of melting materials in the furnace.
6.2. IRON ORES:
Iron ores are rocks and minerals from which metallic iron can be
economically extracted. The ores are usually rich in iron oxides and vary in color
from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually
found in the form of magnetite (Fe3O4), hematite (Fe2O3), goethite (FeO(OH)),
limonite (FeO(OH).n(H2O)) or siderite (FeCO3). Hematite is also known as
"natural ore", a name which refers to the early years of mining, when certain
hematite ores containing up to 66% iron could be fed directly into iron-making
blast furnaces. Iron ore is the raw material used to make pig iron, which is one of
the main raw materials to make steel. 98% of the mined iron ore is used to make
steel.
Ore is a metal bearing mineral. The most important varieties of iron ore are:-
1. Magnetite or black iron ore
2. Hematite or red iron ore.
3. Limonite or brown ore.
4. Siderite (FeCO3).
6.2.1. MAGNETITE:
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of
several iron oxides and a member of the spinel group. The chemical IUPAC name
is iron (II, III) oxide and the common chemical name is ferrous-ferric oxide.
6.2.2. HEMATITE:
42

Hematite is the mineral form of iron (III) oxide (Fe2O3), one of several iron
oxides. Hematite crystallizes in the rhombohedral system, and it has the same
crystal structure as ilmenite and corundum. Hematite and ilmenite form a complete
solid solution at temperatures above 950°C.
6.2.3. LIMONITE:
Limonite is an ore consisting in a mixture of hydrated iron(III) oxide-
hydroxide of varying composition. The generic formula is frequently written as
FeO (OH) ·nH2O, although this is not entirely accurate as limonite often contains a
varying amount of oxide compared to hydroxide. Limonite is heavy and yellowish-
brown.
6.2.4. SIDERITE:
Siderite is a mineral composed of iron carbonate FeCO3. It takes its name
from the Greek word sideros, “iron”. It is a valuable iron mineral, since it is 48%
iron and contains no sulfur or phosphorus. Both magnesium and manganese
commonly substitute for the iron.
6.3. MANGANESE ORES:
Manganese ores are used for smelting ferromanganese, cast iron and pig iron
containing about 1% Mn. Manganese is present in either of its following oxide and
carboniteform: Pyrosulite MnO2, braunite Mn2O3, hausmanniteMn3O4 and
rhodochrosite MnCO3.
6.4. FLUXES:
Fluxes are added to sinter or charged directly into the blast furnace in order
to liquefy ore and sinter gangue and fuel ash, converting them to free flowing slag
43

that can be run of the furnace. The flux is decided by the gangue and ash analysis.
The limestone is the most popular flux in blast furnace and sintering process.
The limestone charged in the blast furnace must be in lumps (25-60 mm across),
firm, not prone to fines and most important, free from harmful sulphur, phosphorus
and silica.
Commonly used Fluxes:
1. Limestone,
2. Quartzite,
3. Dunite.
7. RESULT AND DISCUSSION:
We concentrated on the Blast furnace data in the period of OCT 10 TO MAR 11
in JSW Blast furnace for our study and we compared the effect of Blast Furnace
parameters during different Sinter percentages.
44

PRODUCTION RATE:
Sinter Range
(%)
BF(MT)
<55 1124
55-60 1275
61-65 1424
66-70 1462
>70 1475
45

Inference:
For the sinter amount less than 55% the Production per day is 1124 THM. With
further increase of sinter up to 70%, Hot metal Production increases to 1462 MT.
For sinter values of more than 70%, the Production increases to 1475 MT. Hence,
the result concludes that with increase in percentage sinter, Hot Metal
Production increases in linear rate.
SKIP IRON ORE BEARING:
Sinter Range
(%)
BF (Kg / THM)
<55 1640
55-60 1633
61-65 1640
66-70 1653
>70 1651
46

Inference:
For the sinter amount less than 55% the skip iron ore bearing per THM is
1640Kg/THM. For sinter values more than 70%, it increases to 1651 Kg/THM.
This increase of Skip Iron bearing is due to the lesser Fe% in Sinter compared to
Iron Ore due to self fluxing in the sinter. Hence the skip iron ore bearing increases
with respect to the increase in percentage sinter.
FLUX RATE:
Sinter Range (%) BF(Kg / THM)
<55 160
55-60 72
61-65 45
66-70 40
>70 36
47

Inference:
For the sinter amount less than 55% the Flux rate per THM is 160Kg/THM. With
further increase of sinter up to 70% decreases the Flux rate to 40 Kg/THM. For
sinter values more than 70%, the Flux rate decreases to 36 Kg/THM. Reduction in
Direct Flux Rate gives significant advantages in Blast Furnace Process such as
lesser fuel rate, lesser cost etc. Hence the Flux rate decreases with respect to the
increase in percentage sinter.
SINTER Fe %:
Sinter Range
(%)
BF (%)
<55 55.78
55-60 55.78
61-65 55.67
66-70 55.96
>70 56.29
48

Inference:
For the sinter amount less than 55% the Sinter Fe % is 55.78%. With further
increase of sinter up to 70% increases the Sinter Fe % to 55.96. For sinter values
more than 70%, the Sinter Fe % increased to 56.29. Hence the Sinter Fe %
increases with respect to the increase in percentage sinter.
FUEL RATE:
Sinter Range
(%)
BF (Kg / THM)
<55 609
55-60 585
61-65 572
66-70 573
>70 577
49

Inference:
For the sinter amount less than 55% the Fuel rate per THM is 609Kg/THM. For
sinter values more than 70%, the Fuel rate decreases to 577 Kg/THM. This is one
of the best benefits which are got through Sinter. As 60 % of Total Steel Cost
comes through Coke’s cost, decrease in Coke’s consumption gives a major
advantage in Cost economics.Hence the Fuel rate decreases with respect to the
increase in percentage sinter.
BLAST:
Sinter Range
(%)
BF(Kg / THM)
<55 1657
55-60 1467
61-65 1184
50

66-70 1163
>70 1129
Inference:
For the sinter amount less than 55% the blast per THM is 1657Kg/THM. With
further increase of sinter up to 70% decreases the blast to 1163. For sinter values
more than 70%, the blast decreased to 1129. Hence the blast rate decreases with
respect to the increase in percentage sinter.
SLAG VOLUME:
Sinter Range (%) BF(Kg / THM)
<55 324
55-60 329
61-65 332
51

66-70 337
>70 344
Inference:
For the sinter amount less than 55% the slag volume per THM is 324Kg/THM.
With further increase of sinter up to 70% decreases the slag volume to 337. For
sinter values more than 70%, the slag volume increases to 344. Slag Volume
increase is due to the presence of higher Al2O3 and SiO2in the Sinter. Eventhough
slag volume increase is not favourable to Blast Furnace Process, by having a limit
to the slag volume, Sinter % is increased for reaping maximum benefits. Hence the
slag volume increases with respect to the increase in percentage sinter.
CONCLUSION:
This detailed Study on Blast Furnace Parameters during different Sinter
percentages brings out several interesting features in the context of Blast Furnace
process.
52

Regarding the productivity is concerned, it gives a direct linear rate of
increase in production with respect to the Sinter percentage and this emphasises the
fact that all over the world blast furnaces are maximising Sinter % in their input.
Regarding the fuel rate is concerned, as we know, reduction of Coke
consumption is the prime objective of a steel plant, increase in Sinter is the best
option for reduction of Coke consumption. As Sinter already a ‘half cooked
product’, the overall requirement of Coke comes down drastically in Blast
Furnaces.
With regard to reduction of Flux rate also, direct flux addition causes several
disadvantages to Blast Furnace Process such as higher fuel consumption, higher
Silicon in the hot metal etc. By adding fluxes through Sinter avoids these
disadvantages.
With respect to reduction in blast rate is concerned, as higher productivity is
achieved with the same amount of blast volume blown inside the furnace,
advantages such as reduction in Blast consumption, reduction in power, Steam etc.
are achieved.
Finally, we can conclude that JSW Blast Furnace has adopted the strategy
for increasing the Sinter in their Input for achieving various advantages listed
above. This is in line with the international standards and we can conclude through
our paper that they are able to achieve the benefits by increasing Sinter percentage
in their burden.
53

1. Gupta S K, Das S N and Chandra Navin, Trans Ind Inst Met 48 (1995) p 409.
2. Kundu A L, Prasad S C, Chottopadhyay D, Bishoyi K, and Prasad M, Some
aspects of production of quality hot metal at Rourkela Steel Plant, Proc National
Seminar on “Technologies for Ironmaking” organised by IIM, Rourkela Chapter
and Rourkela Steel Plant, December (2001).
3. Turkdogan E T, the 1978 Howe Memorial Lecture, the Iron & Steel Society of
AMIE, Metallurgical Transactions B 9B (1978) p 163.
4. A.K.Biswas, Principles of blast furnace iron making.
55

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