Induction Report

Submitted by

RAVI KANT

BSR0825

MANAGEMENT TRAINEE (BSL)

Enhancing The

World Of Steel

ACKNOWLEDGEMENT

I feel extremely indebted to our own organization Bhushan steel

limited for providing me a platform focused on development and

learning which will play a pivotal role in my journey of professionalism.

This induction program gave me exposure of all the departments in the

organization adding finesse to the technical acumen.

Firstly I wish to express my deep sense of gratitude to our managing

director Mr. NEERAJ SINGHAL for providing us this pool of

opportunity of learning.

My sincere thanks to our Human Resource manager Mr. ALOK

PANDEY for organizing this informative induction process. I would

also like to thank all the department heads of various departments for

providing such learning and illuminating environment and allowing me

to start my career in the best possible way, I could have ever imagined.

INDEX

Awareness of quality management system

Environment management

Raw material handling system & RMPP

Direct reduced iron

Sinter plant 1, 2, 3

Blast furnaces 1, 2

Coke ovens 1, 2

Oxygen plant

Lime plant

Steel making shop (BOF)

Hot strip mill

Cold rolling mill

Power plant

QUALITY MANAGEMENT SYSTEM

Definition of quality in industrial sector

It is ability of the material to perform satisfactorily in an application

for which it is intended by user.

Abilities to judge the quality of product

Suitability

Durability

Dependability

Safe workability

Affordability

Appeal ability

Eight quality management principle;

Customer focus

Leadership

Involvement of people

Process approach

System approach to management

Continual improvement

Factual approach to decision making

Mutually beneficial supplier leadership

What is meant by ISO?

ISO means international organization for standardization.

ISO is a worldwide federation of standard writing agencies from

over 180 countries now.

It was formed after Second World War.

It develops product and organizational standards for industries.

All the standards are developed through consensus process.

Objective of ISO implementation

To create a commitment among employees for zero customer

complaint & for ensuring the product quality

To develop competency among employees

To create a confidence in customer Internal/external) that

organization is capable of delivering quality product

Some of the ISO designations are stated as follows:

ISO 9000 Fundamentals

ISO 9001 Design

ISO 9002 Manufacturing

ISO 9003 Service

ISO 9004 Guidelines

FIRE SAFETY TRAINING

FIRE IS CHEMICAL REACTION IN WHICH SUBSTANCE (FUEL) COMBINES WITH

OXYGEN MAKING AN EXOTHERMIC REACTION WITH THE EMISSION OF LIGHT,

HEAT & SMOKE

METHOD OF EXTINGUISHING

COOLING: Removal of heat (Best cooling media is water)

SMOTHERING: Reducing % of oxygen, cutting off the supply of oxygen.

(Blanketing, Use foam)

STARVATION: Removable of fuel and removable of combustible material.

FIRE CLASSIFICATION

CLASS A: - SOLID COMBUSTIBLE SUBUSTANCE. E.g. Wood, Paper, Plastic,

Coal.

CLASS B: - LIQUID COMBUSTIBLE SUBUSTANCE. E.g. Petrol, Diesel, HFO,

Wax, Paint.

CLASS C: - FLAMMABLE GASES. E.g. LPG, Hydrogen, Oxygen.

CLASS D: - REACTIVE METAL FIRE. E.g. Sodium, Magnesium, Aluminium.

FIRE EXTINGUISHERS

WATER TYPE EXTINGUISHER

It is best suited for combating fires involving Solid Organic Carbonaceous

materials like wood, paper, coal, plastic, cloth and rubber. Water knocks down

fire rapidly by striking, instantly Cooling and penetrating the most deep seated A

class fire.

FOAM TYPE EXTINGUISHER

It is powerful flame knockout agent for spill fires involving Flammable and

volatile liquids like petrol, paints and other solvents. Foam extinguishers form a

thick blanket of foam over the burning surface, effectively cutting off the oxygen

supply there by Smothering the fire and prevent re-ignition. Foam extinguishers

are effective against A & B class of fire.

DRY CHEMICAL POWDER

Dry Chemical Powder Extinguishers are versatile and highly effective against B &

C class fires, specially for combating three dimensional or running fires involving

inflammable liquids like petrol, paints and gases. They can also be used on

Energized Electrical Equipments.

CARBON-DI-OXIDE

Carbon dioxide fire extinguishing media is highly effective against B & C class of

fire. They can also be used on Energized Electrical Equipments.

RAW MATERIAL HANDELING SYSTEM (RMHS)

WAGON TIPPLERS

Tippler is used for emptying the loaded wagons by tipping it. Tippler retains

wagon from top as well as from side by using clamping devices provided on it.

Apart from that track stops, wheel grippers and different type of limit switches are

provided as features of wagon tippler.

Figure: Wagon tippler in action

For the expansion of Bhushan Steels steel plant at Meramandali, india, Larsen and

Toubro carried out the design, engineering, supply, erection, testing and

commissioning of the raw material handling system that included 43 kilometres of

belt conveyors.

Bhushan Steel Ltd. (BSL) is a globally renowned company and one of the

prominent players in the steel Industry. It is one of Indias largest manufacturers of

auto-grade steel and has transformed itself as the third largest producer of cold

rolled steel in the country.

Bhushan Steels Phase III expansion of its integrated steel plant at Meramandali,

Orissa from 3 to 6 million tonnes per year comprised of facilities such as blast

furnace, Direct Reduced Iron (DRI) kilns, sinter plant, basic oxygen furnace, coke

oven, steel melting shop, matching lime and dolomite plant including auxiliary

facilities such as coal/ore crushing, captive power plant, coal washery etc. Here it

is noteworthy to mention that Larsen and Toubro (L&T) was entrusted with the

responsibility for the complete Raw Material Handling System (RMHS) for

Bhushan Steels Phase III Expansion which is the largest executed by L&T till

date.

The Flow of Raw Materials

The production of steel requires various raw materials such as coal, coke, iron ore,

flux, mill scale, sinter etc. and they undergo processes like unloading, stacking,

reclaiming, blending, crushing, grinding and screening and are finally conveyed to

the sinter plant, coke oven battery and blast furnace. The RMHS in a steel plant is

designed to cater to these materials and is critical to achieve the desired production

capacity. The course of the material in this system is shown in Fig. 2.

Coal, limestone, dolomite and iron ore are unloaded by wagon tipplers, track

hoppers and truck unloading systems (BSL scope) and stacked in the stock yard by

yard machines and reclaimed.

Coking coal is fed to the coke oven battery after blending, crushing and mixing.

The quenched coke after segregation as per separation size is fed to blast furnace

stock house or base blending system.

Iron ore fines, limestone, dolomite from the stock yard, mill scale from trucks, nut

coke/coke fines from coke oven, sinter fines from stock house are fed to base

blending system for production of base mix. The sinter produced from base mix is

fed to blast furnace and emergency storage is available to ensure continuous feed

to blast furnace.

Iron ore fines from blast furnace stock house is fed to stock yard for feeding to

DRI plant and nut coke from blast furnace stock house is fed into base blending

system.

Non-coking coal is fed to coal washery and the washed coal (5 to 22 mm) is sent to

DRI plant for further processing. Iron ore lump from stock yard through Raw

Material Processing Plant (RMPP) and dolomite from trucks/ground hoppers is

also fed to DRI plant for processing. The output DRI is then fed to the steel

melting shop.

Blast furnace once ignited need to operate continuously, hence to ensure

continuous feed of material, all the raw materials such as blast furnace coke, sinter,

iron ore, additives, pellets are stored in the stock house and proportionately fed to

the blast furnace via charging conveyors.

The slag generated from the blast furnace is conveyed to the wagon loading area

for transportation outside the plant.

Non-coking coal (-6 mm) from the stock yard through coal crushing and screening

system is fed to a captive power plant

Operational Scheme

Based on the flow of material, the complete RMHS at Bhushan Steel is packaged

into various systems such as base blending system for sinter plant, coal and coke

handling system for coke oven, blast furnace stock house and charging conveyors,

yard machines, wagon unloading equipment and associated conveying system and

slag handling system. In addition to these systems, RMHS work for Bhushans

captive power plant and coal washery was also carried out by L&T. The major

scope (see Fig. 3) and working of each system is covered in the following sections

Wagon Unloading System

Run-of-Mine (ROM) coal, imported coal, limestone, dolomite and iron ore are

unloaded by five Rotaside wagon tipplers (three by others) and the truck unloading

system and are sent to stock yard through series of belt conveyors. In hauling of

loaded wagons, placement and out hauling of empty wagons is done by rack and

pinion type side arm charger (one for each tippler). The raw materials unloaded

from each wagon tippler are drawn by two nos. Apron feeders installed below the

hoppers and fed on to the conveyors below.

ROM coal is also unloaded at two track hopper complexes (twin type, 210 m long)

with four traveling type paddle feeders in each complex, see Fig. 4. The track

hopper unloads material from bottom discharge type wagon by opening gates

pneumatically/manually and the same is fed onto four underground belt conveyors

at the bottom of track hopper complexes

The material received from both the track hopper and wagon tippler stream will be

fed onto conveyors for transportation to stockyard via junction towers.

Stockyard and Yard Machines

Stockyard and the yard machines are designed to cater the raw material needs for

the 6 million tonnes per year stage. The stock yard is serviced by eight

stacker/reclaimers and three bucket wheel reclaimers (see Figs. 5 and 6). Out of the

total eleven yard machines, ten machines have been supplied and erected by L&T

including one stacker/reclaimer which comes within a covered storage area. The

brief specifications of the yard machines are furnished in Fig. 7.

Sinter Base Blending System

This circuit comprises of the raw material preparation and handling system for

feeding raw materials from stock yards to sinter plants SP2 and SP3, conveying

product sinter to the blast furnace stock house, coke and lump ore to blast furnace

stock house and handling coke/sinter fines generated in stock house.

The primary reason of adding sinter in the blast furnace is to increase its efficiency.

Sinter is produced using base mix in the base blending system and the course of

raw materials is given in the following sections.

Iron ore fines reclaimed from the yard will be discharged on to eight bins in the

base bin building through reversible shuttle conveyor and charging hatches.

Limestone and Dolomite Circuit

The limestone and dolomite reclaimed from the stock yard is fed on to the surge

bins in the flux crushing and screening building. The flux (+25 to 50 mm) is

crushed to predominantly (-3 mm) with the help of three reversible hammer mill

crushers (2W+1S) and the oversize material (+3 mm), screened using flip flop

screens, is crushed with the help of three secondary reversible hammer mill

crushers (2W+1S). The flip flop screens ensure recirculation of (+3 mm) size to the

secondary crushers. Thus (-3 mm) flux produced during closed loop crushing and

screening system is transported to the four bins in the base bin building through

four high angle conveyors (vertical conveying system) due to space constraint and

reversible shuttle conveyor. Vibro feeders are used to regulate the feed to crushers

and screens.

Coke Circuit

Coke fines arising from the existing plants and purchased coke unloaded in the

ground hopper are conveyed to six bins in the coke fines bunker building through a

series of conveyors. Coke from the coke fines bunker building is fed to the coke

crushing building through high angle conveyors. The coke is screened for 3 mm

separation using flip flop screens and the oversize material (+3 mm) is discharged

into four surge bins with the help of a reversible shuttle conveyor. Coke stored is

crushed with the help of rod mills (2W+2S) installed below respective surge bins.

Crushed coke (-3 mm) and screened out (-3 mm) is conveyed to the four bins in the

base bin building.

Base Mix and Product Sinter

The base blending building is the heart of the base blending system and it

comprises of 20 bins each of capacity 360 m3 to store iron ore, flux (crushed

limestone and dolomite), coke, mill scale and sinter fines. The bins are provided

with bin level indicators and air blaster system. The raw materials stored in the

base blending building are reclaimed at required proportion with the help of belt

weigh feeders to form the base mix. The base mix produced is stacked in either of

the stock yards by the twin boom stacker machine and the barrel reclaimer is used

to retrieve base mix across the full width. The barrel reclaimer machine will be

transferred to either of the beds by transfer car. One bed will have the formation of

the base mix while the other will be under reclamation. The reclaimed base mix is

conveyed to the sinter plant after necessary trimming, addition of coke fines and

lime fines. There is also a provision of transportation of base mix directly to the

sinter plant without stacking and reclaiming

Product sinter received from the sinter plant is either conveyed to an emergency

sinter storage building or directly to the blast furnace stock house. The emergency

sinter storage building consists of 16 bins each having a volume of 485 m3 to store

sinter as emergency stock.

Coal and Coke Handling

This system comprises of the coal circuit which carries coking coal from the yard

to the coal tower and the coke circuit that conveys the product coke to the blast

furnace and base blending system. The details of the system are given in the

following section.

The coal handling system is designed for a nominal capacity of 750 tph and caters

to the total coal requirement of two coke oven batteries and the plant will operate

365 days per year (two shifts per day). Its major sub systems are coal reclaiming

from yard, coal blending, coal crushing and mixing and coal tower feeding.

Coking coal stored in the yard is reclaimed by a stacker/reclaimer machine and fed

to one of 12 storage bins in the coal blending building. The bins are designed for a

total storage capacity of 8800 t (735 t each) corresponding to 20 hours storage

availability and Nitrogen inertising system is provided in each of the bins to avoid

any risks. To achieve the desired blend, coal stored in the bins is reclaimed at the

required proportion with the help of belt weigh feeders installed below each of the

bins.

The blended coal is fed to the rotating conveyor in the coal crushing building

which can feed to any of the four surge hoppers (one in future). Vibro feeders

installed below the surge hoppers feed the coal to four reversible hammer mill

crushers (2W+2S). The feed (0 to 50 mm) is ground to predominantly (-3 mm).

After crushing, the coal is transported to the mixing station using high angle

conveyors. A distribution system consisting of reversible belt feeders and diverter

gates feeds the material to three 750 t/h mixers (BSL scope). Subsequently after

crushing and mixing the blended coal is fed to the coal tower through a series of

conveyors. A coal sampler station is also installed in one of the conveyors to

collect samples to check the quality of blending.

The 500 t/h coke handling system is designed to operate continuously on three

shifts per day, 365 days a year. The quenched coke is dumped on the wharf and fed

to the wharf conveyor by means of 400 t/h plough feeders (BSL Scope). A cooling

water system is installed in both the wharf conveyors to avoid damage of belt

conveyors due to hot pieces (if any).

The material is then fed to the two vibrating grizzly screens (separation -80 mm)

inside the coke treatment building. The oversize material is fed onto two smooth

double roll crushers (BSL scope) to reduce the grain size. Subsequently the

screened out and crushed material (-80 mm) is screened by three double deck

screens (BSL scope) to segregate coke fines (0 to 15 mm), nut coke (15 to 25 mm)

and coke for blast furnace (15 to 80 mm).

DIRECTLY REDUCED IRON

A solid porous metallic mass

Appear like a honey comb structure with minute holes all over the surface

Produced through solid state reduction of iron ore

Escape of gaseous products

DRI Advantage

More Volumetric Weight :

Considerably higher (10-100%) than other types of scraps.

Consistent Chemical Analysis :

Avoids product quality deviations, residual element free.

Continuous Charging :

Eliminates scrap recharging; consistent power loading during melting.

Reduced Flicker & Noise Level :

Significant reduction in noise and flicker than that of scrap.

Reduced Nitrogen content :

Lower nitrogen level (~20 ppm) for 100% DRI.

Better Bath Stirring :

Highly effective bath stirring due to CO boiling.

Foamy Slag :

Easy Generation of foamy slag.

SL/RN Sponge Iron Plant

Rotary Kiln

ROTARY KILN

IMPORTANCE OF SIZE OF RAW MATERIAL IN DR PROCESS

5mm to 18mm size of Iron Ore mostly preferred for DRI production.

5mm to 20mm size of Feed Coal & Coarse Coal preferred.

0mm to 5mm size of Fines Coal preferred.

0 mm to 8 mm size of Dolomite preferred.

General Discussion about Iron Ore

The iron ore of 62 - 65 % Fe (T) can give Fe (M) 81 - 83 % for 90 %

Metallization on reduction.

So iron ore of 65 % to 68 % Fe ( Total) is suitable for sponge iron making

IRON ORE TESTS

TUMBLER INDEX: It is a relative measure of resistance of material to

breakage on impact. It should be > 88 %.

SHATTER INDEX : Dropping a certain amount of material from a standard

height for a certain number of drops. Range 0.7 % - 1.0 %.

ABRASION INDEX : It is the relative measure of the degradation of

material by abrasion. It should always be < 2%.

DECRIPITATION INDEX : When iron ore is suddenly exposed to the kiln

through feed tube breakdown may occur due to thermal shock. This is

known as Decripitation. It is measured by dropping a certain amount of

material in a previously heated furnace to a temperature of 400-6000 C under

normal atmosphere, inert atmosphere or under mildly reducing conditions.

After the charge attains the desired temperature, it is removed, cooled and

screened to measure the % age of breakdown.

Decripitation Index = 1.5 - 2.8% (% of -1mm in reduced product)

REDUCIBILITY DEGRADATION INDEX : 500 gms of dry sample in the

size range of 10-15mm is charged in a vessel (700mm x 75mm). The vessel

is pushed in an electric muffle furnace maintained at 550 deg C. then mixed

with gas of N2 & CO in the ratio 70:30 is passed for 30 min at 15 ltr / min.

subsequently the sample is cooled down to room temperature by passing N2

gas @ 5 Ltr / min. Reacted sample is rotated in a small tumbling drum

(200mm x 130 mm) at 30 rpm for 30 min. Resultant sample is screened on

6mm and 3mm screens. % age of 3 mm fraction is reported as R.D.I. of iron

ore.

THERMAL DEGRADATION INDEX : It is defined as the fragmentation

and breaking up points showing generation of fines when the material is

subject to heating in an Oxidizing or Reducing Atmosphere. The iron ore

solid is susceptible to thermal degradation when heated to a temperature

more than 4000C. The reduction degradation is the chemical phenomenon

which occurs while conversion of Hematite to Magnetite in the initial stage

of reduction.

REDUCIBILITY TEST (dr/dt) : This test aims at measuring the rate of

reduction of iron ore under rotary kiln conditions. The use of reduction

temperature in the range of 900 1050 deg C and an atmosphere of reducing

gases (CO or CO & H2). The sample of a known weight & of fixed size is

placed in the furnace in the form of static bed. dr / dt should be 0.5-0.6 %

per min.

COAL (COMPOSITION):

Coal Size = ( 5 - 20 mm )

B grade F grade WASH grade

Moisture 5-10 % 5-10% 15-18%

Fixed Carbon 40-45% 25-28% 35-38%

Volatile Matter 28-32% 20-24% 28-32%

Ash 25-30% 45-50% 32-37%

Direct Reduced Iron

Cross section of partially reduced sponge iron:

METALLIZATION :

Fe (Metallic) / Fe (Total) = Metallization in Sponge Iron.

Metallization checked by chemical process in our Laboratory.

Instant Metallization can be checked by the machine called

SATTMAGAN.

SATTMAGAN Result is the Ratio of gravitational weight & magnetic

weight.

In normal process Metallization is observed physically by our process

engineers every hour by breaking the sample and analyzing the % age of

reduction for best process control.

Quality Of The Product:

The important constituents determining the quality of sponge iron are the Fe total,

Fe metallic , sulphur, phosphorous, carbon and gangue content.

Fe total:

The Fe total content in sponge iron purely depends on Fe con tent in iron ore and

the degree of reduction achieved in the process. Fe total content of 90%min is

required for steel making requirement.

Fe metallic:

Fe metallic content in sponge iron depends on the effective control of process

parameters

Like temperature profile, retention time , mean particle size of iron ore/coal. Fe

metallic content of 78-82% is desirable for steel making. Fe metallic content of

grain size fractions of 4-12mm, +12-16mm, +16mm should also be determined

once in a week for control of consistency in product quality.

Carbon content:

The carbon content in sponge iron produced by coal based rotary kiln processes are

generally low and is in the range of 0.08% to 0.20%.The carbon content in gas

based processes can be controlled to a level of 1.5% to 2.0% based on requirement

for steel making.

Sulphur content:

The sulphur content in sponge iron is controlled by adding 1-6mm of

limestone/dolomite along with feed materials which picks up sulphur from the coal

preventing the sulphur pick up in sponge iron. The sulphur content in sponge iron

can be controlled in the range 0.012 to 0.025%

Phosphorous content:

The phosphorous present in the iron ore is retained as P2O5 in sponge iron with out

any change. The phosphorous content in sponge iron is generally varies from

0.06% to 0.09%.

SINTER PLANT

In Bhushan Steels Limited for the preparation of input material for the blast

furnace that is called sinter the company has three Sinter plants.

Technology Used Sintering area (m2)

SINTER PLANT 1 Chinese 177

SINTER PLANT 2&3 German 204

SINTER MAKING:

Due to increased mechanization in the mines, lot of fines are generated which

cannot be charged into the Blast Furnaces directly. In order to conserve these,

otherwise waste material, they are compacted together and made into lumps by a

process known as sintering. Sintering is

defined as the agglomeration of the fine mineral particles into a compact lumpy

mass by incipient fusion caused by the heat produced during the combustion of the

solid fuel within the moving bed of loosely particles.

ADVANTAGES OF SINTER:

Helps in the conservation of raw materials.

Enhances the productivity of Blast Furnace.

Decreases coke rate in BF.

Decreases the flux rate in BF.

Improves the permeability of BF.

Helps in the smooth running of the BF.

SALIENT FEATUES AND SPECIFICATIONS OF SINTER

PLANT 2 & 3

Technology Supplier: Outotec ltd.

Production Start Date: (SP2) 23rd OCT 2012 & (SP3)24th MAY 2013

Particulars Details Plant capacity (rated) (Net) : 2.00mtpa

Plant capacity (rated) (Gross) : 2.30mtpa (Net fines @ 15%)

Sintering Area : 204 m2

Product size range : 5-40 mm

Annual working days : 330 days/year

Suction at grate bar : 1600-1700 mm WC(max)

Depth of Sinter bed : 700 mm

Pellet Width : 3 m

Sinter machine length : 77 m

No. of Wind box : 17

No. of Pellets : 164

Mixing Drum size : 4m*15m (Diameter*length)

Mixing Drum capacity : 424tph

Cooler type : Circular, dip rail

Waste gas fan(max pressure) : 1702 mbar

Motor Power : 8.4MW

ESP Volumetric flow rate : 170m3/s NTP (WG ESP) : 92m3/s NTP (PD ESP)

Electro Static Precipitator (ESP) : WG ESP(95kV,1700mA) - 5 field PD ESP(110kV,1100mA) - 3 field

Stack outlet gas dust content :

INPUT MATERIAL:

1. Iron ore fines 2. Lime stone fines 3. Dolomite fines 4. Coke Breeze 5. Return fines 6. Mill Scale 7. LD Slag

Input in the form of Base Mix (a homogeneous mixture of Iron ore fines, Flux,

Coke Breeze, and Plant Returns) is supplied from RMHS.

PROCESS OF SINTERING:

The Sinter Plant-II & III has a rated capacity of 2.0 million tones of sinter per year.

There are two sinter machines supplied by Outotec private limited with 204 sq.

meter working area. The raw materials as specified above are brought, stored,

crushed and sent to proportionating bins. The different materials are drawn from

these bins in a fixed ratio on to a common belt conveyor leading to the primary

mixing drum. Here water and return fines are added. The raw mix is stored in two

intermediate bins from where it is fed into the two pelletizing drums. Here further

water is added to facilitate balling which increases the permeability of the raw mix.

This is carried to the charging hopper over the sinter machine 2 & 3. The material

is fed over the sinter machine pallets and the height of the bed is maintained 650-

700 mm depending upon quality of raw material used and sinter to be made. The

sinter machine is provided with 17 wind boxes at the bottom to suck the air

through the bed. As the bed travels through the Ignition Furnace, the top layer is

ignited. This combustion zone proceeds downwards till the pallets reaches the

discharge end. The temperature in the last wind box is maintained at around C. The hot sinter coming out from the machine is broken by the sinter breaker and

then screened. The -6 mm fraction is sent to the Return fines bin. The sinter is then

cooled in the cooling strand by blowing air through it and finally it is sent to the

double deck cold screen. Here it is separated into 3 fractions. The +25 mm is either

stored in the sinter storage bunker (1200 T capacity) or is directly sent to the Blast

furnaces. The -25 mm and +15 mm fraction is used as a bedding hearth layer on

the sinter machine in order to:

1. Increase the permeability of the bed. 2. To protect the grate bars from the direct contact with the hot sinter. -15 mm

fraction is again screened with 6mm screen. +6 mm fraction is sent to the

Blast furnace along with +25 mm fraction. -6 mm fraction is sent to return

fines bin.

Two space dedusting fans with Electro Static Precipitators are installed for

dedusting from various transfer points. Two waste gas fans with Electrostatic

Precipitators are installed for creating suction in the sinter bed from bottom.

SINTERING BED

BLAST FURNACE

Blast Furnace is a counter current heat & mass exchanger, in which the burden

(solid raw materials like Iron ore, Sinter, Coke & additives / fluxes) is charged

from top of the furnace & hot blast is sent through the bottom via tuyeres. The

heats transferred through the ascending Hot Blast to the descending burden &

oxygen from the burden to the gases. In the counter current process, the iron ore &

reducing agents (Coke, Coal) are transformed to hot metal & slag, formed from the

gangue of the iron ore, sinter & the ash of coke. The liquid hot metal & slag do no

mix and remain separated from each other with the slag floating on top of the

denser iron. The liquid iron & slag are separated in the cast house during casting.

The other product from the blast furnace is dust laden, blast furnace gas, which is

further cleaned in the gas cleaning plant and is used as a fuel all over the plant. The

raw materials require 6 to 8 hours to descend at the hearth of the furnace where

they become the final product of liquid metal and slag. These liquid products are

drained from the furnace at regular intervals through tap hole. The gases generated

into the furnace ascend to the top in 6 to 8 seconds after going through numerous

chemical reactions.

These 2 Blast Furnaces in BSL were commissioned with the technical and

financial assistance Of Paul Wurth.

The raw materials required for production of hot metal are Iron ore, Sinter, coke,

LD Slag, Quartzite & Manganese ore (as per requirement of SMS). Apart from

these solid raw materials, it also requires air and oxygen for burning of coke, water

for cooling various parts & equipment of furnaces. Iron ore supplied from OBBP,

Sinter from Sintering Plant (I & II), Coke from Coke Oven, LD Slag and scrap

from SSD.

The main sections supporting the furnaces are:

1. High line Stock House & charging section

2. Furnace proper and cast house

3. Hot Blast Stoves

4. Gas Cleaning plant

5. Slag Granulation plant

6. Pig Casting machine

7. Fleet of Hot metal ladles

Raw Material Sources for Blast Furnace

Iron Ore:

Sinter: Sinter Plant I & II Coke: Coke Ovens (Coals from.. & imported coal) Mn Ore: Purchased

Quartzite: Purchased

LD Slag: SMS through SSD

Nut Coke: Coke Ovens through Sinter

Pig Iron Chips: PCM through SSD

RAW MATERIAL USED IN BLAST FURNACE AND THEIR

SPECIFICATION

Material Chemical Specification

Iron Ore Fe : 63-64 %

SiO2 : 2-3%

Al2O3 : 2-3%

Sinter Fe : 54-55%

SiO2 : 4.5-5%

CaO : 9.5-10%

MgO : 2-2.5%

Al2O3 : 2.5-3%

Coke Carbon: 87%

Ash : 12%

S : 0.6%

Lime Stone CaO : 45-50%

MgO : 2.5-3%

SiO2 : 5-5.5%

Al2O3 : 1.5-2%

Dolomite

CaO : 28-30%

MgO : 19-20%

SiO2 : 3-4%

Al2O3 : 0.5-1%

Quartz SiO2 : 98%

BLAST FURNACE 1(BF 1)

Stoves - 3 nos, (Max temp. 1250 deg C)

Dust Catcher - (Inlet load 50g/Nm3, Outlet load 5 g/Nm3)

Scrubber - 1 no, (Inlet load 5 g/Nm3, Outlet load 5 mg/Nm3)

Slag Granulation Plant - 1 unit, (Capacity 2.75 to 5.5 t/min, Max 8

tons/min)

Pig Casting Machine - 2 units, (Capacity 2100 t/day/Unit)

Pulverized Coal Injection - 1 unit, (Capacity 150 kg/thm, Max 250 kg/thm)

Stock House

Iron Ore : 2 Bunkers

Sinter : 6 Bunkers

Coke : 8Bunkers

Fluxes : 6 Bunkers (One each)

Charging System - Paul wurth Bell less top charging system.

Waste heat recovery system - To utilize the heat of stove flue gases

Technical Specification

Total Volume 1681 m3

Working Volume 1462 m3

Throat Diameter 6.73 m

Belly Diameter 10.0 m

Hearth Diameter 8.40 m

Stack angle 85.20

Bosh angle 81.00

Throat volume 89 m3

Stack volume 901 m3

Belly volume 172 m3

Bosh volume 210 m3

Hearth volume 219 m3

Production data

Production Rated 3625 t/day

Productivity 2.48 t/m3/day

Coke Rate 400 kg/thm

PCI Rate 150 kg/thm

Fuel Rate 550 kg/thm

Carbon Rate 455 kg/thm

Ore / Coke 4.0

Fe / C 2.0

Operational Data

Blast Volume 2600 2800 Nm3/min

Blast Pressure 2.4 2.8 bar

Hot Blast temp 1100 1200 C

Top Pressure 1 1.5 bar

Top Temp 80 100 C

O2 Enrichment 4 %

Steam Injection 20 35 g/Nm3

Pulverized Coal Injection 6 30 t/hr

BLAST FURNACE 02

Main Constructive Characteristics:-

Number of notches 4

Number of tuyeres 34

Top hoppers effective volume 65 Charging system With the help of conveyor belt

Top closing system Parallel bell less top(BLT), paul Wurth

Hearth Cast iron staves

Number and type of probes for stockline

control

1 mechanical and 2 radar

Tuyer belt Cast iron staves from middle stack to

throat

Pressure equalizing system: semi-clean gas + nitrogen

Cooling system

Under-hearth: water pipes

Hearth: cast-iron staves

from Bosh to lower Stack: copper staves (approx. 11,500 mm)

Tuyere belt: cast iron stavesfrom middle Stack to Throat: cast iron staves

Number and type of probes for stockline control: 1 mechanical, 2 radar

Technical Specification

Throat Diameter 9.500 m

Belly Diameter 14.700 m

Hearth Diameter 13.000 m

Throat height 1.600 m

Belly height 2.100 m

Bosh height 3.950 m

Working height 25.900 m

Inner height 30.300 m

Total height 33.100 m

Tap hole inclination 10

Hearth volume 584 m3

Working Volume 3,230 m3

Inner volume 3,814 m3

Total Volume 4,186 m3

Production Data:-

Annual hot metal production: 2,500,000 tHM

Working days per year: 350 d/y

Daily hot metal production (average): 7,150 tHM

Peak daily hot metal production: 7,850 tHM

Reactions in the Blast Furnace

Upper Stack Zone

Reduction of oxides

3 Fe2O3 + CO = 2 Fe2O3 + CO2

Fe3O4 + CO = 2 FeO + CO2

FeO + CO = Fe + CO2

Decomposition of Hydrates

CO + H2O = CO2 + H2

Decomposition of Carbonates

Middle Stack Zone Direct / Indirect reduction

FeO + CO = Fe + CO2

CO2 + C = 2 CO

FeO + C = Fe + CO

Lower Stack Zone Calcination of lime

Reduction of reduced iron

Reduction of Silica / MnO2

Formation / melting of slag

Combustion Zone Burning & combustion of coke & complete reduction of iron

oxide.

C + CO2 = CO2 + 94450 Cal (Direct Reduction)

CO2 + C = 2CO 41000 Cal (Solution loss reaction) Race way

Coke & Hydrocarbons are oxidized

Large evolution of heat.

Top Charging System

In Bell Less Top (BLT), these are no bells as the nomenclature states. The skips

dump the materials to a receiving hopper, which is separated from the BLT by

upper material gate and upper gas seal valve. After opening of upper material gate

& upper seal valve, material is discharged into BLT material bin placed over the

lower material gate & lower gas seal valve. Then the UMG (Upper Material Gate)

& USV (Upper Seal Valve) are closed to seal the furnace from the atmosphere &

the receiving hopper is ready to receive material from the skips. To dump the

material into the furnace, the lower seal valve opens and then the lower material

gate is opened. The material is dumped through a rotating chute, which can dump

material at any position of the furnace and can complete the dumping in variable

number of rotation so that desired burden distribution is achieved. The whole BLT

system is hydraulically operated & PLC controlled. Besides achieving perfect

burden distribution, BLT ensures very good gas sealing at the furnace top so that

furnace can be operated at a high top pressure.

Hot Blast Stoves & Associated System

The function of Hot Blast Stoves is to pre heat the air blast before its admission

into furnace through tuyeres. Each furnace is provided with 3 hot blast stoves

which are tall cylindrical shell with dome shaped top. Each stove consists of two

parts namely combustion chamber & checker brick work. The combustion chamber

is lined with fire clay brick & checker bricks are Alumina bricks. BF gas is burnt in

combustion chamber and the sensible heat of the flue gases heat up the checker

bricks while passing through them from top towards bottom. The period of heating

is called On Gas & normally a stove remains on gas for 1 hour minutes at a stretch. After heating, cold blast, supplied from turbo blowers of CPPI is passed through the checker works from bottom and the air got heated up by taking

sensible heat from checkers. The period of blast heating is called On Blast condition of stove. The blast period is usually for 1 hour.

The hot blast stoves are provided with several attachments such as burners to burn

the premixed air and BF gas in the combustion chamber. Different valves are

provided for controlling the BF gas, combustion air, waste gas, cold blast and hot

blast to or from the stoves. The hot blast from stoves passes through insulating

refractory bricks lined pipes (hot blast main, bustle main & tuyeres stocks) and

then injected through tuyeres into the furnaces. The entire operation & control of

stoves & hot blast is made from a control room adjacent to stove.

Cast House

The Cast House is the most important section of Blast Furnace. The function of

cast house is to tap the liquid metal & slag from the hearth of furnace on schedule,

separate the metal & slag in troughs and flow them through runners to metal ladles

and slag pots respectively. Production of Blast Furnace is greatly influenced by

effective tapings which depend on a good cast house practice.

Hydro pneumatic drill machines are used to drill the tap hole up to 2 m into the

hearth to tap the metal & slag. Oxygen lancing through mild steel pipes is resorted

to, if taping is not possible by drilling alone. Hydraulic powered mud guns are used

to close the tap hole after casting is over with anhydrous tap hole mass which get

quickly hardened inside the tap hole. The main components of cast house is the tap

hole, troughs, iron runners, slag runners, iron & slag spouts, mud gun and drill

machine.

Cast House Slag Granulation Plant.

BF 1 and 2 both have Cast House Slag Granulation Plant (CHSGP) where the slag

after beingseparated from iron in troughs, is diverted to the granulation plant.

Major units of CHSGP arehot runner, old runner, Blowing box, Receiving hopper,

Dewatering drum & disposal belts.As the Hot slag flows down from the Hot

runner, several water jets from the blowing box, breakthe slag stream into droplets

&carried them into a receiving hopper as a slurry. The slurryfalls on wire nets and

paddles of a rotating drum, wherein water passes through and goes to thehot water

tank whereas the granulated slag is captured by the paddles, which move along

withthe drum rotation. When the paddles come over a belt running at the center of

the drum, thegranulated slag falls into the conveyor and is carried away to the

disposal yard. The yield ofgranulated slag of CHSGP is around 90%. It has been

designed by M/s Paul Wurth. Granulated slag is a major raw material for Portland

slagcement. Therefore by granulating slag not only is the waste material used

economically, it alsoavoids environmental problem that is associated with liquid

slag dumping.

Gas Cleaning Plant (GCP)

BF1 and 2 both have dedicated GCP to clean the BF Gas coming from furnace.

The BF gasleaving from top of BF is having about 20 25 g / Nm3 dust. BF gas is subjected tosuccessive cleaning in dust catcher (by changing the direction of the

flow of the gas), ventury scrubber (washing with water sprays) and Electrostatic

precipitator (by ionizing the dust particle byapplying high potential to electrodes),

where by dust content is reduced to the extent of 4 to 6g/Nm3.

COKE OVEN PLANT

Coal carbonization is used for processing of coal to produce coke using

metallurgical grade coal.

Coal carbonization involves heating of coal in the absence of air. Coke making

process is multistep complex process and variety of solid liquids and gaseous

products are produced which contain many valuable products. Various products

from coal carbonization in addition to coke are coke oven gases, coal tar, light oil,

and aqueous solution of ammonia and ammonia salt.

Coke oven gases are about 310-340 cubic meter per tone of dry coal which

contains gaseous products coal tar,vapors, light oil and water. With the

development of steel Industry there has been continuous development in coke oven

plant since latter half of nineteenth Century to improve the process conditions,

recovery of chemicals and environmental pollution control strategies and energy

consumption measures.

Carbonization can be carried out at low temperature or high temperature. Low

temperature carbonization is used to produce liquid fuels while high temperature

carbonization is used to produce gaseous products.

Low temperature carbonization (450-750 degree C): In low temperature

carbonization quantity of gaseous product is less while liquid products are large.

High temperature carbonization (above 900degree C): In high temperature

carbonization, the yield of gaseous product is more than liquid products with

production of tar relatively low.

In any integrated steel plant, Coke Oven Department is the first production unit.

Coke is

required in Blast Furnace for reducing iron ore (Fe2O3) to molten iron, which is

also termed as

Hot Metal. The major advantages of using coke in Blast Furnace are:

It is strong & hard and can withstand the abrasive action inside the blast

furnace and remains in solid form till it reaches the tuyere zone.

Because of its strength, it can take the load of the burden above it.

It is porous which allows good contact between the carbon (present in coke) & oxygen in air.

It is uniform in size for better distribution inside the furnace.

It is having a high heating value.

The Coke

Coke is made from coal. Normally two varieties of coals are available in the earth's

crust.

Non-coking coal Coking coal

India has vast reserve of Non-coking coal, which is generally used for power

generation by Thermal Power Plants . Coking coal is scarce, and is used form

metallurgical purpose only.

When coking coal is heated in the absence of air, pyrolytic cracking of coal

occurs with the evolution of number of volatile products like Ammonia, Tar,

Benzol and Coke Oven gas. The solid carbonaceous residue is called coke which is

hard dense & porous. The residue of non-coking coal does not agglomerate

butremains in powder form.

Coal Blending:

Coking coal is sub-divided into two categories depending upon its coking

characteristics.

(i) Prime Coking Coal (PCC)

(ii) Medium Coking Coal (MCC)

In India, the availability of PCC coal is scarce and hence its usage is also restricted.

Further due to inherent high ash content, the coke made from above coal also has

high ash rendering it unsuitable for use in Blast Furnace. In order to lower the ash

in Indian coals, it has to be suitably blended with low ash imported coking coals.

Two varieties of coals are usually imported primarily from Australia, USA & New

Zealand.

Blast furnace requires coke of uniform size, high mechanical strength, and porosity

with minimum volatile matter and minimum ash. Coking coal may be diveded on

the basis of their coking properties: prime coking coal, medium coking coal, semi

coking coal. The prime coking coal produce strong metallurgical coke while coals

of other groups yield hard coke only the concentration of moisture ash, sulphur and

sometime phosphorous and ash fusion temperature are important in determining

the grade of coking coal since they influence the quality of coke produced. Low

moisture, ash, sulphur and phosphorous content in the coal are desirable for

production of good quality coke. The desired analysis of typical coal charge to

coke oven is.

Ash content 16%0.5%

Moisture 6% - 7%

Volatile matter 22%-25%

Fixed Carbon 58%-60%

Sulphur 0.56%

Phosphorus 0.009%

Some of the other factors affecting quality of coke are rank of coal, particle size,

bulk density, weathering of coal, coking temperature and coking rate, soaking time,

quenching practice.

Coal Preparation

Coal as it comes from the mine ranges in size from large lumps to dust and is

known as "Run of Mine". This coal contains a lot of impurities which are to be

removed before it can be used. "Run of Mine" coal is sent to washery for

cleaning. After removal of gangue material the coal is sent to steel plants in box

wagons. Imported coking coal is brought through sea route, and is unloaded in

ports from where it is loaded in box wagons & dispatched to all steel plants.

The Coking Process

The carbonization of coal is carried out at high temperature in long, narrow silica-

brick chambers called ovens in which coal is coked by the combustion of fuel gas

in flues built in the refractory brick walls which separate the ovens.Numbers of

ovens are placed side by side and together it is called a Battery.The walls of the

ovens are maintained at a temperature of >1000C by burners which are located

inside the walls. Here CO gas, BF gas or mixed gas are used as fuel for

maintaining the wall temperature. The annular spaces between the walls are filled

with coal taken from coal towers. The coal is indirectly heated for a period 20 to 23

Hrs. All volatile

matters present in coal escape. The residue coke is pushed out from the oven,

quenched with water to prevent combustion of coke and dumped into a wharf.The

empty oven is again refilled with coal & the process continues. The by-products of

carbonization namely Ammonia, Benzol, Tar & Coke Oven gas generated during

the process are sent to By-Product division for removing impurities. The gas after

cleaning is used as fuel throughout the steel plant.

BY PRODUCT DIVISION

The By Product Division Plant at Bhushan Steel serves two purposes:

(i) To recover the primary products like ammonia, crude tar to clean and cool the

Coke Oven gas, so that it can be conveniently used for heating purpose.

(ii) To further process and refine the crude tar to yield a number of marketable

Products .

Ammonium Sulphate Plant

The gases from exhaust goes to ESP where tar is separated and the tar free gases

goes bubbled through dil. solution of sulphuric acid in saturators. Ammonia is

absorbed by sulphuric acid and ammonium sulphate is formed. One tonne of coal

yields about 0.3 tonne tar and 5-8 gm ammonia per m3 of gas.

Benzoyl Recovery Section

The gases from saturator goes to series of coolers and then to benzoyl scrubbers

where benzoyl is scrubbed with wash oil. Benzoyl crude oil goes to benzoyl

recovery section where benzoyl is removed and the wash oil after treatment is sent

to the scrubbers. Crude Benzoyl thus recovered goes to benzoyl rectification plant.

Light crude benzoyl contains low boiling sulphur compound, BTX, solvents, still

bottom residue. Benzoyl after washing and neutralization with caustic soda is

send to benzoyl column for fractionating into different fraction.

Coal Tar Distillation

Coal tar is produced as result of high temperature carbonization and is a viscous

dark brown product with characteristic odour and consists of about 300 different

products. some of the major constituents are the aromatics and heterocyclic

compounds; benzene, toluene, xylene, phenol cresol, naphthalene, anthracene,

phenanthrene, pyridine, carbazole, coumarone etc..

OXYGEN PLANT

Oxygen Plant is used to produce liquefied Oxygen, Nitrogen and Argon at

Cryogenic Temperature as well as gaseous Nitrogen and Oxygen too. It uses

atmospheric air as its raw material. Atmospheric air is converted into liquid

Oxygen, Nitrogen and Argon with the help of Adiabatic Compression, the

principle which is used in Cooling System.

USES OF PRODUCTS OF OXYGEN PLANT

1. Oxygen- Used for ignition at high pressure in SMS (Steel Melting Shop), BF

(Blast Furnace), CO (Coke Oven) etc.

2. Nitrogen- Used for purging in SMS, for cooling purpose in BF, BOF, CRM,

HSM as well as a carrier for various materials in different shops.(eg. used as a

carrier in PCI (Pulverized Coal Injection).

3.Argon- Used in BOF, SMS only.

VARIOUS COMPONENTS OF BOP

1. AIR SEPERATOR- In Air Separator CO2, moisture, and hydrocarbons are

separated with the help of various processes. CO2 is removed by freezing at a

temperature of -150 degree Celsius, moisture is removed with the help of use of

absorbent and Molecular Sieve method is used of the removal of hydrocarbons.

2. BOOSTER/COMPRESSOR- features-

50 gauge pressure

Maximum refrigeration occurs here.

3.MAIN HEAT EXCHANGER- features-

Counter current type

Air and liquid O2 and N2 is passed for heat

exchange.

4.TURBINE- features-

Cooling effect

Constant Speed

Iso-entropy

-110degree Celsius inlet temperature

-170degree Celsius outlet temperature.

LIME PLANT

Basically limestone is used as a slag former. Dolomite is used as a slag former,

slag modifier and as a refractory material.

The process of iron making is the reduction of iron ore to produce iron. Iron ore

normally contain gangue materials such as silica (SiO2), Alumina (Al2O3) along

with sulphur (S) and Phosphorus (P). Removal of these impurities is done by

combining the gangue materials with CaO and/or MgO to form slag which consists

of low melting point complex compounds such as calcium silicate, calcium

aluminate etc. CaO and MgO is charged along with other raw materials in the form

of lime stone and dolomite or it is charged through sinter where again fines of

limestone and dolomite is used. This limestone or dolomite is first decomposed

into CaO or CaO+MgO which then combine with gangue to form slag. Further

lime from limestone reacts with sulphur present in the raw materials to form CaS

which goes into slag.

During pretreatment of hot metal in desulphurization plant lime is an essential

component of the desulphurizing compound. During steel making high basicity of

the steel making slag is being maintained with the help of lime. Lime is also used

in secondary steel making. In steel melting shop, fettling of the lining as well as

patching is done with dolomite based compounds. Calcined dolomite is also used

in converters to maintained MgO levels in the steel making slags. It also acts as a

slag modifier in case of slag splashing. Burnt dolomite is also used for making

refractory bricks for the purpose of lining in steel melting shop.

There are three types of kilns used in Lime Plant :

1. Single Shaft Kiln

2. Rotary Kiln

3. Twin Shaft kiln

Twin Shaft Kiln has been further specified into 4 types-

1.Circular

2.Rectangular

3.Stretch O [Used in BSL]

4.D-type

QUANTITY OF LIME AND DOLO REQUIRED IN BSL ANGUL-

1) 60 kg of Lime per ton of steel.

2) 40kg of Dololime per ton of steel.

USES OF LIME

1) SMS (Calcined) Lime-10 to 80mm.

2) Sinter Plant-0 to 10mm.

SOURCES OF RAW MATERIAL (LIMESTONE)-

1)Katni (MP)

SiO2 content is 3.5% (required 1%) hence it is not suitable.

2)Rajasthan

Present in less quantity as well as high cost make it unsuitable.

3)Dubai

Used in Bhushan Steel Plant.

BASIC OXYGEN STEEL-MAKING

Basic oxygen steelmaking (BOS, BOP,BOF, and OSM), also known as Linz-

Donawitz-Verfahren.

steelmaking or the oxygen converter process is a method of

primary steelmaking in which carbon-rich molten pig iron is made into steel.

Blowing oxygen through molten pig iron lowers the carbon content of thealloy and

changes it into low-carbon steel. The process is known

as basic because fluxes of burnt lime ordolomite, which are chemical bases, are

added to promote the removal of impurities and protect the lining of the converter.

The process was developed in 1948 by Robert Durrer and commercialized in

19521953 by Austrian VOEST and AMG. The LD converter, named after

the Austrian towns Linz and Donawitz (a district of Leoben) is a refined version of

the Bessemer converter where blowing of air is replaced with blowing oxygen. It

reduced capital cost of the plants, time of smelting, and increased labor

productivity.

At SMS 3 in BSL there are 2 top blown oxygen converter called as LD Converter

(L&D stands for Linz and Donawitz) or Basic Oxygen Furnace (BOF)/converter is

having capacity 220MT.

Basic oxygen steelmaking is a primary steelmaking process for converting the

molten pig iron into steel by blowing oxygen through a lance over the molten pig

iron inside the converter. Exothermic heat is generated by the oxidation reactions

during blowing.

The basic oxygen steel-making process is as follows:

1. Molten pig iron (sometimes referred to as "hot metal") from a blast furnace is poured into a large refractory-lined container called a ladle;

2. The metal in the ladle is sent directly for basic oxygen steelmaking or to a pretreatment stage. High purity oxygen at a pressure of 100-150 psi (pounds

per inch square) is introduced at supersonic speed onto the surface of the

iron bath through a water-cooled lance, which is suspended in the vessel and

kept at few feet above the bath. Pretreatment of the blast furnace hot metal is

done externally to reducesulphur,silicon, and phosphorus before charging

the hot metal into the converter. In external desulphurising pretreatment,

a lance is lowered into the molten iron in the ladle and several hundred

kilograms of powdered magnesium are added and the sulphur impurities are

reduced to magnesium sulphide in a violent exothermic reaction. The sulfide

is then raked off. Similar pretreatments are possible for external

desiliconisation and external dephosphorisation using mill scale (iron oxide)

and lime as fluxes. The decision to pretreat depends on the quality of the hot

metal and the required final quality of the steel.

3. Filling the furnace with the ingredients is called charging. The BOS process is autogenous, i.e. the required thermal energy is produced during the

oxidation process. Maintaining the proper charge balance, the ratio of hot

metal, from melt, to cold scrap, is therefore very important. BOS vessel can

be tilted up to 360 and is tilted towards the deslagging side for charging

scrap and hot metal. The BOS vessel is charged with steel or iron scrap

(25%-30%) if required. Molten iron from the ladle is added as required for

the charge balance. A typical chemistry of hotmetal charged into the BOS

vessel is: 4% C, 0.20.8% Si, 0.08%0.18% P, and 0.010.04% S all of which can be oxidised by the supplied oxygen except sulphur (requires

reducing condition).

4. The vessel is then set upright and a water-cooled, copper tipped lance with 3-7 nozzles is lowered down into it and high purity oxygen is delivered at

supersonic speeds. The lance "blows" 99% pure oxygen over the hot metal,

igniting the carbon dissolved in the steel, to form carbon

monoxide and carbon dioxide, and causing the temperature to rise to about

1700C. This melts the scrap, lowers the carboncontent of the molten iron

and helps remove unwanted chemical elements. It is this use of pure oxygen

instead of air that improves upon the Bessemer process, as the nitrogen (a

particularly undesirable element) and other gases in air do not react with the

charge.

5. Fluxes (burnt lime or dolomite) are fed into the vessel to form slag, to maintain basicity more than 3 and absorbs impurities during the steelmaking

process. During "blowing," churning of metal and fluxes in the vessel forms

an emulsion that facilitates the refining process. Near the end of the blowing

cycle, which takes about 20 minutes, the temperature is measured and

samples are taken. A typical chemistry of the blown metal is 0.30.9% C, 0.050.1% Mn, 0.0010.003% Si, 0.010.03% S and 0.005-0.03% P.

HOT STRIP MILL (HSM)

Hot Strip Mill (HSM) is a fully continuous millcomprising of 2 Reheating Furnace

of capacity 600 T/Hr. 1 Roughing Mill i.e. 4 highReversing Mill, Coil Box, Six

Stand continuous 4 High Finishing Mill in tandem and 2 Hydraulic down coiler.

Coil box, Quick Work Roll, Change Roll in Finishing Mill, High Speed Descaler,

Reheating Furnace were installed under modernisation for rolling heavier and

longer slabs to coils. The HSM was originally designed and commissioned on

turnkey basis by SMS SIEMAG, West Germany and mill driven by SIEMENS.

It is designed to roll the slabs of thickness 180 250 mm to finished strip gauge of

1.6 to 5mm in 800 1680 mm width. The annual production capacity of the mill is

5.2 Million Tons of slab weight.

The HSM being an integrated unit of BSL supplies Hot Rolled Coils as input

materials to its downstream customers such as Cold Rolling Mills and also to

Dividing Line. It also caters to the requirements of external customers.

Sections:

1. Slab Yard

2. Reheating Furnace

3. Roughing Mill

4. Coil Box

5. Finishing Mill

6. Down Coiler

7. Coil Yard

8. Roll Shop

9. Utility

Slab Yard

All the slabs are produced are stored in six slab yards. If required slabs are further

cut to required length before being dispatched. There are two types of slabs hot

slab and cold slabs both type of slabs are proceed to reheating furnace via shifting

car.

Reheating Furnace

Two Walking Beam Reheating Furnaces of 600 T/Hr. capacities were

commissioned during modernization of HSM. Each Furnace is having 9 zones

(Preheating zone top & bottom, heating zone top & bottom and Soaking zone top

& bottom). Preheating and heating zones are having dual firing system with mixed

gas and furnace oil, where as Soaking zones are having only mixed gas firing.

Slabs are put on charging side roller table from depiler with the help of depiler

crane with tong / EOT crane with magnet. Each slab is weighed on Charging

Roller Table Weigh Bridge. Spotting of slab is done with laser beam and after

spotting, the slab is pushed inside the furnace with the help of pusher. Movement

of slabs inside the furnace takesplace by the movement of walking beams called

movable skid pipes (4 nos.), which move in lift,forward, lower and reverse

direction in one complete cycle.

There are also 4 nos. of fixed skid pipes inside furnace on which the slabs rest

while in stationary state. Tracking and heating of slabs to required temperature is

done by computerized thermal model. Once the slab reaches the discharge end, it is

detected in the discharge pulpit by the Gamma ray system provided at the

discharge side. After slab detection and getting clearance from cabin, slab is

extracted from furnace by extractor and is placed on the discharge roller table and

sent to through primary descaler for rolling.

TYPE- WALKING BEAM FURNACE:

No. of Fce: TWO (FURNACE No. 1 & 2)

FUEL: MIXED GAS (COG & BOF)

CAPACITY: 600 TONS / HOUR (SLAB Wt.)

Primary Descaler

To remove the scale formed on the surface of slabs during its heating inside

furnaces, water jet at high pressure of 145-160 Bar is applied on top and bottom

surface of slabs.

Roughing Mill

Roughing stand is reversing type 4 High Mill with full automation. It has twin

drives with AC motors (with Cyclo-Converters) of 3000 kW each.

Heated slabs are given 7 passes maximum and reduced to desired thickness and

sent to isvertical edger for width control by squeezing slab width up to 230 mm.

Slabs after rolling at are called Intermediate Transfer Bars.

Coil Box

The Intermediate Transfer Bar after Roughing Mill travels through the Delay Table

to Coil Box, where it is coiled in hot condition and subsequently uncoiled to feed

tail end of transfer bar into the Finishing Mills. In general coils with finish gauge

less than 35 mm are taken through coil boxwhere as for finish gauge more than 35

mm are taken directly to Finishing Mills in Pass Through Mode (PTM). The head

end of the transfer bar/ Coiled transfer bar is cropped at Crop Shear and after

descaling at scale washer pinch roll, the transfer bar enters the Finishing Mill for

rolling to the required gauge.

Advantages of Coil Box Technology :

1. Uniform temperature of the transfer bar

2. Reduced power rating and lower energy consumption in the finishing train

3. Shorter total length of hot strip mill

4. Smaller number of finishing stands

5. Optimum rolling time adjustment between roughing train and finishing train

6. Extended range of dimensions

7. Improved strip quality

8. Improved thickness control

Finishing Mill

The bar enters 6 stands, 4 high continuous mills where reduction is given to the bar

in each stand. In between the stands, loopers are provided to maintain constant

tension. There are two R-30 process computers of Siemens make. One is speed

computer, for regulating the speed of all mill stands, ROT, coiler wrapper rolls and

mandrel. The other one is AGC computer for automatic gauge control to get

uniform thickness of the strip. AGC hydraulic cylinders are provided in last four

stands F3, F4, F5, F6. After rolling in finishing stands, the strip temperature is

controlled on Run OutTable (ROT) by laminar cooling by water through cooling

banks.

Down Coiler

The strip moves over ROT and gets coiled in one of the two hydraulic down

coilers. There are two Hydraulic down Coilers each having three Wrapper Rolls.

Coils are taken out from coiler and placed on Conveyor. The hot coils are

circumferentially strapped on the body by Automatic Strapping Machine and

marked for identification. Necessary samples are cut fromthe coils for its testing.

Coils are then transferred to coil yard where coils are allowed to cool toroom

temperature before they are sent for further processing in different units of BSL or

to the external customers of HR Coils. The capacity of the Coiler is 35 Tons (max.)

coil weight.

Parts of Down Coiler:

1. Top & Bottom Pinch Roll

2. Three Numbers of Wrapper Rolls.

3. One Mandrel with Two Stages of Expansion.

4. Coil Car for Taking out The Coil

5. Centering Arm for Lifting Of Coils

6. Tilter for Tilting the Coil to the Conveyor

7. Mandrel Dia: 762 740 725 MM

Hold Down Roll for Preventing Tail end Shifting

Coil Yard

Shipping Area dispatch of coils to internal as well as external customer. The HR

sheets are shipped through different areas by RailWagaon and Trucks.

Slitter Line:Hot Rolled Coils meant for converting into HR plates are uncoiled in

Uncoiler, levelled in Leveller-I and then sheared at Dividing Shear to the required

lengths as per requirement of the customer. After shearing, the plates are levelled

once again in Leveler-II and piled in Pilers. There is also provision of plate

inspection for both the sides each plate at Plate Turn overDevice (PTOD) before

Piler

Roll Shop

Roll are used for rolling purpose in rolling mill.The are made of High Speed Steel

(HSS). Rollers are subjected to very high temps and continuous colling so the

roller gets hard. To soften the outer surface and making it reusable for rolling

purpose grinding is performed. The CNC grinding machine sense the hardened

thickness are remove the material so we can reuse it again.

Utility

In the HSM the equipments and machines used are subjected to very high

temperature. In the descaler very high pressure of water is required for descaling

the slab. Water used in HSM for various purpose and treatment of water before

making it usable for next cycle comes under Utility Section. There are many tanks,

reservoir for storing the water. Many filters for water treatment and motors are

used for suppling the water and providing the required pressure in HSM.

COLD ROLLING MILL

Cold Rolling Millis one of the complex units of BHUSHAN STEEL PLANT,

producing bulk amounts of quality finished steel. Purpose of cold reduction is to

achieve the following:

1. A reduction in the thickness of the final product. 2. A designed surface finish. 3. Desirable mechanical properties. 4. Close dimensional tolerance. 5. Producing as per customer requirements.

The input to Cold Rolling Mills is the Hot Rolled Coils (HR Coils).

PICKLING LINE

The first unit of CRM after HSM is Pickling line. During the hot rolling process, a

layer of

Scale(Iron oxides) is formed on the strip surface, which must be removed prior to

further

processing. This removal of scale is performed by physically breaking of scales by

mechanical means & then chemically treating the surface of hot rolled strip with an

acid. The process, called Pickling, removes the remaining scale by dissolving it

in acid. In CRM, BSL HR Coils are treated chemically by hot dilute Hydrochloric

acid to remove the oxide scales, so that it can be further rolled to thinner gauge.

The Acid Concentration, Salt Concentration are shown below.

Tank No. Acid

Concentration(HCL %)

Salt

Concentration(gm/liter)

1 3 TO 5 MAX 200

2 5 TO 10 150

3 10 TO 15 100

4 15 TO 18 50

The temperature is controlled by Steam heating. The spent liquor from Tank is sent

to the Acid Regeneration plantwhere the Ferric chlorideis separated by

Crystallisation and Refrigeration Process and the acid is brought to original

concentration by adding new makeup acid.

COLD ROLLING :

The next operation is the cold reduction of the pickled coil. After pickling, the

main cold rolling

Operation, i.e. cold reduction, is performed in cold reduction mill where pickled

strip is fed

Between very hard rolls. This is done in a single reversing stand, equipped with an

uncoiler and a coiler, by making several passes in reversing directions.

COLD REVERSING MILL-1 (TOTAL 3 MILL )

This is one, 4-Hi reversing mill which makes 2-5 passes to reduce thickness. It has

a single stand with reels located on either side of the mill. Steel strip is passed back

and forth till the required thickness is obtained. On the entry side of the mill,

means are provided for the coil to be threaded through the mill to the tension reel

on the delivery side. After the first pass, the tail end of the coil coming from the

uncoiler is gripped by the second tension reel on the entry side of the mill. In each

unit, the reel serving as the pay-off unit is operated as a generator, providing back

tension to minimise the rolling friction and feeding of the coil into drive reel

motor. In the last pass, the tail end of the coil is released from the unwinding

tension reel. This is one, 4-Hi reversing mill which makes 2-5 passes to reduce

thickness. It has a single stand with reels located on either side of the mill. Steel

strip is passed back and forth till the required thickness is obtained. On the entry

side of the mill, means are provided for the coil to be threaded through the mill to

the tension reel on the delivery side. After the first pass, the tail end of the coil

coming from the uncoiler is gripped by the second tension reel on the entryside of

the mill. In each unit, the reel serving as the pay-off unit is operated as a generator,

providing back tension to minimise the rolling friction and feeding of the coil into

drive reel motor. In the last pass, the tail end of the coil is released from the

unwinding tension reel.

PRODUCTS

1. CRCA (COLD ROLLED CLOSED ANNEALED)

PARAMETERS TECHNICAL DETAILS/SPECIFICATIONS

Thickness (mm) 0.10 to 4.00

Width (mm) 10 to 1700 (Max)

Coil Weight (MT) Up to 30 MT (7 to 18

kg/mm width)

Surface Finish Super Bright, Bright, Dull & Matte. (RaValue

with controlled Rmax on request).

Grades

Specifications - As per JIS/BIS/ ASTM/EN

Standards

Low Carbon CRCA Grades Super EDD/DD/D (SPCX, SPCEN, SPCD,

SPCC) non-aging, IF-HighStrength steel(IF-

HSS), High Strength Low Alloy Steel (HSLA),

viz., ST -42,ST-45, ST-52, SAPH-400/41O, Steel

for Porcelein Enammeling, CorrosionResistant

Steel, viz., Tin Mill Black Plate (TMBP)

Medium & High Carbon CRCA Grades C- 30, C-40,MC -ll,EN - 8, for spring steel

application, C-55,MC-12, EN- 9 C-62,C-60, C-

80,HC-14,EN-42J

ELECTRICAL Grades Elec -I, Elec-n, Elec-nI,

Semi Processed Elect. Steel

OTHER CRCA Grades Case Hardening Steel- 15Cr3, SAE 1010, SAE

1012

Through Hardening Grades- SAE 1040, SAE

1045, 1055, 1065, 1080, 1541

H.R PICKLED/ SKIN PASSED & OILED

Thickness Up to 3.00 mm

3.00 mm - 4.00 mm

Above 4.00 mm

Width for coil 50 mm - 1700 mm

50 mm - 1700 mm

50 mm - 1700 mm

H.R PICKLED/ SKIN PASSED & OILED

Thickness Up to 3.00 mm 3.00 mm - 4.00 mm Above 4.00 mm

Max. Width for Cut Size 1500 mm 1250 mm 600 mm

Width for Coil 50 mm - 1700 mm 50 mm - 1700 mm 50 mm - 1700 mm

Thickness (mm) 0.10 t0 4.00

Width (mm)

10 to 1700 (Max)

Cut- to -Length (mm) Max. Width for Cut Size

PROCESS ROUTE OF CRCA MATERIAL

Coil Weight (MT) Up to 30 MT (7 to 18 kg/mm width)

Surface Finish Super Bright, Bright, Dull & Matte. (RaValuewith controlled Rmax on request).

Grades

Specifications - As per JIS/BIS/ ASTM/EN Standards

Low Carbon CRCA Grades Super EDD/EDD/DD/D (SPCX, SPCEN, SPCD, SPCC) non-aging, IF-High Strength steel (IF-HSS), High Strength Low Alloy Steel (HSLA), viz., ST -42, ST-45, ST-52, SAPH-400/41O, Steel for Porcelein

Enammeling, Corrosion Resistant Steel, viz., Tin Mill Black Plate (TMBP)

Medium & High Carbon CRCA Grades C- 30, C-40,MC -ll, EN - 8, C-55, MC-12, EN- 9 C-62, C-60, C-80, HC-14, EN-42J

ELECTRICAL Grades Elec -I, Elec-n, Elec-nI, SemiProcessed Elect. Steel

OTHER CRCA Grades Case Hardening Steel- 15Cr3, SAE 1010, SAE 1012 Through Hardening Grades- SAE 1040, SAE 1045, 1055, 1065, 1080, 1541

(A) ANNEALING PROCESS:

Cold rolled strip as such is not suitable for drawing and deep drawing operations

due to

lack of ductility. The loss is caused by the work hardening effects of cold

reduction. After

the cold reduction process, the internal structure of the steel is as follows:

1. The grains in the steel have been elongated in the direction of rolling.

2. Longitudinal rolling stresses have been set up in the steel and any foreign matter

present in the core zone of the rimmed steel have been rolled out into the form of

segregated bands.

3. The steel being very hard and brittle will fracture very easily in the direction

oftransverse to the rolling.

4. Myriads of stress points are found to be present in each grain.

Now these CR coils are to be annealed to remove the stresses. The various

purposes of

annealing are listed below:

1. To improve the mechanical properties.

2. To increase ductility, particularly to restore the normal conditions of steel after

cold

working.

3. To relieve the internal stresses.

4. To remove chemical non-uniformity.

5. To change the micro-structure of steel from the distorted structure of cold

worked steel

to the equi-axed structure.

(B) SKIN PASSING:

Skin passing is a cold reduction method and the steel surface or skin is hardened by

cold Working, keeping the steel core soft & ductile. In Cold Rolling Mills of BSL,

one single stand 6- high mills and one twin stand 4-high mill have been installed.

Skin Pass Mills ( SP 1 To 3)

The softened or annealed Steel is then skin passed or Temper rolled with the aim of

imparting a work hardened skin to the steel strip leaving its core soft in the

annealed condition.

Following are the main advantages of Skin Passing.

a. To impart different surface finishes to the strip required for painting, coating

enamelling etc.

b. To give a flat surface to the strip.

c. To impart the desired mechanical properties to the strip.

d. To keep the strip free from stretcher strains and luder bands that may develop

during the forming operations.

Applications:

Used for making steel furniture, refrigerator bodies, automobile bodies, railway

coach paneling, drums, barrels, deep drawing and extra deep drawing available as

per Indian Standard specifications. Besides CR coils and sheets CRM, BSL also

produces Galvanised plain and corrugated sheets.

2. GALUME

Introduction

BHUSHAN has set up the technology of manufacturing a very

new coated product called BHUSHAN GALUME being the

brand name. This alloy coating consists of 55% Aluminum and

43% Zinc and the balance contains Silicon around 1.5% to

affect excellent adhesion to the steel substrate.

Galume Production Technology

This coating is given on the cold rolled substrate processed from selective Hot

rolled coils with selective chemistry for getting the desired mechanical properties

specified by the customers. The Galume product is made by the continuous hot dip

process. The cold rolled coils are welded end to end and passes through 3 stage

degreasing section for achieving excellent cold rolled strip surface. The coating

system is 2 pot system- premelting pot and the main coating pot. The bath

chemistry is continuously controlled and monitored at the pre melting pot which

continuously feeds the main coating pot through the refractory tunnel.

Galume market:

We have produced about 3,00,000 MT as on date from the commissioning of our

Galume production. Our line is fully booked and hopes to produce continuously

about 1,30,000 MT per month.

In India, we are supplying Galume and Pre-painted Galume to reputed companies.

To mention few of them, we supply to Kirby, Tigger steels, Lloyds Insulation,

Multicolor, GSP Power, ERA Metal Bldg, Unimet Profiles, Isolloyds Eng, Color

Roofing, Hawells India Ltd, MG Industries, Ganga roofers, Metco Roof-Pondy,

Century wells and others. Our 80 % of production is exported to various counties

all over the world, USA, European Countries and Spain, South Africa, Italy and

South East Asian countries. There are no Indian standards for this product. We

have established our product in international market against ASTM / EURO and

AS standards. It is imperative to mention to you that now our product or brand is

preferred over Arcelor and Blue scope. Some of our Global direct customers are

Defer co-USA, NOVO Steel USA, Toyota Tshuho, America Nialco SA Belgium,

Savogni Italy, Gibbs Steel, South Africa, Arcelor BarbaDOS, Global Roofing-

Durban and others.

3. GALAVANISED

Hot-dip galvanization is a form of galvanization. It is the process of

coating iron and steel with a layer of zinc by immersing themetal in a bath of

molten zinc at a temperature of around 840 F (449 C). When exposed to the

atmosphere, the pure zinc (Zn) reacts with oxygen (O2) to form zinc oxide (ZnO),

which further reacts with carbon dioxide (CO2) to form zinc carbonate (ZnCO3), a

usually dull grey, fairly strong material that stops further corrosion in many

circumstances, protecting the steel below from the elements. Galvanized steel is

widely used in applications where corrosion resistance is needed without the cost

of stainless steel, and can be identified by the crystallization patterning on the

surface (often called a "spangle").

Galvanized steel can be welded; however, one must exercise caution around the

resulting toxic zinc fumes. Galvanized steel is suitable for high-temperature

applications of up to 392 F (200 C). The use of galvanized steel at temperatures

above this will result in peeling of the zinc at the inter metallic layer. Electro

galvanized sheet steel is often used in automotive manufacturing to enhance the

corrosion performance of exterior body panels; this is, however, a completely

different process which tends to achieve lower coating thicknesses of zinc.

Like all other corrosion protection systems, galvanizing protects steel by acting as

a barrier between steel and the atmosphere. However zinc is a more electronegative

metal in comparison to steel, this is a unique characteristic for galvanizing which

means that when a galvanized coating is damaged and steel is exposed to the

atmosphere, zinc can continue to protect steel through galvanic corrosion (often

within an annulus of 5 mm above which electron transfer rate decreases).

Application:

Galvanizing Sheet is used extensively for roofing, paneling, industrial sheeting, air

conditioning ducts and structural applications.

Shipping Section:

All Cold Rolled products like CR Coils/Sheets are packed, weighed and dispatched

through Road or Rail Wagons. ETP & GP/GCpackets are packed in the line itself.

Weighment and loading is done in Shipping Section.

POWER PLANT

Introductory overview

In a coal based power plant coal is transported from coal mines to the power

plant by railway in wagons or in a merry-go-round system.Coal is unloaded

from the wagons to a moving underground conveyor belt. It is taken to the

Crusher house and crushed to a size of 20mm . Raw coal from the raw coal

bunker is supplied to the Coal Mills by a Raw Coal Feeder.coal air mixture is

burnt in the boiler in the combustion zone.The boiler is a water tube boiler .

Water is converted to steam in the boiler and steam is separated from water in

the boiler Drum. The saturated steam from the boiler drum is taken to the Low

Temperature Superheater, Platen Superheater and Final Superheater

respectively for superheating. The superheated steam from the final

superheater is taken to the High Pressure Steam Turbine (HPT). In the HPT the

steam pressure is utilized to rotate the turbine and the resultant is rotational

energy.The outlet of the Turbine is sent to the condenser for condensing back

to water by a cooling water system.This condensed water is collected in the

Hotwell and is again sent to the boiler in a closed cycle. The rotational energy

imparted to the turbine by high pressure steam is converted to electrical energy

in the Generator.

Principle

Coal based thermal power plant works on the principal of Modified Rankine Cycle.

Typical diagram of a coal-fired thermal power station

1. Cooling tower 10. Steam Control valve 19. Superheater

2. Cooling water pump 11. High pressure steam

turbine

20. Forced draught

(draft) fan

3. Transmission line (3-

phase)

12. Deaerator 21. Reheater

4. Step-up transformer (3-

phase)

13. Feedwater heater 22. Combustion air

intake

5. Electrical generator (3-

phase)

14. Coal conveyor 23. Economiser

6. Low pressure steam

turbine

15. Coal hopper 24. Air preheater

7. Condensate pump 16. Coal pulverizer 25. Precipitator

8. Surface condenser 17. Boiler steam drum 26. Induced draught

(draft) fan

9. Intermediate

pressure steam turbine

18. Bottom ash hopper 27. Flue-gas stack

Boiler

A boiler is a closed vessel in which water or other fluid is heated. The fluid does

not necessarily boil. The heated or vaporized fluid exits the boiler for use in

various processes or heating applications, including water heating, central

heating, boiler-based power generation and cooking.

The lower part of the boiler has air nozzles below the sand bed and so the name

comes fluidized bed , from which air is supplied for the combustion of coal. The

bed is covered with sand due to its excellent property of heat absorption and to

maintain the heat for coal being injected. The walls of the furnace also contain air

supply for complete combustion of coal. The coal is supplied from the holes

provided on the walls of furnace. Just above the furnace walls are made of tubes

through which water flows and gets the heat from the flue gases generated by

burning coal.

Economizers

Economisers , are mechanical devices intended to reduce energy consumption, or

to perform useful function such as preheating a fluid. The term economizer is used

for other purposes as well. Boiler, power plant, heating, ventilating, and air

conditioning (HVAC) uses are discussed in this article. In simple terms, an

economizer is a heat exchanger. Economiser uses hot flue gases generated by

burning coal to pre heat water. It is a tube type heat exchanger. The main purpose

of using the economizer is to use the heat of flue gases to the maximum extent for

better efficiency.

Air preheater

An air preheater (APH) is a general term used to describe any device designed to

heat air before another process (for example, combustion in a boiler) with the