This document provides a summary of the vocational training completed by Rishav Ghosh at the Bokaro Steel Plant (BSL) operated by Steel Authority of India Limited (SAIL). It includes an acknowledgement, abstract about BSL, and sections covering the organizational profile of SAIL and key parts of the integrated steel plant including the raw material handling plant, coke oven, sinter plant, blast furnace, steel melting shop, continuous casting, and rolling mills. The training covered various processes and gave Ghosh practical knowledge of the blast furnace and steel melting shop operations.

1. REPORT ON VOCATIONAL
TRAINING (BSL)

2. Name – RISHAV GHOSH
College – JADAVPUR UNIVERSITY
Department of Metallurgical and Material Engineering
DURATION – 2 WEEKS (02/06/2014 T0 14/06/2014)
REGISTRATION NO. — 5912697

3. ACKNOWLEDGEMENT
I would like to extend our heartiest gratitude to all the officials in charge of Vocational
Training in the Bokaro Steel Plant, SAIL for giving me the opportunity to undergo
industrial training under their guidance.
I am also thankful to Mr. B.K.Singh and Mr.S. Mitra for imparting their practical
knowledge of Blast Furnace and Steel Melting Shop respectively. Without their
corroborated help, this industrial training would have been incomplete.
I also extend my gratitude to the Head of the Department, Metallurgical and Material
Engineering, Jadavpur University for granting me permission to carry out the industrial
training at BSL, SAIL.

4. ABSTRACT:
Bokaro Steel Plant - the fourth integrated plant in the Public Sector - started
taking shape in 1965 in collaboration with the Soviet Union. It was originally
incorporated as a limited company on 29th January 1964, and was later
merged with SAIL, first as a subsidiary and then as a unit, through the Public
Sector Iron & Steel Companies (Restructuring & Miscellaneous Provisions) Act
1978.
The Plant is hailed as the country’s first Swadeshi steel plant, built with
maximum indigenous content in terms of equipment, material and know-how.
Its first Blast Furnace started on 2nd October 1972 and the first phase of 1.7
MT ingot steel was completed on 26th February 1978 with the commissioning
of the third Blast Furnace. All units of 4 MT stage have already been
commissioned and the 90s' modernization has further upgraded this to 4.5 MT
of liquid steel.

5. CONTENTS
1.0 Organisational Profile…………………………………………….………….....……1
2.0 Parts of Integrated Steel Plant ….....…………………..……………………………..3
2.1 Raw Material Handling Plant(RMHP)…...…………………………………....3
2.2 Coke Oven………….………………………………………………………….4
2.3 Sinter Plant…………………………………………………………………….5
2.4 Blast Furnace………………………………………………………….……….6
2.5 Steel Melting Shop (SMS)………………………………………………….....9
2.6 Continuous Casting Shop………………………………………………….......9
2.7 Slabbing Mill…………………………………………………………………10
2.8 Hot Strip Mill………………………………………………………………...11
2.9 Cold Rolling Mill……………………...…………………………….……….11
3.0 Conclusion……………………………………………………………………...…...12

6. ORGANISATIONAL PROFILE
Steel Authority of India Limited - A Maharatna Company
Steel Authority of India Limited (SAIL) is the leading steel-making company in
India. It is a fully integrated iron and steel maker, producing both basic and special
steels for domestic construction, engineering, power, railway, automotive and
defence industries and for sale in export markets. SAIL is also among the five
Maharatnas of the country's Central Public Sector Enterprises.
SAIL manufactures and sells a broad range of steel products, including hot and
cold rolled sheets and coils, galvanised sheets, electrical sheets, structural, railway
products, plates, bars and rods, stainless steel and other alloy steels. SAIL
produces iron and steel at five integrated plants and three special steel plants,
located principally in the eastern and central regions of India and situated close to
domestic sources of raw materials, including the Company's iron ore, limestone
and dolomite mines. The company has the distinction of being India’s second
largest producer of iron ore and of having the country’s second largest mines
network. This gives SAIL a competitive edge in terms of captive availability of iron
ore, limestone, and dolomite which are inputs for steel making.
SAIL's wide range of long and flat steel products are much in demand in the
domestic as well as the international market. This vital responsibility is carried out
by SAIL's own Central Marketing Organization (CMO) that transacts business
through its network of 37 Branch Sales Offices spread across the four regions, 25
Departmental Warehouses, 42 Consignment Agents and 27 Customer Contact
Offices. CMO’s domestic marketing effort is supplemented by its ever widening
network of rural dealers who meet the demands of the smallest customers in the
remotest corners of the country. With the total number of dealers over 2000, SAIL's
wide marketing spread ensures availability of quality steel in virtually all the
districts of the country.
SAIL's International Trade Division ( ITD), in New Delhi- an ISO 9001:2000
accredited unit of CMO, undertakes exports of Mild Steel products and Pig Iron
from SAIL’s five integrated steel plants.
With technical and managerial expertise and know-how in steel making gained
over four decades, SAIL's Consultancy Division (SAILCON) at New Delhi offers
services and consultancy to clients world-wide.
SAIL has a well-equipped Research and Development Centre for Iron and Steel
(RDCIS) at Ranchi which helps to produce quality steel and develop new

7. technologies for the steel industry. Besides, SAIL has its own in-house Centre for
Engineering and Technology (CET), Management Training Institute (MTI) and
Safety Organization at Ranchi. Our captive mines are under the control of the Raw
Materials Division in Kolkata. The Environment Management Division and Growth
Division of SAIL operate from their headquarters in Kolkata. Almost all our plants
and major units are ISO Certified.
Bokaro Steel Plant - the fourth integrated plant in the Public Sector - started taking
shape in 1965 in collaboration with the Soviet Union. It was originally incorporated
as a limited company on 29th January 1964, and was later merged with SAIL, first
as a subsidiary and then as a unit, through the Public Sector Iron & Steel
Companies (Restructuring & Miscellaneous Provisions) Act 1978.
The Plant is hailed as the country’s first Swadeshi steel plant, built with maximum
indigenous content in terms of equipment, material and know-how. Its first Blast
Furnace started on 2nd October 1972 and the first phase of 1.7 MT ingot steel was
completed on 26th February 1978 with the commissioning of the third Blast
Furnace. All units of 4 MT stage have already been commissioned and the 90s'
modernization has further upgraded this to 4.5 MT of liquid steel.
The new features added in modernization of SMS-II include two twin-strand slab
casters along with a Steel Refining Unit. The Steel Refining Unit was inaugurated
on 19th September, 1997 and the Continuous Casting Machine on 25th April,
1998. The modernization of the Hot Strip Mill saw addition of new features like high
pressure de-scalers, work roll bending, hydraulic automatic gauge control, quick
work roll change,etc.
A new hydraulic coiler has been added and two of the existing ones revamped.
With the completion of Hot Strip Mill modernization, Bokaro is producing top quality
hot rolled products that are well accepted in the global market.
Bokaro is designed to produce flat products like Hot Rolled Coils, Hot Rolled
Plates, Hot Rolled Sheets, Cold Rolled Coils, Cold Rolled Sheets, Tin Mill Black
Plates (TMBP) and Galvanized Plain and Corrugated (GP/GC) Sheets. Bokaro
has provided a strong raw material base for a variety of modern engineering
industries including automobile, pipe and tube, LPG cylinder, barrel and drum
producing industries.

8. PARTS OF INTEGRATED STEEL PLANT
RAW MATERIAL HANDLING PLANT
RMHP is the area where raw material are handles and kept uniformly on bed and hence further
processed and send to the required areas in the plant.
>Materials handled-
· Coal
· Lime Stone
· Flux
>Work done in RMHP-
· Tippling (4 tipplers)
· Conveying (length range from 40 to 45 KM)
· Stacking (7 stackers)
· Reclaiming (6 reclaimer)
Raw Material handling plant is meant for transporting materials from Raw material yard/Base
mix yard to various process units of the plant. The Major Raw materials required for Iron and
Steel making are Iron ore lump, Iron Ore fines, Sized iron ore, Flux limestone / dolomite,
manganese, Quartzite coking coal, Non-coking coal ( for Boiler operation & For Pulverized coal
injection )and coke. Lump iron ores, iron ore fines and flux such as limestone and dolomite
received by railway rake are unloaded in wagon tippler and stored in open storage yard with
help of various stockyard machines.
Iron ore lump, flux such as limestone and dolomite, Coke is reclaimed by suitable stock yard
machine and are crushed in Ore crushing plant, Flux crushing plant and coke crushing plant
respectively to produce the size required. The above material is proportionately stacked by
suitable stacking machine in base mix yard and blended while reclaiming by blender reclaimer,
while preparing base mix which then transported to Sinter plant for sinter production.
For feeding material to new blast furnace, sized ore and flux is reclaimed by stock yard machine
from respective yard and conveyed by conveyor. Sinter produced in sinter plant and coke from
existing/new coke ovens is transported directly to BF-3 stock house by conveyor. Purchased
coke and necessary calcined lime from stock yard and new lime calcining plant respectively is
transported to SMS by Conveyor. The waste product from the plant is mainly dust and method
of their disposal is through dust suppression system and inter plant transportation.
The Raw Materials and Material Handling Plant receives, blends, stores and supplies different
raw materials to Blast Furnace, Sinter Plant and Refractory Materials Plant as per their
requirements. It also maintains a buffer stock to take care of any supply interruptions.
Some 9 MT of different raw materials viz. Iron ore fines and lumps, Limestone (BF and SMS
grade), Dolomite lumps and chips, hard Coal and Manganese ore are handled.
Iron ore and fluxes are sourced from the captive mines of SAIL situated at Kiriburu,
Meghahataburu, Bhawanathpur, Tulsidamar and Kuteshwar. Washed coal is supplied from
different washeries at Dugda, Kathara, Kargali and Giddi, while raw coal is obtained from Jharia
coalfields.

9. COKE OVEN
It is a shop where coal is charged and converted to coke. Here the charged coal is imported
from different countries like Australia and New Zealand.
There are 81 coal storage chambers where coal is stored and then from here coal is send to the
charging oven where coal is charged at a temperature of 900oC to 950oC.
After the coal is charged it is loaded in the quenching car which brings the charged coal to the
quenching chamber where it is charged and then it becomes coke.
The Coke Oven Complex at Bokaro converts prime coking coal from Jharia, Dugda and
Moonidih and medium coking coal form Kargali, Kathara and Mahuda, blended with imported
coal, into high quality coke for the Blast Furnaces, recovering valuable by-products like
Anthracene Oil, Benzene, Toluene, Xylene, Light Solvent Naphtha, Ammonium Sulphate and
Extra-hard Pitch in the process. Bokaro is situated in the prime coal belt of the country.
The Coke Oven battery has 8 batteries with 69 ovens each, maintained meticulously in terms of
fugitive emission control, use of phenolic water and other pollution control means.
Bokaro has five 2000-cubic metre Blast Furnaces that produce molten iron - Hot Metal - for steel
making. Bell-less Top Charging, modernized double Cast Houses, Coal Dust Injection and Cast
House Slag Granulation technologies have been deployed in the furnaces. The process of iron-
making is automated, using PLC Charging System and Computer Controlled Supervision
System. The wastes products like Blast Furnace slag and gas are either used directly within
plant or processed for recycling / re-use.
>Process—
Coal Carbonisation:
Coal is converted into coke by heating the prepared coal blend charge in the coke ovens in the
absence of air at a temperature of 1000oC-1050oC for a period of 16/19 hours. The volatile
matter of coal liberated during carbonization is collected in gas collecting mains in the form of
raw coke oven gas passing through stand pipes and direct contact cooling with ammonia liquor
spray. The gas cooled from 800oC to 80oC is drawn to Coal Chemical Plant by Exhauster. The
residual coke is pushed out of the oven by pusher car through a guide into coke bucket. The
red-hot coke is taken to coke dry cooling plant for cooling.
The main by product in the process of coke making is crude coke oven gas and this has lot of
valuable chemicals. Coal Chemical Plant recovers Ammonia (NH3), Tar and Benzol from CO-
Gas. The primary By-products from Crude CO Gas are Ammonium Sulphate (NH4)2SO4, Crude
Tar, Crude Benzol and cleaned coke oven gas. The cooled coke from CDCP (Coke Dry Cooling
Plant) is separated into 3 fractions, BF Coke i.e. +25-70 mm which is sent to Blast Furnaces,
Coke Breeze i.e. +0-15 mm which is sent to Sinter making and nut coke i.e., +15-25 mm, which
is also used in the Blast Furnaces.

10. SINTER PLANT
Charge material is put on a sinter machine in two layers, the first layer may vary in thickness
from 30 to 75 mm,a 12 to 20 mm sinter fraction is used, also referred to as the hearth layer. The
second layer, which covers the first layer, consists of mixed materials, making for a total bed
height up to 600 mm (may vary from 350 to 660 mm). The mixed materials are applied with a
drum feeder and nine roll feeders. The upper layer is evened out using a leveler. Then the charge
enters the ignition furnace, where there are two rows of multislit burners. The first zone of the
ignition furnace where eleven burners are installed is called the ignition zone, and the next part
of the ignition furnace where 12 burners are installed is called the soaking zone (also referred
to as the annealing zone). A total of 23 burners are used in the ignition furnace. The temperature
is maintained between 1150 and 1250 °C in the ignition zone and between 900 and 1000 °C in
the soaking zone to prevent sudden quenching of the sintered layer. The top 5 mm from screens
of screen house two goes to the conveyor carrying the sinter for the blast furnace and along with
blast furnace grade sinter either goes to sinter storage bunkers or to BF bunkers. Blast furnace
grade sinter consists of sinter sizes 5 to 12 mm as well as 20 mm and above.
>Advantage of Sintering
1. Better use of the huge quantity of iron ore fines generated at mines.
2. Gainful use of various metallurgical wastes like flue dust, mill scale, lime dust, sludge, etc.
3. Use of super fluxed sinter eliminates raw flux from the blast furnace burden. This leads to
considerable coke saving and productivity improvement in blast furnaces.
4. Due to the higher reducibility of super fluxed sinter, direct reduction of iron oxide is enhanced,
which contributes to further coke saving.
Sintering is a technology for agglomeration of iron ore fines into useful Blast Furnace burden
material. This technology was developed for the treatment of the waste fines in the early 20th
century. Since then sinter has become the widely accepted and preferred Blast Furnace burden
material. Presently more than 70% of hot metal in the world is produced through the sinter. In
India, approximately 50% of hot metal is produced using sinter feed in Blast Furnaces.
The major advantages of using sinter in BFs are:
 Use of iron ore fines, coke breeze, metallurgical wastes, lime, dolomite for hot metal
production
 Better reducibility and other high temperature properties
 Increased BF productivity
 Improved quality of hot metal
 Reduction in coke rate in blast furnaces
>Process-
Raw Materials – Iron ore fines (-10 mm), coke breeze (-3 mm), Lime stone & dolomite fines (-
3mm) and other metallurgical wastes. The proportioned raw materials are mixed and moistened
in a mixing drum. The mix is loaded on sinter machine through a feeder onto a moving grate
(pallet) and then the mix is rolled through segregation plate so that the coarse materials settle
at the bottom.

11. The top surface of the mix is ignited through stationary burners at 1200oC. As the pallet moves
forward, the air is sucked through wind box situated under the grate. A high temperature
combustion zone is created in the charge -bed due to combustion of solid fuel of the mix and
regeneration of heat of incandescent sinter and outgoing gases. Due to forward movement of
pellet, the sintering process travels vertically down. The different zones created on a sinter-bed
are shown in the adjoining figure.
Sinter is produced as a combined result of locally limited melting, grain boundary diffusion and
recrystallization of iron oxides.
On the completion of sintering process, finished sinter cake is crushed and cooled. The cooled
sinter is screened and + 6 mm fraction is dispatched to blast furnace and -6 mm is recirculated
as return sinter.
For feeding material to new blast furnace, sized ore and flux is reclaimed by stock yard machine
from respective yard and conveyed by conveyor. Sinter produced in sinter plant and coke from
existing/new coke ovens is transported directly to BF-3 stock house by conveyor. Purchased
coke and necessary calcined lime from stock yard and new lime calcining plant respectively is
transported to SMS by Conveyor. The waste product from the plant is mainly dust and method
of their disposal is through dust suppression system and inter plant transportation.
BLAST FURNANCE
Bokaro has five 2000-cubic metre Blast Furnaces that produce molten iron - Hot Metal - for steel
making. Bell-less Top Charging, modernized double Cast Houses, Coal Dust Injection and Cast
House Slag Granulation technologies have been deployed in the furnaces. The process of iron-
making is automated, using PLC Charging System and Computer Controlled Supervision
System. The wastes products like Blast Furnace slag and gas are either used directly within
plant or processed.
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.
>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 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

12. 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 a 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 in 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 flux .This flux can be pure high calcium
limestone, dolomitic limestone containing magnesia or a blend of the two types of limestone.
Since the limestone is melted to become the slag which removes sulfur and other impurities,
the blast furnace operator may blend the different stones to produce the desired slag
chemistry and create optimum slag properties such as a low melting point and a high fluidity.
All of the raw materials are stored in an ore field and transferred to the stock house before
charging. Once these materials are charged into the furnace top, they go through numerous
chemical and physical reactions while descending to the bottom of the furnace.
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:
1) 3 Fe2O3 + CO = CO2 + 2 Fe3O4 Begins at 450° C
2) Fe3O4 + CO = CO2 + 3 FeO Begins at 600° C
3) FeO + CO = CO2 + Fe
or
FeO + C = CO + Fe
Begins at 700° C
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.

13. 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 as follows:
C + O2 = CO2 + Heat
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:
CO2+ 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 as follows:
CaCO3 = CaO + CO2
This reaction requires energy and starts at about 900°C. 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 liquid 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 fuel in the "hot blast stoves" which are
used to preheat the air entering the blast furnace to become "hot blast". Any of the gas not
burned in the stoves is sent to the boiler house and is used to generate steam which turns a
turbo blower that generates the compressed air known as "cold blast" that comes to the
stoves.
In summary, 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. A typical hot metal chemistry follows:
Iron (Fe) = 93.5 - 95.0%
Silicon (Si) = 0.30 - 0.90%
Sulfur (S) = 0.025 - 0.050%
Manganese (Mn) = 0.55 - 0.75%

14. Phosphorus (P) = 0.03 - 0.09%
Titanium (Ti) = 0.02 - 0.06%
Carbon (C) = 4.1 - 4.4%
STEEL MELTING SHOP (SMS)
Hot Metal from the Blast Furnaces is converted into steel by blowing 99.5% pure Oxygen through
it in the LD converter. Suitable alloying elements are added to produce different types and variety
of producing steel and their byproducts.
Bokaro has two Steel Melting Shops - SMS-I and SMS-II. SMS-I has 5 LD converters of 130T
capacity each. It is capable of producing Rimming steel through the ingot route. SMS-II has 2
LD converters, each of 300 T capacity, with suppressed combustion system and Continuous
Casting facility. It produces various Killed and Semi-Killed steels.
The main function of Steel melting shop are as follows:-
• Oxygen blowing process (purging).
• Receiving hot metals from blast furnace.
• SMS 1 output—ingot form.
• SMS 2 output— slab form.
• Steel melting- process of removal of impurities like carbon and silicon.
CONTINUOUS CASTING SHOP
The Continuous Casting Shop has two double-strand slab casting machines, producing high
quality slabs of width ranging from 950 mm to 1850 mm. CCS has a Ladle Furnace and a Ladle
Rinsing Station for secondary refining of the steel. The Ladle Furnace is used for homogenizing
the chemistry and temperature. The concast machines have straight moulds, unique in the
country, to produce internally clean slabs.
Argon injection in the shroud and tundish nozzle prevent re-oxidation and nitrogen pick-up,
maintaining steel quality. The eddy current based automatic mould level control, unique in the
country, gives better surface quality. The air mist cooling and continuous straightening facilities
keep the slabs free from internal defects like cracks. The casters are fully automated with
dynamic cooling, on-line slab cutting, de-burring and customized marking. The shop is equipped
with advanced Level-3 automated control systems for scheduling, monitoring and process
optimization.
CCS produces steel of Drawing, Deep Drawing, Extra Deep Drawing, Boiler and Tin Plate
quality. It also produces low alloy steels like LPG, WTCR, SAILCOR and API Grade.

15. SLABBING MILL
It is a high-output rolling mill designed for the pressure shaping of large ingots weighing up to
45 tons into large, flat billets, called slabs. Slabs are a semifinished product used in the
manufacture of wide sheets. Unlike blooming mills or blooming-slabbing mills, slabbing mills are
highly specialized rolling mills with two pairs of rolls—horizontal and vertical. They are installed
in metallurgical plants and in rolling shops equipped with high-output strip mills.
General-purpose, two-stand slabbing mills are the most common type. The first stand has two
horizontal rolls, each measuring 1,100-1,370 mm in diameter. The second stand has two vertical
rolls, each measuring 900–1,220 mm in diameter, and is arranged alongside the first stand in
such a way that the slab is rolled simultaneously in both stands, as in a continuous mill. The
annual output of such a slabbing mill is 3-7 million tons. The rolls are driven by reversing DC
motors. The power rating of the individual drive for each horizontal roll is up to 7 megawatts, and
the total power rating of the drive for both vertical rolls is 4 megawatts. The mechanical
equipment of a slabbing mill may weigh as much as 9,000 tons.
Modern general-purpose slabbing mills use integrally cast frames for the horizontal stand; the
frames are fastened to the foundation plates by means of anchoring collars. The barrel length
of the horizontal rolls corresponds to the maximum width of the slabs, which makes it possible
to roll the slabs at higher pressures. The screw-down mechanisms incorporate helical and worm
gears driven by high-speed motors; these components provide a lift of the upper roll up to 2,000
mm or more and speeds up to 250 mm/sec. The vertical stand consists of three parts, which are
also connected by anchoring collars. Rotation is imparted to each vertical roll by means of
separate reduction gears and vertical universal spindles.
A slabbing mill proper consists of a work stand, motors, and mechanisms for driving and
changing the rolls. Auxiliary equipment includes ingot buggies, roller conveyors, a scarfing
machine for cleaning the slabs, shears for cutting the slabs, coolers, stackers, and other
mechanisms.
The production process in a slabbing-mill shop consists of several operations. Hot ingots from
the smelting shop are delivered to the soaking pits, where they are reheated in a vertical position
to 1100°–1280°C, dependent on the type of steel. The ingots are then transported by buggies
to the receiving roller conveyor, weighed, and delivered to the rolls. General-purpose stands roll
the slabs in 19 to 31 passes. The horizontal rolls provide a compression of 50–120 mm per pass,
and excess spread is removed by the vertical rolls. The surface of the metal is scarfed as the
slabs are being transported, and the slabs are cut to the required lengths and stamped with
markings. The slabs are then transported on a roller conveyor to an intermediate storage
location for cooling and inspection or to a wide-strip, hot-rolling mill installed next to the slabbing
mill

16. HOT STRIP MILL
Slabs from CCS and Slabbing Mill are processed in the state-of-the-art Hot Strip Mill. The fully
automatic Hot Strip Mill with an annual capacity of 3.363 million tonnes has a wide range of
products - thickness varying from 1.2 mm to 20 mm and width from 750 mm to 1850 mm. The
mill is equipped with state-of-the-art automation and controls, using advanced systems for
process optimization with on-line real time computer control, PLCs and technological control
system.
Walking Beam Reheating Furnaces provide uniform heating with reduction in heat losses,
ensuring consistency in thickness throughout the length. High-pressure De-scaling System
helps eliminate rolled-in scale. Edgers in the roughing group maintain width within close
tolerance. The roughing group has a roughing train of a Vertical Scale Breaker, one 2-high
Roughing Stand and four 4-high Universal Roughing Stands. The finishing group consists of a
Flying Shear, Finishing Scale Breaker and seven 4-high Finishing Stands. Hydraulic Automatic
Gauge Control system in the finishing stands ensures close thickness tolerance. The Work Roll
Bending System ensures improved strip crown and flatness. The rolling speed at the last
finishing stand is between 7.5-17.5 metres per second. The Laminar Cooling System is a unique
feature to control coiling temperature over a wide range within close tolerance. The Hydraulic
Coilers maintain perfect coil shape with On-line Strapping system. On-line Robotic Marking on
the coil helps in tracking its identity.
COLD ROLLING MILL
The Cold Rolling Mill at Bokaro uses state-of-the-art technology to produce high quality sheet
gauge material, Tin Mill Black Plate and Galvanized Products. Cold rolling is done to produce
thinner gauge strips of very smooth and dense finish, with better mechanical properties than hot
rolling strips. Rolling is done well below re-crystallization temperature without any prior heating
of the material. The products of CRM are used for deep drawing purposes, automobile bodies,
steel furnitures, drums and barrels, railway coaches, other bending and shaping jobs and coated
steels. The CRM complex comprises of two Pickling Lines (including a high speed Hydrochloric
Acid Pickling Line with re-generation facilities), two Tandem Mills, an Electrolytic Cleaning Line,
a Continuous Annealing Line, Bell Annealing Furnaces, two Skin-Pass Mills, a Double Cold
Reduction Mill (DCR), Shearing Lines, Slitting Lines and a packaging and dispatch section. The
5-stand Tandem Mill is capable of rolling sheet gauges up to 0.15 mm thickness. It has
sophisticated Hydraulic Automatic Gauge Control, computerized mill regulation and optimization
control.

17. CONCLUSION:-
There’s a difference between reading about something for 3 or 4 years, and seeing
it with one’s own eyes. And that difference is- understanding. This was something
I realized in my 2 week training at BOKARO STEEL PLANT. Earlier, in my plus
two level or in college, where I had read that a blast furnace has a height of 30
metres but I could not gauge the enormity of the matter. But seeing it was a
different thing altogether.
Having seen the different processes happening in front of us, it would now be
easier to understand them when I read about them, being a student of Metallurgical
Engineering.
If the blast furnace was an experience, the visit to the Steel Melting Shop (SMS- I)
was even more so, as was the coke oven plant.
All in all, as an aspiring metallurgist, this vocational training to BOKARO STEEL
PLANT was as helpful as it was inspiring