1

TABLE OF CONTENTS

Table Of Figures......................................................................................................... 3

List Of Tables ............................................................................................................. 3

A Brief Introduction To Bhilai Steel Plant ................................................................ 4

Human Profile ......................................................................................................... 6

Bhilai Steel Plant - Major Landmarks .................................................................... 6

Ore Handling Plant ..................................................................................................... 9

Salient Features Of OHP ......................................................................................... 9

Receipt / Unloading Of Raw Materials ................................................................... 9

Storage / Bedding -Blending Of Raw Materials ................................................... 10

Supply Of Raw Materials To Consumer Shops .................................................... 10

Objectives Of OHP ............................................................................................... 11

Sintering Plant-I ....................................................................................................... 12

Function................................................................................................................. 12

Raw Materials Receiving Section ......................................................................... 12

Raw Materials Screening And Flux Crushing Section ......................................... 13

Fuel Crushing & Flux Screening Section ............................................................. 13

Raw Materials Storage & Proportioning Section ................................................. 13

General .................................................................................................................. 15

Raw Materials ....................................................................................................... 15

Raw Material Section ............................................................................................ 16

2

Raw Material Receiving Bins ............................................................................ 16

Installation Of Raw Material Screen ................................................................. 17

Steel Melting Shop-I ................................................................................................ 20

Mixer ..................................................................................................................... 21

Stock Yard ............................................................................................................. 21

Furnace .................................................................................................................. 23

Stripper Yard ......................................................................................................... 26

Merchant Mill ........................................................................................................... 27

Raw Materials ....................................................................................................... 27

The Working Of The Mill ..................................................................................... 29

Notes On Important Modifications ....................................................................... 31

Power Systems Department ..................................................................................... 33

BSP Power Supply Scheme .................................................................................. 33

Functioning ........................................................................................................... 34

PCMS (Power Consumption Monitoring System) ............................................... 35

Safety ..................................................................................................................... 35

Power Factor Improvement ................................................................................... 35

PSD At A Glanace ................................................................................................ 35

Conclusion ................................................................................................................ 37

Reference .................................................................................................................. 38

3

TABLE OF FIGURES

Figure 1: A Layout Of Bhilai Steel Plant ................................................................... 8

Figure 2: Flow Diagram Of SP-II ............................................................................ 18

Figure 3: Electrostatic Precipitator SP-II ................................................................. 19

Figure 4: Flow Chart Of SMS-1 .............................................................................. 22

Figure 5: Furnace In SMS-1 ..................................................................................... 24

Figure 6: Slide Gate Mechanism For Teeming Ladle .............................................. 25

Figure 7: Layout Of Merchant Mill ......................................................................... 28

Figure 8: Rolling Operation At Merchant Mill ........................................................ 29

Figure 9: TMT Bars ................................................................................................. 32

LIST OF TABLES

Table 1: Raw Materials For BSP ............................................................................. 13

Table 2: Raw Materials For SP-II ............................................................................ 17

Table 3: Major Equipment At MSDS-1 ................................................................... 36

4

A BRIEF INTRODUCTION TO BHILAI STEEL PLANT

Bhilai Steel Plant - a symbol of Indo-Soviet techno-economic collaboration, is one of the first

three integrated steel plants set up by Government of India to build up a sound base for the

industrial growth of the country, The agreement for setting up the plant with a capacity of 1 MT

of Ingot steel was signed between the Government of erstwhile U.S.S.R. and India on

2nd

February,1955, and only after a short period of 4 years, India entered the main stream of the

steel producers with the commissioning of its first Blast Furnace on 4th

February, 1959 by the then

President of India, Dr. Rajendra Prasad. Commissioning of all the units of 1 MT stage was

completed in 1961. A dream came true-the massive rocks from the virgin terrains of Rajhara

were converted of metallurgical wastages and slag etc., minimizing the length of various inter

plant communications, utilities and services.BSP is the sole manufacturer of rails and producer of

the widest and heaviest plates in India. Bhilai specializes in the high strength UTS 90 rails, high

tensile and boiler quality plates, TMT bars, and electrode quality wire rods. It is a major exporter

of steel products with over 70% of total exports from the Steel Authority of India Limited being

from Bhilai. The distinction of being the first integrated steel plant with all major production

units and marketable products covered under ISO 9002 Quality Certification belongs to BSP.

This includes manufacture of blast furnace coke and coal chemicals, production of hot metal and

pig iron, steel making through twin hearth and basic oxygen processes, manufacture of steel slabs

and blooms by continuous casting, and production of hot rolled steel blooms, billets and rails,

structural, plates, steel sections and wire rods. The plant's Quality Assurance System has

subsequently been awarded ISO 9001:2000.Not content with the Quality Assurance system for

production processes, Bhilai has one in for ISO 14001 certification for its Environment

Management System and its Dalli Mines. Besides environment-friendly technology like Coal

Dust Injection System in the Blast Furnaces, de-dusting units and electrostatic precipitators in

other units, BSP has continued a vigorous forestation drive, planting trees each year averaging an

impressive 1000 trees per day in the steel township and mines. A leader in terms of profitability,

productivity and energy conservation, BSP has maintained growth despite recent difficult market

conditions. Bhilai is the only steel plant to have been awarded the Prime Minister's Trophy for

the best integrated steel plant in the country seven times. Bhilai Steel Plant, today, is a panorama

of sky-scraping chimneys and blazing furnaces as a modern integrated steel plant, working round

5

the clock, to produce steel for the nation. Bhilai has its own captive mines spread over10929.80

acres. We get our iron ore from Rajhara group of mines, 85 kms south-west of Bhilai. Limestone

requirements are met by Nandini mines, 20 kms north of Bhilai and dolomite comes from Hirri in

Bilaspur district, 135 kms east of the plant. To meet the future requirement of iron ore, another

mining site Rowghat, situated about 100 km south of Rajhara, is being developed; as the ore

reserves at Rajhara are depleting. Bhilai expanded its production capacity in two phases - first to

2.5 MT which was completed on Sept. 1, 1967 and then on to 4 MT which was completed in the

year 1988. The plant now consists of ten coke oven batteries. Six of them are 4.4 meters tall. The

7 meter tall fully automated Batteries No 9& 10 are among the most modern in India. Of Bhilai's

seven blast furnaces, three are of 1033 cu. meter capacity each, three of 1719 cu. meter and one

is2000 cu. meter capacity. Most of them have been modernized incorporating state-of-the-art

technology.

Steel is made through twin hearth furnaces in Steel Melting Shop I as well as through LD

Convertor -continuous Casting route in SMS II. Steel grades conforming to various national and

international specifications are produced in both the melting shops. Production of cleaner steel is

ensured by flame enrichment and oxygen blowing in SMS I while secondary refining in Vacuum.

Arc degassing ensures homogenous steel chemistry in SMS II. Also in SMS II is a 130 T capacity

RH (RuhshatiHeraus) Degassing Unit, installed mainly tore move hydrogen from rail steel and

Ladle Furnace to meet present and future requirements of quality steel. Bhilai is capable of

providing the cleanest and finest grades of steel. The rolling mill complex consists of the

Blooming & Billet Mill, Rail &Structural Mill, Merchant Mill, Wire Rod Mill and also a most

modern Plate Mill. While input to the BBM and subsequently to Merchant Mill and Wire Rod

Mill comes from the Twin Hearth Furnaces, the Rail & Structural Mill and Plate mill roll long

and flat products respectively from continuously cast blooms and slabs only. The total length of

rails rolled at Bhilai so far would circumvent the globe more than 4.5 times. To back this up, we

have the Ore Handling Plant, three Sintering Plants – of which one is most modern, two captive

Power Plants with a generating capacity of 110 MW, two Oxygen Plants, Engineering Shops,

Machine Shops and a host of other supporting agencies giving Bhilai a lot of self-sufficiency in

fulfilling the rigorous demands of an integrated steel plant. Power Plant No.2 of 74 MW

capacities has been divested to a 50:50 SAIL/NTPC joint venture company. The plant has

6

undertaken massive modernization and expansion plan to produce 7.5 MT of hot metal by the

year 2010.

HUMAN PROFILE

More than the machinery and processes, it is the men i.e. the engineers, technicians, skilled and

unskilled workers behind them that constitute the flesh and blood of this steel plant. Bhilai at

present has around 34000 persons to run this pulsating giant. The culture which has today

become the hallmark of Bhilai is a result oriented approach to work. It is their effective and co-

operative working relationship nurtured in a spirit of dedication and enthusiasm that has shaped

Bhilai's image today.

Adjoining the plant, a modern township - Bhilai Nagar, having the spaciousness of a village and

the cleanliness of a modern town is spread – over in 17 self sufficient sectors with schools,

markets, parks and other facilities. Free Medical aid is given to all the employees and their

dependents through a network of health centers, dispensaries and hospitals. Medical facilities are

extended to retired employees & their spouses also. The Education Department runs a number of

higher secondary, middle, primary, and pre-primary schools in Bhilai and also in the mines

townships at Rajhara, Nandini and Hirri.

BHILAI STEEL PLANT - MAJOR LANDMARKS

Signing of Agreement for setting up of the plant Feb. 02, 1955

Commencement of work at site May 06, 1956

Commissioning of Coke Oven Battery # 1 Jan. 31, 1959

Commissioning of Blast Furnace # 1 Feb. 04, 1959

Commissioning of Power & Blowing Station Jun. 04, 1959

Commissioning of Steel Melting Shop O.H. Fce # 1 Oct. 11, 1959

Commissioning of Blooming Mill 1150 stand Nov. 12, 1959

Commissioning of Billet Mill Dec. 24, 1959

Commissioning of Rail & Structural Mill Oct. 27, 1960

Commissioning of Sintering Plant # 1 Jul. 03, 1961

7

Commissioning of Merchant Mill Feb. 02, 1961

Commissioning of Wire Rod Mill Sep. 01, 1967

Commissioning of Sintering Plant #2 Aug. 01, 1979

Commissioning of Plate Mill Mar. 31, 1983

Commissioning of Converter #1 Jul. 29, 1984

Commissioning of Continuous Casting Shop M/C #1 Mar. 15, 1986

Commissioning of First Twin Hearth (at SMS-1) Sep. 12, 1986

Commissioning of Blast Furnace #7 Aug. 30, 1987

Commissioning of Coke Oven Battery a Mar. 31, 1988

Commissioning of Second Twin Hearth Jan. 01, 1990

Commissioning of VAD unit at SMS-2 Jan. 17, 1991

Commissioning of Third Twin Hearth Jun 29, 1992

Commissioning of Fourth Twin Hearth Jan 21, 1998

Commissioning of Ladle Furnace at SMS-2 Dec 23, 1999

Commissioning of RH Degasser Unit at SMS-2 Mar. 30, 2000

Commissioning of Sintering Plant # 3 Dec. 12, 2001

Only Steel Plant in India to cross 5 MT Mar 31, 2006

Crude Steel Production in the financial year.

Bhilai's expansion &modernization to 7.5 MT Feb. 09, 2008

8

Figure 1: A Layout Of Bhilai Steel Plant

9

ORE HANDLING PLANT

The Central Raw Material Blending and Storage Yard (CRMBSY) renamed as Ore Handling

Plant (OHP) has come up Under 4 MT expansion programmed of BSP in 1983. With this, Bhilai

got bedding / blending facilities for raw materials for the first time, along with facilities for

unloading of raw materials at the periphery of the steel plant.

SALIENT FEATURES OF OHP

Under 4MT Expansion of Bhilai Steel Plant, the principal scheme and material flow in OHP

comprises the following:

1. Receipt / unloading of raw materials.

2. Bedding / Blending and reclaiming facilities, in a big stock yard.

3. Supply of raw materials to the consumer shops: SP-2, SP-3 RMP-2, CONVERTOR SHOP,

&B.F -7, 6, 5, 4, 1.

Above scheme facilitates handling of following raw materials in OHP:

a. Blended Ore Fines for SP-2 & SP-3.

b. Dolomite & Lime stone for SP-2 & SP-3.

c. Screened Iron Ore to Blast Furnaces. ( Iron Ore screen installed in 1996.)

d. Low Silica Lime Stone and Iron Ore for SMS 2.

RECEIPT / UNLOADING OF RAW MATERIALS

Mainly two categories of Raw Materials are received in OHP

1. from captive mines.

2. from other than captive mines.

Raw materials from our captive mines are generally received in BOBS type of wagons which

railways have specially designed for BSP. These wagons are unloaded in the track hoppers in the

peripheral yard of OHP There are two rows, of 20 hoppers each, in track hopper building. Lime

stone (SP -grd.) form Nandini for both Sinter Plants (SP-2 &SP-3). Iron Ore fines / Lumps Iron

Ore from Dalli Rajhara are received in BOBS type of wagons and unloaded in two row of

10

hoppers called Track hoppers. Dolomite from Hirri Captive mines & raw material from other

than captive mines like Low Silica lime stone dolomite Mn Ore etc. are received in BOX type of

wagons & unloaded at wagon tippler of OHP.

STORAGE / BEDDING -BLENDING OF RAW MATERIALS

The raw materials unloaded in peripheral yard are transported to open Storage yard of OHP by

conveyor belts. The facilities for stacking bedding - blending are provided to handle different

types of raw materials in the stock yard.

The storing in OHP stock yard provides sufficient reserve of raw materials to guarantee

continuous operation of consumer shops. The blending methodology is a process of mechanized

stacking and reclaiming functions. The bedding-blending process consists of spreading out

different grades of raw materials in many layers over full length of bed by using stackers and

reclamation of the same by blender reclaimed in successive cross -sections of the bed. The

blending efficiency of a bed is defined as the ratio of the standard deviation of the input &output

of the bed.

SUPPLY OF RAW MATERIALS TO CONSUMER SHOPS

Reclaiming is the process of transportation of the raw materials from the storage yard beds to the

consumer shops with the help of excavators, declaimers& belt conveyors to fulfill needs of

different consumer shops.

At present, raw materials being supplied to the consumer shops are:

1) Blended Ore Fines to SP-2 & SP-3.

2) High Silica Lime Stone and Dolomite to SP-2 & SP-3

3) Low Silica Lime Stone to RMP-2.

4) Hirri dolomite to RMP-2.

5) Iron Ore, High Silica Dolomite & Low Silica Lime Stone to SMS-2.

6) Iron Ore to BF-7 and High line bunkers of B.Fs 6 & 5, 4

7) Quartzite & High Silica Mn Ore to BF-7.

11

OBJECTIVES OF OHP

a) To reduce interference of internal Railway traffic movement and to Unload Raw Materials

at the periphery of the plant, by avoiding detention of railway wagons.

b) Blending by making homogeneous pile of raw materials received from our captive mines and

other sources / purchased raw materials, soas to achieve consistent quality. a. Keeping buffer

stock of raw materials and their uninterrupted supply to different Consumer shops.

12

SINTERING PLANT-I

Sintering Plant-I has the capacity of 2.04 MT/yr based on the production from 4m/cs. It works on

the principle of Dwight-Lloyd process - down draft system.

Sintering Plant No.1 comprises:-

a. Raw material receiving section.

b. Raw material screening & flux crushing section.

c. Fuel crushing & flux screening section.

d. Storage & Proportioning section and

e. Machine building.

FUNCTION

To produce fluxed or super fluxed sinter. We are now manufacturing sinter of basicity 1.8 to 2.0

with the following proportions of the material.

Ore fines: 53.53%

Lime Stone: 23.4%

Coke breeze: 5.18%

B.F. Sinter return is 16.63 and moisture in the charge is 6 to 8% Iron content of the sinter is 51 to

53%. The proportions shown above are not constant and the composition changes as per the

requirement of blast furnace.

RAW MATERIALS RECEIVING SECTION

Ore fines, lime stone and dolomite are transported from the yard/ trench by OBC to sintering

plant receiving bunkers (20 nos.) coke breeze comes from coke oven by belt conveyor to four

coke receiving bunkers. The same also comes from B.F. by wagons and by trucks from different

yards. Volume of each bunker is 90cu.m. Ore fines can also be unloaded from BOBS wagons

received from mines.

13

RAW MATERIALS SCREENING AND FLUX CRUSHING SECTION

Functions of this section are:

a. Preparation of the ore mixture. The ore fines, after being mixed up with mill-scale & lime dust

is subjected to screening whereby 12mm goes to the storages section and ore mixture and +

12mm is treated as waste. Flue dust is directly transported to storage bins.

b. Crushing & flux screening section - Fuel crushing is carried out in four-roll crushers, each with

the average capacity of 16 to 20 tones/hr. for proper sintering more than 90% of the crushed

material should be of 3mm size. The fuel after being crushed is sent to the storage section.

FUEL CRUSHING & FLUX SCREENING SECTION

Fuel crushing is carried out in four-roll crushers, each with the average capacity of 16 to 20

tones/hr. For proper sintering more than 90% of the crushed material should be of 3mm size. The

fuel after being crushed is sent to the storage section. Crushed flux received from the hammer

mills is screened and 3mm size is transported to the storage section +3mm size is again sent to

hammer crusher for closed circuit grinding.

RAW MATERIALS STORAGE & PROPORTIONING SECTION

Screened ore mixture, crushed flux and fuel and sinter returns are stored in this section in twenty

bunkers arranged in two rows. Flux and fuel bunkers are provided with batch meters while other

is having disc feeders. A proportioned sinter charge is made out of these ingredients and supplied

to machine building through belt conveyors.

Table 1: Raw Materials For BSP

14

MACHINE BUILDING

The building is equipped with four downdrafts Dwight Lloyd sintering m/cg. Each having the

following dimensions:

Length: 25 meters

Width: 02 meters

Area: 50 sq. meters

Sinter charge from the proportioning section is stored in 4 bunkers, one for each Machine. The

sinter charge from the bunkers goes to pug mill. The function of pug mill is mixing and

moistening the charge. The charge after proper mixing is fed on to pendulum feeder which

distributes the material uniformly on to the pallets of sintering machine. Each sintering machine

is provided with an ignition hood where a mixture of 12% coke oven gas and 88% blast furnace

gas is burnt. The temperature of the hearth zone is 1250 to 1300°C.Top layer of sinter charge is

ignited under the ignition hood. Suction of air through the charge propagates the ignition. By the

time the charge moves to the end of the sintering machine, the entire charge is converted to sinter.

Combustion of coke breeze within the charge takes place resulting in the following chemical

equations:

C + O2 = CO2 + 94,220 cal

2C + O2 = 2CO + 53,140 Cal

The heat liberated from the reactions stated above, raises the temperature of the charge a creates a

condition necessary for the following reactions to occur:

CO + 3Fe2O3 = 2Fe3O4 + CO2 + 8870 Cal

CO + Fe3O4 = 3FeO + CO2 - 4990 Cal

FeO so formed combines with SiO2 and fluxes resulting in the formation of fluxed sinter. Sinter

cakes are crushed in a sinter cutter, which cuts the sinter discharged from the moving pallets to -

80mm size and the broken pieces are afterwards screened on a self-balancing screen in hot

condition. Sinter having size between 10-80mm is discharged on to the pan coolers (one each

m/c). -10mm size is utilized as return sinter.

15

SINTERING PLANT-II

Sintering Plant-II (SP-II) was set up during 6th BF stage; started on 1st August1979 with one

inter machine of 75 M2 sintering area with rated capacity of o. 75 MT/YR Subsequently, three

more machines were added to it, making the total capacity of SP-II as 3.137 MT/YR. Initially, the

acceptability of sinter was very poor at blast furnaces, and the sinter process was basically for

utilization of metallurgical waste of mines and plant, viz. iron ore fines, lime stone chips, flue

dust, mill scale etc. Later on the importance of Sinter gained momentum and it was accepted as a

major raw material in BF burden due to its good metallurgical properties. The requirement of

sinter went up necessitating the setting up of second Sintering Plant.(Subsequently Sintering

Plant-III has also been set up).

GENERAL

Sinter now is the major component in BF burden. Sintering process originally started as a process

of agglomeration of iron ore fines. Later on, it was advanced to utilize not only fine ore, but also

other in-plant metallurgical waste materials such as flue dust, mill scale, converter slag etc. It has

also become a source for introducing all the required flux into the BF. The following are the

major advantages of sintering process of agglomeration:

1. Simplicity of unit.

2. High specific productivity of unit.

3. Less conversion cost.

4. Better metallurgical properties of sinter.

RAW MATERIALS

The various raw materials used at SP-II for producing sinter are as follows:

1. Iron ore fines 0 - 8 mm

2. Lime stone 10 - 50 mm

3. Raw Dolomite 0 - 50 mm

4. Coke Breeze 0 - 16 mm

5. Lime Dust 0 - 5 mm

16

6. Mill Scale 0 - 3 mm

7. Sinter Return 0 - 5 mm

8. Settling Tank Dust 0 - 3 mm

9. LD slag 0 - 10 mm

The SP-II is located South-East of Coke Ovens. It comprises following main sections:

A. Raw Material Section.

B. Mixing and proportioning section.

C. Sintering Building.

D. Priority Route.

RAW MATERIAL SECTION

The Raw Material section has following sub sections:

a) Raw Material Receiving Bins.

b) Raw Material Preparation Section.

c) Flux crushing section.

d) Fuel Receiving Bins.

e) Fuel & Flux Preparation Section.

RAW MATERIAL RECEIVING BINS

There are 24 Nos. bins of 85 cum volume each, in two rows, 12 in each row; where various raw

materials are being received from different sources. On one side of bins, flux materials are being

received, and on the other side iron bearing materials are received. The flux side bins,

bins/bunker nos. 1 to 10 and 21 & 22 are located over conveyor RB-2; and the iron bearing side

bins, bins/bunker nos. 11 to 20 and 23 & 24are located over conveyor RB-1. All the bins, except

bins no. 11, 21 & 22 are having disc feeder discharge system of 2400 mm diameter and the bins

no. 11, 21 & 22 are equipped with variable speed belt feeder discharge system.

17

INSTALLATION OF RAW MATERIAL SCREEN

In the existing layout, Iron ore mix, contains Iron ore fines, Sinter Return from BFs, lime, mill

scale etc. removal of +8 mm fraction of ore mix by 1.5 to 2 % leads to better homogenization of

ore mix and reduced sinter return generation.

Table 2: Raw Materials For Sp-II

18

Figure 2: Flow Diagram Of SP-II

19

Figure 3: Electrostatic Precipitator SP-II

20

STEEL MELTING SHOP-I

Steel Melting Sop - 1 (SMS-1) follows the conventional route of steel making in which steel is

produced through Twin Hearth furnaces and cast into ingot moulds. The ingots are stripped off

from the ingot moulds and are sent to BBM for further heating and rolling into blooms. Initially

SMS-I was set up to produce 1 MT steel annually, from 6 Open-Hearth furnaces of 250 T

capacities each. First tapping was done on 12th October 1959.Sixth Open-hearth furnace was

commissioned on 22nd February 1961. Later on it was decided by the corporate management to

increase the capacity of the shop to2.5 MT, by installing 4 more open hearth furnaces of 500 T

capacities and converting OH no. 6 from 250 T to 500 T capacities, which was completed on

14th

April 1967.Steel production through Open-hearth furnaces, had the following drawbacks:

1. Low productivity.

2. Cumbersome operation of the furnaces.

3. Higher fuel & refractory consumption.

To overcome the above drawbacks it was decided by the management to replace open hearth

furnaces by Twin Hearth furnaces (Both hearths having capacity of 250T each). The following

table shows the commissioning of different twin-hearth furnaces (by replacing different open-

hearth furnaces)

Remaining two open-hearth furnaces, i.e. No. 7 & 9 have been scrapped, and presently SMS-I

has four twin hearth furnaces only. The production capacity of the Shop is 2.5 MT by running 3

Twin-hearth furnaces at a time. SMS-I comprises of various sections for melting, casting &

stripping of 2.5 MT ingots annually. The main sections are:

1. Mixer

2. Stock Yard

3. Furnace

4. Pit side

5. Mould Yard

6. Stripper Yard

21

MIXER

Mixers in any Steel Melting shop serve the following purpose:

i) They act as a reservoir, for storing liquid pig iron hot metal received from Blast Furnaces and

supplying it to the SMS furnaces when required.

ii) For homogenization of chemical composition and temperature of hot metal received from

different blast furnaces. Two mixers have been installed in SMS-I, one at each end of the main

building. Both the mixers are drum-type, inactive mixers, lined with magnetite bricks, having a

capacity of 1300T each. An average temperature of 1300°C is maintained with burners using

coke oven gas as fuel.

Each mixer building is provided with a crane of 125T/30T capacity. The hot metal received from

the blast furnace is poured into the mixer, through the pouring in spout, with the help of these

cranes. Hot metal up to 500T in the mixer is called zero level. The mixer balance, as a practice, is

always maintained above -200T level. Each mixer is provided with one electric loco of 800 HP

capacities. This loco pulls three ladle chassis, coupled with each other, with ladles place over it.

Whenever hot metal is required by the furnaces, Mixer Loco pushes the chassis and positions one

ladle under the pouring spout of mixer. Mixer is then tilted towards the ladle and hot metal is

poured into the ladle. The poured out metal is weighed on the weighing bridge provided in the

mixer section itself. After filling one ladle mixer is tilted back and next empty ladle is positioned

under the spout by the loco. Mixer is again tilted to fill the ladle and in this fashion, all the three

ladles are filled with required tonnage of hot metal, which varies from 200T to 230T per order.

Capacity of each ladle is100 T and therefore requirement or one furnace is easily fulfilled by 3

ladles.

There are two hatches provided near both the ends of the main building (near THF-I & THF-II)

from where the hot metal ladles arriving from the blast furnace can be lifted directly by Hot

Metal Cranes of main building and poured into the furnaces. The hatches are used whenever the

mixer cranes are under maintenance or under breakdown and also when the mixer is under repair.

STOCK YARD

The stockyard is located parallel to the main building and comprises the Magnetic yard and Bulk

charge yard (Backyard). In Magnetic yard steel scrap, rejected ingots; rejected castings from

Foundry etc. are stored. Handling of these materials is done by 5 cranes provided with

22

electromagnets of 15T capacity each. Bulk charge materials are stored in BC Yard in bins. They

are iron ore; limestone, bauxite, magnetite and raw dolomite. These materials are handled with

the help of two cranes, each having a grab bucket of 10M3 capacities. Burnt dolomite and lime

are continuously drawn from RMP-I through conveyors and are kept in hoppers. Weigh bridges

are installed at both ends of the stockyard. All outgoing materials from the yard are weighed. At

the far end of BC Yard, we have Ferro alloy yard. In this yard Ferro-manganese and Silicon-

manganese are stored and weighed quantity of these Ferro-alloys is supplied to the furnaces in

tilting boxes, as per the requirement. Materials here are handled by two finger grab cranes of 10T

capacity each.

Figure 4: Flow Chart Of SMS-1

23

One set consists of 3 charging bogies. Each bogie can accommodate four charging boxes. On an

average 45-60 Ton of scrap, which consists of 80% steel scrap & 20%iron scrap, is loaded on two

sets. This is done on line no. 98 with the help of electromagnetic cranes. Similarly, 9-12 T of

limestone and 10 T of iron ore are loaded in another one set. This is done on line no. 100 with the

help of grab cranes. Thus, one complete set of charge consists of two sets of charging bogies

loaded with scrap& one set loaded with limestone and iron ore. Each set is weighed separately,

on weigh bridges located on line no. 93 and 94, at both ends of the main building, and

Supplied to the furnaces from both ends of the main building. On an average, 30complete sets of

charge are loaded every day, and supplied to the furnaces after weighment. Diesel locos are used

for placement of charges and removal of empty bogies.

FURNACE

The furnaces are housed in the main building of the shop. There are at present 4Twin hearth

furnaces of 2 x 250 T capacities. Of these, only 3 furnaces are kept in operation and one is kept as

cold reserve. The section is equipped with 6 charging machines (10 T capacity) and 5 over-head

hot metal cranes (capacity 125/30 T). The furnaces are fixed type with basic lining (magnetite)

and basic roof (magnetite-chrome).Twin hearth furnace consists of two hearths separated by a

bridge wall with a common roof. Twin hearth furnace works on synchronization between the two

hearths; there by both the hearths are engaged in different operations. While one heath is in solid

period the other is in liquid period. The technological regime of a Twin Hearth Furnace is based

on equal duration for both "Solid" and "Liquid" periods of a heat in both hearths.

The major operations during Solid period are:

1. Tapping and fettling

2. Charging

3. Heating and sill making

4. Hot metal pouring.

The major operations during Liquid period are:

1. Melting

24

2. Refining

3. Holding.

Figure 5: Furnace In SMS-1

25

Figure 6: Slide Gate Mechanism For Teeming Ladle

26

STRIPPER YARD

Mould trains, after teeming at pit side, are brought to stripper yard. Here ingots are stripped off

and are sent to soaking pits. The main function of stripper yard is as follows:

i) Sending hot ingots to soaking pits.

ii) Storing return ingots, or ingots made during BBM repair day, in Ingot Storage Yard.

iii) Shifting of ingots from ingot storage yard to other places in case of accumulation of ingots in

this yard.

iv) Proper identification of cold ingots and supplying the same to soaking pits as and when

required.

v) Release of mould striker and butts. Stripper yard is equipped with three cranes of capacity

250T / 50T / 25T.Sometimes ingots do not separate freely from the moulds. In these situations,

the pusher from the top of the ingot can apply a force of 250T to separate them. Ingot storage

yard is equipped with two overhead cranes of 50T capacity each. With 180 no. of mould bogies,

the entire activities of mould yard, and stripper yard are managed. Rolling stock is handled by 6

diesel locos, 3 for mould yards & 3for stripper yard. Total requirements of mould& bottom stool

are met by our captive foundry shop.

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MERCHANT MILL

The "350 mm" Merchant Mill is a semi continuous high capacity mill designed to roll 500,000

tones of finished products per year as per present market demand. Main products are:

Rounds Bars 28,32,36,40,50,53,56,60,63 & 67 mm diameter; TMT bars of 28,32, 36, 40 and 45

mm are also being rolled.

Angles 50x50, 65x65, 75x75, 80x80 and 90x90 mm leg lengths and thickness ranging from 5 to

10 mm.

Channels 100x50, 75x40 mm.

RAW MATERIALS

Raw materials used are billets of size 100x100, 105x105, 110x110, 150x150and shaped billet of

size 122x135x80, length ranging from 5 M to 6 M. Billets are supplied from billet yards by

magnetic cranes on to the charging device. Three charging devices are installed one in each of the

three bays of billet yard. Approach tables at the billet shipment in the first, second and the third

bays are designed to push the billets on the furnace approach roll table. Furnace approach table,

which extends up to the first bay in billet shipment, is designed to receive billets from the

charging devices and deliver them to the furnaces. The furnace pusher installed at the charging

side of the reheating furnace, pushes the billets after leveling from the approach roll table into the

furnace and moves the entire charge in the furnace pushing the heated billets on to the delivery

roll table at the discharge end of the furnace.

The Merchant Mill consists of three main sections:

1. Re-heating furnaces.

2. The mill stands and cooling beds.

3. Finishing zone & shipping.

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Figure 7: Layout Of Merchant Mill

Important technical parameters of the furnace are:

There are three zones of heating, preheating, heating and soaking zones. In the first part of the

furnace (preheating and heating zones), the billets move over the water cooled skids and are

heated by top and bottom zone burners. The burners are injector type which sucks air

automatically. In the second part(soaking zone) the furnace has a solid chrome magnetite brick

bottom with solid skids, where the billets are soaked to a uniform temperature. The fuel used in

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the furnace is a mixture of coke oven and blast furnace gas in the ratio of 20:80 with calorific

valve of 1350 kcal/Cu M and at a pressure of 1500 mm water column. Normally air is preheated

in ceramic recuperates to 400°C - 500°C and gas in metallic recuperates to 250-300°C.

The temperature of the metal to be heated depends on the following factors:

1. Quality of steel

2. Rate of rolling

3. Size of the billet

4. Profile being rolled

5. Calorific value etc.

While rolling beams, the soaking zone temperature is maintained at 1250-1280°Capprox and

while rolling rounds, the soaking zone temp. is maintained in the range from 1220 to 1250°C.

THE WORKING OF THE MILL

As the billets from furnace are discharged, they fall on the furnace delivery side roll table

approaching stand No.1 at the mill side. The turn-over devices or tilters are installed on the

rolling lines before stands 1, 2, 6 and 10, and are used for turning over billets by 90° before

delivering them to the respective stands(as per requirement).There are 12 working stands in the

mill, out of which 9 stands are horizontal and 3 are vertical.

Figure 8: Rolling Operation At Merchant Mill

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Roughing group comprises of stands 1,2,3,5 being 500 mm two high horizontal stands and 4th

stand is a 400 mm, 2 high vertical stands. Intermediate group comprises 6,8,9 stands of 400 mm 2

high horizontal and 7th

stand 400 mm two high vertical. Finishing group consists of 10th stand of

400 mm and 12th of 350 mm 2 high horizontal stands and 11th being 350 mm 2 high vertical.

The first line of rolling consists of 8 stands. After the 8th stand there is a chain transfer to deliver

the bar from 1st line to 2nd line of rolling i.e. from stand 8 to stand9. There is a second chain

transfer after 10th stand for delivering the bar from second line to third line of rolling. The third

line of rolling consists of two stands 11and 12, connected by the approach and delivery roll tables

respectively. The chain transfers are used while rolling structures only.

All stands are of non reversing type and driven individually by D.C. motors. Working stand

consists of pinion stand, universal spindles (except stand 6 which has geared spindle), splinted

transmission shaft, reducer stand, main drive displacement mechanism and clamping mechanism.

The top roll adjustment mechanism with individual screw down drives is located on the housing

cap of horizontal stand. The mechanism is driven by two electric motors through double

reduction worm reducers. An indicator is coupled to each of the worm reducers to indicate the

distance through which each end of the top roll is displaced. The level of bottom roll is adjusted

by putting different size of pickings as required. Work rolls are mounted on oil film bearings.

Balancing of the top roll is accomplished by the aid of springs resting on the transverse beam.

Axial adjustment mechanism located on the idle side of the stand with double balanced lever

system.

After cooling, the bars are fed (while rolling structural’s) to the straightening machine, one at a

time. The length of cooling bed is 90m. To facilitate single piece feeding to straightening

machine, the bars are distributed one ahead of other on cooling bed. Adjustable guides are

provided at the end of the roll table for directing the bar to the vertical guides before straightened.

There are two machines one on each side of the cooling bed to straighten the fed bars. A

cantilever crane is provided on each machine for changing the rollers. After the straightening

machine there are shear approach roll tables from where bars are transferred to the cold shear

approach table by the rope transfer. There are two cold shears installed in the line of rolling, one

on each side to cut, the rolled bars into desired lengths. The lengths are adjusted by the shear

adjustable gauge before cutting into suitable lengths.

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The bars are weighed and bundled. A card indicating the heat no., weight, &quality is attached to

the binding wire and kept on the stack. Stage inspection for the rolled profile is carried out during

the process of rolling for finding out rolling defects, surface defects, steel defects and any other

mechanical defects. Samples from each cast are sent to laboratory for mechanical testing and for

ascertaining chemical composition. There are fifteen cranes in the mill provided on the different

bays for load lifting, roll changing etc. The oil film bearings are used to support the rolls of the

working stands. Each roll is supported on two bearings fitted on the roll necks. The roll assembly

is supported in the stand housing. The bearings are of precision type totally enclosed and well

proportioned. The coefficient of friction is between 0.0001 & 0.0003. The sleeve or conical

journal is alloy steel forging, hardened and ground to a mirror finish fitted and keyed to the

tapered roll neck. The bushing has a special bore of displaced centers. The shape and dimensions

of the bore are such that the bearing clearance has a wedge shape. Hydrodynamic pressure takes

place in the oil layer dragged into this clearance by the revolving shaft due to wedge shape of the

clearance. This pressure raises the sleeve and creates an oil film between the rubbing parts of the

bearing and balances the outer pressure. The thickness of the film depends upon operating

conditions, oil etc. Adjacent to the outward end of the sleeve is a thrust bearing. In case of

bearings of horizontal stands two thrust rings, (one full ring and one half ring) provided on the

sleeve collar to take up the axial loads.

NOTES ON IMPORTANT MODIFICATIONS

1. Both the chain transfers are working in auto. This has been achieved by using pho to sensors

after stand VIII and before stand-10.

2. Earlier Mercury Arc Rectifiers were used for the drive of main motors of stands, which has

been replaced by thyristor converters.

3. While rolling of TMT bars, operation of lifting valve mechanism is carried out in "Auto". This

is achieved by using HMD (Hot Metal Detector) installed at section 201,301 on either sides of

cooling bed. For other profiles, operation of lifting Valve mechanism is done manually through

control pulpit no. 6.

4. The old straightening machines have been replaced by BRONX straightening M/c.(England).

These machines are capable of straightening the bars with higher accuracy.

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5. Conventional Russian Stands 9.10.12 have been replaced by "Housing less" stands supplied by

Morgard Shimmers, Sweden.

Figure 9: TMT Bars

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POWER SYSTEMS DEPARTMENT

Power Systems Department takes care of distribution of Electrical power to the entire production

and service units of Bhilai Steel Plant and its township. This is made possible through a large

power system network consisting of 5 EHT (Extra High Tension) sub-stations, 42 HT (High

Tension) sub-stations and more than 150 LT (Low Tension) sub-stations scattered throughout the

plant. We receive power from Chhattisgarh State Electricity Board (CSEB) at 220 and 132 kV at

two EHT substations, which operate in synchronism with two captive power plants feeding the

critical processes of the integrated steel plant.

In order to ensure uninterrupted power supply to each unit, regular maintenance and repair of all

types of electrical equipments such as Circuit Breakers, Transformers, MG sets, Thyristor units,

HT cables, Over-head lines, Batteries, Battery Chargers etc. are carried out. Besides regular

maintenance, condition based maintenance system is also being implemented for some critical

equipments to ensure smooth functioning of the power system. Close monitoring and analysis of

Electrical Energy Consumption of all units and township is done and based upon these, many

energy conservation measures have been introduced to reduce the input cost of production. We

have also been taking Cost Control measures on a continuous basis to optimize our maintenance

cost. There is a separate section called General Services, which takes care of general illumination

inside the plant such as lighting towers, street lights etc.

BSP POWER SUPPLY SCHEME

Bhilai Steel Plant imports power supply from Chhattisgarh State Electricity Board= (CSEB). The

plant also has two generating stations Power Plant-1 and Power Plant-2.PP-2 is under

NSPCL.BSP receives CSEB supply through two 132 KV lines at MSDS-1 (Main Step Down

Sub-station) from BRSS (Bhilai Receiving Sub-station) and through two 220KV lines at MSDS-

II from Khedamara Sub-Station (S/S). MSDS-I and MSDS-II are interconnected through a 132

KV Tie-Line called as Tie-Line-3. PP-I is connected to MSDS-I through three 6.9 KV tie lines

whereas PP-2 is connected to both MSDS-I and MSDS-II through 132 KV tie lines called as Tie-

Line-2 and Tie-Line-1 respectively. MSDS-I and PP-1 cater power supply to entire 2.5 MT area

including SP-3; MSDS-II and PP-2 cater to entire 4.0 MT area. The two power generating

stations at BSP are of following capacities:

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PP-I: 3 x 12 MW + 1 x 15 MW = 51 MW

PP-II: 2 X 30 + 1 X 14 MW = 74 MW

There are 3 more MSDS at BSP namely MSDS-III, MSDS-IV and MSDS-VI, which take care of

power supply to Plate Mill, SP-3 and OP-2 respectively. MSDS-III and MSDS-VI receives

supply at 132 KV from MSDS-II through two lines each whereas MSDS-IV receives supply at

132 KV from MSDS-I through two lines. The total average load of BSP including township is of

the order of 260MW.Normally an average of around 110 MW is generated in the captive power

plants of BSP and remaining 150 MW power is imported from CSEB. In case of power supply

failure from CSEB grid, power supply to all critical loads of BSP is ensured from available

generation at PP-I and PP-II.

FUNCTIONING

Most of the HT Sub-Stations are manned round the clock. Two Shift Managers at MSDS-I and

MSDS-II control rooms, control and monitor all operations through Switch Board Attendants /

Substation Operators of various manned sub-stations. Maintenance & Repair of all types of

equipments of the department, such as Transformers, Switchgears, O/H lines, Isolators, Cables,

Pumps, Compressors, MG sets, Thyrisyors, Battery Chargers, Battery, CT, PT, LA etc., is done

once or twice a year as per the requirement for their better performance. For this, an Annual

Maintenance Schedule is prepared every year and all efforts are made to follow it strictly.

In an effort to further minimize the downtime and avert breakdowns of the equipment, Condition

Based Maintenance System is being practiced in several areas these days. For this, on-line

monitoring of certain parameters such as temperature, physical condition etc. is done to assess the

healthiness of the equipment. Temperature is being monitored by Thermo-scanner gun and

Thermo vision camera. A daily/weekly energy statement is prepared giving details of import

through CSEB, power generated at power plants and power consumed by each and every major

unit. This serves as a guideline for all the energy conservation projects and to calculate specific

energy consumption.

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PCMS (Power Consumption Monitoring System)

The load flow of BSP can be continuously monitored in real time using our SCAD A system

called as Power Consumption Monitoring System. Data regarding Maximum Demand, Load

Flow at PP-1 &2 can be obtained in real time from PCMS along with hourly, daily and monthly

reports of power consumption of different shops.

SAFETY

All members of the department strictly adhere to standard safety norms. Only authorized persons

are allowed access to electrical equipments. Central Electricity Authority subjects all electrical

equipments to regular inspection. Safety lectures are given to every group by the respective area

in-charges. Safety awareness among employees is created by regular safety meeting through

safety circles, safety week celebrations and safety training.

POWER FACTOR IMPROVEMENT

As per our power purchase agreement with CSEB, penalty has to be paid if the import power

factor for a given month goes below 0.9. But if the power factor goes above 0.95, CSEB gives

substantial incentive. Power factor of import power from CSEB to BSP usually was somewhere

between 0.90 and 0.92 depending upon the available captive generation and nature of load. With

present arrangement, it was not possible to avail power factor incentive; in fact there always use

to be a threat to pay a penalty for low power factor. Therefore, Capacitor banks were installed at

BSP for improving the import power factor to avail maximum incentive from CSEB. Depending

upon the load conditions of BSP, according to a careful study carried out to improve the import

power factor from 0.9 to 0.99 (maximum possible), 42MVAR of Capacitors have been installed

at various locations. After installation of Capacitors bank, BSP is getting an incentive of 3 to 4 %

(Rs. 30 lakhs per percent) per month from CSEB.

PSD AT A GLANACE

No. of 132KV S/Ss. - 5

No. of 11KV Substations. - 14

No. of 6.6KV Substation. - 32

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No. of LT. Substations. - 228

No. of H.T. Breaker panels - 1760

No. of Transformers - 748

Length of cable tunnel - 25 km

Table 3: Major Equipment At MSDS-1

There is one feeder from MSDS-I to PP-I for feeding auxiliaries of Power plant I incase of

emergency in PP-I auxiliary supply.There are two station Transformer each of 320 KVA

capacity, 6.9 KV/230V forauxiliaries and lighting loads of MSDS-I.The neutral of 6.9KV

sections is grounded through Arc suppression coils (Petersoncoils) in order to neutralize the

capacitance current flowing in case of 6.9KV system earth fault.

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CONCLUSION

Our visit to Bhilai Steel plant was very fruitful and productive since it gave us the basic

understanding about the operations being performed in the plant. Also it enhanced our practical

approach towards various subjects and also helped in strengthening our concepts. Our guide

during our training sessions was very cooperative and helped us as far as he can.

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REFERENCE

1. B. Ravidranath And M. Chander , Power System Protection And Switch Gear, New Age

International (P) Ltd., 1977.

2. The Transmission And Distribution Of Electrical Energy , H. Cotton

3. Cory, B.J., High Voltage DIRECT Current Converters And Systems, Macdonald,

London.

4. T.J. Miller, “Reactive Power Control In Electric Systems” John Willey And Sons 1982.

5. Power System Analysis, W.D. Stevenson Jr. 2nd

Edition Mcgraw Hills.

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