72 OM Institute of Technology & Management

A Training Report On JINDAL STAINLESS LIMITED (HISAR)

MECHANICAL ENGG. SECOND YEAR

Submitted to: Submitted By :

Mr.RAJESH DUDDI ASHEESH

H.O.D. Mechanical Engg. Roll no.5911707

72ACKNOWLEDGEMENT

This report is an output of our collaborative efforts. However it could not have been possible without the help and guidance of some people whom we would like to acknowledge before we begin.

First of all, our sincere thanks to Mr. Abhishek Sharma (AM- HR) , JSL to give us this opportunity to get training in JSL which helped us to materialize our theoretical knowledge into practical one. We would like to express our deep sense of gratitude towards Mr. Deepak Jain (DGM-STECKEL MILL) for his constant support and motivation.We would like to thank Mr. Virender Singh(AGM-HYDRAULICS) & Gaurav Bansal (GET-STECKEL MILL) for being helpful enough to give us time from his busy schedule & guided and supervised us through his lectures throughout our training session. Although we cannot mention all the names, we found ourselves in anonymous debates with several remarkable thinkers, especially about some of the important but not so common topics in the technical guideline.

Heartfelt gratitude towards the entire staff of JSL, Hisar for being a wonderful host.

Asheesh

5911707

72TABLE OF CONTENT

Topic Name Page Number

1) Introduction 3

2) Steel Melting Shop 6

i) Raw Material 8

ii) Scrap Yard 10

iii) Charging Section 11

iv) Electric Arc Furnace 16

v) AOD 24

vi) Laddle Refining furnace 26

vii) Pollution Control System 28

viii) Continuous Casting Shop 29

ix) Shot Blasting and Grinding 31

3) Hot Strip Mill 33

4) Steckel Mill 41

5) Cold Rolling Division 49

i) Annealing Pickling Line 52

ii) Facilities in CRD 56

iii) Special Product Division 62

6) Coil Blanking Line 68

7) References 71

72

INTRODUCTION

Jindal Organization, set up in 1970 by the steel visionary Mr. O.P. Jindal, has grown from an indigenous single-unit steel plant in Hisar, Haryana to the present multi-billion, multi-national and multi-product steel conglomerate. The organization is still expanding, integrating, amalgamating and growing.

The group places its commitment to sustainable development, of its people and the communities in which it operates, at the heart of its strategy and aspires to be a benchmark for players in the industry the world over. The Jindal Organization today is a global player. It's relentless quest for excellence has reaped rich benefits and it is today one of the worlds most admired and respected groups within the steel fraternity

JSL Limited is in many ways very much like the material it produces. Like stainless steel the company is versatile in its thought process, strong and unrelenting in its operations, environment friendly in its manufacturing process, bright, shining and beautiful in its community support activities. The list of the properties of stainless steel is endless, just as our values are all encompassing.

JSL Limited has always been committed to innovation and progression, research and development. Our innovations are admired beyond the geographical boundaries of our country. No wonder we are the strategic partners of global leaders by choice. Our achievements narrate a story of our determination to succeed and our passion to win. We will continue to leverage our opportunities in creating excellence that the world cannot even think about. Today we are the largest integrated stainless steel producer in India, tomorrow we will rule the world.

JSL Limited, a $780 million plus ISO: 9002 & ISO: 14001 company is the flagship company of the Jindal Organization. The company today has come a long way from a single factory establishment, started in 1970. As the numero uno it has taken on the task of making stainless steel a part of everybody's life by taking a 360 degrees approach from production of raw materials to supply of architecture and lifestyle related products.

72 Hisar Plant, India

At Hisar, JSL Limited has India's only composite stainless steel plant for the manufacture of Stainless Steel Slabs, Blooms, Hot rolled and Cold Rolled Coils, 40% of which are exported worldwide.

Precision Strips the company produces stainless steel precision strips in various grades. These strips are produced in narrow 20-Hi mills in the precision cold rolling unit.

Blade Steel The Company is the exclusive producer of stainless steel strips for making razor and surgical blades in India.

Coin Blanks Besides supplying CR Strips to the Government of India, the plant at Hisar houses a coin blanking line for supply of coin blanks to the Indian Mint and Mints in the global markets

The JSL plant at Hisar can be broadly classified into the following two categories:

1.) HOT ROLLING DIVISION (HRD)

2.) COLD ROLLING DIVISION (CRD)

In the hot rolling division, the starting materials are the raw materials for producing stainless steel, which includes the stainless steel scraps, mild steel scraps, various ferroalloys, pure materials like copper, Nickel etc which are melted in furnace and cast in the caster to produce slabs and blooms of steel. These are then send to the Steckel Mill in the HRD itself to be rolled into strips of desired thickness and are then converted into coils for cold rolling. In the cold rolling division the coils undergo processes like annealing and pickling which restores the shine characteristic of stainless steel to the coils that were initially black when received from HRD. The coils may also be further processed to obtain very thin plates of steel. Proper care is given to the categories of steel used to manufacture blade steel and surgical blades right from the selection of raw materials to their final processing. They may also undergo special processes or processes like vacuum oxygen decarburization.

72Fig. Flow chart for a basic idea of the plant working:

Production Planning & control department plays a very important role in the smooth working of JSL. Main function of PPC is preparing schedule for different-2 department on daily basis, according to demand. It mainly takes orders of

CRD Plates Slit Coils Orders from Indonesia & other countries Flat

Then accordingly prepares schedule for SMS, Steckel mill, Strip mill etc. Some orders comes directly through e-mails whereas some orders comes via marketing department.

Raw Materials

Steel Melting Shop

Hot Rolling (Steckel Mill)

Cold Rolling

Dispatch

SMS I

SMS IISlabs (grinding + shotblasting)

Purchase Dept.

(ensures L1 grade

materials availability)

Other departments include the:

*Quality Control Department

*Production Planning and Control Department

72STEEL MELTING SHOP

The two Steel Melting Shops, SMS I & SMS II, comprises of Ultra High Power- Electric Arc Furnace, Argon Secondary Metallurgy Converter, LRF (Ladle Refining Furnace). and a continuous slab caster while SMS II is also equipped with twin strand bloom caster. In addition to above SMS I is also equipped with VOD (Vacuum Oxygen Decarburization) unit to produce steel with low inclusion and gas content. The present installed capacity of both SMS put together is 7,20,000 MT per year. The slabs produced in the steel melting shops are then subjected to surface conditioning in a slab grinding section.

Fig: Process Flow Steel Melting Shop

The entire process of the Steel Melting Shop II can be represented by the following flow chart diagram:

72

Charging Section

Electric Arc Furnace

Argon Oxygen Decarburisation

Ladle Refining Furnace

Continuous Casting Shop

Shotblasting and Grinding Slabs to Steckel Mill

72RAW MATERIALS

Nickel

Pure Nickel - it is of two types cathode and bricked.

o Cathode form is more pure than bricked form but cathode is very heavy so if we have to add small quantity we use bricked form.

Ferronickel – contains mostly 20 – 30% nickel.

Both types of nickel are imported from Australia, South Africa, U.S.S.R and U.S.A.

Copper

1. Copper is bought in two forms Commercial grade (impure) and cathode(pure).

2. Commercial grade is mostly used for cost reduction.

Chromium

1. It is bought from JSL Orissa in the ferrochrome form.

2. Ferrochrome contains 60% chromium, 4% silicon, 7 – 8% carbon and rest iron.

Molybednum

1. It is bought in the Fe- Mo alloy form.

2. Fe- Mo contains 60% Mo, 1.4% Si, 0.089% carbon.

Titanium

1. It is brought as Fe-T alloy in two forms open and in titanium wire.

2. Fe-T contains 70% titanium.

3. When open Fe-T is used it get oxidized due to contact with atmosphere but by the use of titanium wire it can be poured directly inside the molten metal, so it reduce the loss of metal.

72 Refractory

1. Refractory for Furnace -:

a. Magnesia and carbon bricks are used for furnace lining.

b. Gunning mass is used for repairing of hot furnace.

c. Ramming mass (BC 1/3) is used for repairing of cold furnace.

d. Gunning mass contain 80-85% MgO and ramming mass contain more than 85% MgO.

2. Refractory for A.O.D -:

a. Dolomite is used for A.O.D lining.

b. Pentaram is used as cement for A.O.D lining.

3. Refractory for L.R.F -:

a. DB-3(Dolomite Bricks Bottom Block) used for lining of L.R.F.

b. Pentarep is used as cement of L.R.F lining.

Other raw materials -:

1. Fluorspur (halide mineral composed of CaF2) is brought from china. It is used to reduce viscosity of slag.

2. Cu-Ni scrap is also kept in shaded yard which contains (80:4, 70:30, 90:10, 72:2,) composition of copper and nickel.

3. Aluminum bar is brought from India.

4. Fe-V is brought from Oswal Alloys Pvt. Ltd.

5. Calcium Silcide is brought in two forms open and in iron wire. It contains calcium, silicon, iron.

6. Graphite electrode is brought from India(mostly) and China.

7. Al mix which is used to replace Cr and other imp metals from slag, is brought from Al manufacturing companies. It contains 10-20% Al and rest ash.

72Scrapyard

Stainless steel scrap

Material Nickel (%) Cr (%) Mo (%) P (%)

316 9 -10 16 1.5 – 2.5

317 13.5 17 3 – 3.5

Low Ni – Mo 0.75 – 1.5 negligible .8 – 1.5

304 7.5 – 9 17 - 18

Plate cutting .65 0.030-0.032

Circle cutting 0.5 – 1 15

Utensil 2 – 3 15 - 17

Blade steel (440) 12

409,410,430 mix (400 series)

16 (max)

Low Ni bricked 3 12

Internal materials (J42, J7)

Internal materials (J42, J7,J1 mix grade)

2 – 2.5 15 - 17

Blade steel J1 (JSL AUS) 4 – 4.5 15 - 17

72Mild steel scrap : mainly phosphorus composition is taken into consideration .

Material Phosphorus (%)

Sponge iron 0.032

Sponge Iron coal based 0.035 – 0.04

Maruti bundle 0.025 – 0.032

Auto bundle 0.032 (max)

M. S. shredded More than 0.04

CHARGING SECTION

The charge preparation is a very critical step in the entire heat making process. The first step in making a heat is the selection of a grade of steel that has to be prepared. Every grade of steel that is prepared at JSL Limited has an already established schedule( made by ‘Production Planning & control’ department) .

This charging may be done in one, two or more steps (charges’ are accordingly named as the first charge, second charge etc.) depending on the volume of the furnace, amount and type of the steel and density of the raw materials.

The operator will prepare buckets of scrap according to the needs of the melter. Preparation of the charge bucket is an important operation, not only to ensure proper melt-in chemistry but also to ensure good melting conditions. The scrap must be layered in the bucket according to size and density to promote the rapid formation of a liquid pool of steel in the hearth while providing protection for the sidewalls and roof from electric arc radiation

Some Grades that are manufactured at JSL

1. 200 Series (J1 to J7, JSL AUS, 204 Cu)

2. 300 Series (301, 304, 309, 310, 316, 327, etc.)

723. 400 series (409, 410, 430RF2)

4. IRSM 44-97

Heat Size for different series of stainless steel:

200 Series : 42000MT

300 Series : 45000MT

400 Series : 46000MT

The following is the composition of the various raw materials used:

COMPOSITION OF MATERIALS

MATERIALS C Mn Si P Cr Ni Cu MS Shredded H/P 0.3 0.75 0.3 0.45 0.2 0.2 0.35 SAF METAL 4.5 4.25 0.55 0.08 12.0 1.5 0.90 SS BLADE STEEL 0.6 0.6 0.25 0.025 13.0 0.0 0.10 HCFeCr Prime 7.5 0.0 3.5 0.040 60.0 0.0 0.0 HCFeCr L/P 7.5 0.0 3.5 0.025 60.0 0.0 0.0 HCFeCrFine 7.5 0.0 3.5 0.040 57.0 0.0 0.0 Grinding Dust 0.2 4.5 0.5 0.07 14.0 3.0 1.5 SS Sorted 0.2 5.5 0.5 0.07 12.0 3.0 1.5 SS 304 0.1 1.4 0.5 0.035 18.0 8.0 0.5 SS 316 0.06 1.4 0.5 0.035 16.0 10.0 0.6 SS J1+J4 0.2 8.5 0.5 0.080 15.0 3.0 1.5 SS 430 0.12 1.0 0.5 0.035 16.0 0.0 0.0

72FLOW CHART OF CHARGING PROCESS

Charging process starts

MS/SS Scraps from scrap yard is taken in buckets

Buckets are emptied on the charging trolley

Required quantity of lime and dolomite lime is added at the bottom of the charging bucket

This also ensures the safety of the refractory lining of the furnace.

Heavy materials like JAM, SAF, COIL, etc. is put before any kind of scrap for safety of electrodes

Required quantity of SS Jits and Scraps are added

Addition of ferroalloys like FeCr, FeNi, FeCr fine,, G dust and pure copper are added as per the grade requirement

Required quantity of the MS Scrap is added and the first charge is prepared

Similar steps are repeated to prepare the 2nd, 3rd and 4th charge

Charging process ends.

72The Instruments and machines used at charging.

1)Cranes & Other Machinery:-

40.0 MT (B) EOT Crane. ( Make:-FAFECO)

15.0 MT Magnet Crane (Load Cap. Magnet 1.0 Mt. To 1.2 Mt)

Make :-WMI

Dia:-2280 MM

Thickness :-550 MM

Chain Size & no of Chains :-1200 MM (03 nos)

15.0 MT Grab Bucket Crane

Crane Make :-Jindal

Grab Bucket :-Make :-Aramatic Engg. Bangalore

Load Capacity 3.0 Mt. Approx.

Charging Trolley. (01 nos)

No of wheels :-04

Diaof Wheel :-800 MM

Gear Box :-92 :1

Gear Oil :-460

Motor Capacity :-12.0 KW / 725 RPM

72Charging Bucket. (04 nos)

Wt of Charging Bucket :-12.0 Mt.approx

Capacity by Vol:-11m3 , dia3.0 m, ht. 3.3m

Capacity by Weight :-25.0 to 27.0 Mt. Approx.

Weighing Bridges :-

1) 60.0 MT (Model: - 52NL225)

Measurements :-( 6000 mm X 4100 mm X 794 mm)

No of Load Cells:-04 nos

Cap. of each Load Cell:-45.0 Mt

2) 100.0 MT (Model:-52 N L225)

Measurements (5300mm X 4100 mm X 750 mm)

No of Load Cells:-04 nos

Cap. of each Load Cell:-45.0 Mt.

72ELECTRIC ARC FURNACE

The electric arc furnace operates as a batch melting process producing batches of molten steel known "heats". In the furnace, the electrons liberated from electrode move towards scrap. These electrons are accelerated throughout their movement towards the scrap due to the existence of an applied potential difference. When they strike the scrap at their existing high velocities, large amount of heat is generated.

The electric arc furnace operating cycle is called the tap-to-tap cycle and is made up of the following operations:

Furnace charging

Melting

Refining

De-slagging

Tapping

Furnace turn-around

72The first step in any tap-to-tap cycle is "charging" into the scrap. The roof and electrodes are raised and are swung to the side of the furnace to allow the scrap-charging crane to move a full bucket of scrap into place over the furnace. The bucket bottom is usually a clam shell design - i.e. the bucket opens up by retracting two segments on the bottom of the bucket. The scrap falls into the furnace and the scrap crane removes the scrap bucket. The roof and electrodes swing back into place over the furnace. The roof is lowered and then the electrodes are lowered to strike an arc on the scrap. This commences the melting portion of the cycle. The number of charge buckets of scrap required to produce a heat of steel is dependent primarily on the volume of the furnace and the scrap density.

After the charge has been taken in, it is heated by two mechanisms:

The electrical mechanism

The chemical mechanism

Melting & heating in the furnace :

The melting period is the heart of EAF operations. The EAF has evolved into a highly efficient melting apparatus and modern designs are focused on maximizing the melting capacity of the EAF. Melting is accomplished by supplying energy to the furnace interior. This energy can be electrical or chemical. Electrical energy is supplied via the graphite electrodes and is usually the largest contributor in melting operations. Initially, an intermediate voltage tap is selected until the electrodes bore into the scrap. Usually, light scrap is placed on top of the charge to accelerate bore-in. Approximately 15 % of the scrap is melted during the initial bore-in period. After a few minutes, the electrodes will have penetrated the scrap sufficiently so that a long arc (high voltage) tap can be used without fear of radiation damage to the roof. The long arc maximizes the transfer of power to the scrap and a liquid pool of metal will form in the furnace hearth At the start of melting the arc is erratic and unstable. Wide swings in current are observed accompanied by rapid movement of the electrodes. As the furnace atmosphere heats up the arc stabilizes and once the molten pool is formed, the arc becomes quite stable and the average power input increases.

Another energy used in the heating process in the furnace is the chemical energy.

There are two burner sites in the furnace located at two cold spots in the furnace. There are two ports at each site. The lower one is used for the coke injection in the furnace

72and the upper one is used for implementing the Co Jet System. The nozzle for the Co jet (nozzle diameter 85mm) system has a total of 17 holes perforated in it.

There is one central hole, which is the largest in dimension (20 mm diameter) and is used for the supply of the oxygen/nitrogen. Then 8 holes are present for supplying shroud oxygen having diameter of 3mm and further 8 holes are present for supplying propane. These are the smallest holes in the nozzle having a diameter of 1.5 mm. The CO jet is nothing but an injector nozzle that delivers a laser like jet of oxygen at supersonic velocity into the molten bath. It is a specialized injector nozzle which allows the jet of O2 to retain its original diameter and velocity up to 2.1 metres. The propane that is injected burns to produce carbon monoxide and liberates heat.

Also Manual Lancing is done to ensure supply of enough oxygen in the EAF during its operation and thereby increasing productivity. In this process workers at the EAF take up the lance and insert it in the furnace manually after connecting it to suitable oxygen supplying valves.

The Electrodes that are used up in the furnace are graphite electrodes having following composition:

Graphite: - 99.7% and Ash : - 0.3%

These electrodes are water cooled by a water spray system located at the top where the electrodes are clamped. This prevents the excessive heating of the electrodes at the upper unused portion of the electrodes. These electrodes are having a diameter of 450mm and a length of 2100mm.

De-Slagging :

De-slagging operations are carried out to remove impurities from the furnace. During melting and refining operations, some of the undesirable materials within the bath are oxidized and enter the slag phase. It is advantageous to remove as much phosphorus into the slag as early in the heat as possible (i.e. while the bath temperature is still low). The furnace is tilted backwards and slag is poured out of the furnace through the slag door. Removal of the slag eliminates the possibility of phosphorus reversion.

72During slag foaming operations, carbon may be injected into the slag where it will reduce FeO to metallic iron and in the process produce carbon monoxide, which helps foam the slag. If the high phosphorus slag has not been removed prior to this operation, phosphorus reversion will occur. During slag foaming, slag may overflow the sill level in the EAF and flow out of the slag door.

The following table shows the typical constituents of an EAF slag :

Components Source Composition Range

Cao Charged 40 - 60 %

SiO2 Oxidation Product 5 - 15 %

FeO Oxidation Product 10 - 30 %

MgO Charged as dolomite 3 - 8 %

CaF2 Charged – Slag Fludizier

MnO Oxidation product 2 - 5%

S Absorbed from steel

P Oxidation product

At the end of every Heat or cycle Al- Mix ( contains around 18-20% Aluminium) is added to the molten material for the recovery of chromium from the slag

Proper maintenance of the furnace is done from time to time. A very frequently done process is Gunning in which a spray mass of the refractory powder is sprayed over the areas where the lining has reduced due to furnace conditions. Due to the presence of the high temperature in the furnace this powder sinters and attaches to the refractory lining.

72Specifications of the Electric Arc Furnace used at JSL

Capacity:-40 MT

Shell Diameter of Furnace:-4600mm

Shell Diameter (inner):-4580mm

Furnace Height from Ground level:-6500mm

Bottom Depth:-650mm

Make: -ABB

This EAF also employs the use of a world class Co jet system that is used only at few places throughout the whole country

Co jet Make: - Praxair

The other equipments used at the EAF of SMS II are

Dog House:- Make: - Jindal

Coke/ Si injector Make: - Stein

Transfer Ladle: - Refractory=High Alumina70% (4 nos), Capacity=45 Mt

Tapping trolley:- Wheel center=3200mm Gear oil= 460

Motor capacity=12 KW Gear box ratio =92:1

Gunning Machine

Weigh Bridge: – Make: - Sartorius100 MT

Crane: - Make: - Faefco

72Construction of Electric Arc Furnace :

72The furnace body is in the form of a cylinder with a spherical shaped bottom. The roof is circular, bent at the circumference to form a cap to the furnace body. There are two regions each in the furnace body and in the roof. The main furnace shell is made of Mild Steel, but the upper part consists of a Water-cooled copper panels joined in a water cooled copper cage to form part of the furnace body. The water cooled copper panels are innovative and modern in design and construction and it is thus one of the striking features of the furnace being used. The roof when made up completely for use, consists of two concentric regions. One is the part at the centre, which consists of three holes to allow the passage of electrodes through them. This is called the DELTA and is actually made up of castables (high alumina). The other part consists of again the water cooled copper panels with a lining of castables on the inside.

Hydraulic system :

The hydraulic system provides motive power for almost all EAF movements including roof lower/raise, roof swing, electrode arms up/down/regulation/swing, furnace tilt forward/backward, slag door raise/lower and movement of any auxiliary systems such as the burner lance. The hydraulic system consists of a central reservoir, filters, an accumulator, hydraulic valves and hydraulic piping. As hydraulic fluid passes through valves in one of two directions within a given circuit, hydraulic cylinders are extended or contracted to provide movement of various mechanical components. Without sufficient fluid flow and pressure within a circuit, movement is impossible.

A total of 15 hydraulic cylinders are used in the entire furnace mechanism including 3 for electrode lifting and 3 for their clamping, 1 for roof movement in the vertical direction and 1 for the roof and electrode swing. Also 2 other cylinders are involved in the roof tilting process.

Cooling Water System :

The panels are made from copper because copper is a very good conductor of heat, and therefore it transmits all the heat it takes to the water flowing in the panels. Again it is essential to maintain a velocity of water above some critical value so that no steam is generated inside the panel. Any steam that would be generated will prove harmful as steam will not conduct the heat as appropriately as water would have.

72The panels are supported on a water cooled cage thus allowing for individual replacement of panels with minimum downtime. The thermal expansion of cage is thus avoided by making it too a water cooled system which further prevents warping & gap generation between panels. Thus the furnace is now allowed to work under higher temperatures and further extreme conditions.

Important influencing factors are water quality & quantity, flow rate & velocity, inlet water pressure and pressure drop across panel, pipe/panel construction material and pipe diameter.

During the time of charging scrap can strike panels causing dent or splitting, thus the panels must have a good ability to withstand the mechanical loads. For improving this one can increase the thickness of the copper panels, but a greater thickness will result in decreased thermal conductivity across the panels. Thus a compromise is met and an optimum thickness is selected. In the case of the furnace used at JSL, the panel thickness

is selected around 8mm.

It is always attempted to build a slag coating on the panel surface exposed to interior of furnace to reduce the thermal cycling of the metal and that the metal’s yield stress is not exceeded. Slag is an excellent insulator with a thermal conductivity of 0.12 –0.13W/mk

Vertical configuration of panels is preferred to minimize pressure drop across panel. Generally water temperature rise is 8-17 degree Celsius to a max of 30. The water in the closed loop circuit passes through a heat exchanger to remove heat. The circuit on the open loop side of the heat exchanger typically flows to a cooling tower for energy dissipation.

An interesting point worth mentioning here might be that if the panels are not airtight air will be sucked into furnace as the furnace operates at a lower pressure than the atmosphere.

Once the desired steel composition and temperature are achieved in the furnace, the tap-hole is opened, the furnace is tilted, and the steel pours into a ladle for transfer to the next batch operation (usually a ladle furnace or ladle station).

72ARGON OXYGEN DECARBURISATION

The heat from the Transfer Ladle is tapped into the AOD Vessel.The goal of the Argon Oxygen Decarburisation is to achieve:

1) The near Aim Chemistry in the heat.

2) Desired heat size

3) Desired near aim temperature

4) Achieve all the above stated in the minimum possible time.

The salient features of the AOD are as follows:

Bottom backside tuyeres (5 in number), used to supply the required oxygen and the shrouding gas, i.e., the nitrogen or argon gas

The Intelligent Refining System (IRS),

Ferroalloy Feeding System (FAFS).

Top lance

72

A sample of the heat is taken from the transfer ladle and is then send to the SMS Laboratory for analysis. The use of spectroscopy, Leco Analyzers or other such Gas (Oxygen and Nitrogen) Analyzers and Carbon/Sulphur Analyzers or still advanced equipments like the XRF are used to know the composition of the heat put in the AOD.

CONTROL OF AMT OF METALS -: After a very quick analysis of the sample the composition is reported to the AOD control room where the operator makes appropriate calculations of the materials to be added to achieve the aim chemistry. After this calculation he feeds in the information in the IRS for addition of the required alloys.

This Feeding System at the AOD consists of 4 Hoppers or Silos in which required materials are stored. The materials, which are added here, are generally the pure versions. When a command is input by the AOD operator, weighed amounts of these materials are now transferred from the hoppers on to a conveyor, which takes it up to the AOD through a pipe near the mouth of the AOD Vessel.

CONTROL OF AMOUNT OF CARBON AND TEMP -: First the controller just feed the value of carbon and temp in the IRS software, which has different recipe for different inputs which were prepared by past experience. This software actually controls the value of carbon and temp by controlling the flow rates of nitrogen, argon and oxygen. This software recipe is divided in four steps 1st blow, 2nd blow, 3rd blow and reduction step.

AOD mouth

AOD Cap

AOD Vessel

AOD Bottom

Tuyere zone

Conical Section

Fig: AOD Convertor/Vessel

721st Blow-: In this blow the ratio of oxygen and nitrogen is kept around 22:1 and most of nitrogen is used for cooling purpose.

2nd Blow-: In this blow the ratio of oxygen and nitrogen is kept around 5:1 to 1:1 and now nitrogen is used for both cooling and to reduce the partial pressure of CO.

3rd Blow-: In this blow the ratio of oxygen and nitrogen is kept around 1:5 as partial pressure of CO become very large, so the amt of N2 will be increased to reduce the partial pressure of CO so that the reaction will move in forward direction.

Reduction Step-: After a desired carbon and temperature level have been reached the process moves to reduction. Reduction recovers the oxidized elements such as Cr from the slag. To achieve this, alloy additions are made with elements that have a higher affinity for oxygen than Cr, using either a Silicon alloy or Aluminum (silicon is mostly used because it is cheaper). The reduction mix also includes lime (CaO) and fluorspar (CaF2). The addition of lime and fluorspar help with driving the reduction of Cr 2O3 and managing the slag, keeping the slag fluid and volume small.

In AOD basicity is also maintained greater than 1.5 by the formula (CaO +MgO)/SiO2

>1.5.

Samples at appropriate time are taken from the AOD to know the effect of addition of the various materials and the various chemical reactions taking place in the Vessel and also to know the proximity of the heat chemistry to the desired or the aim chemistry of the heat. Once a near aim chemistry is achieved the tapping from the AOD is done. The excess slag is initially tapped off in a slag pot on the same turret on which the TEEMING LADLE is placed. The molten steel from the AOD is tapped in the teeming ladle. This teeming ladle is then taken to the Ladle Refining Furnace.

LADDLE REFINING FURNACE

HISTORY-: Previously LAF was not used and final chemistry was achieved in AOD and from AOD it directly went for the continuous casting. This process reduced the production as only one heat could be casted at one time because after pouring of one heat into the ladle which went to the caster, it takes minimum one hour to prepare second heat, in this time ladle had poured all the metal in the caster, so that second heat could be casted only after the completion of casting of first heat, i.e. the concept of ladle refining furnace would be introduced.

72

Application-: The LRF is used as a place to store teeming ladles containing steel with perfect chemistry and perfect lifting temperature essential sequential casting,. In ladle refining furnace, arcing is done to increase the temperature of the liquid steel bath.

Thus the main functions of the LRF are as follows:

1.) To perform trimming additions to achieve the aim chemistry

2.) Continuous argon purging to achieve homogeneous steel in the ladle

3.) To achieve a perfect lifting temperature of the steel so that when it reaches the caster it may acquire the required temperature configuration essential for casting.

In the teeming ladle the central hole is used for the argon purging and the one away from the centre is used for casting.

To achieve the required temperature profile arcing is done in a similar manner as was done in the EAF. Here also there are three graphite electrodes that are employed for the purpose. But these electrodes are smaller in diameter than the ones used at EAF. Their diameter is 300mm and they have a length of 1800 mm.

Here these electrodes and roof can move in the vertical direction but they are never swung and there is an arrangement of the ladle car allowing teeming ladle to be brought under the electrodes and the roof.

Whereas the trimming additions are made before taking it under the ladle roof by the use of cranes which pick up weighed amount of pure materials to be added to achieve the perfect final chemistry

POLLUTION CONTROL SYSTEM

72

Fixed Elbow Dilution damper

Forced

Draft Fan Filter Bags

Heat

Exchanger

In EAF and AOD, JSL has pollution control system which makes the company’s environment suitable for working & also keeps environment pollution free. The basic layout of pollution control system of EAF is shown above. In EAF there is elbow attached to the roof of EAF furnace and this elbow is not fixed it moves with the roof. Hot gases from the EAF go from this elbow to the fixed elbow which is attached with combustion chamber. The hot gases has temp around 1500oC, i.e. the wall of elbow and combustion chamber is made of M.S. seamless pipe in which water is supplied to cool the walls. In combustion chambers due to gravity heavy particles settles down and collected in the box kept below the chamber. Then it goes to the heat exchanger with temp around 600oC and there its temp reduces to around 150oC.

Then it goes to the dilution chamber where it gets diluted with air which comes through dilution damper. Then it goes to the filter bags and then finally released in the surrounding through chimney. In JSL, EAF has 8 modules of air bags and AOD has 7 modules of air bags. One more important component of pollution control system is Induced drought ( ID) fan . ID fan creates suction or Pressure drop so that due to pressure difference hot gases can pass from EAF , AOD to atmosphere via different components of pollution control system.

EAF Combustion

Chamber

Dilution Chamber

Combustion Chamber

72

CONTINUOUS CASTING SHOP

The main parts of the caster are:

1.) Shroud

SMS II

CCSSLAB CASTER

(235-1285) mm*200mm

BLOOM CASTER

200mm*200mm and 260mm*200mm

Fig: Layout of continuous casting shop

722.) Tundish

3.) Submerged entry nozzle

4.) Automatic Level Control System

5.) Water cooled copper moulds (nickel coated copper moulds may also be used depending upon grade)

6.) Slag detector

In the continuous casting shop ladles from the LRF are supplied after a performing of the sequencing at the CCS. Thus the operator at the CCS as well as the LRF would know how

many heats are to be casted in the caster.

Once the heat in the LRF has been sufficiently superheated it is then loaded on the ladle car which takes it to the casting shop. At the casting shop, it is taken up by the crane and loaded on to the ladle turret.After an opening of the nozzle of the teeming ladle (preferred is a free opening) is achieved molten steel is made to flow through a shroud into the tundish.The function of the shroud is to protect the steel from coming in contact with atmosphere.

The tundish acts as a reservoir in sequencing and maintains a supply of molten steel to the caster even when the ladle is changed.

72A perfect flow rate of the steel into the mould has to be achieved for better quality of the emerging slabs. This is maintained at the caster with the help of an automatic level control system. For the first ladle the flow is regulated manually by the workers at the casting shop. After this it is regulated automatically.

This automatic system uses a silica float which gives the level of the molten metal in the tundish. If this level drops due to an increased flow rate through the mould, then the level of the silica float also drops which is used to send out a message for lowering the level of the SEN. Thus the flow rate through the mould is decreased till it reaches the desired level. Similarly for a decreased flow rate the nozzle is made to move upwards.

The moulds that are used are water cooled. Since copper is an excellent conductor of heat, therefore copper moulds are used. For lubrication purposes and also for disallowing steel to stick to the mould a powdered layer of oxides is constantly put in the sides near the walls of the moulds which forms slag and performs the desired functions.

Meanwhile the steel had been flowing into the tundish from the ladle. When the steel level in the ladle had decreased considerably, the slag at the top starts to flow into the tundish which is undesired. This slag flow is determined by a slag indicator which measures the vast differences in conductivity of the slag and the metal.

Thus the ladles are changed, as and when they are emptied and new ones are supplied by the LRF. Thus a proper sequence of casting is achieved at the CCS and the empty ladles are sent back. A sequence casting of as many as 17-18 heats have been said to be achieved at the CCS

SHOTBLASTING AND GRINDING

72The slabs that are produced from the CCS have various unwanted surface deposits and oxides. Before they can be further processed these are to be removed from the slabs. The methods employed to do so are:

1.) Shotblasting

2.) Grinding

SHOTBLASTING:

In shot blasting the basic principle is the removal of the unwanted surface oxide layer by charging shots on the surface with sufficient velocity so that these shots may remove these particles when they strike the surface of the slab.

These shots may belong to any of the following forms:

1.) Wire cut shots

2.) Triangular shots

3.) Round shots

4.) Mixed shots are also used very frequently

The slab rolls and enters one end of the shotblasting apparatus, undergoes the entire process and then emerges from the other end.

The following are the major parts of the apparatus:

1.) Inlet vestibule

2.) Blasting Vessel: they contain 4 impellers of which 2 are used to charge shots on the top surface and 2 on the bottom surface of the slab

3.) Outlet vestibule: they remove the shots from slab surface to recycle them and charge them again on the slab surface. Their major parts are the V flow brush off drive, auxiliary blower

72There is a fan arrangement to suck the dust emerged in the process. The other facilitating parts of the apparatus are the conveyor and bucket elevator which takes back the shots to the shots feed tank.

AUTO-GRINDING

In grinding the slabs are placed on a cable trolley which takes it underneath a grinding wheel which in turn is so attached such that it exerts an optimum pressure on the slab as it rolls and finishes the surface removing many defect types like the longitudinal defects (LD), longitudinal cracks (LC) and pin holes present on the slab surface.

The major machine parts are as follows:

1.) Main Spindle

2.) Cable Trolley

3.) Blower

4.) Bag House and the

5.) Cyclone Chamber.

The grinding wheel is made of alumina and needs replacement when the wheel diameter reduces considerably. As the grinding is done on one surface at a time, therefore, the slabs are to be inverted to allow grinding on both the surfaces. For certain special grades edge grinding is also done. Once the grinding is done the slabs are sent off for further processing.

HOT STRIP MILL

72The hot strip mill of Jindal stainless ltd. (JSL) performs an intermediate operation of converting blooms and slabs obtained after casting into coiled strips under hot working conditions. So input materials to this mill are casting products and output materials are hot rolled coils. Mill operation includes heating of slabs above their recrystallization temperature in a furnace followed by descaling and thickness reduction by power driven rolls to convert them into strips of reduced thickness(3 to 15 mm) after which coiling of strip is done over a rotating mandrel . It is capable of producing a huge quantity of strips with a maximum capacity of producing 535 MT (metric ton) in narrow and 1200 MT in flat coils in a span of 24 hours.The good quality management, dedicated manpower and technically sound set up has induced success to the mill and laid the path for ‘KAIZEN’ of this mill.

LAY OUT OF HOT STRIP MILL

20.5727.96 3.35 3.05

m3.05 7.923.05 2.74

Reheating Pusher Furnace

Descaling Roughing Mill

2- Hi 5 Stand Tandem Mill

Pinch Roll

Down Coiler

72HOT STRIP MILL PROCESS & SPECIFICATION

PUSHER FEED SYSTEM: It is used to feed the slabs into the reheating furnace. It has hydraulically operated ram which are connected with guide rods for pushing.

SPECIFICATIONS

No of cyl inder 02

Pressure 85-110 kg/cm2

Piston diameter 150 mm

Stroke 750 mm

Fluid(oil) servo system-32/68

REHEATING FURNACE : This furnace has one Preheating zone (raises temperature upto 800˚ C ) & five heating zones –

i) Top heating Zone A

ii) Top heating Zone B For top heating of bloom (3 burners)

iii) Bottom Heating Zone For lower heating of bloom ( 3 burners)

iv) Top shocking zone A

v) Top shocking Zone B For heating of core of the bloom (4 burners)

produces different temperature zones inside the furnace. Heat is produced by combustion of furnace oil in atomized state, a recuperator is used to heat up the

72induced air by making use of the flue gas temperature thereby improving the efficiency of the furnace.

REHEATING PUSHER FURNACE

Function To heat the Blooms

Furnace size 20 m x 5.1m

No. of burners 12

No. of blowers 3

No. of zones 04(PHZ, THZ, BHZ, TSZ)

Capacity of Furnace 45 TPH

Fuel Type LVFO/FO

EXTRACTOR: It draws completely heated blooms out of furnace, it has a frame to grip the blooms and is capable of horizontal to and fro and vertical up and down motion, it is driven by hydraulic cylinders.

CONVEYORS: These are motor driven cylindrical shaped barrels which are used to transport blooms through the entire mill.

DESCALING: This system removes the oxide scale on the heated bloom by the water jet of very high pressure (210 Bar) before rolling in R/mill.

SPECIFICATIONS :

Descaler pressure 175-220kg/cm2

Descaler header upper

72 No. of nozzle 07

Nozzle No. 907

Nozzle angle 150

Descaler header lower

No. of nozzle 07

Nozzle No. 907

Nozzle angle 150

ROUGHING MILL (2-HI):

Roughing mill contributes for the major reduction in thickness of blooms or slabs. During the process the bloom is passed through it seven times. So it is also called REVERSIBLE MILL. The 2-hi roughing mill has two work rolls rotated in opposite direction by a D.C motor.

Motor Gear

boxLead screws

upper work roll

Bottom work roll

End coupling

2-Hi Gear Box

D.C Motor

Housing

Spindle

Flange Coupling

2 HI ROUGHING MILL

722 HI ROUGHING MILL MOTOR SPECIFICATIONS

Function Rolling of work rolls.

Motor capacity 7000KW, DC

Max speed 115-170 m/min

Working range 20-65(RPM)

Voltage 750

Max current 11000 amp

Work roll dia 813-710 mm

No. Of gears 2

Type of gear helical gear/spur gear

Tandem Mill: The slab after passing through roughing mill passes through 1 to 5 continuous 2 HI tandem mill. The Tandem Strip mill comprises of reheating furnace, 2-Hi roughing stand, five finishing stands and down coiler to hot roll stainless steel blooms into flat bars anarrowcoils. The present rolling capacity of both the mills put together is 700,000 TPA The tandem mill are similar in construction to roughing mill, each mill has 2 work rolls driven by d.c motors, the rolls are supported by choke and gap adjustment between the rolls is done manually by wheels provided at the top by the motion of lead screw. In tandem rolling, the material to be rolled undergoes reduction in all mill stands at a time .In order that the material is rolled without excessive pulling or looping it implies that the same volume of steel should pass through all the stands at any time.

72SPECIFICATIONS :

HOUSING NO 1 2 3 4 5

WORK ROLL

DIA(MM)473-533 464-418 464-418 473-418 473-418

MOTOR (KW) 2000 2000 1800 1800 2250

MOTOR

TYPE

DC DC DC DC DC

RPM 116 116 125 150 210

VOLTAGE 750 750 750 750 750

Lubricating oil used in motor bush - (1, 2) – 20w40

Grease used in bearing (3,4,5) – Servo EP-2

PINCH ROLL: The pinch roll is set just before the down coiler. The pinch roll has a motor driven upper roll which pinches the strip, that is, it creates tension and also removes the looping from strip.

It has big upper roll and smaller lower roll. The gap is adjusted with help of hydraulic cylinder supporting the roll.

SPECIFICATIONS:

Upper pinch roll 610mm dia

Lower pich roll 350.75mm dia

Gear box ratio 1: 2.7

Motor DC, 50kw, 600-1200RPM

72 COILING :This is the final process of the strip mill and is done in coiler. The

strip is fed to coiler through pinch roll, this strip falls inside coiler upon wrapper

rolls which ultimately wraps up the coil upon mandrel, the first wrapper roll

bends the coil which afterwards is guided by another rolls over mandrel surface

and critical coiler roll finally pinches this strip over mandrel. When entire length

of the strip is wrapped then the mandrel collapses radially inwards and an axial

force acts on coil simultaneously by the coiler car which removes the coil from

mandrel and this coil is then taken away by the overhead cranes.

DOWN COILER:The down coiler consists of a rotating mandrel driven by a motor

and it is surrounded by 3 wrapper rolls which are hinged at one end and their

rotation about this fixed axis is controlled by 3 hydraulic cylinders. The mandrel

shaft itself is collapsible and can contact and expand radially.

Function: Coil Wrapping

System Hydraulic Pressure: 45-60 Bar

No of Wrapper Rolls: 03 (01 powered)

Motors

Dia(mm) Face(mm) CouplingPOWER

(KW)SPEED(RPM)

Mandrel shaft 520-500 600 112 560 800

Wrapper roll 1 285-270 457 Rigid 50 600

Wrapper roll 2 285-270 457 Idle

Wrapper roll 3 285-270 457 Idle

72STECKEL MILL

A Steckel mill, also known as a reversible finishing mill, is similar to a reversing rolling mill except two coilers are used to feed the material through the mill. One coiler is on the entrance side and the other on the exit side. The coilers pull the material through the mill, therefore the process is more similar to drawing than rolling. The material is fed back and forth through the mill until the desired thickness is reached, much like a reversing rolling mill.

It is also used to process steel slabs into hot rolled coil (HRC). The Steckel mill allows the rolling of a large slab by providing heated reels on both sides of the mill to store the increased length produced during rolling. These drums allow for additional heat retention and thermal consistency in the rolled piece, which in turn produces improved uniformity throughout the rolled product.A furnace is provided in both sides of the mill, which covers the mandrels each in one side upon which the slab is rolled after every complete pass. Output from Steckel mill varies from 2.5 to 3mm. A cutter mechanism is also provided in this mill to cut the irregular head and tail of the incoming slab.

In the Steckel mill, several passes have to be taken to get the desired reduction. The Steckel mill has quality problems due to temperature losses. The rate of production in a Steckel mill is lower than a tandem mill as steckel mill is reversible.

In JSL, Hot rolling comprises of Hot Steckel Mill and Tandem Strip mill. The hot steckel mill comprises of slab reheating walking beam furnace, 4 Hi reversing roughing mill, 4 Hi reversing Steckel Mill equipped with Hot Coilers on both sides and a down coiler. Slabs are rolled to hot rolled coils and plates. The mill is equipped with level-2 automaton system consisting of automatic hydraulic gap setting, roll bending system, automatic pass scheduling and mill setup, automatic sequencing, mill supervisory system automatic X-ray gauge control and descaling unit. The mill is capable of rolling plates and coils upto 1250 mm width weighing upto 18 MT .

72GENERAL LAAYOUT OF STECKEL MILL

CAPACITY : 125 TPH( with pre-heating f/c) & 85 TPH (w/o preheating f/c)

72PROCESS FLOW

Slab from SMS 1 &2

Walking BeamPreheating furnance

Walking Beam Heating and soaking furnance

Primary Descaler

Secondary Descaler

Roughing Mill

Entry Hot Coiler

Twin Stand Steckel Mill

Exit Hot coiler

Downcoiler

Strapping machine

Plate Shear

To Hot Rolling

Finishing Section

Plates

Only for 400 series SS

72

PROCESSING UNITS: IN DETAILS

I. Furnaces: Preheating (PHF) and Heating (HF) :

After the completion of production of slabs in SMS, they come to the steckel mill for hot rolling. Before rolling they are heated to approx 1200oC temp by the help of preheating and heating furnace.

How heating takes place in these furnaces - Firstly, the hydraulic controlled gate of preheating furnace opens and a robotic arm lift the slab and put it into the furnace and after that gate closes. In the furnace there is a hydraulic controlled walking beam system through which slab moves in the furnace and after heating up to 300-600°C, there is electrically operated robotic arm which

take out the slab from furnace and put it on the conveyer. Then slab goes to heating furnace where heating takes place in two zones heating and soaking

Heating Zone – In this zone there are burners installed at the top and bottom which heats the coil from top and bottom.

Soaking Zone - In this zone slab is kept for some time so that slab get heated up to the core i.e. core and surface both get heated to the required temp which is around 1200°C.

When final temp is acquired and the system used for putting, moving and taking out the slab is similar to the preheating furnace.

Why preheating is done – In JSL preheating is done to increase the production rate. If only heating furnace is used it takes more time to heat a coil than to process it in steckel mill, so preheating furnace is used which heats the slab to 300-600°C temp and now it takes less time to get heated in heating furnace.

What is walking beam mechanism – In steckel mill both preheating and heating furnace have this mechanism to move the slab inside the furnace. In these furnaces there are total 11 beams on which slab rests in which 6 are fixed and 5 are walking or moving beams alternatively. These walking beam lifts the slab & moves 500 to 600 mm forward & then moves down and put the slab back on the fixed beam and then these moving

72beams comes back to its original position. Surface quality or finish of a slab is one of the important parameter for any stainless steel industry and Due to this transfer mechanism as a result of walking beam rubbing of lower surface of slab is prevented which is more prominent in case of pusher type mechanism (used in strip mill) & surface finish or quality of slab is not degraded.

If wheel will move up on the ramp then moving or transfer beam will get upward movement & slab will be lifted and then by the help of hydraulics transfer beam will move in forward direction, so slab will move in forward direction and then wheel moves down, so transfer beam will get downward movement and it put the slab on fixed beam and after that it will come back to its original position.

All of the above movements, lift, forward, downward & backward movements are hydraulically operated.

Slab

Transfer Beam or Moving Beam

Lifting Beam

Ramp

Wheel

72Capacity: 85 MT/hr for heating furnace only (without pre-heating furnace) and 125 MT/hr with preheating and heating furnace

Sr No.

Parameters Pre-heating F/C Heating F/C

1. Dimensions L : W : 11.2 m L:19 m W: 11.2 m

2. Fuel used LVFO/LDO LPG/LDO/LVFO

3. Temp at each zone PH : 300-350 C; H : 450-500 C ; S : 600 C

H : 900 C (if thru PHF), else 820-840 C

H - 400 series : 790 C

S – 300 series : 1240 C ; for 200 series : 1240 C

For 400 series : 1150-1170 C

4. Residence time 1-1.5 hrs 3-3.5 hrs

5. Defects Sliver B (Sulphur inclusions at grain boundaries, leading to localized hot spots and surface rupture)

Scale pits : high temp oxidation due to higher residence time

II. Descaling Unit:

Primary descaling unit :

o Objective : Remove the primary scales on the slab surface (mostly Fe3O4 oxides)

o High pressure water jets are applied from both the top and bottom nozzles at 205-210 bar pressure

72 Secondary descaling unit:

o Objective : Remove the secondary scales from the slab surface (mostly Fe2O3 oxides)

o High pressure water jets applied at a pressure of 205-210 bar

Scale loss: 0.35-0.5% of slab weight.

III. 4 HI Roughing Mill

After descaling unit slab reach to the roughing mill which is a 4 HI reversible mill. There slab is rolled from 200mm to 32-40mm which depends on the grade. It is called roughing mill as the gap between its rolls is controlled by automatic gauge control and mechanical screws which have low accuracy, so this mill gives a rough thickness, for example grade 430 is rolled to 32 mm through roughing moll i.e. this mill gives a thickness around 32 mm not exactly. The rolls of this mill are made of S.G Iron. In this mill there is problem of variation in width ranging +10mm/ -5mm.

IV. Steckel Mill

After roughing mill it reaches to the steckel mill where it is rolled to the final thickness.

Steckel mill has two hot coilers: entry hot coiler and exit hot coiler. These two coilers are used to provide space for accommodating the entire length of the coil for rolling in Steckel mill and to maintain temp of coil depending on grade of steel rolled

200 series : 1050 C,

300 series : 1050 C

400 series : 900-950 C.

72

These hot coilers have 6 burners : 4 running, 2 standbye and LVFO is used as a fuel in these burners. Between these two hot coilers twin stand 4 hi reversing mills has been installed. Minimum thickness that can be rolled on this mill is around 5-6 mm. Number of passes through steckel mill are depend upon final product. If final product requirement is plate then only one pass is required but for coils either 3 or 5 passes are required. Thickness in each pass is controlled or governed with the help of X-ray & hydraulic auto gauge control. Basically thickness is measured with the help of X-rays which gives a feedback to hydraulic auto gauge control, accordingly automatically distance between the rolls is adjusted. Also for the smooth & accurate movement of rolls servo valves has been installed. Average speed of steckel mill is around 3-4 m/sec & it varies according to grades rolled. Work rolls are changed after every 250 MT of rolling.

According to costumer demand for coils, positive crown or negative crown rolls are used for rolling in steckel mill. Here in JSL more demand is for positive crown coils due to which negative crown rolls are used

How thickness is measured through X-ray – X-ray can pass through materials but in doing so they lose energy. If the initial intensity is known, the thickness of material can be determined by measuring the intensity remaining after going through the material. Therefore, this type of a gauge is composed of an emitter usually placed under the strip and a receiver, located on the top of strip. (These gauge are calibrated with standard plates of various alloys to be rolled).

Defects generated :

Scratches at head and tail end generated from hot coiler Gauge variation Crown Camber Wedge

72VI. Cooling unit:

Cooling is done after exit from the Steckel mill

Laminar cooling with water jets are done for grades : JSL-AUS, 446, 439, 436

For other grades, no cooling is done

Finish Rolling temp is generally > 900 C

Coiling temp without laminar cooling is around 800-850 C; while CT with cooling is around 600-700 C

Overall line yield from Steckel Mill rolling unit: 97.5% (target); actual: 98%

For 400 series coils, yield: 96-97% For 200, 300, 400 series in plates of thickness >

12 mm : 99.5% For coils in 300 series : 98.5% For coils in 200 series : 98.5%

STRAPPING OF COILCOILING AT DOWN COILER

72COLD ROLLING DIVISION

Cold rolling division in this plant has four cold rolling lines with total capacity of 300,000 tons per annum. During the year FY 2009, Cold rolling division produced 115,080 tons Cold Rolled Stainless Steel and 62,143 tons of hot rolled annealed pickled saleable products. Further, the special product division of the company has produced 10,561 tons of coin blanks and 13,038 tons of special steel, during the year.

Cold Rolling Complex has a capacity to produce 275,000 tons per annum of Cold Rolled Stainless Steel Flat products. The complex is equipped with four 20 Hi-Sendzimir Cold Rolling Mills, four continuous Anneal and Pickle lines, three of these are equipped with Electrolytic Pickling, one bright Annealing Line, three Coil Preparation Lines, four Slitting Lines, one Leveling and Sheet Shearing Line with associated facilities.

JSL is fully equipped to produce material with No.1, 2D, 2B, BA and No.4 and customised surface finish. It can also produce other specialized finishes such as moon rock, hammerstone and honey comb.

4-Hi mills and 20-Hi mills are used for reduction rolling to thinner gauges with close thickness tolerances. To impart various finishes in the final products, the complex has Strip Grinding Line, Skin Pass Mill and Tension Leveler. Such product then passes through the Precision Slitters to achieve precise dimensions.

The razor blade cold rolled strips of up to 0.076mm thickness are produced in this complex and supplied to leading Indian and International razor blade manufacturers for example Gillette.

The cold rolling mill complex comprises of the four units CRD I, CRD II & CRD III & CRD IV. CRD I , CRD III & CRD IV comprises a combination of 20 Hi Sendzimer mills, annealing and pickling lines and various sophisticated associated equipments and processing lines to produce Cold Rolled Coils and Sheets with quality surface finishes, precise dimensional control and good flatness control in wider coils (>600mm width). The facilities at Hisar is equipped to produce and sup-ply material in 2D, 2B, No.3, No.4 and BA surface finishes. CRD II is engaged in production of precision strips in thinner sizes (0.05mm to 0.50mm thick) e.g. Razor Blade, other ferritic and Martensitic stainless steel.

The present installed capacity of cold rolled products is 150,000 TPA.

72OVERVIEW OF FACILITIES IN CRD

OUTPUT FROM SURFACE FINISH

HR-AP NO. 1

Z1, Z2, Z3, Z4 CRFH

CR-AP 2D

SPM 2B

SGL NO.4

BA BA FINISH

CRD

CRD 1 CRD 2 CRD 3 SPD CB

ANN. 1PICKL. 1AP2Z1 MILLZ2 MILLST – 1 ST – 2 ST – 3CTL

AP3Z3 MILLZ4 MILLSPMSGLST4BACPL

AP4SPMTLL

PROVIDED IN DETAILS UNDER SPD

72

COLD ROLLING DIVISION : PROCESS FLOW CHART

HRAPNO.1 COIL

Bright Annealing Line

2D FINISH

2B FINISH

BA FINISH

FULL HARD

NO.4 / NO.3 FINISH

SPECIALFINISH

COIL FORM SHEET FORM

2D FINISH

2B FINISH

NO.4 / NO.3 FINISH

SPECIALFINISH

BA FINISH

Z Rolling Mill

Skin Pass Mill

Cut To

Length

StripGrinding

Line

Annealing & Pickling Line

Z Rolling Mill

72General Layout Of Annealing Pickling Line

Black coils from Hot Rolling division (Raw

material)Furnace for heating

Static cooling by cooling jackets & spray cooling by

water & air

Scale breakerShot blasing with the help of steel shots

Pickling by H2SO4, HF & HNO3

White coils free from internal stresses

72Final coils obtained from Hot Roll ing division have low surface quality and it is black in color due to formation of oxide layer and also their mechanical properties are very poor due to internal stresses and excessive hardness, that’s why they can’t rolled further and if they rolled without any heat treatment coil cracking and necking wil l generate and side by side more load is required to roll the coils. So, before cold roll ing HRD coils are sent to the Annealing and Pickl ing Line In this section annealing is done for improvement of mechanical properties & Pickl ing is done for surface quality improvement of coils by removing oxide layer.

ANNEALING AND PICKLING LINE

In this l ine, f irst the coils are installed and they are welded to each other and to keep the continuous supply of coil , there are two stations to install coil , so that when one station wil l emptied other station wil l supply the coil . First al l coil is passed through breeder roll for providing tension in the coil . The main function of breeder roll is to keep coil in tension & remove waviness in the coil ( if any). After this, coil is passed through furnace where annealing is done.

ANNEALING

Basically there are two type of zones in annealing section

Preheating Zone : No burner is used only hot gases from heating zone are used for heating.

Heating Zone : This Zone is further divided into 4 Zones. Zone 1 to Zone 4.In every zone 5 to 6 burners are used for heating and burners are

Fig: Annealing Pickling Line

72instal led at the top and bottom of the furnace alternatively, i .e. there is no direct contact of f lame and coil . There coil is heated to approx 1200 C.

After Heating, cooling is done; f irst static cooling with the help of cooling jackets & then spray cooling with the help of water & air.

Then coil is passed through scale breaker where tensile & bending forces are applied for breaking scales or for loosening scales and remove waviness in coil which is generated after annealing. Then it is passed through shot blasting section where small spherical steel balls are shooted on the coil with high velocity to remove scales & other impurities. Then finally coil is passed through pickl ing section.

PICKLINGPickling section has 3 online tanks and 6 holding tanks, 2 holding tanks for each online tank. Three online tanks are

1) H2SO4 Tank

2) Mix Acid Tank- 1

3) Mix Acid Tank- 2

First coil passed through H2SO4 tank which has mixture of H2SO4 and water and this mixture is maintained at the H2SO4 conc. 8- 12% and Fe conc below 7% by the help of holding tank, when the conc of Fe become more than 7% or H2SO4 conc changes, then some part of solution is drained and some fresh solution is added from holding tank which maintains the composition of solution in H2SO4 tank.

After this coil goes to the Mix Acid Tank- 1, this tank contains mixture of HNO3 and HF and this tank has two holding tank, in one tank bath for 300 grade coils is prepared and in other tank bath for 200 and 400 grade coils is prepared. The composition of solution depends on the grade.

After this coil passes through the Mix Acid Tank-2, this tank contains HNO3 and it also has two holding tanks both contains HNO3 of same conc i .e. it has same composition for al l grades. After al l the three tanks there is a brush with water supply which removes the acid and scales from the surface of coil and there is abrasive brush after f irst two tanks and nylon brush after f inal tank. After pickl ing, surface of coil becomes very smooth

72and white and after pickl ing on coil a layer of HNO3 remains on the coil which protects the coil from further making of scales.

Then quality of coil is checked and it is cut to the length where it is welded.

Final coil obtained from this section is white in color & free from internal stresses & this coil is known as HRAP (hot rolled annealed & pickled coil) . Then some HRAP coils are packed and dispatched and some coils are further processed which depends on the customer’s demands and to fulf i l l al l the customer’s demands JSL has various faci l it ies.

FACILITIES IN COLD ROLLING DIVISION

Fig: Coil After Pickling

721) 20 Hi Mill: If a customer demands for reduction of thickness in HRAP, then JSL has

four 20 hi mills Z1, Z2, Z3 and Z4 to reduce the thickness of coil. It is a reversible mill i.e. thickness is reduced in several passes. 20 hi mill is named so as it contains 20 horizontal rollers, 10 above and 10 below as shown in following diagram

For cold rolling of stainless steel, load requirement is quite high. It has been observed that this can be done efficiently by smaller diameter of work rolls, where force per unit area will be quite high. So, 20 hi mills are used in CRD which has work rolls of small diameter and also they have very high tension around 50 ton and load around 80 ton.

As shown in above fig 20 hi mill has 10 above and 10 below rollers in which two are work rollers, one above and other below and four intermediate rolls, two above and two below and four drive rolls, two below and two above and two idler, one above and one below and eight backup rolls, four above and four below.

72

DIFFERENT TYPES OF ROLLS IN 20 HI MILL

Work Rolls: These rollers has small diameter of range 60-85 mm and there actual diameter depends on type of coil which is rolled. They are small in diameter to increase the force per unit area.

Intermediate Rolls: These rolls have diameter in range 106-121 mm and they are provided with taper at the ends with roll shifting arrangement and for different grades different rollers are used. This helps in reducing the over rolling of the strip edges and to give the required crown in the sheet. Top inter rollers are provided with taper in the front while bottom rolls have taper in the backside.

How does they work – In this mill load is applied on the ends of roll, so due to bending moment rolls apply more load on the edges than in the middle and that’s why strip get over rolled on the edges. If there is a taper on the edges it provides some relief on the edges. During rolling if front edge is over rolled then top inter roll moves back i.e. reduction in length of flat portion or more relief at edges and if front edge is too short, the top inter roll moves out i.e. increase in length of flat.

Idler and Drive Rolls: These rolls have diameter in range of 106-121 mm and they also have taper but there taper is fixed. Drive roller is used to give drive to all the rollers and idler roller is used for motion transformation.

Backup Rolls :These rollers also have taper shape but it is fixed. Bottom two back up rolls are responsible for maintaining pass line, while side back up for accommdat6ing the various diameters of rolls and maintaining vertical axis. The top two back up rolls are responsible for providing roll force and also have provision of crown adjustment for improving the shape of the strip being rolled.

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2) Skin Pass Mill : The skin pass mill is designed and installed in dust proof housing. It is used to give cold rolled pass by polished ground work roll on 2D finish dull material to convert to 2B bright surface finish and it is also used to improve strip shape and eliminate minor surface blemishes. In this mill grinded rollers are used for cold rolling so that there impression comes on the sheet and the surface of the sheet becomes very smooth and it starts to shine like mirror and no reduction takes place in this mill. The mill is designed to meet requirements in 600 to 1600mm width coils in 0.40 to 3.00mm thickness.

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3) Slitting Line: Slitting lines are used to side trim the coils and cater the market requirements in smaller width coils with a thickness from 0.45mm to 6mm.

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Slitting principle

Slitting principle- In this line cutting is done by the knives on the roller, these knives gradually move towards one another, deform and tear the strip as shown in

72above figure, cutting of strip line takes place between male and female assembly as

shown in above figure.

4) Strip Grinding Line: The strip Grinding line is used to produce No.3, No.4 and some special finishes and also for removing the defects from strip. The finish strip of this line is used for decorative purposes in architectural applications, restaurant equipments, dairy equipments, lifts, elevators etc.

5) Shearing Line: Many fabricators procure strip in cut sheet form, for punching, pressings or merely bending and welding for making various parts for end-users. There first foremost requirement is that sheets should be flat or otherwise uneven twisted sheet will get jammed, resulting in stoppage of automatic machines and even damage to whole line. So, the flying shearing line with Voss Leveller is used to produce sheets with good flatness.

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SPECIAL PRODUCT DIVISION :

SPD is one of the important division of CRD. Hot rolled coils obtained from stckel mill has thickness around 3-4 mm, for reducing thickness and improving surface finish, coil is sent to special product division. Coil obtained from HRD is work hardened coil therefore for further rolling of coil, first its hardness is reduced using Bell annealing. Basically bell annealing breaks larger grains of work hardened coils into smaller grains as a result of which hardness of coil reduces. After bell annealing coil is sent to slitting line. Then for removing scale pits coil is sent to pickling line where scale pits are removed by reacting coil with H2SO4,HNO3 & HF acids. Then after all these processes coil is made available for further rolling.

For rolling, coil is sent to Roughing mill-2.It is a 4 Hi reversible mill in which thickness of coil is reduced from 3mm to 1mm in 6 passes.

1st pass 3.00 – 2.7

2nd pass 2.70 – 2.1

3rd pass 2.10 – 1.9

4th pass 1.90 – 1.5

5th pass 1.50 – 1.2

6th pass 1.20 – 1.0

72After this coil is sent PTF line for annealing. In SPD there are three PTF annealing line PTF-1 to PTF-3.After this coil is sent to pickling line and then to slitting line for trimming then coil is sent to old 20 Hi rolling mill where thickness is reduced from 1.0mm to 0.40mm .Again the coil is sent to PTF line then to pickling line & finally to slitting line for finishing.

Now depending on costumer demand either coil is directly dispatched from here or sent for further rolling.

For further rolling coil is sent to either new 20 HI mill or 4 Hi roughing mill-1 depending upon coil material. As rolling on 20 Hi mill is costly, therefore only rolling of some costly or critical material like 430 series,304 series,316 series,420 series,J4 or blade steel is done here. Otherwise rolling has been done on roughing mill-1 where thickness has been reduced from 0.40mm to 022mm. Again same processes annealing,pickling & trimming is repeated & then coil is sent to 4 hi Frohlimg mill where thickness is reduced from 0.22 to 0.14mm & then sent to 4 hi bharat foil mill where thickness is reduced to 0.097 or 0.90 mm.

After all these operations, finally for mirror like finish coil is sent to Bright annealing line for bright annealing (according to customer demand). Here in JSL there are three Bright annealing line : BA-1, BA-2 & BA-3 in which BA-3 is the latest .Then after bright annealing according to surface of the coil (if there any oxide layer) if required coil is sent for pickling.

Now after all these operations still waviness remains in the coil. The main reason of this waviness is more rolling at the edges of the strips or coils as compare to its center because more roll load has been acting at the edges. To make coil table flat it sent to tension leveler.

WHAT IS BELL ANNEALING ?

Bell annealing also known as batch annealing is a non continuous process in which 3 or 4 coils are simultaneously heated inside a furnace for 40 to 60 hrs depending upon grades of coils. The coils comes from hot rolling mills are work hardened coils & have larger grains size.

The purpose of Bell annealing operation are:

1. To improve mechanical properties like malleability & ductility

722. To soften the material & improve its drawability

3. To modify crystallographic structure.

4. To convert martensite phase if present to ferritic.

5. To relieve internal stresses.

6. To change the microstructure of steel from the distorted structure of cold worked steel to anneded structure.

7. To improve machinability of steel.

EQUIPMENTS : Bell annealing is performed with the help of following equipments:

Annealing base: These are the support for the material to be annealed and are provided with the inlet & outlet for the protective atmosphere, the thermocouples and a circulation fan at the center. The base carries the base plate, which has the radial spiral vent for the inert atmosphere to pass. The inert atmosphere comes in through the center of the coil comes out through these vents.

Protective Hood: The protective hood or inner cover is made of special heat resistant chromium-Nickel steel to cover the coils. An inert atmosphere is maintained inside the hood.

Annealing Furnace: Bell annealing is done in the box type annealing furnaces, also known as bell type furnaces or stack annealing furnaces. The annealing in these type of furnaces are quite cost effective.

Cooling Hood: After completion of heating & soaking period, the cooling of material is done under protective atmosphere but with a forced air circulation outside the inner cover. The cooling hood are provided with a powerful fan at the top, for fast cooling.

In JSL , SPD has 10 furnaces & 20 bases for bell annealing. One base is required for 1 furnace. As after heating of 40-60 hrs , coils required some cooling time that’s why 10 extra base has been provided for next set of coils for overcoming of cooling time.

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In JSL there are 3 types of bases

Company name Number of furnaces Number of base

Ebner 2 4

LPG 6 12

LDO 2 4

BELL TYPE ANNEALING FURNACE

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WHAT IS BRIGHT ANNEALING ?

Bright annealing is nothing but the annealing in which annealing is done in controlled atmosphere of cracked ammonia to avoid any oxidation of metal which ensures a bright finish called as BA finish. The bright annealing (BA) line at Jindal Hisar works is one of its kind in India. Bright annealing is a continuous process in which coil runs continuously in the sytem. On completion of first coil next coil is welded to first coil so that continuity can be maintained. To overcome the welding time, two loopers has been provided, entry looper at the entry & exit looper at the exit . For uncoiling of coils two uncoiler has been installed in the system. From uncoiler, coil is passed from a degreasing tank where coil is washed with alkali soap solution such that if there is any lubricant or coolant content over the coil then it will be completely washed away. Red colour pipes with nozzles known as headers has been provided for forcing alkali solution over the coils. Then coil is passed through brushes & squeeze rolls for squeezing out water through the coil. For its further washing it is passed through 2 tanks containing dimineral water. Water is forced with the help of headers (red & green in colour) then for drying out water coil is passed through dryer where temperature around 90 to 100 degree Celsius is maintained depending upon grade of coil & coil is dried with the help of hot air. Then it is passed through inlet looper which will starts moving downward at the time of welding at the inlet. Then finally coil is passed through furnace where amount of oxygen is controlled & maintained around 0.08 ppm so chances of oxide formation has been reduced & coil is transformed into mirror like surface finish. There are 4 zones & 16 burners inside the furnace (each zone having 4 burners) & temperature inside the furnace is maintained depending upon the grade.

Cooling of coil is done with the help of air, for this purpose 4 blowers has been provided at the top of the furnace. Then it is passed through exit looper & then to coiler where surface finish coil is coiled.

DIFFERENCE BETWEEN BRIGHT ANNEALING & PTF ANNEALING

The whole process of PTF annealing is similar to Bright annealing ,the only difference between these two annealing is that in bright annealing a controlled atmosphere of cracked ammonia is maintained to avoid any oxidation of metal which ensures a bright finish called as BA finish where as in PTF annealing atmosphere is not controlled such that chances of oxide formation is more.

72As maintaining controlled atmosphere is an expensive process as a result bright annealing is costly & therefore generally it is done once only in the end where further rolling is not required whereas PTF annealing is cheaper so in intermediate processes PTF annealing is done.

MAIN EQUIPMENTS IN SPD

New 20 HI Rolling mill

4 Hi Frohling mill

4 Hi BF(Bharat foil) mill

4 Hi Roughing mill-1

4 Hi Roughing mill-2

Old 20 Hi rolling mill

4 Hi Sherman rolling mill

Bell Annealing line (10 furnaces)

Bright Annealing lines -

a) Bright Annealing line-1 (BA-1)

b) Bright Annealing line-2 (BA-2)

c) Bright Annealing line-3 (BA-3)

Pull Through Furnace Annealing lines –

a) Pull Through Furnace Annealing line-1 (PTF-1)

b) Pull Through Furnace Annealing line-2 (PTF-2)

c) Pull Through Furnace Annealing line-1 (PTF-2)

Grinding mill

72COIN BLANKING LINE

Jindal Stainless has been supplying AISI 430 grade ferritic stainless steel coils & blanks to India Govt. Mint & Foreign mint for making coins on regular basis. To diversify its product range, coin blanking and associated processing facilities of world-class quality has been installed and commissioned.

CBD

PRESSES – 4 NOS.

DEBURRING & DRYER – 4 NOS

RIMMING M/C – 6 NOS

MESH-BED F/C – 4 NOS

INSPECTION TABLE - MANUAL

SORTING M/C – 1 NO

AUTOMATIC INSPECTION & SORTER – 1NO

ROTARY DRYERS – 3 NOS

DENOMINATION PRODUCED:

10 RUPEE5 RUPEE2 RUPEE1 RUPEE50 PAISE25 PAISE

Total capacity**: 10,000 MT/annum

Total production: 10,500 MT/annum

** Capacity calculated as equivalent of 1 rupee coins

General Overview of CBL

72At present Jindal Stainless is supplying Ferritic Stainless Steel coin blanks of denomination of 25 Paise, 50 Paise and 1 Rupee to Govt. of India, Mint. In addition to these we have developed Cupro-Nickel coin blanks of 2 and 5 rupees denomination. The present installed capacity for coin blanking is 10,000 MTPY.

Production Process

The cold rolled and bright annealed coils are processed at coin blanking lines. This comprises of a blanking press, deburring machine, edge rimming machine, annealing furnace and polishing machines. Subsequently the coin blanks are inspected on Inspection Conveyors, then counted by counting machine and packed in drums for despatch.

The punched out strips of AISI SS430 is a by-product while making coin blanks. These are aesthetically pleasing and elegant and have a vide variety of applications such as cable trays, kitchen racks, Paper Basket etc. These can be supplied in coil forms.

Cupro-Nickel Complex

In order to expand the business for coin blanks, an independent production line has been installed to produce high value copper-base non-ferrous alloys importantly cupro-nickels. The production facility includes induction melting, continuous horizontal strip casting, cold rolling, annealing, pickling and slitting. The installed melting and casting capacity is 6000T per annum. Apart from Cuppro-Nickels, the unit can produce Aluminum-Bronze, Phosphorus Bronze, Nickel-Silver and Tin bearing copper for various engineering and jewellry applications. Aluminum-Bronze along with Cupro-Nickel is used to manufacture duplex coins.

RAZOR AND SURGICAL BLADE STEELJindal Stainless is an exclusive producer of stainless razor blade steel in India. . The microstructure of their strips is designed to optimize / facilitate hardening, sharpening and honing operations at customers end and to develop ideal characteristic for intended end application. These are achieved with stringent quality checks utilizing modern and sophisticated testing equipments such as Metallurgical microscope with advanced

72image analyzer, digital micro-hardness tester, microprocessor controlled Tensile testing machine and scanning electron microscope. Persistent R & D activity had led to the improvement in quality of product enabling us, not only to cater to the Indian razor blade steel requirement but also to export a substantial quantity on a regular basis. The current capacity for precision strip production is 12,000 TPA

72REFERENCES

1) Dr. L. K. Singhal, R. K. Gupta: Practical Tips on Cold Rolling of Strip, 2012.

2) Clarence E. Sims: Electric Furnace Steelmaking-Vol 1, Design, operation & practice, Physical Chemistry of Steel Making Society.

3) Knowledge Centre, JSL Ltd.

4) www.wikipedia.org