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SUMMER TRAINING REPORT

HINDALCO INDUSTRIES

Sambalpur ,Hirakud

Submitted by

RASHMI RANJAN SAHOO

(Reg No:RA1411002010350)

Department of Mechanical Engineering

Faculty of Engineering and Technology SRM University

(Under section 3 of UGC Act, 1956) SRM Nagar, Kattankulathur – 603203

Kancheepuram Dist.

June 2016

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Acknowledgement

It is always a pleasure to remind the fine people in the Engineering

program for their sincere guidance I received to uphold my practical

as well as theoretical skills in engineering.

Firstly I would like to thank Mr.D.K.Tiwari

for meticulously planning academic curriculum in such a way that i

was not only academically sound but also industry ready by including

such industrial training patterns.

I would also thank him for the positive attitude

he showed for my work, always allowing me to question him and

giving prompt replies for my uncertainties in all the fields including

educational, social and managerial work and continuously supported

me in every possible way, from initial advice to encouragement till

this date.

I express my immense pleasure and deep sense

of gratitude to Mr.Sameer Jena (casting)for spending his valuable

time with me and also helped me in completion of task.

Finally, I would also like to thank Mr.Anand

Padhee(maintenance) for giving me this opportunity and guiding me

during the course of the training.

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HINDALCO INDUSTRIES

HIRAKUD

ABSTRACT

This is a study project mainly based on the detail of aluminium smelting

process and all the mechanical equipments associated with the process. The

aluminium smelting process at Hindalco is an electrolysis process and is carried

out in smelting pots. In smelting pots alumina powder (Al2O3) is fed to produce

liquid aluminium. The aluminium smelter is located near large power stations

as a large amount of electricity is consumed in aluminium smelting. The

machineries associated with aluminium smelting are point feeder, crust

breaker, anode jack, compressor, vacuum crucible, EOT Crane, beam raising

machine and cooling tower.

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INDEX CONTENTS PAGE NO

Company Profile 4 o History………………………………………………………………………….…4 o Site map……………………………………………………………………….…4 o Site location………………………………………………………………….…4

Sections of plant o Pot rooms……………………………………………………………………….5 o Casting house …………………………………………………………………5

Safety rules 7

Details of study 7 o Introduction………………………………………………………..………….7 o Concept ………………………………………………………………………….8 o Flow chart………………………………………………………….………….11 o Smelting ……………………………………………………………………….11 o Casting ………………………………………………………………………….13 o Maintenance……………………………………………..………………….14 o Transportation…………………………………………….………………..15

Structure details 16 o Anode……………………………………………………………………………..16 o Cathode ………………………………………………………………………….16 o Cryolite ………………………………..……….….…………………………….17 o Alumina ………………………………..…….………………………………….17

Amenities 18 o Point feeder………………………………….………………………………..19 o Crust breaker…………………………….……………………………………20 o Vaccum crucible …………………………………………………………….21 o Anode jack…………………………………………..…………………………22 o Electric overhead travelling crane ...……………………………….22 o Beam raising machine ……………..…………………………………….24

Maintanance 25

o Cooling tower……………………………………………………….…………25 o Compresor …………………..…………………………………………………26

Applications 28 o Forging……………………………………………………………………………28 o Rolling ………..…………………………………………………………………29 o Extrusion ………………………………………………………………………..30

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COMPANY PROFILE

HISTORY The Hindustan Aluminium Corporation Limited was established in 1958 by the Aditya Birla Group. In 1962 the company began production in Renukoot in Uttar Pradesh making 20 thousand metric tons per year of aluminium metal and 40 thousand metric tons per year of alumina. In 1989 the company was restructured and renamed Hindalco.

Hindalco Industries Ltd., an aluminium manufacturing company, is a subsidiary of the Aditya Birla Group. Its headquarters are at Mumbai, Maharashtra, India. It is the Flagship company of the company in the metals business.

The company has annual sales of US$ 15 billion and employs around 20,000 people. It is listed in the Forbes Global 2000 at 895th rank.Its market capitalisation by the end of May 2013 was US$ 3.4 billion.Hindalco is one of the world's largest aluminium rolling companies and one of the biggest producers of primary aluminium in Asia.

SITE MAP

SITE LOCATION The Hirakud smelter and power complex is in Odisha, about 320km by road from the capital city of Bhubaneswar. The Hirakud smelter, set up by Indal in 1959, was the country’s second aluminium smelter operating on grid power

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sourced from the hydro power station of the Hirakud Dam. After facing severe power scarcity, Hirakud’s captive coal-based power plant came up in 1993. It was the first in India to adopt clean coal combustion technology that uses a circulating fluidised bed, which is considered environmentally friendly. The metal from this facility is processed to produce FRP.

SECTIONS OF PLANT

POT ROOMS

The plant consists of a series of pots in the pot room .the pots are assembled

as in DC-1,DC-2,DC-3,Continuos caster,DC-4.the smelting takes place in the pot

room and the molten metal is contained in the crucible or container by vacuum

.the crucible is then transferred to the casting house where it is casted into

blocks of specific dimensions according to the customer demand .the molten

metal is mixed with certain elements to form the alloys in the furnace where it

is oil fired .it consists of two burners which fire for 45 seconds each.

CASTING HOUSE

The molten metal is casted into blocks through continuous flow of water

through jets .there can be either single of double jet according to the casting

method .there are two processes through which the metal is casted .

They are :

1.direct chilling

2.indirect chilling

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The metal casted is kept under water for extra 30 minutes to ensure proper

cooling and hardening of the metal in order to prevent any kind of defects.

The molds are graphite or grease aligned to ensure smooth running of the

molten metal and prevention of the defects in the aluminium molds.

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SAFETY RULES Safety rules list the specific activities to do or avoid for completing the job effectively and safely. Important things to keep in mind regarding safety rules include: 1.No single list of safety rules is adequate for all types of businesses. 2.Develop your own list of safety rules based upon standard industry practices and your own accident experience. 3.Don’t rely solely on generic lists or examples from other employers. 4. All rules need to be completely and clearly communicated to management and staff alike. 5. All rules should be strictly and consistently enforced. 6. If written safety rules are not consistently and equitable enforced, the employer’s actual practices outside the written rules may create a legal liability if challenged in a legal or regulatory dispute. 7.Follow the manufacturer’s recommendations when creating rules for the operation of equipment. 8.All injuries must be reported as soon as possible. 9. No horseplay, alcohol, or drugs allowed on premises. 10. No alcohol usage allowed during lunch break. 11.PPE must be worn as prescribed by management. 12.All tools/equipment must be maintained in good condition. 13.Only appropriate tools shall be used for specific jobs. 14.All guards must be kept in place. 14.No spliced electrical cords/wiring allowed. 15.Only authorized personnel can operate forklift vehicles. 16.Smoking allowed only in lunchroom. 17.Seat belt use required of all drivers/passengers.

DETAILS OF STUDY

INTRODUCTION

1.Aluminium compounds make up 7.3% of the earth's crust, making it the third most common crustal element and the most common crustal metal on earth. Aluminium was first produced in 1808. There are three main steps in the process of aluminium production. First is the mining of

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aluminium ore, most commonly bauxite, referred to as bauxite mining. Second is the refining of bauxite into aluminium oxide trihydrate (Al2 O3), known as alumina, and third is the electrolytic reduction of alumina into metallic aluminium. The process requires approximately two to three tonnes of bauxite for the production of one tonne of alumina, and in turn, approximately two tonnes of alumina is required for making one tonne of aluminium. 2.Aluminium occupies a special place in extractive metallurgy because it can be produced as a high-purity product, enabling its special properties to be utilized. It has many economically attractive applications in the construction sectors, in the transportation sector, in numerous industrial products, packaging, and containers. The substitution of aluminium for common materials such as steel, copper, and certain composites can generate large energy savings over the net life of various products. It also reduces the production of the greenhouse gas, carbon dioxide, particularly in transportation applications because lightweight aluminium-intensive vehicles will use less fuel than conventional vehicles. 3.In an aluminium smelter, direct current (DC) is fed into a line of electrolytic cells connected in series. These electrolytic cells are the nerve centre of the process. While the cells (pots) vary in size from one plant to another, the fundamental process is identical and is the only method by which aluminium is produced industrially. It is named the Hall-Heroult process after its inventors. 4.Each smelting cell is a large carbon-lined metal container, which is maintained at a temperature of around 960°C and forms the negative electrode (or cathode). The cell contains an electrolytic bath of molten salt called 'cryolite' (Na3AlF6), into which a powder of aluminium oxide (Al2O3) is fed and becomes dissolved to form a solution. Aluminium fluoride (AlF3) is added to maintain the target bath chemistry. Large carbon blocks, made from calcined petroleum coke and liquid coal tar pitch, are suspended in the solution; and serve as the positive electrode or anode. 5.The electrical current passes from the carbon anodes via the bath, containing alumina in solution, to the carbon cathode cell lining. The current then passes to the anode of the next pot in series. As the

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electrical current passes through the solution, the aluminium oxide is dissociated into molten aluminium (Al) and oxygen (O2). The oxygen consumes the carbon (C) in the anode blocks to form carbon dioxide (CO2), which is released.

CONCEPT

THE HALL-HEROULT SMELTING PROCESS

Simply, the Hall-Heroult process is the method by which alumina is separated into its component parts of aluminium metal and oxygen gas by electrolytic reduction. It is a continuous process with alumina being dissolved in cryolite bath material (sodium aluminium fluoride) in electrolytic cells called pots and with oxidation of the carbon anodes. The bath is kept in its molten state by the resistance to the passage of a large electric current. Pot temperatures are typically around 920°- 980°C. The aluminium is separated by electrolysis and regularly removed for subsequent casting. The pots are connected electrically in series to form a ‘potline.’

In each pot, direct current passes from carbon anodes, through the cryolite bath containing alumina in solution, to the carbon cathode cell lining and then to the anodes of the next pot and so on (see Figure 1.1). Steel bars embedded in the cathode carry the current out of the pot while the pots themselves are connected through an aluminium bus-bar system. The pot consists of a steel shell in which the carbon cathode lining is housed. This lining holds the molten cryolite and alumina in solution and the molten aluminium created in the process. An electrically insulated superstructure mounted above the shell stores alumina automatically delivered via a sealed system and holds the carbon anodes, suspending them in the pot.

The electrolyte, which fills the space between the anodes in the pot, consists of molten cryolite containing dissolved alumina. A solid crust forms at the surface of the electrolyte. The crust is broken periodically and alumina is stirred into the electrolyte to maintain the alumina concentration.

As the electrolytic reaction proceeds, aluminium which is slightly denser than the pot bath material is continuously deposited in a metal pool on the bottom of the pot while oxygen reacts with the carbon material of the anodes to form oxides of carbon. As the anodes are consumed during the process, they must be continuously lowered to maintain a constant distance between the anode

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and the surface of the metal, which electrically is part of the cathode. The anodes are replaced on a regular schedule.

The vigorous evolution of carbon dioxide at the anode helps mix the added alumina into the electrolyte but carries off with it any other volatile materials and even some fine solids. If any carbon monoxide does form it usually burns to carbon dioxide when it contacts air at the surface of the crust. Compounds of fluoride formed in side reactions are the other main volatile product. Approximately 13 -16 kilowatt-hours of direct current electrical energy, one half kilo of carbon, and two kilos of aluminium oxide are consumed per kilo of aluminium produced.

Cross section of an aluminium producing pot containing pre-baked carbon anodes

As electrolysis progresses, the aluminium oxide content of the bath is decreased and is intermittently replenished by feed additions from the pot's alumina storage to maintain the dissolved oxide content at about 2 to 5 percent. If the alumina concentration falls to about 1.5 to 2 percent, the phenomenon of "anode effect" may occur. During anode effect, the bath fails to wet the carbon anode, and a gas film forms under and about the anode. This film causes a high electrical resistance and the normal pot voltage, about 4 to 5 volts, increases 10 to 15 times the normal level. Correction is obtained by computer controlled or manual procedures resulting in increased alumina content of the bath.

Reducing the prevalence of anode effects produces process benefits and also reduces the potential emissions of perfluorocarbons (CF4 and C2 F6) that are greenhouse gases.

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FLOW CHART

SMELTING The electrolytic reaction can be expressed as follows: 2 Al2O3 + 3 C → 4 Al + 3 CO2

All modern primary aluminium smelting plants are based on the Hall-Heroult process, invented in 1886. Alumina is reduced into aluminium in electrolytic cells, or pots. The pot consists of a carbon block (anode), formed by a mixture of coke and pitch, and a steel box lined with carbon (cathode). An electrolyte consisting of cryolite (Na3AlF6) lies between the anode and the cathode. Other compounds are also added, among those are aluminium fluoride and calcium fluoride. The latter to lower the electrolyte's freezing point. This mixture is heated to approximately 9800C. At this point the electrolyte melts and refined alumina is added. Reduction of aluminium ions produce molten aluminium metal at the cathode and oxygen at the anode, which react with the carbon anode itself to produce CO2.

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Aluminium smelting process is an electrolysis process, so an aluminium smelter uses prodigious amounts of electricity. The smelters tend to be located near large power stations, often hydroelectric ones and near ports since almost all of them use imported alumina. A large amount of carbon is also used in this process. Once aluminium is formed, the hot, molten metal is alloyed with other metals to make a range of primary aluminium products with different properties and suitable for processing in various ways to make end-user products.

It takes about 2 tonnes of bauxite to produce 1 tonne of alumina; and approximately 2 tonnes of alumina to produce 1 tonne of aluminium.

In an aluminium smelter, direct current (DC) is fed into a line of electrolytic cells connected in series. These electrolytic cells are the nerve centre of the process. While the cells (pots) vary in size from one plant to another, the fundamental process is identical and is the only method by which aluminium is produced industrially. It is named the Hall-Heroult process after its inventors.

Each cell is a large carbon-lined metal container, which is maintained at a temperature of around 960°C and forms the negative electrode (or cathode). The cell contains an electrolytic bath of molten salt called 'cryolite' (Na3AlF6), into which a powder of aluminium oxide (Al2O3) is fed and becomes dissolved to form a solution. Aluminium fluoride (AlF3) is added to maintain the target bath chemistry. Large carbon blocks, made from calcined petroleum coke and liquid coal tar pitch, are suspended in the solution; and serve as the positive electrode or anode.

The electrical current passes from the carbon anodes via the bath, containing alumina in solution, to the carbon cathode cell lining. The current then passes to the anode of the next pot in series. As the electrical current passes through the solution, the aluminium oxide is dissociated into molten aluminium (Al) and oxygen (O2). The oxygen consumes the carbon (C) in the anode blocks to form carbon dioxide (CO2), which is released.

Aluminium is formed at about 900°C, but once formed has a melting point of only 660°C. In some smelters this spare heat is used to melt recycled metal, which is then blended with the new metal. Recycled metal requires only 5 percent of the energy required to make new metal. Blending recycled metal with new metal allows considerable energy savings, as well as the efficient use of the extra heat available. When it comes to quality, there is no difference between primary metal and recycled metal.

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The smelting process required to produce aluminium from the alumina is continuous, the potline is usually kept in production for 24 hours a day year around. A smelter cannot be easily stopped and restarted. If production is interrupted by a power supply failure of more than four hours, the metal in the pots will solidify, often requiring an expensive rebuilding process.

The hot, molten, metallic aluminium obtained in the process sinks to the bottom of the reduction cell, while the gaseous by-products form at the top of the cell. The aluminium is siphoned from the bottom of the cell in a process called tapping (done by rotation every 24 hours), and transported to dedicated casting operations where it is alloyed; then cast into ingots, billets and other products.

In addition to carbon dioxide, the aluminium smelting process also emits hydrogen fluoride (HF) an extremely toxic gaseous emission. Fume treatment plants ("FTPs") are used to capture the hydrogen fluoride and recycle it as aluminium fluoride for use in the smelting process. During abnormal smelting conditions, known as anode effects, perfluorocarbon ("PFC") gases are emitted. Two PFC compounds are released during anode effects, namely tetrafluoromethane (CF4) and hexafluoroethane (C2F6), which have greenhouse gas warming potential of 6,500 and 9,200 times greater than CO2 respectively.

The aluminium smelting process is extremely energy intensive, which is why most primary aluminium smelters are located where there is ready access to abundant energy/power resources. It is also a continuous process: a smelter cannot be stopped and restarted easily. To the contrary, if production is interrupted by a power outage for more than four hours, the molten aluminium in the cells will solidify. This is because metallic aluminium is formed at 900°C but, once formed, has a melting point of only 660°C. When cells 'freeze' in this way, the only recourse for recovery is to rebuild the smelter.

There are two main types of aluminium smelting technologies, known as Prebake and Soderberg.

CASTING The molten metal is casted into blocks through continuous flow of water

through jets .there can be either single of double jet according to the casting

method .there are two processes through which the metal is casted .

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They are :

1.direct chilling

2.indirect chilling

The metal casted is kept under water for extra 30 minutes to ensure proper

cooling and hardening of the metal in order to prevent any kind of defects.

The molds are graphite or grease aligned to ensure smooth running of the

molten metal and prevention of the defects in the aluminium molds.

MAINTANANCE

There are three types of Maintenance:

Maintenance Improvement

Improvement maintenance efforts to reduce or eliminate the need for maintenance are like the thumb, the first and most valuable digit. We are often so involved in maintaining that we forget to plan and eliminate the need at its source. Reliability engineering efforts should emphasize elimination of failures that require maintenance. This is an opportunity to pre-act instead of react.

Corrective Maintenance

Better improvement maintenance and preventive maintenance, however, can reduce the need for emergency corrections. A shaft that is obviously broken into pieces is relatively easy to maintain because little human decision is involved. Troubleshooting and diagnostic fault detection and isolation are major time consumers in maintenance. From a preventive maintenance perspective, the problems and causes that result in failures provide the targets for elimination by viable preventive maintenance. The challenge is to detect incipient problems before they lead to total failures and to correct the defects at the lowest possible cost. That leads us to the middle three fingers the branches of preventive maintenance.

Preventive Maintenance

As the name implies, preventive maintenance tasks are intended to prevent unscheduled downtime and premature equipment damage that would result in corrective or repair activities. This maintenance and management approach

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is predominately a time-driven schedule or recurring tasks, such as lubrication and adjustments that are designed to maintain acceptable levels of reliability and availability.

TRANSPORTATION

These are the various mode of transport involved in the movement of raw materials :

The modes of transport can be broadly divided into three categories:

1.Land transport

2.Water transport

3.Air transport

(I) Land Transport:

Land transport refers to activities of physical movement of goods and passengers on land. This movement takes place on road, rail, rope or pipe. So land transport may further be divided into Road transport, Rail transport, Ropeway transport, pipeline transportBusiness Studies

a. Road Transport

Roads are the means that connect one place to another on the surface of the land.

b. Rail transport

Transportation of goods and passengers on rail lines through trains is called rail transport. It occupies an important place in land transport system of our country and is the most dependable mode of transport to carry goods and passengers over a long distance. Besides long distance, local transport of passengers is also provided by local trains or metro-rail in some metropolitan cities. Rail transport is available throughout the country except some hilly or mountainous regions. In India two types of trains are found. One is passenger train and other is goods train. While passenger trains carry both human beings and a limited quantity of goods, the goods trains are exclusively used for carrying goods from one place to another. These trains are driven by rail engines and they use steam, diesel or electric power to move.

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c. Pipelines transport

In modern times, pipelines are used for various purposes. Water supply to residential and commercial areas is carried on with the help of pipeline. Petroleum and natural gas are also transported from one place to another through pipelines. This is the most convenient as well as economical mode of transport for petroleum as well as natural gas in comparison to road and rail transport, provided the volume to be transported is large. But the cost of installation and maintenance requires large capital investment.

d. Ropeway transport

Ropeway refers to a mode of transport, which connects two places on the hills, or across a valley or river. In the hilly areas, trolleys move on wheels connected to a rope and are used for carrying passengers or goods, especially building materials, food, etc.

STRUCTURE DETAILS

These can also be called as the various components of the plant on which the plant runs efficiently .

ANODE

In the electrolytic production of aluminium the consumption of carbon is second only to the consumption of alumina in quantity. 415 KG of carbon is used for each MT of metal production.

Carbon quality is of great interest to the Potroom not only because it is an expensive operating supply but because of the effect poor quality can have on the on the pot operation

Anodes are made of carbon containing as few impurities as possible. Calcined petroleum coke and pitch as a binder are used for raw materials.

CATHODE

The cathodes are made up of carbon and needs to be replaced in every 28 days

.each pot consists of 12 cathode rods which are lowered accordingly to sustain

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the reaction using beam raising machine .the cathode gets used up and is

replaced by another cathode using crane which the cathode .the cathodes in a

pot are connected in series but opposite cathodes are connected in parallel

where the current is divided .as the cathode gets used up its distance from the

electrolytic bath increases and the voltage fluctuates and the demand for

voltage increases hence increasing the overall demand .For this the cathode is

moved to maintain correct and efficient flow of the current. The carbon lining

which forms the pot cavity consists of carbon blocks, preformed by external

manufacturers. These blocks are placed in the steel pot shell and cemented

together with a paste similar to that used in making the blocks. Thermal

insulation consisting of firebrick, vermiculite, or similar materials is placed

between the cavity lining and the steel shell. Large steel bars, serving as

electrical current collectors, are embedded in the bottom portion of the cavity

lining and extend through openings in the shell to connect with the electrical

bus which links one pot to the next.

CRYOLITE

The electrolyte is a molten bath of cryolite (Na3AlF6) and dissolved alumina. Cryolite is a good solvent for alumina with low melting point, satisfactory viscosity, low vapour pressure. Its density is also lower than that of liquid aluminium (2 vs 2.3 g/cm3), which allows natural separation of the product from the salt at the bottom of the cell. The cryolite ratio (NaF/AlF3) in pure cryolite is 3, with a melting temperature of 1010 °C, and it forms a eutectic with 11% alumina at 960 °C. In industrial cells the cryolite ratio is kept between 2 and 3 to decrease its melting temperature to 940-980 °C.

ALUMINA

It is used as raw material for the production of aluminium.it is obtained from bauxite and is enriched with fluorine gas to make the reaction more efficient.

It is in the powder form and is fed into the bath through the hopper and using a pot feeder.

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AMENITIES

They are as follows :

Point feeder Crust breaker

Vacuum crucible

Anode jack

Electric overhead travelling crane

Beam raising machine

POINT FEEDER

Point feeder is the device through which the powder alumina is fed to the

smelting cell (pot). The feeder is a fully pneumatic component which works on

compressed air. The feeder is a fully pneumatic component operated on

compressed air. A breaking hole is present in the smelting cell through which

the powder alumina is fed in to the pot. The feeder is present just above the

hole. The powder is first carried to the feeder through the channels and the

feeder feds the powder alumina directly into the hole. The feeder has two

ports one for air intake and the other for air return at the top head and the

bottom head of the cylinder respectively. The piston has a piston rod which is

connected to another rod inside the guide tube. The guide tube provides

support to the piston rod assembly and has sealing elements to avoid air

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leakage to the opposite side of the piston. The piston rod assembly is

connected to a cone at the bottom of the guide tube. The cone is provided to

open and close the feeder passage for feeding the alumina powder.

The whole process is digitalized and operated by computerized systems (EPC-

Electronic process control) . There is a definite time interval for the cyclic

feeding process which is preset in the computer. Here the time interval for

feeding is set as 4 minutes (i.e. feeding will be done in the feeder in every 4

minutes).

When the compressed air is supplied through the inlet channel, the piston

moves towards the bottom head which provides a forward movement to the

piston rod and as a result the cone connected at the bottom is pushed

downward and closes the powder passage. At that time the alumina powder is

fed to the feeder through the hopper.

At the return stroke when the piston moves upward the cone is dragged up

and the alumina powder present inside the feeder is fed to the feeding hole of

the smelting cell (pot).

Both for the feeder and the breaker the air pressure is given as 75psi.

Here every single pot has two point feeders placed at one line. The feeding is

done in every 4 minutes and in every feeding 1.8 kg alumina powder enters

into the pot. The feeding timing and feeding amount has been preset and

controlled through the computerized system.

CRUST BREAKER

Crust breaker is a pneumatic device used for breaking. Here breaking means

clearing the path for the feeding of alumina powder. So the crust breaker

clears the path for the alumina powder to enter into the pot and take part in

the electrolysis process.

The crust breaker and the point feeder both work in a cyclic manner. First the

crust breaker clears the hole for the feeding of alumina powder and then the

feeder feeds the powder. The air enters into the crust breaker cylinder through

a small inlet channel present at the top head. The pressure of this compressed

air pushes the piston downward towards the bottom head. As the piston

moves towards the bottom head the hammer attached to the piston rod

moves downward and breaking takes place. After breaking the air returns

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through the return pipe and the piston returns to the top head thus the cyclic

process goes on.

There are 10 magnets fitted at the top head for holding the piston. Breaking is

a cyclic process and there is a definite time interval between the first cycle to

the next cycle. The magnets hold the piston in this time interval. Here breaking

is done in every 4 minutes so the magnet holds the piston at the top head for

this 4 minutes.

VACUUM CRUCIBLE

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Vacuum crucible is the carriage used for extracting the molten aluminium from

the smelting pot and for carrying the liquid aluminium to the casting plant.

Alumina is fed inside the pot and molten aluminium is produced. The

aluminium produced in the pot is extracted with the help of vacuum crucible

and this metal extraction operation is called metal tapping. Metal tapping is

done in all the pots in every 32 hours. This tapped metal is then carried out to

the casting plant.

ANODE JACK

In a smelting pot anode jack is used for lifting the anode up and downward i.e.

for adjusting the height of the anode. It is also called as pot jack.

The anode is made of carbon. As the anode is used the lower part of the anode

is consumed in the reaction. Due to which there are chances that the anode

may not come in contact with the molten metal and the electrolysis process

may stop. To eliminate this problem aluminium smelters are provided with

anode jacks.

There are 12 anode beams on both sides of a prebake pot and 2 anode buses

on two sides to hold 6 anode beams on each side. There are 4 jacks in a pot

and are connected to the anode bus. In case of requirement the jacks lift the

bus bar as a result of which all the anodes are lifted at a time.

The anode jacks are operated electrically. After tapping whenever the molten

metal level inside the pot decreases the anode jack is automatically adjusted

and the beams moves downward to continue the process.

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There are 4 jacks in a single pot, two on each side. The bus is clamped to the

jack. As the shaft rotates the rotational motion is converted to translational

motion at the jack due to which the anode bus is lifted up and downward.

When the motor switch is on the driving or motor shaft rotates. The driving

shaft is connected to the short intermediate shaft through bevel gear

arrangement. So the motion of the driving shaft provides motion to the short

intermediate shaft. The short intermediate shaft is connected to the long

intermediate shaft through worm gear arrangement. So when the short shaft

rotates the long shaft also rotates simultaneously. The jacks are connected to

the long intermediate shaft at its two ends. The jacks hold the anode bus.

The rotational motion of the intermediate shafts is converted to reciprocating

motion of the anode jack as a result of which it moves up and down resulting

in raising and lowering of anodes.

ELECTRIC OVERHEAD TRAVELLING CRANE (E.O.T.)

E.O.T. crane stands for Electric Overhead Travelling crane. The most adaptable and the most widely used type of power driven crane for indoor service is undoubtedly the three motion EOT crane. It serves a larger area of floor space within its own travelling restrictions than any other permanent type hoisting arrangement. This used in industries for handling and moving a maximum specified weight of the components called capacity of the crane within a specified area. Use of E.O.T. cranes in industries is both an efficient and cost effective method of handling the materials. As obvious from the name, these cranes are electrically operated by a control pendant, radio/IR remote pendant or from an operator cabin attached with the crane itself.

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As the name implies, this type of cranes are electrically operated by a control pendant, radio/IR remote pendant or from an operator cabin attached with the crane itself and provided with movement above the floor level. Hence it occupies no floor space and this can never interface with any movement of the work being carried out at the floor of the building.

An overhead crane consists of parallel runways with a travelling bridge spanning the gap. A hoist, the lifting component of a crane, travels along the bridge. If the bridge is rigidly supported on two or more legs running on a fixed rail at ground level, the crane is called gantry crane. Unlike construction cranes overhead cranes are used for either manufacturing or maintenance applications, where efficiency or downtime are critical factors. The three motions of such crane are the hoisting motion and the cross travel motion. Each of the motions is provided by electric motors.

The above characteristics have made this type of crane suitable for medium and heavy workshop and warehouses. No engineering erection shop, machine shop, foundry, heavy stores is complete without an EOT crane.

In a steel plant, rolling mill, thermal power plant, hydraulic power plant, nuclear power plant, this type of crane is considered indispensable. In short in all industries, wherein heavy loads are to be handled, EOT crane find its application.

Overhead cranes are commonly used in the refinement of steel and other metals such as copper and aluminium. At every step of manufacturing process, until it leaves a factory as a finished product, metal is handled by overhead cranes. From raw material pouring to the lifting of finished products to trucks or trains every work is done by overhead cranes. In steel industries E.O.T. cranes are used in almost every sectors starting from the pouring of raw material to repair and maintenance of every machinery. In aluminium industries E.O.T. cranes are used in most of the operations such as metal tapping, anode beam raising, anode changing, breaker and feeder changing and in other maintenance operations. Almost all paper mills use EOT cranes for regular maintenance needing removal of heavy press rolls and other equipment. These are used in initial construction of paper machines for installing heavy cast iron paper drying drums. In all other industries also EOT cranes are used in most of the fields for holding and travelling large weights.

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BEAM RAISING MACHINE

Beam raising machine is the device used in the aluminium smelters for raising

the anode beams used in the smelting pots.

Here all the pots are prebake pots and the life span of a prebake anode is 28 to

30 days. We also know that the carbon anode is consumed in the process. As

the anode gets consumed it should be held downward so that it will take part

in the electrolysis process. So the height of the anode is maintained with the

help of beam raising machine.The beam raising machine has 12 legs, 6 on each

side to hold the 12 beams of a pot. Holding clamps are attached on the legs for

holding the beams.It has 4 stands, 2 on each side for maintaining the height

and keeping the BRM stable.There are 36 diaphragm valves present, 3 on each

leg for operating the legs of the beam raising machine.The beam raising

machine is fully operated by compressed air. First the BRM is fitted in the pot

with the help of EOT Crane. After that the air pipe of the BRM is connected to

the air point present beside the pot.

There are 3 diaphragm valves on each leg, two are at the lower end and one at

the upper end. The valves at the lower end helps to tilt the holding clamp and

the valve at the upper end help to tilt the leg so that the legs hold the beams

tightly. All these valves are operated by compressed air. The beam raising

machine has air channels through which the air operates the valves. The legs

tilt inside opposite to the holding clamp to hold the beam tightly. The stand

helps to maintain the height of the beam.

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The operating air pressure for BRM is maintained as 80 psi.

MAINTANANCE

The maintenance section consists of mainly the cooling tower and the

compressors .

COOLING TOWER

Cooling towers are a very important part of many chemical plants. The primary

task of a cooling tower is to reject heat into the atmosphere. They represent a

relatively inexpensive and dependable means of removing low-grade heat

from cooling water. The make-up water source is used to replenish water lost

to evaporation. Hot water from heat exchangers is sent to the cooling tower.

The water exits the cooling tower and is sent back to the exchangers or to

other units for further cooling.

Cooling tower extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near the dry-bulb air temperature.

Common applications include cooling the circulating water used in oil refineries, petrochemical and other chemical plants, thermal power stations and HVAC systems for cooling buildings. The classification is based on the type of air induction into the tower: the main types of cooling towers are natural draft and induced draft cooling towers.

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Cooling towers vary in size from small roof-top units to very large hyperboloid structures (as in the adjacent image) that can be up to 200 meters (660 ft) tall and 100 meters (330 ft) in diameter, or rectangular structures that can be over 40 meters (130 ft) tall and 80 meters (260 ft) long. The hyperboloid cooling towers are often associated with nuclear power plants, although they are also used to some extent in some large chemical and other industrial plants. Although these large towers are very prominent, the vast majority of cooling towers are much smaller, including many units installed on or near buildings to discharge heat from air conditioning.

Compressor Compressors are widely used in industries to transport fluids. It is a mechanical device that compresses a gas. Generally, the compression of gases may be accomplished in device with rotating blades or in cylinders with reciprocating pistons. There are many types of compressors, thus a proper selection is needed to fulfil the typical necessity of each industry. TYPES OF COMPRESSORS Compressor is a device used to increase the pressure of compressible fluid, either gas or vapor, by reducing the fluid specific volume during passage of the fluid through compressor. One of basic aim of compressor usage is to compress the fluid, then deliver it to a higher pressure than its original pressure. The inlet and outlet pressure level is varying, from a deep vacuum to a high positive pressure, depends on process’ necessity. This inlet and outlet pressure is related, corresponding with the type of compressor and its configuration. compressors are generally classified into two separate and distinct categories: dynamic and positive displacement.

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CALCULATIONS Here at HINDALCO 2 types of compressors are used

1. Ingersollrand compressor (IR) (Reciprocating compressor) 2. Screw compressor (Rotary compressor)

1. IR(Ingersollrand) compressor It is a reciprocating compressor. The main components of this compressor are the air filter, LP cylinder, HP cylinder, intercooler, aftercooler, lubricating cylinder. In the IR compressor there are 4 suction and delivery valves in LP cylinder. Similarly in the HP cylinder there are 2 suction and delivery valves. There is a non-return valve (NRV) present between the compressor and the receiver. When the compressor is off the NRV doesn’t allow the air to return to the compressor so as to avoid bursting of compressor. As the piston reciprocates continuously a lot of heat is developed inside the cylinder to reduce that temperature water jackets are provided. IR COMPRESSOR Make:- siemens Kw/hp:- 110/150 Volt:- 415 +- 10% Amp:- 193A Rpm:- 1485 rpm Delivery pressure: LP side:- 3kg HP side:- 4 kg Suction valve temperature:- 500c

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Delivery valve temperature:- 1200c Coil temperature:- 60-650c Intercooler temperature:- below 400c Aftercooler temperature:- below 400c Intercooler pressure:- 28 psi Oil pressure:- 1.5-2 psi Potroom delivery pressure:- 85 psi 2. Screw compressor Model:-ZR 250 Kw:- 250 kw Compressor outlet pressure:- 6 bar Air filter:- -0.038 bar(when it becomes -0.044 bar, a warning rings and the filter is cleaned and fitted again) Oil pressure:- 2.32 bar Intercooler:- 2.3 bar Compressor outlet temperature:- 310c Element-1(intercooler outlet) temperature:- 1700c Element-2(intercooler inlet) temperature:- 520c Aftercooler outlet temperature:- 1550c Cooling water in:- 260c LP Cooling water out:- 400c Cooling water out:- 380c Oil temperature:- 650c

APPLICATIONS

Forging Rolling

Extrusion

FORGING

Forging is a manufacturing process involving the shaping of metal using

localized compressive forces. The blows are delivered with a hammer (often

a power hammer) or a die. Forging is often classified according to the

temperature at which it is performed: cold forging (a type of cold working),

warm forging, or hot forging (a type ofhot working). For the latter two, the

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metal is heated, usually in a forge. Forged parts can range in weight from less

than a kilogram to hundreds of metric tons. Forging has been done

by smiths for millennia; the traditional products

were kitchenware, hardware, hand tools, edged weapons, and jewellery. Since

the Industrial Revolution, forged parts are widely used

in mechanisms and machines wherever a component requires high strength;

such forgings usually require further processing (such as machining) to achieve

a finished part. Today, forging is a major worldwide industry.

ROLLING

In metalworking, rolling is a metal forming process in which metal stock is

passed through one or more pairs of rolls to reduce the thickness and to make

the thickness uniform. The concept is similar to the rolling of dough. Rolling is

classified according to the temperature of the metal rolled. If the temperature

of the metal is above its recrystallization temperature, then the process is

known as hot rolling. If the temperature of the metal is below its

recrystallization temperature, the process is known as cold rolling.

In terms of usage, hot rolling processes more tonnage than any other

manufacturing process, and cold rolling processes the most tonnage out of

all cold working processes.[1][2] Roll stands holding pairs of rolls are grouped

together intorolling mills that can quickly process metal, typically steel, into

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products such as structural steel (I-beams, angle stock, channel stock, and so

on), bar stock, and rails.

Most steel mills have rolling mill divisions that convert the semi-finished

casting products into finished products.

EXTRUSION

Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed through a die of the desired cross-section. The two main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections, and to work materials that are brittle, because the material only encounters compressive andshear stresses. It also forms parts with an excellent surface finish.[1]

Drawing is a similar process, which uses the tensile strength of the material to pull it through the die. This limits the amount of change which can be performed in one step, so it is limited to simpler shapes, and multiple stages are usually needed. Drawing is the main way to produce wire. Metal bar and tube are also often drawn.

Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing many pieces). The extrusion process can be done with the material hot or cold. Commonly extruded materials include metals, polymers, ceramics, concrete, play dough, and foodstuffs. The products of extrusion are generally called "extrudates".

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Hollow cavities within extruded material cannot be produced using a simple flat extrusion die, because there would be no way to support the centre barrier of the die. Instead, the die assumes the shape of a block with depth, beginning first with a shape profile that supports the center section. The die shape then internally changes along its length into the final shape, with the suspended center pieces supported from the back of the die. The material flows around the supports and fuses together to create the desired closed shape.

The extrusion process in metals may also increase the strength of the material.

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