Durgapur Steel Plant (দুর্গাপুর ইস্পাত কারখানা) is one of the integrated steel plants of Steel Authority of India Limited, located in Durgapur, in the eastern Indian state of West Bengal. It is one of the plants that have played a historically important part in the industrial development of India. Although not a separate company, it is the largest industrial unit in the state of West Bengal.
Set up in the late 50's with an initial annual capacity of one million tonnes of crude steel per year, the capacity of Durgapur Steel Plant (DSP) was later expanded to 1.6 million tonnes in the 70's. A massive modernisation programme was undertaken in the plant in early 90's, which, while bringing numerous technological developments in the plant, enhanced the capacity of the plant to 2.088 million tonnes of [hot metal],1.8 million tonnes crude steel and 1.586 million tonnes saleable steel. The entire plant is covered under ISO 9001: 2000 quality management system.
The modernized Durgapur Steel Plant now has state-of –the-art technology for quality steel making. The modernized units have brought about improved productivity, substantial improvement in energy conservation and better quality products. DSP’s Steel Making complex and the entire mills zone, comprising its Blooming & Billet Mill, Merchant Mill, Skelp Mill, Section Mill and Wheel & Axle Plant, are covered under ISO: 9002 quality assurance certification.
After the commissioning of the modernized units, DSP is all set to produce 2.088 million tones of hot metal, 1.8 million tones of crude steel and 1.586 million tones of saleable steel annually.
Situated at a distance of 158 km from Calcutta (now Kolkata), its geographical location is defined as 230 27' North and 880 29' East. It is situated on the banks of the Damodar river. The Grand Trunk Road and the main Calcutta-Delhi railway line pass through Durgapur.
Durgapur, which is on the main Kolkata – New Delhi line, is fast turning into the most happening city in the region. From a sleepy settlement, the town today boasts of a variety of educational institutions, posh shopping malls, complexes with eateries and a multiplex, etc. With the change in the mindset of the people has come a change in the lifestyle also. Quality consciousness has steeped in, accompanied with quality brands making their presence felt in the market. Durgapur is fast turning into the central location for the entire region – with the entry of big business houses and entrepreneurs, the city is all set to undergo a change in its own lifestyle and in the outlook of its residents.
|Wheels & Axles||58,000|
|Total Saleable steel||15,86,000|
Iron ore, coal and limestone are the three basic raw materials for the steel industry. Durgapur Steel Plant draws its coal from the adjacent Jharia-Ranigunj coal belt. A good amount of prime coking coal, having fairly low ash content, is also imported. Bulk of iron ore lumps and fines come from the mines at Bolani in Orissa. Lime stone comes from a variety of sources: Birmitrapur (Orissa), Jaisalmer (Rajasthan), and Jukehi and Nandwara (Madhya Pradesh).
To improve and ensure consistency in raw material quality, the facilities, which have been installed, are:
Beneficiation/washing facilities, both for lump ore and fines at Bolani Screening of lump iron ore inside the plant, Selective crushing of coal at Coal Handling Plant, Base blending facilities for Sinter Plant, Silo-cum- Blending bunkers As part of the modernisation programme, new raw material handling storage and blending facilities with selective crushing of coal have been installed in order to ensure consistency in raw material quality.
The beneficiation/washing facilities, both for lump ore and fines at Bolani, have a capacity to process 3.44 million tonnes (wet basis) per annum so as to be capable of catering to the entire requirement of the plant after modernisation.
Durgapur is the only steel plant in the country to have a coal washery at the plant site.
Durgapur Steel Plant consumes about 7.4 million tonnes of different raw materials annually which comprises over 1.84 million tonnes of coal and 2.9 million tonnes of iron ore lump and fines. Besides the two major raw materials, the plant also requires limestone, dolomite, manganese ore, bauxite, silicomanganese, ferromanganese, ferrosilicon, etc.
No. of batteries - 6 of which one battery is currently waiting for rebuilding. No. of ovens per battery - 78
The coke ovens and coal chemicals zone is divided into four basic sections namely coal preparation plant, coal carbonisation plant, coke handling plant and coal chemicals. Presently, DSP is operating only three batteries.
The Blast Furnace grade coke produced in Coke Ovens is directly used in Blast Furnaces while the undersized coke is used for sinter making.
The volatile matters, which emanate during the process of coke making subsequently produce a variety of by-products like naphthalene oil, heavy creosote oil, light oil, crude tar partially distilled tar, “Raja” brand fertiliser, nitration grade benzene, nitration grade toluene, industrial grade toluene, light solvent naphtha etc.
The coke oven gas is generally used in combination with the Blast Furnace gas and BOF gas as fuel and is carried through pipelines to the different areas of the plant. The adjoining Alloy Steels Plant under SAIL is also supplied with this fuel gas from DSP.
In order to enhance the productivity of blast furnaces, a high percentage of sinter charge is a prerequisite. Sinter is an agglomeration of iron ore fines, coke and limestone in the form of cakes. To ensure sinter burden in the blast furnaces at 75 per cent, a total of 3 million tonnes of sinter was envisaged for a production of about 2 million tonnes of hot metal. A technologically modern and fuel efficient sintering machine having 198 sq metres sintering area has been added as part of the modernisation scheme to produce 1.7 million tonnes of sinter. The balance requirement will be met from the revamped old sinter plant.
Sinter mix, a mixture of fines of iron ore, limestone, coke, dolomite and flue dust, blended proportionally at the RMHC, is a prepared material which is self fluxing. In ignition strands it is burnt under controlled conditions to form a porous cake type substance called sinter, which used in blast furnaces enhances productivity and reduces coke rate.
Durgapur Steel Plant requires annually over 7.4 million tonnes of different raw materials, which comprises over 1.84 million tonnes of coal and 2.9 million tonnes of iron ore lump and fines. Besides the two major raw materials, the plant also requires limestone, dolomite, manganese ore, bauxite, silicomanganese, ferromanganese, ferrosilicon, etc.
Blast furnaces are referred to as the ‘mother unit’ of an integrated steel plant. Iron ore as available in nature is basically an oxide. It is charged into a blast furnace either as lump ore or in the form of sinter and reduced to molten iron by the coke at temperatures ranging from 1, 200 – 1, 400 degrees Celsius. The limestone, acting as flux, absorbs the impurities in the molten iron and goes out as slag. The major portion of liquid hot metal is transferred to steel melting shop for conversion to steel and the rest portion is cast into pig iron in pig casting machines. Blast furnace slag high in lime-content is used for cement making.
There are three numbers of blast furnaces operating presently at DSP. The useful volume of two furnaces is 1,400 cubic meters each and that of the other one is 1,800 cubic meters. The furnaces are presently operating at a productivity level of 1.3-1.4 tonnes/cubic meter/day. The furnaces are equipped with sophisticated and modern computerised control system and are operated with high blast temperatures (1,100 degree Celsius) and high top pressure (0.7 kg/ sq. cm). The cast houses are provided with facilities like twin tap holes, rocking runners etc. There are also two numbers of Slag Granulation Plants, which convert molten blast furnace slag into granulated forms for ready use in the cement industry. There are three pig casting machines, with a total capacity of 2,12,000 tonnes/year.
Blast furnaces No 1 No 2 No 3(being modernised) No 4 Capacity (t/day) 1,250 1,820 1,820 2,340 Useful volume (cum) 1,323 1,400 1,400 1,800 Stoves 3 3 3 3 Productivity 1.000 1.3 1.3 1.3 (t/cu m/day)
Mixers - 2 x 1, 300 t Converters - 3 x 110 t (nominal heat size)
Molten iron is further refined at the Steel Melting Shop (SMS) to produce steel, which is hard and malleable.
At DSP, there are 3 converters (Basic Oxygen Furnace) of 110-130 tonnes each. The SMS also has a Vacuum Arc Degassing (VAD) unit for making special grades of steel & 2 ladle refining furnace of same capacity (supplied by Danieli India Ltd).
A major portion of the steel is routed through the Continuous Casting Plant. Another major portion of the steel is taken to the teeming bay, where it is top poured into 8 tonne ingot moulds for making ingot steel. A portion of highly controlled steel is cast at the Special Casting Bay into fluted ingots and special quality blooms. Fluted ingots are bottom poured and are used for making wheel steel for DSP’s Wheel & Axle Plant. A portion of the liquid steel is also bottom poured to make axle ingots.
The state of the art CCP has 2 Nos machines having 6 strands each. The other basic details are as follows: -
Design limits - 80-150 sq .mm casting radius - 6 metres Casting time – 85 minutes Cut-off lengths - 6/9/12 metre No of ladle treatment stations - 2 Mould level controller - Automatic (Radio-active Co-60)
In 2007 a 4 strand bloom caster machine has been added to DSP having a capacity of 0.75 MT per annum.
The steel ladle from BOF is taken to the ladle treatment station. At the ladle treatment station, liquid steel is rinsed with nitrogen to homogenise its temperature and composition. After the rinsing, the ladle containing liquid steel is placed on the turret and brought over the tundish. The tundish acts as a buffer and enables the liquid steel to move homogeneously down through the six nozzles, provided at the bottom of the tundish into moulds. The automatic mould level controller controls the steel level in the mould. The subsequent primary and secondary cooling transforms the liquid steel into billets of the required dimensions and is drawn out with the help of a withdrawal and straightener unit and cut into the required length by the shear provided in each strand. The continuous casting process is the result of a unique synchronisation between Basic Oxygen Furnace and CCP. Once a ladle is emptied, another ladle is brought into casting position and the casting continues.
The billets are gradually shifted to the cooling beds and then stacked orderly at the despatch end for outside despatch. The details about the cast number and quality of the billets are marked on the billet stack. The Merchant Mill of Durgapur Steel Plant utilises billets for rolling TMT bars and other merchant rounds, while a sizeable portion is sold in the domestic and foreign markets.
Ingots weighing 8 tonnes each are heated in the soaking pits (numbering 20) for about 7 to 12 hours at around 1, 200 degrees Celsius and thereafter rolled in the 42” primary and the 32” secondary blooming mills. These are rolled further into different shapes and sizes in different finishing mills.
Installed Mill capacity - 1.47 million tonnes/year Ingot weight - 8 tonnes
42" Mill: 42" x 102" reversible Blooming Mill Output bloom size (min) - 300 mm x 250 mm
32" Mill: 32" x 84" reversible Intermediate Mill Output bloom size (min) - 180 mm x 180 mm
Installed Mill capacity - 0.957 tonnes / yr. Type - Continuous Morgan design Horizontal stands - 6, Vertical stands - 2
Billets - 100 mm square to 125 mm square Sleeper bars - 352 mm x 12.5 mm Skelp slabs - 140 mm x 75 mm to 240 mm x 90 mm
The ingots after heating are rolled in the Blooming Mill to make blooms of the sizes mentioned in the table and then a part of the same are then further rolled in the Billet Mill for making rolled billets or slabs as per the above details.
The Section Mill rolls out light and medium structural like joists, channels and angles.
Mill capacity - 0.2 million tonnes / year Re-heating furnaces - 2 x 40 t/hr Roughing Mill - 2 high reversible Intermediate Mill - 2 stands of 3 high non-reversible Finishing Stand - 2 high non-reversible
Joists - 200 mm x 100 mm, 175 mm x 85 mm, 150 mm x 75 mm, 116 mm x 100 mm Channels - 200 mm x 75 mm, 175 mm x 75 mm, 150 mm x 75 mm, 125 mm x 65 mm Angles - 150 x 150 mm, 130 x 130 mm, 110 x 110 mm, 100 x 100 mm
Fish plate bars for 52 kg rails was rolled earlier.The material after leaving Finishing stand is cut by two hydraulically fed Hot Saw.Then they go to cooling bed & finally to Straightening Machines where the materials are straightened & ready for despatch.Ther is a plan to install two new stands in Intermediate Mill in 2008 which will be more rigid to produce accurate dimensions by suitable hydraulic arrangement.
The Merchant Mill produces plain round and Thermo-Mechanically Treated (TMT) bars in the range of 16 mm - 28mm. The entire product range of TMT bars and rods at DSP is branded and has been able to create a niche market.
Capacity - 0.28 million tonnes / year Type of mill - continuous Morgan design Horizontal stands - 13 Repeaters - 4
Plain rounds - 12 - 32 mm dia TMT bars - 12 - 25 mm dia
The Skelp Mill produces skelp in the range of 146 to 235 mm primarily for tubes and pipes making industry.
Capacity - 0.25 million tonnes / year Type of Mill - Continuous Loewy design Horizontal stands - 11 Vertical stands - 6
Strips & Skelps - 75-242 mm wide to 1.47-2.34 mm thick
Durgapur Steel Plant is the only major indigenous supplier of wheel sets, loco wheels, carriage and wagon wheels, and axles to the Indian Railways. As per demand of the Railways, the plant has developed loco wheels, which were imported earlier. The Wheel & Axle Plant is producing wheels manufactured as per the latest IRS specifications, i.e. R-19/93 for carriage and wagon wheels, R-34/99 for loco wheels and R-16/95 for axles.
The wheel plant of the Wheel & Axle Plant is provided with six PLC controlled band saws for accurate slicing of the 14” and 16” fluted ingots. A fully computerised 63/12 MN oil hydraulic press is there for forging and punching of the wheel blanks along with a fully computerised vertical wheel mill and other down stream facilities. All the wheels are 100 per cent rim-quenched, tempered and tested as per IRS specifications.
Machining of these forged rolled and heat-treated wheel blanks are carried out in the 15 CNC machines. All the wheels are ultrasonically tested and inspected by RITES on behalf of the Indian Railways. A number of sophisticated and modern online testing facilities are there to conform to the stringent testing requirements of the Indian Railways.
Annual production of finished wheels - 1,00,000 nos. Production rate in rolling/forging - 25 nos./hr Production rate in machining - 22 nos./hr
Durgapur Steel Plant has a number of captive engineering shops for repairs and supply of spare parts. The Central Engineering Maintenance has a Machine Shop, Structural Shop, Fitting and Assembly Shops. The Foundry produces Ingot moulds and bottom plates for the steel melting shop. There are also Auxiliary Repair Shops such as Electrical, Wagon and Loco repair.
The Research & Control laboratories are entrusted with the responsibility of maintaining quality of products and also developing new products. It is well equipped for carrying out sophisticated chemical, metallurgical and other tests.
An extensive computerisation has been undertaken in DSP for personnel, commercial, process control, production and maintenance applications. The Production Planning and Control network is thoroughly used for tracking of customer orders, material, monitoring of quality parameters and ensuring availability of accurate, real time data to all agencies needing access to the data.
In order to be fully competitive on the quality front, Durgapur Steel Plant has set out to acquire ISO 9000 certification for all its units. The Merchant Mill is the first to secure the prestigious ISO 9002 certificate. Subsequently, steel melting shop, basic oxygen furnace shop, continuous casting plant, and wheel and axle plant were also awarded the ISO 9002 certification and recently the Skelp Mill has been awarded the ISO 9002 certification.
Durgapur Steel Plant has always made relentless efforts to maintaining a healthy and clean environment. The units in DSP are provided with necessary pollution control facilities and the liquid effluents and chimney emissions from the plant are well within norms. DSP has undertaken massive afforestation to maintain clean environment. Some of land have been covered with 1,400,000 plantations. In order to develop healthy awareness about the environment amongst the younger generation, eco-clubs have been formed in DSP schools.
DSP has always attached maximum importance on proper training and development of its employees. Its Centre for Human Resource Development has all modern facilities including the state-of-the-art Electrical and Electronics laboratory, Hydraulics and Pneumatics laboratory and workshop for effective training and development of its employees.
The Public Relations Department publishes monthly house journals in English, Bengali and Hindi for extensive information of company affairs to the employees. DSP also has an in-house TV studio (DSTV) along with all modern facilities, which telecast news and a gamut of other programs covering various aspects of plant and township activities.
The Durgapur Steel Plant township is spread over a sprawling 40 km and has more than 25,000 dwelling units. And it has housing facilities for the employees of Durgapur Steel Plant, Alloy Steel Plant and other business associates. The other amenities include schools, both primary and secondary, a modern 640 beds hospital with modern medical facilities, the picturesque park, a number of cultural centres, a stadium with a sitting capacity of 15,000, etc.
Over the years, it has contributed in a major way for providing tube well facilities in the water-scarce peripheral areas. Another notable contribution has been the efforts taken towards enlightenment of the region through up-gradation or additions to educational facilities in basically rural areas surrounding the steel township. It has also assisted in developing roads and other facilities.
Durgapur Steel Plant has played a major role in encouraging and developing many small-scale industries in the region.