Raw Materials & Material Handling Plant
The Raw Materials and Material Handling Plant receives blends, stores and supplies different raw materials to Blast Furnace, Sinter Plant and Refractory Materials Plant as per their requirements. It also maintains a buffer stock to take care of any supply interruptions.
Different raw materials viz. Iron ore fines and lumps, Limestone (BF and SMS grade), Dolomite lumps and chips and Manganese ore are handled here every year.
Iron ore and fluxes are sourced from the captive mines of SAIL situated at Kiriburu, Meghahataburu, Bhawanathpur, Tulsidamar and Kuteshwar. Washed coal is supplied from different washeries at Dugda, Kathara, Kargali and Giddi, while raw coal is obtained from Jharia coalfields.
Coke Ovens & By-product Plant
The Coke Oven Complex converts prime Indigenous coking coal and medium Indigenous coking coal ,blended with imported coal, into high quality coke for the Blast Furnaces, recovering valuable by-products like Anthracene Oil, Benzene, Toluene, Xylene, Light Solvent Naphtha, Ammonium Sulphate and Extra-hard Pitch in the process. Bokaro is situated in the prime coal belt of the country.
The Coke Oven battery has 8 batteries with 69 ovens each, maintained meticulously in terms of fugitive emission control, use of phenolic water and other pollution control measures.
Sinter is produced in Sintering Machines from Iron Ore fines, Coke fines and flux (Limestone & Dolomite) and other metallurgical wastes generated in the plant like Mill Scale, Flue dust etc.
There are 3 Sintering Machines at the Sintering plant in Bokaro Steel Plant. Two machines have a hearth area of 252 m2 each and one of 276 m2. Annual capacity of gross sinter production is 6.9 MT.
Bokaro Steel Plant has 5 Blast Furnaces, four with 2000-cubic metre useful volume and one with 2500 cubic metre useful volume that produce molten iron - Hot Metal - for steel making. Total Hot metal production capacity of Blast furnaces is 5.25 MT. Bell-less Top Charging, modernised double Cast Houses, Coal Dust Injection and Cast House Slag Granulation technologies have been deployed in the furnaces. The process of iron-making is automated, using PLC Charging System and Computer Controlled Supervision System. The waste products like Blast Furnace slag and gas are either used directly within plant or processed for recycling / re-use.
Steel Melting Shops
Hot Metal from the Blast Furnaces is converted into steel by blowing 99.5% pure Oxygen through it in the LD converter. Suitable alloying elements are added to produce different grades of steel.
Bokaro has two Steel Melting Shops – SMS- NEW and SMS-II. SMS-NEW has 3 LD converters of 130T capacity each. 1 single strand caster with capacity of 1.305 MT or 33 Heats/day has been installed. It can produce slab of width range from 850 mm to 1650 mm, the slab length will vary from 7.5 mts. to 10.5 mts. The product mix contains of low, medium, high carbon and micro alloyed steel such as LPG, API, SAILMA etc. The facility also includes Tundish Preparation Bay, Slab Yard and mould repair section. The new facility includes one twin LF with common arcing facility for both LF.
Steel ingot route through mould yard and Stripper yard earlier has been closed from 2nd 2021 and now all steel is produced from LF and Caster route. It was capable of producing Rimming steel. SMS-II has 2 LD converters, each of 300 T capacities, with suppressed combustion system and Continuous Casting facility. It produces various Killed and Semi-Killed steels.
Continuous Casting Shop (SMS-II)
The Continuous Casting Shop has two double-strand slab casting machines, producing high quality slabs of width ranging from 950 mm to 1850 mm. CCS has a Ladle Furnace and a Ladle Rinsing Station for secondary refining of the steel. The Ladle Furnace is used for homogenising the chemistry and temperature. The concast machines have straight moulds, unique in the country, to produce internally clean slabs.
Argon injection in the shroud and tundish nozzle prevent re-oxidation and nitrogen pick-up, maintaining steel quality. The eddy current based automatic mould level control, unique in the country, gives better surface quality. The air mist cooling and continuous straightening facilities keep the slabs free from internal defects like cracks. The casters are fully automated with dynamic cooling, on-line slab cutting, de-burring and customised marking. The shop is equipped with advanced Level-3 automation and control systems for scheduling, monitoring and process optimisation.
CCS produces steel of Drawing, Deep Drawing, Extra Deep Drawing, Boiler and Tin Plate quality. It also produces low alloy steels like LPG, WTCR, SAILCOR and API Grade.
Slabbing Mill converts ingots into slabs by rolling them in its 1250 mm Universal Four-High Mill. The rolling capacity of the Mill is 1.9 MT per annum. The shop has Hot and Cold Scarfing Machines and 2800 T Shearing Machine. Controlled heating in Soaking Pits, close dimensional accuracy during rolling and hot and cold scarfing help produce defect-free slabs. With the commencement of caster route in SMS (New), Slabbing mill is likely to be un-operational by the end of July 2021.
Hot Strip Mill
Slabs from CCS and Slabbing Mill are processed in the state-of-the-art Hot Strip Mill. The fully automated Hot Strip Mill with an annual capacity of 4.5 million tonnes has a wide range of products - thickness varying from 1.2 mm to 20 mm and width from 750 mm to 1850 mm. The mill is equipped with state-of-the-art automation and controls, using advanced systems for process optimisation with on-line real time computer control, PLCs and technological control systems.
Walking Beam Reheating Furnaces provide uniform heating with reduction in heat losses, ensuring consistency in thickness throughout the length. High-pressure De-scaling System helps eliminate rolled-in scale. Edgers in the roughing group maintain width within close tolerance. The roughing group has a roughing train of a Vertical Scale Breaker, one 2-high Roughing Stand and four 4-high Universal Roughing Stands. The finishing group consists of a Flying Shear, Finishing Scale Breaker and seven 4-high Finishing Stands. Hydraulic Automatic Gauge Control system in the finishing stands ensures close thickness tolerance. The Work Roll Bending System ensures improved strip crown and flatness. The rolling speed at the last finishing stand is between 7.5-17.5 metres per second. The Laminar Cooling System is a unique feature to control coiling temperature over a wide range within close tolerance. The Hydraulic Coilers maintain perfect coil shape with On-line Strapping system. On-line Robotic Marking on the coil helps in tracking its identity.
Hot Rolled Coil Finishing
All the Hot Rolled coils from the Hot Strip Mill are received in HRCF for further distribution or despatch. It has an annual capacity of 1.2 MT.HR Coils rolled against direct shipment orders are sheared and finished to customer-required sizes and despatched to customers. The material is supplied as per Indian specifications and many international/ foreign specifications. The shop has two shearing lines for production of Hot Rolled Plate and Sheets.
Cold Rolling Mill I & II
The Cold Rolling Mill at Bokaro produces high quality sheet gauge material, Tin Mill Black Plate and Galvanised Products. Cold rolling is done to produce thinner gauge strips of very smooth and dense finish, with better mechanical properties than hot rolling strips. Rolling is done well below re-crystallization temperature without any prior heating of the material. The products of CRM are used for deep drawing purposes, automobile bodies, steel furniture, drums and barrels, railway coaches, other bending and shaping jobs and coated steels. The CRM complex comprises of two Pickling Lines (including a high speed Hydrochloric Acid Pickling Line with re-generation facilities), two Tandem Mills, an Electrolytic Cleaning Line, a Continuous Annealing Line, Bell Annealing Furnaces, two Skin-Pass Mills, a Double Cold Reduction Mill (DCR), Shearing Lines, Slitting Lines and a packaging and despatch section. The 5-stand Tandem Mill is capable of rolling sheet gauges upto 0.15 mm thickness. It has sophisticated Hydraulic Automatic Gauge Control, computerised mill regulation and optimisation control.
The Hot Dip Galvanizing Complex integrated with the CRM produces zinc-coated Cold Rolled strips resistant to atmospheric, liquid and soil corrosion. The Continuous Coil Corrugation Line in the HDGC produces corrugated sheets and the Galvanised Sheet Shearing Line produces galvanised plain sheets for a variety of applications. The first shop of Bokaro Steel to get the ISO-9001 certification way back in 1994, this complex has maintained a high-standard of coating quality and its SAILJYOTI branded products enjoy a loyal market.
This complex made certain innovations for higher productivity to help re-build earthquake-ravaged Gujarat.
Cold Rolling Mill III:
The new cold rolling mill, CRM-III uses state-of-the-art technology to produce top quality CR and GP coils. It has a capacity of 1.2 MT. The CRM-III complex houses following facilities.
HRCC (Hot Rolled Coil Conveyor): It receives hot coil from HSM and lowers the temperature of the coil as required for rolling in PLTCM unit of CRM-III. It has provision of 700 saddles in its yard equipped with Yard Management System.
PLTCM (Pickling Line Tandem Cold Rolling Mill): It is a long continuous 5 Stand 6-Hi Mill. It processes Coils of thickness 1.5-5 mm & produces reduced coil of thickness 0.25-2 mm. It uses Hydrochloric acid for removal of hard scales from the strip. The line is equipped with SIFLAT System to control the flatness of the stip. The weld produced by Laser welder is rollable by nature.
BAF (Bell Annealing Furnace): Bright Annealing of Cold Rolled Steel Strip in coil form including low Carbon, HSLA, IF & BH Steel. To improve mechanical properties lost during rolling, annealing is done. It has super high convection system which includes forward curved convection fan with matching diffuser for the best atmosphere circulation. Each unit is equipped with a water-cooled corrugated inner cover & automatic PLC controlled hydraulic clamps. Mixed gas Fuel direct fired with 8 tangentially oriented burners. It has 47 bases, 26 Furnaces & 20 Forced Coolers.
ECL (Electrolytic Cleaning Line): After rolling from PLTCM, the strip has emulsion on the surface. To clean this, the electrolytic cleaning line is used. First the strip is passed through a hot alkaline tank & then through a brush scrubber tank after which electrolytic cleaning is done in electrolytic cleaning tank. Two electrodes are dipped in alkaline solution to remove the ionised impurities from the surface. The product from this line has high quality surface finish & is mainly used in automotive industries.
SPM (Skin Pass Mill): It is a 4-HI Mill. It processes annealed coil of thickness 0.25 mm to 2 mm & produces final sellable product. Skin passing of the coil is done to remove yield point phenomena & paint ability in the coil. To control flatness, Shape meter roll is used in the line which provides automatic bending & tilting. Line has facility of Electrostatic oiler for oil coating in the strip to improve corrosion resistance. It also has provision of wet skin passing which enhances roll life & cleanliness of the strip.
TLIL (Tension Leveller & Inspection Line): The processed coil from SPM is directly transported to TLIL by a combination of walking beam conveyor, coil shuttle car & coil transfer cars. The shuttle car places the coil on the either of the two number floor mounted fixed coil saddle. Entry coil car pick up the coil & places on the cradle roller station where the coil width is measured & coil is aligned for de-banding operation.
HDGL (Hot Dip Galvanising Line): HDGL is capable of processing construction steel grades as well as higher quality steel grades required for the automotive application i.e. non-exposed and exposed parts and white goods appliances industries. HDGL with electrolytic cleaning & differential Zn coating for 2 types of products: Galvanised Iron & Galva Annealed.
CPL (Coil Packaging Line): Two nos. of Coil Packaging line are there for coil packaging and despatch of CR Coil from CRM-III. One semi automatic line having capacity 4,00,000 T per annum attached with HDGL and another fully automatic having capacity 10,00,000 T per annum for another route. There is Coil Yard Management System in the yard which ensures yard optimization with proper storage of coils and also efficient dispatch of coils with minimum movement of cranes. The server of CYMS has complete map of the yard with coil locations as well as position and status of cranes.
Services - a valuable support network
The service departments like Traffic, Oxygen Plant, Water Management and Energy Management provide invaluable support to this gigantic plant. Bokaro Steel has a vast networked of railway tracks and over 40 diesel locos to smoothly run its operations. The Oxygen Plant provides Oxygen, Nitrogen and Argon for processes like steelmaking and annealing. Water Management looks after the huge water requirements of the plant and the township, providing different grades of water and taking care of recycling needs. Energy Management juggles the supply and demand of by-product gases and their demand as process fuel.
Bokaro has centralised maintenance departments for large-scale electrical and mechanical maintenance, in addition to shop-based maintenance wings for running repairs and maintenance. These facilities are capable of executing massive capital repairs, supported by the fabrication facilities of the auxiliary shops.
To meet its needs for maintenance and repairs, Bokaro has a cluster of engineering shops such as Machine Shop, Forge Shop, Structural Shop, Steel Foundry, Ingot Mould Foundry, Cast Iron and Non-Ferrous Foundry, Electrical Repair Shop and Power Facilities Repair Shop in addition to shop-specific Area Repair Shops. Most of the repairs and maintenance requirements of the plant are met in-house.
The auxiliary shops and maintenance wings of Bokaro Steel, aided by in-house design teams, have executed a number of highly sophisticated procurement-substitution, productivity enhancement and quality improvement jobs, saving revenues and enhancing equipment availability.
The expertise and operational scale of these departments, along with the service departments, makes Bokaro a truly integrated plant, housing many virtual enterprises within Bokaro Steel.