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JSW STEEL PLANT
Summer Training at JSW AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR SMS-II (BOF) JSW STEEL LIMITED VIJAYANAGAR
Overview Report by ROHIT PAL – USN:01FE15BME147 Under the guidance of Mr. Ravi Kiran
BACHELOR OF ENGINEERING SCHOOL OF MECHANICAL ENGINEERING KLE TECHNOLOGICAL UNIVERSITY VIDYANAGAR, HUBLI-, KARNATAKA, INDIA Duration Period: 11-June-2018 to 4-July-2018
TABLE OF CONTENT
SNo. 1 2 3 4
Topic Certificate Acknowledgement Abstract JSW Steel Limited- Overview • • • •
Page no 1 2 3 4
Introduction History Milestones Input • Flow chart of plant
5 6 7
Departments of JSW Steel Limited Finished Products and its applications Steel Melting Shop -2 :Overview • •
10 17 19
Introduction Process • Flow Chart of SMS-II
8
Hot Metal Pretreatment
22
9
MOVABLE CANBARA REACTOR
24
• • • •
Literature Survey Basic Data for KR Plant KR Process In JSW Steel Basic operation flow and time of KR-2
10
KR Plant Major Equipment Process
36
11
Critical parameters in KR process
48
12 13
Comparison Between KR And Injection Process Major Problems Faced in KR Reactor
50 51
• •
Overheating of hydraulic power bank SRM Bellow leakage • Material discharging problem
14
Conclusion
53
15
References
54
KLE Technological University School of Mechanical Engineering, Hubli
KLE TECHNOLOGICAL UNIVERSITY HUBLI (KARNATAKA)
CERTIFICATE
This is to certify that the Report entitled “AN OVERVIEW OF HOT METAL DESULPHURIZATION SYSTEM IN KANBARA REACTOR PROCESS-2” and submitted by ROHIT PAL having USN no 01FE15BME147 for the partial fulfilment of the requirements of B.Tech. (Mechanical Engineering) degree of KLE Tech University, embodies the bonafide work done by him under my supervision
Signature of the Supervisor Place: Toranagallu Date: 02/07/2018 ‘ Mr Ravi kiran Jr Manager (SMS-II) JSW steel limited, Toranagallu
Mr Shant Kumar Manger (SMS-II) JSW steel limited, Toranagallu AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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ACKNOWLEDGEMENT
The successful completion of any task would be but in complete without the mention of the people who made it possible, whose constant guidance and encouragement crown all the efforts with success. On the occasion of submission of project report, I take this opportunity to express my profound gratitude to KLE Technological University to have been kind enough to accept my proposal to carry out this work. I wish to express my sincere thanks to management of JSW steel limited for giving this opportunity to do the project in their esteemed organization. I am grateful to Mr Pratik Mishra ,G.M (HRD Dept) for his continuous guidance. I am grateful to Mr Shant Kumar, Manager(SMS-2) for his continuous guidance. I am greatly indebted to Mr. Ravikiran, Jr Manager (SMS-2) for supervising and guidance me throughout the work. I express my gratitude to our H.O.D Dr. B Kotturshettar, (Mech dept) KLE Tech University, for providing us an opportunity to do the project work with his valuable support.
ROHIT PAL
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Abstract Sulphur is normally regarded as an impurity and has an adverse impact properties when a steel is high Sulphur. Sulphur improves the machinability but lower transverse ductility and notched impact thoroughness and has little effect on the longitudinal mechanical effect. One of the most unwanted element in this respect is Sulphur as it forms sulphide inclusion and hot shortness in finished product. To achieve high productivity of hot metal desulphurization and also to meet the increasing demands for lower Sulphur steel grades the mechanical stirring KR process was introduced. But excess reagent consumption in De-S it affects the cost of production. This project evaluates different factor responsible for reagent consumption and analyses these factors for finding root causes. Sulphur is normally regarded as an impurity and has an adverse impact properties when a steel is high Sulphur. Sulphur improves the machinability but lower transverse ductility and notched impact thoroughness and has little effect on the longitudinal mechanical effect. One of the most unwanted element in this respect is Sulphur as it forms sulphide inclusion and hot shortness in finished product. Huge demand for automobile grades, interstitial free and electrical grade of steel, these grades of steel consisting low percentage of Sulphur (20–50ppm). A large number of techniques have been developed world wide over the year for desulphurization of hot metal. Hot metal desulphurization was found to be most economic in most of the process routes. In JSW steel limited adapted the two different technologies. i.e. pneumatic (injection process) and mechanical stirring (Kanbara reactor) process.
AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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JSW STEEL LIMITED – AN OVERVIEW Introduction : A multi-billion-dollar conglomerate, JSW Group is a part of O.P. Jindal Group and played a key role in India's growth story. Ranked among India's top business houses, JSW innovative and sustainable forays into the core sectors of Steel, Energy, Cement and Infrastructure are helping build a new nation. The Group continues to strive for excellence with its strengths, differentiated product mix, state of the art technology, excellence in execution and focus on sustainability. The flagship company of JSW Group - JSW Steel, is India’s leading primary and integrated steel producer. It has a production capacity of 18 MTPA with plant located across six locations in South and West India, namely, Karnataka, Tamil Nadu and Maharashtra.
• Specification… • Boasts of a capacity of a whopping 18 million tonnes per annum (MTPA). • Houses India’s widest hot strip mill and one of India’s largest blast furnaces. • Produces 800+ tonnes per person per annum, making it the most productive steel plant in India. • Recognised for its ‘zero-effluent discharge’ status; reuses more than 95 per cent of process waste. • Has a low carbon footprint, with 96% of coke oven gas for power generation being recycled. • Uses Corex technology for hot metal production. • Employs a large-scale, low-grade iron ore beneficiation process AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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• Uses pelletisation based on dry and wet process. • Is the only plant with a combination of both non-recovery and recovery type of coke ovens. • Is the only plant in India with pair-cross technology and twin-stand reversible cold-rolling mill. • Uses sophisticated ambient air control infrastructure beyond and has reduced gas flaring.
History : In 1994, Jindal Vijayanagar Steel (JVSL) was set up with its plant located at Toranagallu in the Bellary - Hospet area in the State of Karnataka, the heart of the high-grade iron ore belt and spread over 10,000 acres (40 km2) of land. Over a decade. It also set up a plant at Salem with an annual capacity of 1 million tonne. It is on the threshold of a major expansion plan of adding 3.2 million tons per annum to its at Vijayanagar Plant to achieve 11 MTPA by 2011. It has established a strong presence in the global value-added steel segment with the acquisition of a steel mill in US and a Service Center in United Kingdom. JSW Steel has also formed a joint venture for setting up a steel plant in Georgia. The Company has further acquired iron ore mines in Chile and coal mines in USA & Mozambique. The current manufacturing capacity of company is 18 MTPA. In Aug 2014, it acquired Welspun Maxsteel Ltd in a deal valued at around 1,000 Crores. JSW has already acquired 3 MTPA Hot Rolling Plant in Dolvi Maharashtra (earlier named Ispat Industries Ltd).
AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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Milestones • 4.8 MTPA
2007
• 1.6 MTPA
2002
• Acquasition of 49.3% stake in Ispat
:
2008 • Iron ore mines acquired in Chile
2004 •Acquired Southern Iron and Steel
2012
• 7.8 MTPA
• JSW-JFE stretegic partnership 2.5 MTPA • 3.5 MTPA of HSM2 • Coal minning consession in US
2009
•2.5 MTPA •Colour Coated Line •Acquired EURO IKON
2006 • 3.8 MTPA
2005
• 4.3 MTPA • Post Ispat merger
• HSM capacity expansion to 5 MTPA
2011
2010
2013
AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
2014 • New CRM phase-1 • 4 MTPA pallet plant • 1 MTPA coke oven plant • Acquired 50% stake in Vallabh Tinplate • Acquired Welpsun Maxsteel
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• New CRM2- Phase 2 • 0.2 MTPA Electrical steel mill
2016 • 18 MTPA • Won Moitra coal mine in Jharkhand
• 74% stake in Paraxair's the industrial gases joint venture • Won 5 iron ore mines in Karnataka (111 millon tonnes estimated resource
2015
2017
Input :
Raw Material 1. 2. 3. 4.
Iron Ore, Fe2O3, Fe3O4 Limestone Dolomite Quartzite
5.Manganese ore 6.Coal 7. Water
Energy 1. Electricity 2. Corex Gas 3. LD Gas
4. BF Gas 5.Mixed Gas
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Flow Chart of Plant :
Raw Material Handling System
Ore Benificiation Plant
Iron Ore Lumps
Iron Ore Fines
Sinter Plant
Coal Lumps
Pellet Plant
Sinter
Coke Oven
Pellet
Flux Air
Coke
Blast Furnace Hot Metal
Coal Fines
Pulverised Coal
Send in BF For Ignition
Slag Slag Granulation Plant
Steel Melting Shop
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Continuos Casting Machine
Slab Hot Strip Mill
Billet Bar Rod Mill
Wire Rod Mill
Cold Rolling Mill
Annealed Sheet
Galvanised Sheet
TMT Bar
AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
Wire
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DEPARTMENTS OF JSW STEEL LIMITED Raw Material Handling System : In the RMHS the all raw material is hold for some time as per its requirement. All the raw material like Iron ore lump and fines, Pellet, Limestone, Dolomite, Quartzite, Manganese ore, Coal, etc. is bring by means of transport (Vehicles, Trains) and directly dumped in RMHS. Major units: 2 wagon tippler, 3 stacker cum reclaimer, 1 barrel reclaimer. Salient technical feature: Approximately 17 km long Conveyor System.
Ore Beneficiation Plant : In OBP the concentrate making of raw material is taking place. By Crushing, Grinding method the Fe content in Iron ore is increases, C content in Coal is Increases. And also lumps and Fines are separated. Iron ore lumps are send in sintering plant for making the sinter which is required in blast furnace. Iron ore fines are send in pellet plant for making the pellet. Coal lumps is send in coke oven for making the coke and coal fines is known as pulverised coal which is send in blast furnace for ignition at the tuyers. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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Sinter Plant : ▪ Sintering is an agglomeration process which produces strong and porous lumps from a powdered uncompacted mass of iron ore with the application of heat to the stage of incipient fusion. ▪ Necessary heat is supplied by the combustion of coke breeze. ▪ The process is performed on a travelling grate on which 500-600 mm thick sinter mix consisting of iron ore, flux, coke breeze and industrial wastesn along with moisture are fed continuously. The complete combustion of coke breeze, initiated in the top layer produces a temperature of 1200-1300°C and is maintained continuously by sucking air through the bed. ▪ The suction of air makes the combustion zone travel through the bed raising its temperature layer by layer to sintering temperature. ▪ Process completes when combustion zone reaches to the lowest layer of the bed. ▪ Sinter cake is tipped from the grate in hot condition, broken, screened and cooled to produce desired fraction.
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Pellet Plant : Palletisation is the technological process designed to transform fines into 8 to 16 mm size balls with the help of balling disc or balling drum. Three stages of palletisation process :1. Raw material preparation. 2. Formation of green balls. 3. Induration of green balls.
Coke Oven : The coke making process involves carbonization of coal to high temperatures (1300°C) in an oxygen deficient atmosphere in order to concentrate the carbon. The commercial coke making process can be broken down into two categories: a) Recovery Coke making and b) Non-Recovery Coke making.
Blast Furnace : The purpose of a blast furnace is to chemically reduce and physically convert iron oxides into liquid iron called "hot metal". The blast furnace is a huge, steel stack lined with refractory brick, where iron ore, coke and limestone are dumped into the top and preheated air is blown into the bottom. The raw materials require 6 to 8 hours to descend to the bottom of
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the furnace where they become the final product of liquid slag and liquid iron. These liquid products are drained from the furnace at regular intervals. The hot air that was blown into the bottom of the furnace ascends to the top in 6 to 8 seconds after going through numerous chemical reactions. Once a blast furnace is started it will continuously run for four to ten years with only short stops to perform planned maintenance.
Steel Melting Shop : In SMS input is the Output of blast furnace i.e hot metal. First hot is came by torpedo ladle and poured in hot metal ladle. Then this first operated in hot metal desulphurisation plant and in kanbara reactor. Here removal of sulphur is taking place and then it send in LD Converter for removal of another impurity like Carbon, Silicon, Manganese, Phosphorous. Here oxidation process is taking place and hot metal fully converted in steel. Upto here the primary steel making process is taking place. After this liquid steel send in ladle heating furnace where alloy addition is taking place and improving temperature. Then it send in RH department where interstitial free steel is produced by vacuum degassing method. Then after this liquid steel is send in continuous casting plant.
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Continuous Casting Plant : In CCM the liquid steel after RH and LHF process is bring by steel ladle and put on turret. After this liquid steel is poured in tundish which is act as a small reservoir and from tundish it is poured in mould. Mould shape is two type firs slab shape and second billet shape. Mould is water cooled and after this solidification is taking place. The semi solid product is passed through rollers and finally cut by torch cutting machine. The products is slab and billet.
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Hot Strip Mill : In HSM the slab is first heated in reheating furnace above recrystallisation temperature of slab. And this passes through high power reducing roller and water is spraying for cooling. Then after this rolled sheet is successively reduced by different roller into thin thickness and make a coil and stored in yard. After this is directly send to CRM or to customer it depend upon requirement.
Cold Roll Mill : After the HSM coil rolled sheet is input of CRM. Here the coil rolled is again rolled to decrease there thickness. First it passes through flattener and after this shear cutter machine. Sheet is flattened; tail and head end is cut properly. Then it passes through pickling line where HCl acid is spraying on it to remove the entire oxide layer. Then after it passes through tandem cold roll mill where decrease in thickness takes place. Then this passes through annealing line where annealing takes place. In which mechanical property is improved. Then after the galvanising was required so it passed through galvanising line where molten zinc bath is present. After this it packed and ready for dispatch. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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Bar Rod Mill : Billet is the input of BRM. Here billet is rolled and converted into TMT Bar. First billet is heated in the reheating furnace up to above its recrystallization temperature and passed through horizontal oval shape roller. After this it just passes through the vertical round roller. Again it passes through successively decreasing set round roller. In last it passes through final round roller which having negative impression inside it. So, finally rough surface bar is formed.
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Wire Rod Mill : Billet is the also input of WRM. Here billet is rolled and converted into wire. First billet is heated in the reheating furnace up to above its recrystallization temperature and passed through horizontal oval shape roller. After this it just passes through the vertical round roller. Again it passes through successively decreasing set round roller. In last it passes through final round roller which groove diameter is less than 5 mm. At last wire is formed and made it in coil form. These all above products sells as per customer requirement.
FINISHED PRODUCTS AND ITS APPLICATIONS 1. Annealed Sheet : This type of steel sheet metal is mostly utilized in automobile and manufacturing industries for body and panel applications. This steel can be used in forming process and can also be utilized in a drawing process which transforms the shape of quadrilateral sheet to a beneficial 3D shape.
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2. Galvanized Sheet:
• To make the galvanized pipes and galvanized wire. • The body parts of trucks, cars and buses. • It is used in high tension electrical towers, protective gears, and highway signs. • Galvanized metal has found its way into several household appliances, such as washing machines, air conditioning • Uses at in corrosive environment like as sewage, pipelines, fuel storage tank.
3. TMT Bar • Bridges • Dams • High-Rise Apartments • Industrial Structure • Fly Overs 4. Wire • • • • •
Machine tools are made from wire rod To make the wire ropes To make the ball of bearing. Uses in the Cosmetics parts To make the rings and use in the building pillars
5. Semi Finished Product: 1. 2. 3. 4.
Slab Billet Hot Rolled Sheet Cold rolled Sheet
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STEEL MELTING SHOP - 2 – OVERVIEW Introduction: In steel making shop, molten iron from iron making unit i.e. blast furnace and scrap and direct reduced iron (DRI) is refined to obtain the desired chemistry of final product known as steel. The output of blast furnace is the hot metal which is main input of SMS II. In this department the steel is produced from hot metal by adding other material like flux, coolant, etc. It consist several units inside it like Hot Metal Desulphurization plant (HMDS), Kanbara Reactor(KR), Ladle preparation Bay(LP Bay), Refractory Engineering Department Pit (RED Pit), LD Converter, Ladle heating Furnace(LHF), Ruhrstahl Heraeus (RH) Deggaser, Continuous Casting Plant (CCP). In SMS II Basically all the impurity is removed by reduction and oxidation process. R is removed by reduction process in HMDS. Carbon, Silicon, Manganese, Phosphorous are removed in LD Converter by oxidation process. After this steel is taken from LD Converter and send in LHF for alloy addition and temperature maintenance. Here Aluminium, Niobium, Tungesten, Chromium, Ferro alloy material is added for production of different grade steel. Steel making having two process • Primary steel making: All the impurities are removed by primary steel making process by the help of LD Converter. The oxidation process is taken place in this process. • Secondary steel making: In this process the high quality grades steel are produced which is depending upon steel application. Here LHF and RH Process is coming, means here some alloying addition and refining of liquid steel takes place. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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After this liquid steel send to CCM unit where casting is takes place. Slab and Billet is the output of steel melting shop.
Process : HOT METAL PRETREATMENT
PRIMARY STEEL MAKING
SECONDARY STEEL MAKING
CONTINUOUS CASTING
Desulphurization Desulphurization is a process to removing the Sulphur from hot metal to desired level. Worldwide a whole range of methods for hot metal desulfurization exists, however three methods are currently used on a larger commercial scale. The Kanbara Reactor (KR) process, with lime as a reagent, the Magnesium mono-injection process (MMI), with magnesium as reagent and the co-injection process, using magnesium and lime or calcium carbide (sometimes all three of them) as reagents.
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Fig1. Kanbara reactor
Fig2. Co-injection
Fig3.Mono injection
Flow Chart of SMS II : HOT METAL FLUX
SCARP
COOLANTS
ARGON HMDS
KR
LD CONVERTER
OXYGEN
AL WIRE
STEEL LADDLE
NITROGEN
FERRO ALLOYS
LHF RH CCP AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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HOT METAL PRETREATMENT 1. Hot Metal Desulphurization System (Injection System): The Hot Metal is the input of HMDS. The hot metal containing the impurities like carbon, silicon, manganese, phosphorous, sulphur. But only sulphur is able to remove here because sulphur is removed by only reduction process. So that condition for removal of sulphur is maintained in HMDS. Condition for removal of sulphur :• High Temperature. • Basicity. • Reducing atmosphere required. This condition is maintained in HMDS so that sulphur is removed and send it to LD Converter for removal of other impurities.
Process • The hot metal is first poured in ladle which has capacity upto 180 ton and after this water cooled copper lance is inserted in bath and nitrogen gas is passed through the lance. Also magnesium and calcium carbide powder spraying with nitrogen gas. • It spraying in powder form because in powder form better reaction is taking place with great surface area contact. Magnesium is helping in that way the magnesium melting point is low and temperature is high upto 1350oC so it is melted and make bond between sulphur and calcium in fusive state. • So finally calcium sulphide is form and goes in top layer as a slag the time taken by process is 18 min and after this slag raking is takes place to remove the slag. Slag raking takes 10 –15 min time.
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General Reaction are FeS + CaC2= CaS (slag) + Fe Input chemistry and temperature of Hot metal before HMDS is C- 4.66%, Si- 0.58%, Mn – 0.35%, P – 0.12% , S –0.045% , Temp 1350oC Output chemistry and temperature of Hot metal after HMDS is C - 4.66%, Si - 0.58%, Mn – 0.35%, P – 0.12%, S – 0.002%, Temp 1320oC When the output chemistry is achieved then the desulphurized hot metal is send to LD Converter.
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MOVABLE KANBARA REACTOR Literature survey KR (Kanbara reactor) is hot metal pre-treatment system for desulphurization process, it was developed in Japan by Nippon Steel in 1963.Learning from this Japanese technique as a cost-effective process JSW steel took initiative and installed the first reactor of such kind in India.KR process in which reaction takes place by addition of reagents and mixing through mechanical stirring refractory impeller. In the KR process, lime is used as the main reagent. Sometimes also calcium fluoride (CaF2, about 10%) and/or aluminium oxide (Al2O3) are mixed with the lime. The reagent is usually added from the top [1]. lime is used more efficiently in the KR process, lime is cheap and easily available from lime plant. As compared to Injection system it is very simple process, further the treatment time is very short. The project lays emphasis on the desulphurization reagent consumption and analysing KR equipment of the JSW Steel limited, in order to propose a more comprehensive and reasonable optimization measures for KR desulphurization.
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Since the final Sulphur achievement at KR is consistently. Very less as compared to injection process, this process is very cheap as far as reagent consumption is concerned. Apart from that it equipped with less automation unlike injection equipment’s, valves, lance handling and sophisticated logics. As far as safety is concern lime is also non-hazardous and safe to keep, since calcium carbide requires more stringent monitoring system for moisture control. The effect of hot metal desulphurization factor in KR method it consists of hot metal temperature, desulphurization agent unit consumption, initial Sulphur content in hot metal, stirring time. Desulphurization efficiency increases with hot metal temperature and increase with desulphurization agent unit consumption and stirring time.
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Basic Data For KR plant
Type of Process : No. of units: Hot metal Capacity: Hot metal ladle free board: Required annual treatment amount: Actual annual treatment capacity:
Annual time: Maintenance time: Impeller exchange time: Impeller exchange annual time: Annual operation time: No. of annual heats: No. of daily heats (annual average):
KR desulfurization process 1 Unit 195 ton/heat 900 mm (@120 rpm) 9000 ton/day 2.9 million ton/day 8,760 hours/year 312 hours/ year 4 hours /once 352 hours /year 8096 hours/ year (8760-312-352) 17600 heats/ year 48 heats/day( 17600/365)
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Hot Metal Composition at KR station
Treatment condition of Desulfurizing is Indicated below.
KR Process In JSW Steel JSW steel has started mechanical stirring desulphurization process in hot metal ladle to reduce operation cost, to achieve high productivity of hot metal desulphurization, and also to meet the increasing demands for low S steel grades. It is well known that desulfurization process depends on the combination
of
thermodynamic
and
AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
kinetic
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Thermodynamic considerations include the type, composition and relative amount of desulfurizing agent, initial temperature of treatment, mass and composition of pig iron. Kinetic conditions depend on the distribution of the particle size of the desulfurizing agent, intensity of agitation of the bath as determined by rotational speed of the reactor, physicochemical properties of the involved phases such as viscosity, besides duration of the pretreatment. In the pretreatment process in Kanbara Reactor (KR), besides the initial temperature, mass and composition of pig iron, composition and mass of the carry over slag from blast furnace composition also influence the desulfurization process. Physicochemical properties of slag and metal and relative amount of the desulfurizing agent and design of the mechanical agitator, determine the energy consumption and efficiency of the process. There are important factors such as variation of velocity field radially and axially due to rotational speeds of impeller which determine the particle metal interaction and homogenization of circulating metal. The circulating metal promotes shear force with refractory walls and this friction will determine the refractory wear. The energy consumption depends on all these factors. Operational parameters, such as: immersion depth of the impeller and its positioning, level of liquid metal also affects the desulfurization process. Hence any model that would be applicable to describe desulfurization should consider these characteristics and specific parameters of the industrial reactor. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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Two type of KR 1) Fixed type: One KR equipment for one KR treatment position. 2) Movable type: with recent KR desulphurization equipment, the time of each operation cycle is greatly reduced, and hot metal up to 185tons can be desulphurised at one time .
KR process in JSW steel is shown in Figure .Before the KR operation, slag raking is operated for the better efficiency of desulphurization. In the KR process, burnt lime based reagent is added to hot metal with high speed of impeller rotation to reduce [S] content down to the target value. After KR operation, slag raking is operated again in order to prevent [S] pick up in BOF process and hot metal is charged to BOF AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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.
Figure2: KR process in JSW steel
Basic Operation Flow & Time of KR-2 1. Torpedo (380 ton) which comes from the blast furnace pours the hot metal into ladle in pouring Building
2. Lifting ladle from pouring building and transferring into ladle lifting car AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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3. Ladle(capacity 180ton) transferring to KR treatment position
4. Sampling and temperature measuring before KR treatment 5. KR Treatment done for 12 min by rotating the impeller at 120 rpm and adding desulfurizing agent ( CaO & CaF2) AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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6. Ladle tilting to slag skimming position and skimmer removes the slag by tilting the ladle
7. Sampling and temperature measuring after KR treatment
8. Ladle transferring to ladle transfer car and transferring to BOF building for further charging process
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Total time for KR process of each ladle =36.4 min In KR treatment, due to a strong downward metal stream initiated by rotating impeller with a high speed, desulphurization reagent particles are engulfed and dispersed deeply and uniformly into hot metal bath. During their stay in hot metal bath, hot metal [S] is reacted with CaO component and removed from hot metal as CaS. Cao + [S] = CaS + [O] (General Reaction) One of the features of KR process is re-penetration of non-reacted desulphurization reagent particles. Dispersed burnt lime particles are forced to float up to metal surface due to their low specific gravity. What have not reacted sufficiently with hot metal [S] can be trapped AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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by a strong downstream and dispersed again and again into hot metal bath. Such a cyclic behaviour of desulphurization reagent leads to high efficiency of desulphurization reaction, resulting in less desulphurization flux consumption than that in injection process. The influence of hot metal temperature on S partition ratio (Ls), which is defined as (%S) / [%S]. (%S) = [S] content in slag, [%S] = [S] content in hot metal The influence of hot metal temperature on S partition ratio is very big, that is, the higher hot metal temperature at KR process, the better desulphurization efficiency (higher S partition ratio) is obtained. Specification of De-S materials:
Characteristics
CaO (Lime) CaF2 (fluospar)
Al ash
Grain Size
0-3 mm
0-3mm
0-3mm
Bulk Density (ton/m2)
1.1
2.0
1.2
Water content(%)
0.0
0.0
0.0
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Fluorspar And Lime lime is responsible for desulfurization. The amount of CaO that can be dissolved in a slag is a function of slag composition and temperature. Once the CaO-saturation point of a slag is reached, any further addition of lime to the hot metal will only increase the viscosity of the slag and will inhibit desulfurization. The addition of fluorspar to along with lime will increase the solubility of CaO and thus give the slags greater desulfurization potential. It is this increased CaO solubility (if the lime is added) that increases the sulfide capacity of the slag, which results in improved desulfurization. The addition of CaF2 to a fully liquid slag, without adding lime will do nothing for desulfurization but drastically increase refractory wear. The component fluorspar by itself is not a good desulfurizing component. This is demonstrated in the following table that shows the optical basicity values for the most common desulphurizing components (higher basicity values are better for desulfurization).
CaF2 added with lime in KR process because 1) To increase the solubility of basic components (CaO) in the slag 2) To maintain fluidity in the slag as the slag temperatures decreases
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KR Plant Major Equipment’s 1. Ladle Tilting and Ladle transferring Car 2. Reagent storage silos 3. Travelling car ➢Hoisting and stirring equipment ➢Impeller ➢ Clamping device ➢ Dedusting Hood ➢Ant falling device ➢Upper bearing and lower bearing 4. Slag racking machine 5. Impeller exchange car 6. Refractory Unit
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1. Ladle Tilting and Ladle Transferring Car:
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2. Reagent Storage Silos and Dispenser • ➢ ➢
Total Number of silos: 7 Trucks fill the silos in the pouring station .Each truck has a capacity of 18 ton. For 1 heat=2 ton of lime and 200 kg of CaF2 is required
CaO silo CaF2 silo AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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CaO and Flurospar RAV
Bag Filter
3. Travelling Car : (Mechanical Stirring system) KR travelling car consist of the following devices: 1. Impeller hoisting and stirring device 2. Impeller 3. Dedusting hood
➢ Impeller hoisting and stirring device The stirring equipment stirs the hot metal mechanically to let the hot metal react with desulfurizing agent efficiently. The hydraulic clamping has been employed to hold the stirring equipment against the hoisting mast rails so that the vibrations get reduced and high speed stirring to be conducted. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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The hoisting equipment lowers the stirring equipment using wire ropes. It has vibration meters and detectors to monitor the vibration and tension during the treatment
Type
Mechanical stirring equipment
Hoisting equipment
1) Quantity
1 units
1 units
2) Speed
100 rpm to 150 rpm with load
Low:1.5m/min High:approx 6.5m/min
3) Motor
Power supply:690V AC,50HZ
Power supply :415V AC,50HZ
4) Gear reduction ratio
1/6.3
1/71
5) Accessories
Lubricator circulation pump, thermometer with contact
Wire ropes , Absocoders, wire tension, detectors
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➢ Impeller • The impeller is connected with
stirring shaft and bolts. The impeller has four steel blades and studs are placed into the blades and shaft to be coated with refractory castable material. • The impeller shaft is hollow shaft in the same way as the stirring shaft and the inner shaft is inserted in hollow shaft to let cool air to flow up to the end.Exhaust air is blown onto the impeller moulting bolt ,playing a role of protecting the bolts. ➢ Dedusting Hood The KR dust collection Hood is designed to control the Powder from littering to the surroundings, which occurs in operation . The Equipment reduces the gap between the hood and ladle and then decrease the littered dust amounts by installing a lifting type of skirt on the circumference of the circular hood
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4. Slag skimming Machine • The deslagging machine is located behind a slag bucket on a platform . The ladles are placed into the tilting cradle in front of slag bucket by means of crane . The deslagging machine is moved into working composition and operator can start with deslagging process. • The main components ➢ Boom ➢ Deslagging shield ➢ Turning gear ➢ Hydraulic Unit ➢ Cabin ➢ Supporting Frame
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5. Impeller exchange Car • It is intended for exchanging
the impeller whose refractory has been worn out in the KR Desulfurization unit. • The impeller exchange car can travel with two impellers, new and old ,loaded. Exchange work is carried out in an area under the KR travelling car dusting hood; it is equipped with a ground deck with ceiling to provide protection against falling skull etc.
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6. Refractory Unit Refractory unit is where the refractory material along with slags from the old impellers are removed and repaired into new impeller. During the KR treatment process the hot metal slag gets still in the propellers of the impeller The refractory material is made up of silica based material called ASC. Its is having high melting point than the hot molten metal , because of these reasons it is used in the impeller for the stirring process at a speed of 120 rpm. STEPS: • After the impeller is moved down the refractory material along with the slag is removed by DE bricking machine. • After removing the slag the anchor (made of steel material) is checked if there is any damage or bending .
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• If the is any damage in the anchor then it is again welded in the refractory casting station. • After that the skeleton mould to be fixed with the anchor for casting There are total 8 moulds for an impeller - 4 moulds of shaft - 4 moulds of propellers
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The impeller should be placed in straight position or else there will be improper casting shape which will lead to vibrations while stirring • Casting material is poured in the mixture machine with 8-7% of water with about 1-1.5 hours of time.
• After that the mixture is poured into the mould and kept for 36 hours for settling . • Then again the impeller is set for natural drying for about 36 hours. • Then it is sent for the impeller pre heat treatment at a temp of 200 degree Celcius for 40 hours
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• Then again natural drying is done for 12 hours because cracks will develop after the heat treatment so in order to decrease the crack thickness the natural drying is done.
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CRITICAL PARAMETERS OF KR PROCESS 1) Effective surface area ratio: An index of effective surface area ratio is introduced to investigate the impeller shape design. The calculation formula is as follows; Effective surface area ratio = (2w+t) x n x h / (D x H) Where w= Propeller length of impeller, t = Propeller thickness of impeller, h = Propeller height of impeller, n = Number of propellers, D = Diameter of hot metal ladle, H = Bath depth
Figure. Symbol of effective surface area ratio
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2) Impeller Design: The impeller is the critical parts and its dimension must be carefully designed depending on the target plant conditions. a) Propeller height: This value usually ranges between 700mm and 900mm, but should be finalized aiming around 0.35 of the effective surface area ratio b) Propeller thickness and propeller width: Once propeller thickness is decided, propeller width is automatically decided. Propeller thickness is designed based on the structural strength of propeller itself and castable refractory wearing rate. Usually propeller thickness is around 500 mm for 200 heats
c) Angle: This angle (α)is critical to refractory wearing of lower part of propeller which is mainly damaged in KR operation. Minimum cast able thickness is the distance between low edge of core metal and the outer surface of cast able. To be 200 heat life, this thickness is around 150 mm and the angle (α) can be calculated, for example, 40in No.2 steelmaking Shop of JSW steel limited [6]
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COMPASION BETWEEN KR AND INJECTION PROCESS
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MAJOR PROBLEMS FACED IN KR REACTOR Overheating of hydraulic power bank The KR reactor works for 24 hour of operation in very harsh condition .The optimum temperature of the Hydraulic power bank should be less than 65 degree celcius , due to continuous operation it sometime reach above 70 degree celcius which results in leakage of oil from the power bank. So there is a need for a cooling system in the power bank.
SRM Bellow leakage During the Skimming process the flange of raking machine vibrates which leads to leakage oil from the bellow
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Material discharging problem Due to its size and nature of the reagents its tendency of choking in the storage bunker, result of this for forcefully clearing or filling of hopper by using external manual resources like hammering or poking of the bunker the material slips and falls in the hopper in uncontrolled way by this hopper was overfilled, which is going to be in the ladle while material addition which is much more than the requirement, which is reagent loss physically.
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CONCLUSION KR process is the best process can be achieving the ultra-low Sulphur by using local availability of cheap raw materials. In this project excess addition of reagent is most favourable cause for reagent consumption in KR process-2.The reagent consumption controlled by small implementation. • In KR process load cell fluctuation happens due to expansion chute from RAV is touching the plate that has been provided below, so in order to change that we increase the Diameter of the plate from 130cm to 150cm to provide proper clearance • In reagent line choke can be reduce by providing additional aeration system to bottom of the silo • over filling of weigh hopper can be avoided by implement a logic interlock. • Addition of reagent with respect input Sulphur and desulphurization should be finished at one time, Avoid double (twice) De-S By above modifications, the reagent consumption from 12.083 kg of lime and 1.211 kg of fluorspar per ton of hot metal is reduced to 11.038 kg of lime and 1.072kg of fluorspar per ton of hot metal.
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REFERENCES • • • • • •
www.jsw.in Technical training Manual for SMS II, JSW Steel LTD. Wikipedia www.ispatguru.com Modern Steel Making by Dr. R. H. Tupkary & V. R. Tupkary. ]M.K. Cho et al. Hot Metal Desulfurization by CaO-SiO2-CaF2-Na2O Slag Saturated with MgO. ISIJ International. 2010. 50: 215-221. • ISIJ International, Vol. 57 (2017), No. 2,217
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Summer Training at JSW AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR SMS-II (BOF) JSW STEEL LIMITED VIJAYANAGAR
Overview Report by ROHIT PAL – USN:01FE15BME147 Under the guidance of Mr. Ravi Kiran
BACHELOR OF ENGINEERING SCHOOL OF MECHANICAL ENGINEERING KLE TECHNOLOGICAL UNIVERSITY VIDYANAGAR, HUBLI-, KARNATAKA, INDIA Duration Period: 11-June-2018 to 4-July-2018
TABLE OF CONTENT
SNo. 1 2 3 4
Topic Certificate Acknowledgement Abstract JSW Steel Limited- Overview • • • •
Page no 1 2 3 4
Introduction History Milestones Input • Flow chart of plant
5 6 7
Departments of JSW Steel Limited Finished Products and its applications Steel Melting Shop -2 :Overview • •
10 17 19
Introduction Process • Flow Chart of SMS-II
8
Hot Metal Pretreatment
22
9
MOVABLE CANBARA REACTOR
24
• • • •
Literature Survey Basic Data for KR Plant KR Process In JSW Steel Basic operation flow and time of KR-2
10
KR Plant Major Equipment Process
36
11
Critical parameters in KR process
48
12 13
Comparison Between KR And Injection Process Major Problems Faced in KR Reactor
50 51
• •
Overheating of hydraulic power bank SRM Bellow leakage • Material discharging problem
14
Conclusion
53
15
References
54
KLE Technological University School of Mechanical Engineering, Hubli
KLE TECHNOLOGICAL UNIVERSITY HUBLI (KARNATAKA)
CERTIFICATE
This is to certify that the Report entitled “AN OVERVIEW OF HOT METAL DESULPHURIZATION SYSTEM IN KANBARA REACTOR PROCESS-2” and submitted by ROHIT PAL having USN no 01FE15BME147 for the partial fulfilment of the requirements of B.Tech. (Mechanical Engineering) degree of KLE Tech University, embodies the bonafide work done by him under my supervision
Signature of the Supervisor Place: Toranagallu Date: 02/07/2018 ‘ Mr Ravi kiran Jr Manager (SMS-II) JSW steel limited, Toranagallu
Mr Shant Kumar Manger (SMS-II) JSW steel limited, Toranagallu AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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ACKNOWLEDGEMENT
The successful completion of any task would be but in complete without the mention of the people who made it possible, whose constant guidance and encouragement crown all the efforts with success. On the occasion of submission of project report, I take this opportunity to express my profound gratitude to KLE Technological University to have been kind enough to accept my proposal to carry out this work. I wish to express my sincere thanks to management of JSW steel limited for giving this opportunity to do the project in their esteemed organization. I am grateful to Mr Pratik Mishra ,G.M (HRD Dept) for his continuous guidance. I am grateful to Mr Shant Kumar, Manager(SMS-2) for his continuous guidance. I am greatly indebted to Mr. Ravikiran, Jr Manager (SMS-2) for supervising and guidance me throughout the work. I express my gratitude to our H.O.D Dr. B Kotturshettar, (Mech dept) KLE Tech University, for providing us an opportunity to do the project work with his valuable support.
ROHIT PAL
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Abstract Sulphur is normally regarded as an impurity and has an adverse impact properties when a steel is high Sulphur. Sulphur improves the machinability but lower transverse ductility and notched impact thoroughness and has little effect on the longitudinal mechanical effect. One of the most unwanted element in this respect is Sulphur as it forms sulphide inclusion and hot shortness in finished product. To achieve high productivity of hot metal desulphurization and also to meet the increasing demands for lower Sulphur steel grades the mechanical stirring KR process was introduced. But excess reagent consumption in De-S it affects the cost of production. This project evaluates different factor responsible for reagent consumption and analyses these factors for finding root causes. Sulphur is normally regarded as an impurity and has an adverse impact properties when a steel is high Sulphur. Sulphur improves the machinability but lower transverse ductility and notched impact thoroughness and has little effect on the longitudinal mechanical effect. One of the most unwanted element in this respect is Sulphur as it forms sulphide inclusion and hot shortness in finished product. Huge demand for automobile grades, interstitial free and electrical grade of steel, these grades of steel consisting low percentage of Sulphur (20–50ppm). A large number of techniques have been developed world wide over the year for desulphurization of hot metal. Hot metal desulphurization was found to be most economic in most of the process routes. In JSW steel limited adapted the two different technologies. i.e. pneumatic (injection process) and mechanical stirring (Kanbara reactor) process.
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JSW STEEL LIMITED – AN OVERVIEW Introduction : A multi-billion-dollar conglomerate, JSW Group is a part of O.P. Jindal Group and played a key role in India's growth story. Ranked among India's top business houses, JSW innovative and sustainable forays into the core sectors of Steel, Energy, Cement and Infrastructure are helping build a new nation. The Group continues to strive for excellence with its strengths, differentiated product mix, state of the art technology, excellence in execution and focus on sustainability. The flagship company of JSW Group - JSW Steel, is India’s leading primary and integrated steel producer. It has a production capacity of 18 MTPA with plant located across six locations in South and West India, namely, Karnataka, Tamil Nadu and Maharashtra.
• Specification… • Boasts of a capacity of a whopping 18 million tonnes per annum (MTPA). • Houses India’s widest hot strip mill and one of India’s largest blast furnaces. • Produces 800+ tonnes per person per annum, making it the most productive steel plant in India. • Recognised for its ‘zero-effluent discharge’ status; reuses more than 95 per cent of process waste. • Has a low carbon footprint, with 96% of coke oven gas for power generation being recycled. • Uses Corex technology for hot metal production. • Employs a large-scale, low-grade iron ore beneficiation process AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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• Uses pelletisation based on dry and wet process. • Is the only plant with a combination of both non-recovery and recovery type of coke ovens. • Is the only plant in India with pair-cross technology and twin-stand reversible cold-rolling mill. • Uses sophisticated ambient air control infrastructure beyond and has reduced gas flaring.
History : In 1994, Jindal Vijayanagar Steel (JVSL) was set up with its plant located at Toranagallu in the Bellary - Hospet area in the State of Karnataka, the heart of the high-grade iron ore belt and spread over 10,000 acres (40 km2) of land. Over a decade. It also set up a plant at Salem with an annual capacity of 1 million tonne. It is on the threshold of a major expansion plan of adding 3.2 million tons per annum to its at Vijayanagar Plant to achieve 11 MTPA by 2011. It has established a strong presence in the global value-added steel segment with the acquisition of a steel mill in US and a Service Center in United Kingdom. JSW Steel has also formed a joint venture for setting up a steel plant in Georgia. The Company has further acquired iron ore mines in Chile and coal mines in USA & Mozambique. The current manufacturing capacity of company is 18 MTPA. In Aug 2014, it acquired Welspun Maxsteel Ltd in a deal valued at around 1,000 Crores. JSW has already acquired 3 MTPA Hot Rolling Plant in Dolvi Maharashtra (earlier named Ispat Industries Ltd).
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Milestones • 4.8 MTPA
2007
• 1.6 MTPA
2002
• Acquasition of 49.3% stake in Ispat
:
2008 • Iron ore mines acquired in Chile
2004 •Acquired Southern Iron and Steel
2012
• 7.8 MTPA
• JSW-JFE stretegic partnership 2.5 MTPA • 3.5 MTPA of HSM2 • Coal minning consession in US
2009
•2.5 MTPA •Colour Coated Line •Acquired EURO IKON
2006 • 3.8 MTPA
2005
• 4.3 MTPA • Post Ispat merger
• HSM capacity expansion to 5 MTPA
2011
2010
2013
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2014 • New CRM phase-1 • 4 MTPA pallet plant • 1 MTPA coke oven plant • Acquired 50% stake in Vallabh Tinplate • Acquired Welpsun Maxsteel
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• New CRM2- Phase 2 • 0.2 MTPA Electrical steel mill
2016 • 18 MTPA • Won Moitra coal mine in Jharkhand
• 74% stake in Paraxair's the industrial gases joint venture • Won 5 iron ore mines in Karnataka (111 millon tonnes estimated resource
2015
2017
Input :
Raw Material 1. 2. 3. 4.
Iron Ore, Fe2O3, Fe3O4 Limestone Dolomite Quartzite
5.Manganese ore 6.Coal 7. Water
Energy 1. Electricity 2. Corex Gas 3. LD Gas
4. BF Gas 5.Mixed Gas
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Flow Chart of Plant :
Raw Material Handling System
Ore Benificiation Plant
Iron Ore Lumps
Iron Ore Fines
Sinter Plant
Coal Lumps
Pellet Plant
Sinter
Coke Oven
Pellet
Flux Air
Coke
Blast Furnace Hot Metal
Coal Fines
Pulverised Coal
Send in BF For Ignition
Slag Slag Granulation Plant
Steel Melting Shop
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Continuos Casting Machine
Slab Hot Strip Mill
Billet Bar Rod Mill
Wire Rod Mill
Cold Rolling Mill
Annealed Sheet
Galvanised Sheet
TMT Bar
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Wire
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DEPARTMENTS OF JSW STEEL LIMITED Raw Material Handling System : In the RMHS the all raw material is hold for some time as per its requirement. All the raw material like Iron ore lump and fines, Pellet, Limestone, Dolomite, Quartzite, Manganese ore, Coal, etc. is bring by means of transport (Vehicles, Trains) and directly dumped in RMHS. Major units: 2 wagon tippler, 3 stacker cum reclaimer, 1 barrel reclaimer. Salient technical feature: Approximately 17 km long Conveyor System.
Ore Beneficiation Plant : In OBP the concentrate making of raw material is taking place. By Crushing, Grinding method the Fe content in Iron ore is increases, C content in Coal is Increases. And also lumps and Fines are separated. Iron ore lumps are send in sintering plant for making the sinter which is required in blast furnace. Iron ore fines are send in pellet plant for making the pellet. Coal lumps is send in coke oven for making the coke and coal fines is known as pulverised coal which is send in blast furnace for ignition at the tuyers. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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Sinter Plant : ▪ Sintering is an agglomeration process which produces strong and porous lumps from a powdered uncompacted mass of iron ore with the application of heat to the stage of incipient fusion. ▪ Necessary heat is supplied by the combustion of coke breeze. ▪ The process is performed on a travelling grate on which 500-600 mm thick sinter mix consisting of iron ore, flux, coke breeze and industrial wastesn along with moisture are fed continuously. The complete combustion of coke breeze, initiated in the top layer produces a temperature of 1200-1300°C and is maintained continuously by sucking air through the bed. ▪ The suction of air makes the combustion zone travel through the bed raising its temperature layer by layer to sintering temperature. ▪ Process completes when combustion zone reaches to the lowest layer of the bed. ▪ Sinter cake is tipped from the grate in hot condition, broken, screened and cooled to produce desired fraction.
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Pellet Plant : Palletisation is the technological process designed to transform fines into 8 to 16 mm size balls with the help of balling disc or balling drum. Three stages of palletisation process :1. Raw material preparation. 2. Formation of green balls. 3. Induration of green balls.
Coke Oven : The coke making process involves carbonization of coal to high temperatures (1300°C) in an oxygen deficient atmosphere in order to concentrate the carbon. The commercial coke making process can be broken down into two categories: a) Recovery Coke making and b) Non-Recovery Coke making.
Blast Furnace : The purpose of a blast furnace is to chemically reduce and physically convert iron oxides into liquid iron called "hot metal". The blast furnace is a huge, steel stack lined with refractory brick, where iron ore, coke and limestone are dumped into the top and preheated air is blown into the bottom. The raw materials require 6 to 8 hours to descend to the bottom of
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the furnace where they become the final product of liquid slag and liquid iron. These liquid products are drained from the furnace at regular intervals. The hot air that was blown into the bottom of the furnace ascends to the top in 6 to 8 seconds after going through numerous chemical reactions. Once a blast furnace is started it will continuously run for four to ten years with only short stops to perform planned maintenance.
Steel Melting Shop : In SMS input is the Output of blast furnace i.e hot metal. First hot is came by torpedo ladle and poured in hot metal ladle. Then this first operated in hot metal desulphurisation plant and in kanbara reactor. Here removal of sulphur is taking place and then it send in LD Converter for removal of another impurity like Carbon, Silicon, Manganese, Phosphorous. Here oxidation process is taking place and hot metal fully converted in steel. Upto here the primary steel making process is taking place. After this liquid steel send in ladle heating furnace where alloy addition is taking place and improving temperature. Then it send in RH department where interstitial free steel is produced by vacuum degassing method. Then after this liquid steel is send in continuous casting plant.
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Continuous Casting Plant : In CCM the liquid steel after RH and LHF process is bring by steel ladle and put on turret. After this liquid steel is poured in tundish which is act as a small reservoir and from tundish it is poured in mould. Mould shape is two type firs slab shape and second billet shape. Mould is water cooled and after this solidification is taking place. The semi solid product is passed through rollers and finally cut by torch cutting machine. The products is slab and billet.
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Hot Strip Mill : In HSM the slab is first heated in reheating furnace above recrystallisation temperature of slab. And this passes through high power reducing roller and water is spraying for cooling. Then after this rolled sheet is successively reduced by different roller into thin thickness and make a coil and stored in yard. After this is directly send to CRM or to customer it depend upon requirement.
Cold Roll Mill : After the HSM coil rolled sheet is input of CRM. Here the coil rolled is again rolled to decrease there thickness. First it passes through flattener and after this shear cutter machine. Sheet is flattened; tail and head end is cut properly. Then it passes through pickling line where HCl acid is spraying on it to remove the entire oxide layer. Then after it passes through tandem cold roll mill where decrease in thickness takes place. Then this passes through annealing line where annealing takes place. In which mechanical property is improved. Then after the galvanising was required so it passed through galvanising line where molten zinc bath is present. After this it packed and ready for dispatch. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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Bar Rod Mill : Billet is the input of BRM. Here billet is rolled and converted into TMT Bar. First billet is heated in the reheating furnace up to above its recrystallization temperature and passed through horizontal oval shape roller. After this it just passes through the vertical round roller. Again it passes through successively decreasing set round roller. In last it passes through final round roller which having negative impression inside it. So, finally rough surface bar is formed.
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Wire Rod Mill : Billet is the also input of WRM. Here billet is rolled and converted into wire. First billet is heated in the reheating furnace up to above its recrystallization temperature and passed through horizontal oval shape roller. After this it just passes through the vertical round roller. Again it passes through successively decreasing set round roller. In last it passes through final round roller which groove diameter is less than 5 mm. At last wire is formed and made it in coil form. These all above products sells as per customer requirement.
FINISHED PRODUCTS AND ITS APPLICATIONS 1. Annealed Sheet : This type of steel sheet metal is mostly utilized in automobile and manufacturing industries for body and panel applications. This steel can be used in forming process and can also be utilized in a drawing process which transforms the shape of quadrilateral sheet to a beneficial 3D shape.
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2. Galvanized Sheet:
• To make the galvanized pipes and galvanized wire. • The body parts of trucks, cars and buses. • It is used in high tension electrical towers, protective gears, and highway signs. • Galvanized metal has found its way into several household appliances, such as washing machines, air conditioning • Uses at in corrosive environment like as sewage, pipelines, fuel storage tank.
3. TMT Bar • Bridges • Dams • High-Rise Apartments • Industrial Structure • Fly Overs 4. Wire • • • • •
Machine tools are made from wire rod To make the wire ropes To make the ball of bearing. Uses in the Cosmetics parts To make the rings and use in the building pillars
5. Semi Finished Product: 1. 2. 3. 4.
Slab Billet Hot Rolled Sheet Cold rolled Sheet
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STEEL MELTING SHOP - 2 – OVERVIEW Introduction: In steel making shop, molten iron from iron making unit i.e. blast furnace and scrap and direct reduced iron (DRI) is refined to obtain the desired chemistry of final product known as steel. The output of blast furnace is the hot metal which is main input of SMS II. In this department the steel is produced from hot metal by adding other material like flux, coolant, etc. It consist several units inside it like Hot Metal Desulphurization plant (HMDS), Kanbara Reactor(KR), Ladle preparation Bay(LP Bay), Refractory Engineering Department Pit (RED Pit), LD Converter, Ladle heating Furnace(LHF), Ruhrstahl Heraeus (RH) Deggaser, Continuous Casting Plant (CCP). In SMS II Basically all the impurity is removed by reduction and oxidation process. R is removed by reduction process in HMDS. Carbon, Silicon, Manganese, Phosphorous are removed in LD Converter by oxidation process. After this steel is taken from LD Converter and send in LHF for alloy addition and temperature maintenance. Here Aluminium, Niobium, Tungesten, Chromium, Ferro alloy material is added for production of different grade steel. Steel making having two process • Primary steel making: All the impurities are removed by primary steel making process by the help of LD Converter. The oxidation process is taken place in this process. • Secondary steel making: In this process the high quality grades steel are produced which is depending upon steel application. Here LHF and RH Process is coming, means here some alloying addition and refining of liquid steel takes place. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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After this liquid steel send to CCM unit where casting is takes place. Slab and Billet is the output of steel melting shop.
Process : HOT METAL PRETREATMENT
PRIMARY STEEL MAKING
SECONDARY STEEL MAKING
CONTINUOUS CASTING
Desulphurization Desulphurization is a process to removing the Sulphur from hot metal to desired level. Worldwide a whole range of methods for hot metal desulfurization exists, however three methods are currently used on a larger commercial scale. The Kanbara Reactor (KR) process, with lime as a reagent, the Magnesium mono-injection process (MMI), with magnesium as reagent and the co-injection process, using magnesium and lime or calcium carbide (sometimes all three of them) as reagents.
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Fig1. Kanbara reactor
Fig2. Co-injection
Fig3.Mono injection
Flow Chart of SMS II : HOT METAL FLUX
SCARP
COOLANTS
ARGON HMDS
KR
LD CONVERTER
OXYGEN
AL WIRE
STEEL LADDLE
NITROGEN
FERRO ALLOYS
LHF RH CCP AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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HOT METAL PRETREATMENT 1. Hot Metal Desulphurization System (Injection System): The Hot Metal is the input of HMDS. The hot metal containing the impurities like carbon, silicon, manganese, phosphorous, sulphur. But only sulphur is able to remove here because sulphur is removed by only reduction process. So that condition for removal of sulphur is maintained in HMDS. Condition for removal of sulphur :• High Temperature. • Basicity. • Reducing atmosphere required. This condition is maintained in HMDS so that sulphur is removed and send it to LD Converter for removal of other impurities.
Process • The hot metal is first poured in ladle which has capacity upto 180 ton and after this water cooled copper lance is inserted in bath and nitrogen gas is passed through the lance. Also magnesium and calcium carbide powder spraying with nitrogen gas. • It spraying in powder form because in powder form better reaction is taking place with great surface area contact. Magnesium is helping in that way the magnesium melting point is low and temperature is high upto 1350oC so it is melted and make bond between sulphur and calcium in fusive state. • So finally calcium sulphide is form and goes in top layer as a slag the time taken by process is 18 min and after this slag raking is takes place to remove the slag. Slag raking takes 10 –15 min time.
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General Reaction are FeS + CaC2= CaS (slag) + Fe Input chemistry and temperature of Hot metal before HMDS is C- 4.66%, Si- 0.58%, Mn – 0.35%, P – 0.12% , S –0.045% , Temp 1350oC Output chemistry and temperature of Hot metal after HMDS is C - 4.66%, Si - 0.58%, Mn – 0.35%, P – 0.12%, S – 0.002%, Temp 1320oC When the output chemistry is achieved then the desulphurized hot metal is send to LD Converter.
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MOVABLE KANBARA REACTOR Literature survey KR (Kanbara reactor) is hot metal pre-treatment system for desulphurization process, it was developed in Japan by Nippon Steel in 1963.Learning from this Japanese technique as a cost-effective process JSW steel took initiative and installed the first reactor of such kind in India.KR process in which reaction takes place by addition of reagents and mixing through mechanical stirring refractory impeller. In the KR process, lime is used as the main reagent. Sometimes also calcium fluoride (CaF2, about 10%) and/or aluminium oxide (Al2O3) are mixed with the lime. The reagent is usually added from the top [1]. lime is used more efficiently in the KR process, lime is cheap and easily available from lime plant. As compared to Injection system it is very simple process, further the treatment time is very short. The project lays emphasis on the desulphurization reagent consumption and analysing KR equipment of the JSW Steel limited, in order to propose a more comprehensive and reasonable optimization measures for KR desulphurization.
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Since the final Sulphur achievement at KR is consistently. Very less as compared to injection process, this process is very cheap as far as reagent consumption is concerned. Apart from that it equipped with less automation unlike injection equipment’s, valves, lance handling and sophisticated logics. As far as safety is concern lime is also non-hazardous and safe to keep, since calcium carbide requires more stringent monitoring system for moisture control. The effect of hot metal desulphurization factor in KR method it consists of hot metal temperature, desulphurization agent unit consumption, initial Sulphur content in hot metal, stirring time. Desulphurization efficiency increases with hot metal temperature and increase with desulphurization agent unit consumption and stirring time.
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Basic Data For KR plant
Type of Process : No. of units: Hot metal Capacity: Hot metal ladle free board: Required annual treatment amount: Actual annual treatment capacity:
Annual time: Maintenance time: Impeller exchange time: Impeller exchange annual time: Annual operation time: No. of annual heats: No. of daily heats (annual average):
KR desulfurization process 1 Unit 195 ton/heat 900 mm (@120 rpm) 9000 ton/day 2.9 million ton/day 8,760 hours/year 312 hours/ year 4 hours /once 352 hours /year 8096 hours/ year (8760-312-352) 17600 heats/ year 48 heats/day( 17600/365)
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Hot Metal Composition at KR station
Treatment condition of Desulfurizing is Indicated below.
KR Process In JSW Steel JSW steel has started mechanical stirring desulphurization process in hot metal ladle to reduce operation cost, to achieve high productivity of hot metal desulphurization, and also to meet the increasing demands for low S steel grades. It is well known that desulfurization process depends on the combination
of
thermodynamic
and
AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
kinetic
parameters. Page 27
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Thermodynamic considerations include the type, composition and relative amount of desulfurizing agent, initial temperature of treatment, mass and composition of pig iron. Kinetic conditions depend on the distribution of the particle size of the desulfurizing agent, intensity of agitation of the bath as determined by rotational speed of the reactor, physicochemical properties of the involved phases such as viscosity, besides duration of the pretreatment. In the pretreatment process in Kanbara Reactor (KR), besides the initial temperature, mass and composition of pig iron, composition and mass of the carry over slag from blast furnace composition also influence the desulfurization process. Physicochemical properties of slag and metal and relative amount of the desulfurizing agent and design of the mechanical agitator, determine the energy consumption and efficiency of the process. There are important factors such as variation of velocity field radially and axially due to rotational speeds of impeller which determine the particle metal interaction and homogenization of circulating metal. The circulating metal promotes shear force with refractory walls and this friction will determine the refractory wear. The energy consumption depends on all these factors. Operational parameters, such as: immersion depth of the impeller and its positioning, level of liquid metal also affects the desulfurization process. Hence any model that would be applicable to describe desulfurization should consider these characteristics and specific parameters of the industrial reactor. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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Two type of KR 1) Fixed type: One KR equipment for one KR treatment position. 2) Movable type: with recent KR desulphurization equipment, the time of each operation cycle is greatly reduced, and hot metal up to 185tons can be desulphurised at one time .
KR process in JSW steel is shown in Figure .Before the KR operation, slag raking is operated for the better efficiency of desulphurization. In the KR process, burnt lime based reagent is added to hot metal with high speed of impeller rotation to reduce [S] content down to the target value. After KR operation, slag raking is operated again in order to prevent [S] pick up in BOF process and hot metal is charged to BOF AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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KLE Technological University School of Mechanical Engineering, Hubli
.
Figure2: KR process in JSW steel
Basic Operation Flow & Time of KR-2 1. Torpedo (380 ton) which comes from the blast furnace pours the hot metal into ladle in pouring Building
2. Lifting ladle from pouring building and transferring into ladle lifting car AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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3. Ladle(capacity 180ton) transferring to KR treatment position
4. Sampling and temperature measuring before KR treatment 5. KR Treatment done for 12 min by rotating the impeller at 120 rpm and adding desulfurizing agent ( CaO & CaF2) AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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6. Ladle tilting to slag skimming position and skimmer removes the slag by tilting the ladle
7. Sampling and temperature measuring after KR treatment
8. Ladle transferring to ladle transfer car and transferring to BOF building for further charging process
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Total time for KR process of each ladle =36.4 min In KR treatment, due to a strong downward metal stream initiated by rotating impeller with a high speed, desulphurization reagent particles are engulfed and dispersed deeply and uniformly into hot metal bath. During their stay in hot metal bath, hot metal [S] is reacted with CaO component and removed from hot metal as CaS. Cao + [S] = CaS + [O] (General Reaction) One of the features of KR process is re-penetration of non-reacted desulphurization reagent particles. Dispersed burnt lime particles are forced to float up to metal surface due to their low specific gravity. What have not reacted sufficiently with hot metal [S] can be trapped AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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by a strong downstream and dispersed again and again into hot metal bath. Such a cyclic behaviour of desulphurization reagent leads to high efficiency of desulphurization reaction, resulting in less desulphurization flux consumption than that in injection process. The influence of hot metal temperature on S partition ratio (Ls), which is defined as (%S) / [%S]. (%S) = [S] content in slag, [%S] = [S] content in hot metal The influence of hot metal temperature on S partition ratio is very big, that is, the higher hot metal temperature at KR process, the better desulphurization efficiency (higher S partition ratio) is obtained. Specification of De-S materials:
Characteristics
CaO (Lime) CaF2 (fluospar)
Al ash
Grain Size
0-3 mm
0-3mm
0-3mm
Bulk Density (ton/m2)
1.1
2.0
1.2
Water content(%)
0.0
0.0
0.0
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Fluorspar And Lime lime is responsible for desulfurization. The amount of CaO that can be dissolved in a slag is a function of slag composition and temperature. Once the CaO-saturation point of a slag is reached, any further addition of lime to the hot metal will only increase the viscosity of the slag and will inhibit desulfurization. The addition of fluorspar to along with lime will increase the solubility of CaO and thus give the slags greater desulfurization potential. It is this increased CaO solubility (if the lime is added) that increases the sulfide capacity of the slag, which results in improved desulfurization. The addition of CaF2 to a fully liquid slag, without adding lime will do nothing for desulfurization but drastically increase refractory wear. The component fluorspar by itself is not a good desulfurizing component. This is demonstrated in the following table that shows the optical basicity values for the most common desulphurizing components (higher basicity values are better for desulfurization).
CaF2 added with lime in KR process because 1) To increase the solubility of basic components (CaO) in the slag 2) To maintain fluidity in the slag as the slag temperatures decreases
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KR Plant Major Equipment’s 1. Ladle Tilting and Ladle transferring Car 2. Reagent storage silos 3. Travelling car ➢Hoisting and stirring equipment ➢Impeller ➢ Clamping device ➢ Dedusting Hood ➢Ant falling device ➢Upper bearing and lower bearing 4. Slag racking machine 5. Impeller exchange car 6. Refractory Unit
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1. Ladle Tilting and Ladle Transferring Car:
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2. Reagent Storage Silos and Dispenser • ➢ ➢
Total Number of silos: 7 Trucks fill the silos in the pouring station .Each truck has a capacity of 18 ton. For 1 heat=2 ton of lime and 200 kg of CaF2 is required
CaO silo CaF2 silo AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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CaO and Flurospar RAV
Bag Filter
3. Travelling Car : (Mechanical Stirring system) KR travelling car consist of the following devices: 1. Impeller hoisting and stirring device 2. Impeller 3. Dedusting hood
➢ Impeller hoisting and stirring device The stirring equipment stirs the hot metal mechanically to let the hot metal react with desulfurizing agent efficiently. The hydraulic clamping has been employed to hold the stirring equipment against the hoisting mast rails so that the vibrations get reduced and high speed stirring to be conducted. AN OVERVIEW OF HOT METAL DESULPHURIZATION PROCESS IN MOVABLE KANBARA REACTOR
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The hoisting equipment lowers the stirring equipment using wire ropes. It has vibration meters and detectors to monitor the vibration and tension during the treatment
Type
Mechanical stirring equipment
Hoisting equipment
1) Quantity
1 units
1 units
2) Speed
100 rpm to 150 rpm with load
Low:1.5m/min High:approx 6.5m/min
3) Motor
Power supply:690V AC,50HZ
Power supply :415V AC,50HZ
4) Gear reduction ratio
1/6.3
1/71
5) Accessories
Lubricator circulation pump, thermometer with contact
Wire ropes , Absocoders, wire tension, detectors
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➢ Impeller • The impeller is connected with
stirring shaft and bolts. The impeller has four steel blades and studs are placed into the blades and shaft to be coated with refractory castable material. • The impeller shaft is hollow shaft in the same way as the stirring shaft and the inner shaft is inserted in hollow shaft to let cool air to flow up to the end.Exhaust air is blown onto the impeller moulting bolt ,playing a role of protecting the bolts. ➢ Dedusting Hood The KR dust collection Hood is designed to control the Powder from littering to the surroundings, which occurs in operation . The Equipment reduces the gap between the hood and ladle and then decrease the littered dust amounts by installing a lifting type of skirt on the circumference of the circular hood
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4. Slag skimming Machine • The deslagging machine is located behind a slag bucket on a platform . The ladles are placed into the tilting cradle in front of slag bucket by means of crane . The deslagging machine is moved into working composition and operator can start with deslagging process. • The main components ➢ Boom ➢ Deslagging shield ➢ Turning gear ➢ Hydraulic Unit ➢ Cabin ➢ Supporting Frame
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5. Impeller exchange Car • It is intended for exchanging
the impeller whose refractory has been worn out in the KR Desulfurization unit. • The impeller exchange car can travel with two impellers, new and old ,loaded. Exchange work is carried out in an area under the KR travelling car dusting hood; it is equipped with a ground deck with ceiling to provide protection against falling skull etc.
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6. Refractory Unit Refractory unit is where the refractory material along with slags from the old impellers are removed and repaired into new impeller. During the KR treatment process the hot metal slag gets still in the propellers of the impeller The refractory material is made up of silica based material called ASC. Its is having high melting point than the hot molten metal , because of these reasons it is used in the impeller for the stirring process at a speed of 120 rpm. STEPS: • After the impeller is moved down the refractory material along with the slag is removed by DE bricking machine. • After removing the slag the anchor (made of steel material) is checked if there is any damage or bending .
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• If the is any damage in the anchor then it is again welded in the refractory casting station. • After that the skeleton mould to be fixed with the anchor for casting There are total 8 moulds for an impeller - 4 moulds of shaft - 4 moulds of propellers
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The impeller should be placed in straight position or else there will be improper casting shape which will lead to vibrations while stirring • Casting material is poured in the mixture machine with 8-7% of water with about 1-1.5 hours of time.
• After that the mixture is poured into the mould and kept for 36 hours for settling . • Then again the impeller is set for natural drying for about 36 hours. • Then it is sent for the impeller pre heat treatment at a temp of 200 degree Celcius for 40 hours
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• Then again natural drying is done for 12 hours because cracks will develop after the heat treatment so in order to decrease the crack thickness the natural drying is done.
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CRITICAL PARAMETERS OF KR PROCESS 1) Effective surface area ratio: An index of effective surface area ratio is introduced to investigate the impeller shape design. The calculation formula is as follows; Effective surface area ratio = (2w+t) x n x h / (D x H) Where w= Propeller length of impeller, t = Propeller thickness of impeller, h = Propeller height of impeller, n = Number of propellers, D = Diameter of hot metal ladle, H = Bath depth
Figure. Symbol of effective surface area ratio
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2) Impeller Design: The impeller is the critical parts and its dimension must be carefully designed depending on the target plant conditions. a) Propeller height: This value usually ranges between 700mm and 900mm, but should be finalized aiming around 0.35 of the effective surface area ratio b) Propeller thickness and propeller width: Once propeller thickness is decided, propeller width is automatically decided. Propeller thickness is designed based on the structural strength of propeller itself and castable refractory wearing rate. Usually propeller thickness is around 500 mm for 200 heats
c) Angle: This angle (α)is critical to refractory wearing of lower part of propeller which is mainly damaged in KR operation. Minimum cast able thickness is the distance between low edge of core metal and the outer surface of cast able. To be 200 heat life, this thickness is around 150 mm and the angle (α) can be calculated, for example, 40in No.2 steelmaking Shop of JSW steel limited [6]
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COMPASION BETWEEN KR AND INJECTION PROCESS
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MAJOR PROBLEMS FACED IN KR REACTOR Overheating of hydraulic power bank The KR reactor works for 24 hour of operation in very harsh condition .The optimum temperature of the Hydraulic power bank should be less than 65 degree celcius , due to continuous operation it sometime reach above 70 degree celcius which results in leakage of oil from the power bank. So there is a need for a cooling system in the power bank.
SRM Bellow leakage During the Skimming process the flange of raking machine vibrates which leads to leakage oil from the bellow
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Material discharging problem Due to its size and nature of the reagents its tendency of choking in the storage bunker, result of this for forcefully clearing or filling of hopper by using external manual resources like hammering or poking of the bunker the material slips and falls in the hopper in uncontrolled way by this hopper was overfilled, which is going to be in the ladle while material addition which is much more than the requirement, which is reagent loss physically.
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CONCLUSION KR process is the best process can be achieving the ultra-low Sulphur by using local availability of cheap raw materials. In this project excess addition of reagent is most favourable cause for reagent consumption in KR process-2.The reagent consumption controlled by small implementation. • In KR process load cell fluctuation happens due to expansion chute from RAV is touching the plate that has been provided below, so in order to change that we increase the Diameter of the plate from 130cm to 150cm to provide proper clearance • In reagent line choke can be reduce by providing additional aeration system to bottom of the silo • over filling of weigh hopper can be avoided by implement a logic interlock. • Addition of reagent with respect input Sulphur and desulphurization should be finished at one time, Avoid double (twice) De-S By above modifications, the reagent consumption from 12.083 kg of lime and 1.211 kg of fluorspar per ton of hot metal is reduced to 11.038 kg of lime and 1.072kg of fluorspar per ton of hot metal.
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REFERENCES • • • • • •
www.jsw.in Technical training Manual for SMS II, JSW Steel LTD. Wikipedia www.ispatguru.com Modern Steel Making by Dr. R. H. Tupkary & V. R. Tupkary. ]M.K. Cho et al. Hot Metal Desulfurization by CaO-SiO2-CaF2-Na2O Slag Saturated with MgO. ISIJ International. 2010. 50: 215-221. • ISIJ International, Vol. 57 (2017), No. 2,217
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