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Raw Material In Iron Making
 

Raw Material In Iron Making

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Dear Readers, ...

Dear Readers,
In this presentation, I have tried to explain main raw material sources of iron making process. Also, with my experience, I have tried to give a concept about the plant engineering related to raw material. I hope that, this presentation will be helpful for young engineers. With this presentation they will get a broad idea about the raw material, based on which they can study more on the subject.
Regards,
Nirjhar.

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  • Dear Readers,
    In this presentation, I have tried to explain main raw material sources of iron making process. Also, with my experience, I have tried to give a concept about the plant engineering related to raw material. I hope that, this presentation will be helpful for young engineers. With this presentation they will get a broad idea about the raw material, based on which they can study more on the subject.
    Regards,
    Nirjhar.
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    Raw Material In Iron Making Raw Material In Iron Making Presentation Transcript

    • A Nirjhar Chakravorti Presentation
      • RAW MATERIAL PLANT
      • FOR IRON MAKING
    • Nirjhar Chakravorti
      • Nirjhar, a Mechanical Engineer by profession, has completed engineering in the year 2000, from Jalpaiguri Government Engineering College, India.
      • Nirjhar has experience in design, development, project and plant engineering.
      • As an engineering professional Nirjhar has worked at different industries.
      • Nirjhar’s interest is to know different technology and process engineering.
    • Where from iron produced?
      • Raw iron is found in earth’s crust, as an ore.
      • Iron ore mostly found as Fe 2 O 3 (the form of iron oxide found as the mineral hematite ).
    • Where from iron produced?
      • At present, blast furnace is most commonly used furnace to produce iron.
      • The Blast furnace iron making process basically consists of the conversion of iron oxide to iron in liquid form . This requires reductant for reduction of iron oxide and heat for the above reduction reaction to take place. The primary source to fulfill both these requirements is carbon (in the form of coke).
    • Where from iron produced?
      • The blast furnace is a vertical counter-current heat exchanger as well as a chemical reactor in which burden material charged from the top descend downward and the gasses generated at the tuyere level ascend upward.
    • Raw Material Section in iron making
      • Broadly a raw material section in iron making plant has the following sections:
      • a. Iron Ore Handling System
      • b. Coke & Coal Handling System
      • c. Lime & Other Material Handling System
      • d. Sinter Plant
    • Flow Diagram Blast Furnace Iron Ore
    • Iron Ore Section Ore crushed & Transported from mine to plant Steel Plant Blast Furnace Iron Ore Mine Stack Yard Material Handling System
    • Iron Ore Section
      • Iron ore chunks dugs from the earth and taken to process plant.
      • Chunks are crushed to small fractions, and impurities are removed by magnetic separator or other means. The small iron fractions are formed into marble sized pellets in forming drums and discs. Then the pellets are transported to stack yard of steel plant.
    • Iron Ore Section Iron ore is collected from mines and crushed
    • Iron Ore Section Processed iron ore are dumped at stack yard Stack Yard
    • Iron Ore Section Iron ore are transported through belt conveyor Belt Conveyor
    • Iron Ore Section Material Handling System Raw Materials are Stored and transported inside steel plant and fed into Blast Furnace through material handling system
    • Flow Diagram Blast Furnace Iron Ore Coal Coke Oven Plant Coke
    • Coal & Coke Section Processed & Transported from mine to plant Steel Plant Transportation by Material Handling System Blast Furnace Coal Mine Stack Yard Coke Oven Plant Coke Stack Material Handling System
    • Coal & Coke Section
      • Coal are collected from mines. Then they are washed & crushed to pieces. After that coal is transported to stack yard of steel plant. From stack through material handling section, they are transported to coke oven section, where coal is baked and converted into coke.
    • Coal & Coke Section Coal is collected from mines
    • Coal & Coke Section Coal is processed, washed and crushed and then transported into stack yard of steel plant
    • Coal & Coke Section Processed coal is dumped at stack yard and transported to coke oven plant by material handling system
    • Coal & Coke Section: Coke Oven Plant
      • Coke is source of thermal energy inside the Blast Furnace, which burns and the converted heat melts the iron ore.
    • Coal & Coke Section: Coke Oven Plant
      • Conventional coke making is done in a coke oven battery. Inside oven battery coal is sandwiched between heating walls. They are carbonized (at a temperature around 1000 o -1100 o C) upto a certain degree of de-volatization to produce metallurgical coke of desired mechanical and thermo-chemical properties.
    • Coal & Coke Section: Coke Oven Plant Coke Stack Storage Bunker (Coal Tower) Stamp Charging Car Coke Oven Battery Quenching Car Water Sprayed Material Handling System Coke Bridge Waste Coke lump collected under ground, Crushed & Stacked Coal Pushed in Coke Pushed out Liquid Chemical Off gas used as fuel Waste Volatile Substance
    • Coal & Coke Section: Coke Oven Plant Schematic View of Coke Oven battery. Here instead of collecting coal at stamp charging car, loose coal is directly fed into the oven from top.                                                               
    • Coal & Coke Section: Coke Oven Plant
      • Stamp Charging of Coal :
      • Stamp charging involves formation of a stable coal cake with finely crushed coal (88-90% - 3mm) by mechanically stamping outside the oven and pushing the cake thus formed inside the oven for carbonisation. Coal moisture is maintained at 8-10% for the formation of cake. Due to stamping, bulk density of charge increases by 30-35% causing significant improvement of coke. Oven productivity increases by 10-12% & there is a possibility of using inferior coking coals to the extent of about 20%.
    • Coal & Coke Section: Coke Oven Plant Stamp Charging Machine: Erection Stage
    • Coal & Coke Section: Coke Oven Plant Stamped Coal cake ready for charging into the oven
    • Coal & Coke Section: Coke Oven Plant Pictorial View Pusher and Charging Car travels & stops in front of the oven, where coal cake needs to be pushed Coke Oven Oven Door Coal cake box front door Coal cake box Coal cake Charging plate Coal pusher plate Coal pusher Plate drive Coal Charging Car Pusher and Charging Car Rail
    • Coal & Coke Section: Coke Oven Plant Stamped Coal cake pushed into the oven
    • Coal & Coke Section: Coke Oven Plant Pictorial View Charging (i.e. pushing) the coal cake inside the oven Oven door in semi open condition Coal cake box Front door in Open position Quenching Car Side Stamping & Charging Car Side
    • Coal & Coke Section: Coke Oven Plant
      • Coke Oven :
      • During carbonization, coals undergo transformation into plastic state at around 350 o -400 o C, swell and then re-solidify at around 500 o -550 o C to give semi-coke and then coke. In coke ovens, after coal is charged inside the oven, plastic layers are formed adjacent to the heating walls, and gradually the plastic layers move towards the centre of oven from either side and ultimately meet each other at the centre. The quality and quantity of plastic layer is of extreme importance and it determines the inherent strength of coke matrix. For producing coke of good quality, coals should have certain degree of maturity, good properties and wide range of fluidity.
    • Coal & Coke Section: Coke Oven Plant Pictorial View Coal cake is pushed inside the oven and charging plate is pulling back Coal pusher plate holds back the coal cake inside the oven, while pulling back the charging plate
    • Coal & Coke Section: Coke Oven Plant Coke inside oven ready for push out from oven
    • Coal & Coke Section: Coke Oven Plant Hot Coke pushed out from oven
    • Coal & Coke Section: Coke Oven Plant
      • Quenching of hot coke :
      • Red hot c oke formed inside oven pushed out by pusher car, and collected on quenching car.
    • Coal & Coke Section: Coke Oven Plant Hot coke being pushed from an oven into a quench car. Quenching Car Locomotive engine of quenching car Coke collected on quenching car Coke Oven
    • Coal & Coke Section: Coke Oven Plant The Quenching car travels and placed below the quench tower. The coke is treated to high-pressure water jets to cool the coke while still in the quench car. The coke is discharged from car and crushed into pieces and stacked. Quench Tower Quenching Car with coke
    • Flow Diagram Flux Blast Furnace Iron Ore Coal Coke Oven Plant Coke
    • Flux Section Flux crushed & Transported from source to plant Steel Plant Blast Furnace Material Handling System Flux Stack Yard
    • Flux Section
      • Flux is added in the blast furnace to remove impurities, by producing slag. Lime is the most commonly used flux material. Lime may be used as a flux in the form of CaO, limestone (CaCO3), dolomite (magnesium calcium carbonate) or dolomitic lime (product obtained from burning or roasting of dolomite).
    • Flux Section
      • Lime is used as a flux in solid, particulate form and reacts with impurities in the charge to form a slag.
      • It is important that the slag be kept fluid, not only to increase its ability to scavenge impurities from molten metal, but also to permit the slag to be readily removed from the furnace.
    • Flux Section
      • Formation of slag has a adverse effect also.
      • Lime in reaction with silica or silicates present in the ore forms dicalcium silicate, which has 3800 0 C melting point. It form a coating on lime particles and prevent it from further reaction.
      • Auxiliary flux is used for the purpose of facilitating the reaction between lime and silica or silicates. Fluorspar is a example of auxiliary flux.
    • Flow Diagram Blast Furnace Iron Ore Coal Coke Oven Plant Coke Flux Sinter Fines from different sources
    • Sinter Plant Section
      • In order to enhance the productivity of blast furnaces, a high percentage of sinter charge is a prerequisite.
      • Sinter is an agglomeration of iron ore fines, coke and limestone in the form of cakes.
      • To ensure sinter burden in the blast furnaces at 75 per cent, a total of 3 million tonnes of sinter was envisaged for a production of about 2 million tonnes of hot metal.
    • Sinter Plant Section Sinter Plant
    • Sinter Plant Section Sinter Plant
    • Sinter Plant Section Simple Flow Diagram of Sinter Plant
    • Sinter Plant Section
      • The raw materials used are as follows - Iron ore fines (-10 mm), coke breeze (-3 mm), Lime stone & dolomite fines (-3mm) and other metallurgical wastes. The proportioned raw materials are mixed and moistened in a mixing drum. The mix is loaded on sinter machine through a feeder onto a moving grate (pallet) and then the mix is rolled through segregation plate so that the coarse materials settle at the bottom and fines onto the top.
    • Sinter Plant Section
      • The top surface of the mix is ignited through stationary burners at 1200 o C. As the pallet moves forward, the air is sucked through wind box situated under the grate. A high temperature combustion zone is created in the charge -bed due to combustion of solid fuel of the mix and regeneration of heat of incandescent sinter and outgoing gases. Due to forward movement of pallet , the sintering process travels vertically down. The different zones created on a sinter-bed are shown in the simple flow diagram of sinter plant.
    • Sinter Plant Section
      • Sinter is produced as a combined result of locally limited melting , grain boundary diffusion and recrystallization of iron oxides.
      • On the completion of sintering process, finished sinter cake is crushed and cooled. The cooled sinter is screened and + 6 mm fraction is dispatched to blast furnace through material handling system and -6 mm is re-circulated as return sinter.
    • Blast Furnace
      • All the raw material is charged into the blast furnace, from top, through variable throat armour or any other means.
      • The purpose of a blast furnace is to chemically reduce and physically convert iron oxides into liquid iron called "hot metal".
    • Blast Furnace
      • 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 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.
    • Blast Furnace
      • 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.
    • Blast Furnace
    • Blast Furnace
      • Thank You
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