sponge iron.pptx

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  • 7/29/2019 sponge iron.pptx


    Sponge Iron is iron ore reduced directly in solid state

    using coal gas, natrual gas or coal as reductants andis also known as Directly Reduced Iron (DRI).

    Sponge Iron

  • 7/29/2019 sponge iron.pptx


    Sponge iron is the metallic product formed by the reduction (removal ofoxygen) of iron ore at temperature below the fusion point of iron while it

    is still in solid state. It is also called direct reduced iron (DRI). Direct-reduced iron (DRI) is produced from direct reduction of iron ore (in theform of lumps, pellets or fines) by a reducing gas produced from natural gasor coal.

    The reducing gas is a mixture of majority of hydrogen (H2) and carbonmonoxide (CO). This process of directly reducing the iron ore in solid formby reducing gases is called direct reduction.A broadly used iron source is also a product known as direct reduced iron("DRI") which is produced by the solid state reduction of iron ore to highlymetalized iron without the formation of liquid iron.

    Sponge iron is the product created when iron ore is reduced to metallic

    iron, in the presence of coal, at temperatures below the melting point ofiron. The external shape of the ore is retained with 30% reduction inweight due to oxide reduction resulting in change in true density from 4.4gm/cc to 7.8 gm/cc in this product

    Sponge Iron or Direct Reduced Iron (DRI)

  • 7/29/2019 sponge iron.pptx


    Electric Arc Furnaces (EAFs) engaged in manufacturing steelstarted facing problems of availability of scrap of desiredquality.

    First DRI plant in 1957 in Mexico

    The reasons for the growth of the sponge iron industrycould be attributed to

    the advantages of using sponge iron in electric arcfurnaces, partly substituting scrap, the conventional chargeto the furnaces.

    The industry is gaining further importance due to provenutility of sponge iron in other steel manufacturing processeslike L.D. Converters, Open Hearth Furnaces (OHFs), Blast

    Furnaces (BFs) & Basic Oxygen Furnaces (BOFs), InductionFurnaces (IFs) and Cupolas.

  • 7/29/2019 sponge iron.pptx



    Use of sponge iron:

    Increases productivity through shorter tap-to-tap time and refining time.

    Simultaneous melting and refining with continuous charging.

    Faster metallurgical reactions and Improved as well as more stable power consumption

    Less electrode consumption due to stable power.

    More precise of steel compositions and quality advantages.

    High degree of metallization (up to 92%) and consistent chemical composition.

    Deep drawing steel grades can be produced in electric arc furnace (EAF).

    Flat products and alloy steels of international standards can be made in electric arcfurnace (EAF).

    Reduction in number of off-grade heats.

  • 7/29/2019 sponge iron.pptx


    The advantages of sponge iron use in EAFs are summarisedbelow:-

    Uniform known composition

    Low levels of residuals/tramp elements

    Capability to maintain phosphorous level in steel within0.002%

    Maintenance of sulphur in steel by its removal in sponge


    Low content of dissolved gases

    Uniform size and higher bulk density as compared to scrapCapability of forming protective cover of foamy slag in thebath

    Lower refining requirements of steel produced

    Potential of sensible heat recovery from waste gases

    Possibility of producing variety of steels

  • 7/29/2019 sponge iron.pptx


    There are a few disadvantages of the use of spongeiron in the arc furnaces such as

    lower liquid metal yield,

    lower metallisation,

    lower carbon content in sponge iron produced in coalbased plants, gangue content of the sponge ironresulting in additional requirement of electrical energyin its melting and higher meltdown time.

    However, an ever widening gap between thedemand and availability of scrap clearly indicates abright future for the sponge iron industry

  • 7/29/2019 sponge iron.pptx


    The substitution of scrap by sponge iron has

    some limitations depending on the furnace

    operating conditions. Only 20% to 30% ofsponge iron can be used in the furnace

    charge when feeding is done in batches. The

    proportion of sponge iron in the charge canhowever be increased to 40-50% by providing

    continuous feeding arrangements. A further

    increase in sponge proportion is possible by

    use of high power furnaces with highercapacity transformers.

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    Various technologies developed for the manufacture of spongeiron may be classified as:

    A. Gas Based TechnologiesFluidised Bed Technologies

    Technologies using hydrogen as reductant

    Technologies using carbon monoxide as reductant

    Technologies using mixture of both hydrogen and carbon monoxide as


    Static bed technologies using mixed gas as reductant

    Moving bed technologies using mixed gas as reductant

    The gas based technologies were capable of using either naturalgas associated with oil or reducing gas derived from coal.

  • 7/29/2019 sponge iron.pptx


    Gas-Based Process:

    This process utilizes natural gas as the reducing

    agent. Natural gas is reformed to enrich with H2and CO mixture and this enriched and reformed gasmixture is preheated in gas-based process. Avertical retort is used for the reduction of iron oreas against a rotary kiln in coal based sponge iron

    process. When the gases are travelling upwards thecharge moves downward by gravity. Gas-basedsponge iron is not subjected for magneticseparation, as no contamination with nonmagneticis possible either it can be cooled indirectly or

    briquetted in hot condition to get hot briquettediron (HBI)

  • 7/29/2019 sponge iron.pptx


    B. Solid Reducant or Coal Based Technologies

    This process utilizes non-coking coal as reducing agentalong with lumpy rich grade iron ore.

    Rotary kiln processes (SL/RN, DRC, and ACCAR/OSIL)

    Retort processes (Kinglor Metor)

    Rotary hearth processes (Inmetco, FASTMET

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  • 7/29/2019 sponge iron.pptx


    MidrexCoal Based Process Flowsheet

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  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx


  • 7/29/2019 sponge iron.pptx