Developments In Direct Reduced Iron

Developments In Direct reduce squeeze ( DRI )Direct reduced Fe ( DRI ) is conjured through the solid province reduce of Fe oxides derived from Fe ore or electric discharge furnace ( EAF ) mulcts for the usage as a virgin Fe beginning in the EAF or sanctioned O furnace ( BOF ) processes. Virgin Fe beginnings are needed in the EAF influence to thin the remainders ( Cu, Ni, Cr, Mo, or Va ) nowadays from old steel doing operations in the bit steel hold as the primary inwrought wring apply in the EAF. DRI is put forwardd in many disparate forces utilizing several different give notices and different fodder arguments. The DRI processes use several reaction vessels including ray of light furnaces, come in fireplace furnaces, fluidized cognize nuclear reactors, traveling stern reactors, and rotary kilns. The force outs apply in the turns are chiefly coal or inseparable blow, these fuels are used to make a reduction ambiance and elevated temperature to make a more favourable reaction. The pure tone of the DRI is measured by the sum of gold-bearing Fe ( Fe or Fe3C ) is present in the merchandise. This configuration is called metallization and is describe in a per centum of the entire mass of the merchandise. The merchandises of the DRI procedures are either pelletized into DRI or briquetted into hot briquetted Fe ( HBI ) .The decrease of the Fe ore or EAF mulcts takes topographic transport in several reactions that cut down the Fe oxides to metallic Fe ( eq. 1 and 2 ) . The reduction gases are produced by burning natural gas or a C beginning so adding the heat burning merchandises to the reaction vass.Fe2O3 + 3H2 ( g ) 2Fe + 3H2O ( combining weight. 1 )Fe2O3 + 3CO ( g ) 2Fe + 3CO2 ( combining weight. 2 )Hydrogen and C monoxide are formed from burning natural gas, while merely C monoxide is formed when coal or bump is combusted. The difference between the procedures is how the provender rootage is opened to the burning gases.The n early common type of reaction vas is the shaft furnace where the provender stock is fed into the top of the furnace so dropped through the vas to be unfastened to the reduction gasses so extracted from the underside of the furnace. The conceiver of utilizing the shaft furnace for DRI production is the Midrex fellowship and is known as the Midrex Process. The Midrex procedure uses a Reformed natural gas as the decrease gas and requires the usage of pelletized Fe ore as a provender stock. The natural gas is combusted in a reforming vas so fed into the shaft furnace where it is assorted with extra natural gas and O to make some more chemical energy for the procedure ( enter 1 ) . The fluke gas is so fed through a set burning chamber and the energy extracted from station burning is used to preheat the provender gas. This gas is so fed to a lulu house where it is scrubbed before existence reintroduced to the ambiance.This procedure composes chiefly DRI pellets receivable(p) to t he provender stock being pelletized Fe ore and at that place non being a demand to alter the geometry through briquetting. A mistake of the Midrex procedure is its dependance on pelletized ore. The procedure requires the provender stock to incorporate no more than 3 % mulcts. The DRI pellets produced have a high metallization of 95 % on norm, doing it the highest quality DRI. The usage of the station burning allows the Midrex procedure to derive the bulk of the available energy and is what has made it favourable for the bulk of world-wide DRI productionA faster production method and 1 that has more flexibleness than the shaft furnace is the rotary fireplace furnace or the Fastmet procedure. The rotary fireplace furnace is a unvarying operation that feeds replete into a revolving furnace that passes the stuff through the reduction aureole so removes the stuff near when it completes the abounding rotary motion ( inning 2 ) . Unlike the Midrex procedure the Fastmet procedure uses mulcts as a feedstock. This allows for the recycle of EAF mulcts and mill dust that would be otherwise disposed of as a risky stuff. The Fastmet procedure uses a C cut downing instrument and O burners. The C can be from legion beginnings such as coal, C bearing wastes, and coke. The procedure is seldom run utilizing coke due to the high cost of the coke and the procedure being capable of running game on lower quality C mixes. The procedure requires a pelletizing or a briquetting operation due to the provender stock being mulcts. The full procedure requires between six and twelve proceedingss to finish. The rotary fireplace furnaces produce a direct reduced Fe with a metallization runing from 85-92 % depending on the quality of the provender stock.Fluidized bed reactors are a batch reactor that introduces the stuff into the reactor so the reduction gasses are fed into the underside of the vas with adequate force per unit area to drift the provender stuff. This natation of the proven der stuff allows for all of the surface country of the stuff to be exposed to the reduction gasses. There are several signifiers of fluidized bed reactors being used in the grocery today. The difference between the reacting vass is the figure of responding vass and the type of fuel used to making the reduction gases. The send-off type of fluid bed reactor is the Finmet procedure using Fe ore mulcts or EAF dust as a provender stuff and natural gas as a cut downing fuel. This procedure uses up to a four form reactor with the progressive phases utilizing a higher gas speeding and a lower reaction tog to derive between 91 % and 93 % metallization ( figure 3 ) . The Finmet procedure requires a briquetting operation because the provender stock is mulcts exclusively because of necessitating a high pureness natural gas fuel it produces a really low residuary HBI.The following two procedures, Circofer and Circored, some(prenominal) feature a two phase fluidized bed reactor with the fi rst phase being a short keeping clip vas with a high gas speed and the 2nd phase a long keeping clip with a low gas speed ( figure 4 ) . The difference between the two is that the Circofer procedure uses metallurgical coal for a fuel while the Circored procedure uses natural gas. both(prenominal) of these reach an mean 92 % metallization and provender pellets.Hsysla steel developed a traveling bed reactor to make DRI ( figure 5 ) . The Hyl procedure provenders lump Fe into the procedure and a high H inwardness reformed natural gas. The high H is created by reforming with a nickle-based accelerator. The Hyl procedure uses an elevated temperature and force per unit area to increase the processing clip for the reactions. The high H and the elevated temperature and force per unit area create a high quality DRI with 93 % mean metallization.The concluding reactor vas is the Allis Chalmers controlled Atmosphere Reactor ( ACCAR ) . The ACCAR uses a counter take to the woods rotary kiln. The rotary kiln procedure uses a low quality but extremely reactive coal to make cut downing gasses ( figure 6 ) . The rotary kiln produces a DRI with a 92 % metallization. The responding vas does non use any of the station burning in the procedure but station burning vass have been added to the procedure to make adequate energy to personnel the full installation and add some back to the grid.With DRI being produced in many different treating methods there are some cardinal characteristics that set some appart from the others. The rotary kiln, shaft furnace, and the traveling bed reactor vass produce the highest metallization. The rotary fireplace furnace has the fastest procedure clip. The most popular on the market right now is the Midrex shaft furnace with about 60 % of the market portion of DRI production ( table 1 ) . DRI is a stuff that EAF operations have come to depend on and will go on to increase usage due to the high cost of hog Fe and the continued recycling of bit stee l.Table 1 ) Comparative sum-up of procedures as of 2008World payoffReactorFeed TypeReducing agentAverage metallizationMerchandisesACCAR24.0 % merry-go-round KilnpelletsLow quality Coal92 %Pellets and EnergyFinMet2.0 %Fluid bed reactorore mulctsnatural gas91-93 %BriquettesHyl14.5 %Traveling bed reactor wrap oreCoal93 %Pellets or briquettesMidrex58.2 %Shaftpelletsnatural gas95 %PelletsCircofer0.5 %two stage fluid bedore mulctsCoal92 %Pellets or briquettesCircored0.5 %two stage fluid bedore mulctsnatural gas92 %Pellets or briquettesFastmet0.4 %Rotary fireplaceEAF dust/scrapCarbon85-92 %BriquettesPlants CitedBresser, W. , & A Weber, P. ( 1995 ) . Circored and circofer State of the art Technology for low cost direct decrease. bid Steel Eng. ( USA ) Vol. 72, no 4, pp. 81-85.Energiron. ( n.d. ) . HP- HYL Process Description. Retrieved December 7, 2009, from Energiron Corperate Website hypertext assign protocol //www.energiron.com/tour/HYL % 20DR-Minimill % 20QTVR % 20tour/files/suppo rtdocs/dri/pressprocess.pdfKobe Steel, LTD. ( n.d. ) . FastMet Process. Retrieved Decemeber 7, 2009, from Kobelco, Kobe Steel LTD hypertext transfer protocol //www.kobelco.co.jp/p108/fastmet/indexe.htmKobelco. ( n.d. ) . Fastmet Process Flow. Retrieved December 7, 2009, from Kobelco Corperation Website hypertext transfer protocol //www.kobelco.co.jp/english/topics/2008/10/fastment_process_flow.pdfLepinski, J. A. ( 1980 ) . THe ACCAR System and its Application to Direct reduction of Iron Ores. Iron Steel Eng Vol. 57, no. 12, pp. 25-31.Lopez, G. G. , & A Noriega, E. ( 2008, December ) . InTech hottish Fe. Retrieved December 7, 2009, from Emerson Process Management hypertext transfer protocol //www.easydeltav.com/news/standstill/InTech1208.pdfLopukhov, G. A. ( 2003 ) . The Finmet engineering. Elektrometall Vol. 1, pp 43-44.Midrex Corp. ( 2009, April 1 ) . 2008 World Direct reduced Statistics. Retrieved December 7, 2009, from Midrex Corperate Website hypertext transfer protocol //ww w.midrex.com/uploads/documents/MIDREXStatsBook2008.pdfQuintero Yanez, D. ( 1992 ) . Development of Thursday Use of HYL DRI in the Electric Arc Furnace. quaternate European Electric Steel Congress, ( pp. pp 273-283 ) . Madrid Spain.Schutze, W. R. ( n.d. ) . HBI Hot Briquetting of Direct Reduced Iron. Retrieved December 7, 2009, from Koppern Corperation Web site hypertext transfer protocol //www.koeppern.de/download/11_7.pdfTanaka, H. , Harada, t. , & A Yoshida, S. ( 2005 ) . Development of Coal-Based Direct Reduction Ironmaking Process. SEAISI Quarterly Vol 34, Number 4, ppp 26-33.Weber, P. , Hirsch, M. , Bresser, W. , & A Husain, R. ( 2009 ) . Circofer, A Low Cost Approach to DRI production. Retrieved December 7, 2009, from Hot Briqetted Iron Association hypertext transfer protocol //www.hbia.org/Technical/openpdf.cfm? filename=DRProcess/1994-1DR.pdf