Developments In Direct Reduced Iron

Developments In Direct Reduced Iron ( DRI )Direct reduced Fe ( DRI ) is produced by dint of the solid responsibility decrease of Fe oxides derived from Fe ore or electric discharge furnace ( EAF ) mulcts for the tradition as a gross(a) Fe beginning in the EAF or basic O furnace ( BOF ) processes. Virgin Fe beginnings atomic number 18 call for in the EAF turn to thin the remainders ( Cu, Ni, Cr, Mo, or Va ) nowadays from old steel doing operations in the combat steel used as the primary natural hooey used in the EAF. DRI is produced in many a(prenominal) different procedures utilizing several different raises and different alimentation stocks. The DRI processes use several reaction vessels including shaft furnaces, whirligig fireplace furnaces, silver-tonguedized bed nuclear reactors, traveling bed reactors, and rophy kilns. The fuels used in the procedures atomic number 18 chiefly burn or natural throttle valve, these fuels are used to fool a reduction ambiance an d elevated temperature to plant a more than favourable reaction. The quality of the DRI is measured by the sum of metallic Fe ( Fe or Fe3C ) is present in the merchandise. This figure is called metallization and is reported 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 point in several reactions that cut down the Fe oxides to metallic Fe ( eq. 1 and 2 ) . The reduction be adriftes are produced by burning natural gas or a C beginning so adding the change 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 shock is combusted. The discrimination betwixt the procedures is how the sustenance stock i s uncovered to the burning gases.The most common instance of reaction vas is the shaft furnace where the nutrition stock is fed into the top of the furnace so dropped through the vas to be exposed 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 corporation and is cognise 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 ( figure 1 ) . The fluke gas is so fed through a station burning chamber and the energy extracted from station burning is used to preheat the provender gas. This gas is so fed to a bag house where it is scrubbed before being reintroduced to the ambiance.This procedure creates chie fly DRI pellets due to the 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 al dispiriteds the Midrex procedure to derive the bulk of the available energy and is what has do it favourable for the bulk of world-wide DRI productionA faster production method and 1 that has more tractability than the shaft furnace is the rotary fireplace furnace or the Fastmet procedure. The rotary fireplace furnace is a uninterrupted operation that feeds stuff into a revolving furnace that passes the stuff through the reduction atmosphere so removes the stuff near when it completes the full rotary motion ( figure 2 ) . Unlike the Midrex procedure the Fastmet procedure uses mulcts as a feedstock. This allows for the recycling of EAF mulcts and molar dust that would be otherwise disposed of as a risky stuff. The Fastmet procedure uses a C cut downing agent 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 on start 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 vault of heaven to drift the provender stuff. This natation of the provender 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 market 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 first 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 phase reactor with the progressive phases utilizing a higher gas speed and a lower reaction preen to derive between 91 % and 93 % metallization ( figure 3 ) . The Finmet procedure requires a briquetting operation because the provender stock is mulcts but because of necessitating a high pureness natural gas fuel it produces a really low residuary HBI.The following both procedures, Circofer and Circored, both feature a two phase fluidized bed reactor with the first phase being a short memory 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 of these authorise 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 suffice 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 celestial sphere to summation 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 allice Chalmers controlled Atmosphere Reactor ( ACCAR ) . The ACCAR uses a counter flow rotary kiln. Th e 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 role the full installation and add some back to the grid.With DRI being produced in many different treating methods thither 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 refine 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 steel.T able 1 ) Comparative sum-up of procedures as of 2008World ProductionReactorFeed TypeReducing agentAverage metallizationMerchandisesACCAR24.0 %lap KilnpelletsLow quality Coal92 %Pellets and EnergyFinMet2.0 %Fluid bed reactorore mulctsnatural gas91-93 %BriquettesHyl14.5 %Traveling bed reactorball oreCoal93 %Pellets or briquettesMidrex58.2 %Shaftpelletsnatural gas95 %PelletsCircofer0.5 %two point in time fluid bedore mulctsCoal92 %Pellets or briquettesCircored0.5 %two stage fluid bedore mulctsnatural gas92 %Pellets or briquettesFastmet0.4 %Rotary fireplaceEAF dust/ moCarbon85-92 %BriquettesPlants CitedBresser, W. , & A Weber, P. ( 1995 ) . Circored and circofer State of the art Technology for low cost direct decrease. Iron brand 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 ecstasy communications protocol //www.energiron.com/tour/HYL % 20DR-Minimill % 20QTVR % 20tour/f iles/supportdocs/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 step-down of Iron Ores. Iron Steel Eng Vol. 57, no. 12, pp. 25-31.Lopez, G. G. , & A Noriega, E. ( 2008, December ) . InTech Hot Fe. Retrieved December 7, 2009, from Emerson Process focal point hypertext transfer protocol //www.easydeltav.com/news/viewpoint/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 protoco l //www.midrex.com/uploads/documents/MIDREXStatsBook2008.pdfQuintero Yanez, D. ( 1992 ) . Development of Thursday Use of HYL DRI in the electric automobile Arc Furnace. 4th 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/ adept/openpdf.cfm? filename=DRProcess/1994-1DR.pdf