Direct iron ore smelting process development
The smelting decrease ( SR ) of Fe ore is an alternate natural stuffs treating method similar to the blast furnace. It begins with solid natural stuffs such as coal and Fe ore. The concluding merchandise of this procedure is a liquid Fe based stuff known as hot metal, or hog Fe when it is solidified. This terminal merchandise is the same as that generated by blast furnaces. Typical hot metal composings are about 4-4.5 % C, .3-1.5 % Si, .25-2.2 % manganese, .03-.08 % S, and.04-.2 % phosphoric. SR is the new age alternate to pig Fe production with the capableness of uninterrupted operation. The engineerings used in this procedure are similar to those used in both modern blast furnaces and conventional non-ferrous smelting operations. As developments in blast furnaces and non-ferrous smelters were made, such as the innovation of the Cu flash smelting engineering, developments were made in SR of Fe.
Smelting Reduction Chemical reactions
The natural stuffs used in SR are: pulverized Fe ore which consist of Fe2O3 and Fe3O4 with remainders, powdered coal, limestone ( CaCO3 ) , and dolomitic limestone ( CaMg ( CO3 ) 2 ) . The transition of Fe ore into a liquid hot metal begins with the combustion of coal into C monoxide ( CO ) and H gas ( H2 ) which are the cardinal compounds for Fe decrease, equation 1. The C monoxide and H gas produced from the burning is used to get down the decrease of Fe ore by equation 2. The chemical reaction for regenerating the CO and H2 with coal from equation 2 merchandises is given by equation 3. Full decrease of the Fe ore is so shown by equations 4 and 5.
Coal + ?O2 > CO + H2 ( 1 )
6Fe2O3 + CO +H2 > 4Fe3O4 + H2O + CO2 ( 2 )
2C + CO2 + H2O > 3CO +H2 ( 3 )
2 Fe3O4 + CO + H2 > 6FeO + H2O + CO2 ( 4 )
2FeO + CO + H2 > Fe + H2O + CO2 ( 5 )
These reactions begin in the solid province ; nevertheless, as decrease series begins the reactions become liquid province. The limestone and dolomitic limestone are added as fluxes/slag agents. The adaptability of many of these procedures to utilize a assortment of coal chemical sciences without the coking measure is the most alone belongings of SR fuel over blast furnace fuel. This usage of coal alternatively of coke eliminates the demand for a coking furnace every bit good as the usage of lower class coal.
Smelting Decrease Firsts
Archaeological finds in Africa show a crude smelting decrease signifier dating back every bit early as 2500BC. These ancient craftsmen would cut down Fe ore utilizing coke by blowing air into a shaft furnace. Martin Wiberg of Sweden every bit good as W. and E. Engell of Denmark began look intoing the smelting decrease procedure in 1938. However, much of the impulse in smelting decrease was lost between the 1950 ‘s and 70 ‘s due to progresss in the solid province decrease procedure known as DRI ( direct reduced Fe ) and in blast furnace engineering. It is of import to observe that without the air separation engineering conceived during the Second World War SR would non be executable. By 1981 the first SR pilot works was constructed in Germany based off the COREX design construct. In 1988 the first all-out SR installation was constructed based off the same pilot works at the site of a old blast furnace.
Smelting Reduction Reactor Types
Three chief SR convertor types exist: the shaft convertor procedure, a two phase chemical procedure, and the intercrossed procedure. Both the shaft convertor procedure and the two phase procedure usage chemical energy for the decrease. However, the two phase procedure differs from the shaft procedure by implementing two transition Chamberss, a solid province chamber followed by a liquid province chamber. The intercrossed procedure is the most alone because it gets energy parts from chemical reactions and electrical current. Of these three types merely two procedures have been put into operation in all-out installations, the COREX procedure and the HIsmelt procedure.
The COREX procedure was the first all-out SR installation as antecedently mentioned. This procedure is a two phase procedure. The first phase in decrease is the solid province reaction and natural stuffs preheating subdivision. Off gas from the 2nd phase is used to cut down and preheat in the first phase. As the ore transforms into a liquid it moves to the 2nd convertor phase where the liquid province decrease is completed.
The COREX procedure has three theoretical accounts, the C-1000, 2000, and 3000. Primary differences between the theoretical accounts are the production capablenesss. The C-1000 installed in 1988 has a day-to-day production capableness of 1000 dozenss of hot metal. The C-2000 will bring forth 2000 tons/day ; it presently has 4 operating workss with the first installed in S. Korea, 1995. [ 2 ] The C-3000 is the newest installation with one works located in China. The SR furnace was installed in 2007 and has a day-to-day production capableness of 4000 dozenss of hot metal [ 7 ] . Figure 2 is an image of the C-3000 works.
The HIsmelt was the 2nd SR procedure to go full production. Pilot proving of this procedure began in 1982. The procedure is a uninterrupted shaft transition furnace. [ 2 ] HIsmelt implements many engineerings presently used in non-ferrous smelting like uninterrupted stuffs feed by spears into the liquefied bath and H2O cooled furnace panels. [ 5 ] The full graduated table works which was built in 2003 was a 400 million dollar undertaking between RioTinto, Nucor, Mitsubishi, and Shougang coprorations. The works is located in Western Australia. [ 9 ] This procedure can utilize the off gas for multiple applications such as fuel for electrical power coevals or preheating the provender stuff. A elaborate position of the reactor vas.
Additional SR procedure which are non presently commercialized include: direct Fe ore smelting ( DIOS, two phase reactor ) , AISI ( two phase reactor ) , and IDI ( intercrossed SR ) . Although SR procedures do non implement coke furnaces the coal demands remain similar holding small consequence on environmental emanations.
SR is an progressing engineering capable of continuously bring forthing hot metal similar to a blast furnace with a wider scope of coal type. This natural stuffs flexibleness is a great advantage to SR. The riddance of the coking furnace lessenings project capital ; although, it has small impact on environmental emanations. SR has many great properties which makes it a competitory option to blare furnaces.
[ 1 ] LIFE. ( n.d. ) . Chinese Premier Wen Jiabao Visits Australia. Retrieved December 06, 2009, from hypertext transfer protocol: //www.life.com/image/57232194
[ 2 ] Chatterjee, A. ( 1994 ) . Beyond the Blast Furnace. Boca Raton, FL: CRC Press.
[ 3 ] Miller, T. W. , Jimenez, J. , Sharan, A. , & A ; Goldstein, D. A. ( 1998 ) . Steelmaking and Refining, Oxygen Steelmaking Processes. In R. J. Fruehan, & A ; 11 ( Ed. ) , The Making, Shaping and Treating of Steel ( pp. 489-490 ) . Pittsburgh: The AISI Steel Foundation.
[ 4 ] Davis, M. P. , Dry, R. J. , & A ; Schwarz, M. P. ( 2003 ) . Flow Simulation of the HISMELT Process. Third International Conferance on CFD in the Minerals and Process Industries ( pp. 305-311 ) . Melbourn, Australia: CSIRO.
[ 5 ] HIsmelt. ( n.d. ) . HIsmelt- The Technology. Retrieved December 06, 2009, from hypertext transfer protocol: //www.hismelt.com/EN/HT_PageView.aspx? pageID=8 #
[ 6 ] Shalimov, A. G. ( 200 ) . The COREX Process for Making High-Quality Steels at Mini-Mills. Metallurgist, 44, 35-39.
[ 7 ] Environment Engineering Solution. ( n.d. ) . Environment-friendly Corex procedure of Fe and steel devising. Retrieved December 06, 2009, from hypertext transfer protocol: //environmentengineering.blogspot.com /2008/02/environment-friendly-corex-process-of.html
[ 8 ] Siemens. ( n.d. ) . Siemens AG – Pictures. Retrieved December 06, 2009, from hypertext transfer protocol: //w1.siemens.com/press/en/presspicture/ ? press=/en/presspicture/2008/corporate_communication/media_summit_2008/soaxx200803-08.htm
[ 9 ] Outotec. ( n.d. ) . HIsmelt undertaking in Western Australia. Retrieved December 06, 2009, from hypertext transfer protocol: //www.outotec.com/pages/Page____7775.aspx? epslanguage=EN
[ 10 ] Changqing, H. , Xiaowei, H. , Zhihong, L. , & A ; Chunxia, Z. ( 2009 ) . Comparison of CO2 Emission Between COREX and Blast Furnace Iron-Making System. Journal of Environmental Sciences, Supplement, 116-120.