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Chapter2钢铁冶金OresandminingIronmakingSteelmaking钢铁冶金在国民经济中的地位材料、能源、信息是现代社会发展的三大支柱产业。而钢铁材料又是材料中的重中之重。钢铁材料性能优良力学性能和物理化学性能加工性能目前尚不能为其它金属材料所代替。铁的蕴藏量极为丰富钢铁的生产成本比其它金属低得多。§2.1Oresandmining铁矿石炼铁坯料铁锭钢锭及钢管IronOretreatments铁矿石生产地壳中元素储量Ironoresarefoundallovertheworld,buttheirdistributionisunequal.Undergroundmining乌克兰的露天采矿场景Openpitmining(露天开采)showinga12.25inchrotarydrillintheforeground.GiantCoalBucketThereareseveraltypesofironoreswhicharelistedinTable1.Therefinedoreisenriched(富含)tobeingover60percentironbythesemethodsandisoftenformedintopellets(小球)beforeshipment.Ironpelletsproducedbydirectreduction§2.2高炉炼铁IronmakinginBlastfurnace2-2-1高炉炼铁的生产工艺过程及特点1.高炉炼铁的本质2.生产工艺过程及特点高炉冶炼过程:是一个连续的、大规模的、高温生产过程。特点:繁重的、连续的、大规模的高温生产。高炉出铁场景2-2-2高炉炼铁原料和燃料1.炼铁原料:铁矿石2.熔剂:石灰石3.燃料:焦炭.炼铁原料Rawmaterialsforironmaking三种原料所起的作用?2吨铁矿石+1吨焦炭+0.5吨石灰石=1吨生铁2-2-3高炉冶炼理化过程Theoperationoftheblastfurnaceiscalledreduction.1)燃料的燃烧:fuel(coke)combustionC+O2CO2generatinghightemperature:1600~1750℃CO2+CCO2)铁的还原:IronoxidescanbereducedwithCO.Thisisaprocessinwhichoxygenisremovedfromacompound,inthiscase,ironore.Theoxygeniscombinedwithcarbontoformcarbondioxide(CO2),andthemetallicironisreleasedfromitsoxidestate,leavingmoltenironwithabout4percentcarbon.Fe2O3,Fe3O4,FeOreactwithCOFe被还原成铁3)铁的增碳4)其它元素的还原:Mn、Si、P(phosphorus)Theseelementscanbereducedwithcarbon.5)脱硫desulfurization:FeS+CaOCaS+FeOCaScanberemovedwithslag.6)造渣slagformation:是矿石中的废料、燃料中的灰分与溶剂的熔合过程。熔合后的产物就是渣。Importantrolesofslag:protectionformetal2-2-4高炉产品1)pigiron:炼钢生铁、铸造生铁、特种生铁纯铁Pureironisasoft,easilybentmetalhavinglimitedusefulness.2)gases:含有CO、CO2、CH4、H2、N2asfuelstoheatfurnacesandfordailyuse3)slag:formakingcement,bricksandpavingThisslagisgroundupandusedasanaggregateforconcreteproductsandasphalticconcreteroads.2-3SteelmakingSteelisironcombinedoralloyedwithothermetalsornonmetalssuchascarbon.2-3-1炼钢用的原材料炼钢实质金属料:非金属料2-3-2炼钢方法1.转炉炼钢法2.平炉炼钢法3.电炉炼钢法1.钢中锰、硫的作用Plaincarbonsteelactuallycontainsasmallamountofthemetalmanganeseasascavengertoremoveunwantedoxygenandtocontrolsulfur.Sulfurisdifficulttoremovefromsteel,andironsulfide(theformitnaturallytakesiniron)isdeleterioustosteel,butifmanganeseispresent,itcombinesmorereadilythanironwiththesulfur,formingmanganesesulfide,whichisnotharmfultothesteel.Forthisreasonnosteelismadewithoutmanganese.2.钢中碳元素的作用Theelementcarboncausessteeltobesuchausefulmaterialsinceitcanbehardenedbyheattreatments.Onlyasmallamountofcarbonisneededtomakesteel:低碳钢(0.20~0.30%)0.20percentto0.30percentforlowcarbonsteel,中碳钢(0.40~0.60%)0.40percentto0.60percentformediumcarbonsteel,高碳钢(0.60~1.0%)0.60percenttoover1percentforhighcarbonsteel.Steelcancontainupto2percentcarbon,butoverthatamountitisconsideredtobecastiron,inwhichexcesscarbonformsgraphite.(C>2%→铸铁,其中的碳以石墨形式存在)3.钢中的合金元素Steelcanbegivenmanydifferentandusefulpropertiesbyalloyingtheironwithothermetalssuchaschromium,nickel,tungsten,molybdenum,vanadium,andtitaniumandwithnonmetalssuchasboronandsilicon.2-3-3炼钢的实质Decarbonization(脱碳)Desulfuration(脱硫)Deoxidation(脱氧)Alloying(合金化)1).Decarbonization(脱碳):mainreactioninsteelmakingBymeansofdirectoxidation:C+O22COindirectoxidation:①2Fe+O22FeO②C+FeOFe+COCarbonmakessteelstrongbuttoomuchofCisharmful.lowcarbonsteel0.2~0.3%ofCmediumcarbonsteel0.4~0.6%ofChighcarbonsteel0.6%~1%ofCcarbonsteelcastironover2%ofC2).Desulfuration(脱硫):FeS+CaOCaS+FeOCaScanberemovedwithslag.butCcanhelpreduceFeOtoformFeinordertopreventoppositereaction:FeS+CaO+CFe+CaS+CO**锰亦能脱硫,形成硫化锰→钢中必不可少的元素3).Deoxidation(脱氧)目的:用氧化剂除去钢液中残留的氧化亚铁中的氧,还原出铁,脱氧剂则被氧化,脱氧产物聚集上浮到钢液表面。Me+FeOMeO+Fe4).Alloying(合金化)Someelementsareaddedtoimprovethepropertiesofsteel.5.SteelmakingMethods炼钢方法steelmakingmethods1.Bessemerizing,Basicoxygenfurnace转炉炼钢法(BOF)2.openhearthfurnace平炉炼钢法3.electricfurnace电炉炼钢法Thesefurnacesarenotusedinterchangeably.Eachsystemrequiresdifferentenergysourcesanddifferentsourcesofrawmaterials.Thekindoffacilityisthereforechosenforeconomicreasonsandtheavailabilityofrawmaterialsandenergysources.Thebasicoxygenfurnace(BOF)isdesignedtoproduceahighqualitysteelinarelativelyshorttime,aboutone200-to300-tonheat(asinglebatch)perhourascomparedtothe100to375tonsperheatin5to8hoursoftheopenhearthprocess.Theprincipalrawmaterialusedinthebasicoxygenfurnaceismoltenpigironfromtheblastfurnace.Thebasicoxygenfurnace(BOF)转炉炼钢法MoltenironfromtheblastfurnaceischargedintooneoftwobasicoxygenfurnacesatBethlehemSteelCorporation'sBethlehem,Pa.plant.Afterthechargehasbeencompleted,thevesselwillreturntoitsuprightpositionfortheoxygenblowduringwhichtheblastfurnaceiron,mixedwithscrapandselectedadditives,willberefinedintosteel.Oneoftwobasicoxygenfurnacesischargedwithscrap.Thechargingmachineemptiesscrapintothevesselbeforethehotmetalisadded.Inadditiontopositioningandchargingtheloadedboxesofscrap,thechargingmachinealsopositionstheheatshieldthatisutilizedfortestingduringfurnaceturndowns.Heatshieldprotectsmembersofthebasicoxygenfurnacecrewwhoaretakingsteelsamplesandatemperaturemeasurementfromthebathofmoltenmetal.Thesteelsampleissentbypneumatictubetothebasicoxygenfurnace(BOF)shopspectrometerlaboratoryfor
本文标题:钢铁冶炼
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