钢铁冶炼

Chapter2钢铁冶金OresandminingIronmakingSteelmaking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+O2CO2generatinghightemperature:1600～1750℃CO2+CCO2）铁的还原：IronoxidescanbereducedwithCO.Thisisaprocessinwhichoxygenisremovedfromacompound,inthiscase,ironore.Theoxygeniscombinedwithcarbontoformcarbondioxide(CO2),andthemetallicironisreleasedfromitsoxidestate,leavingmoltenironwithabout4percentcarbon.Fe2O3,Fe3O4,FeOreactwithCOFe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+CaOCaS+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、N2asfuelstoheatfurnacesandfordailyuse3）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+O22COindirectoxidation:①2Fe+O22FeO②C+FeOFe+COCarbonmakessteelstrongbuttoomuchofCisharmful.lowcarbonsteel0.2～0.3％ofCmediumcarbonsteel0.4～0.6％ofChighcarbonsteel0.6％～1%ofCcarbonsteelcastironover2%ofC2).Desulfuration（脱硫）:FeS+CaOCaS+FeOCaScanberemovedwithslag.butCcanhelpreduceFeOtoformFeinordertopreventoppositereaction:FeS+CaO+CFe+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+FeOMeO+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