Table Of ContentSubir Biswas
Debasish Sarkar
Introduction
to Refractories
for Iron- and
Steelmaking
Introduction to Refractories for Iron- and
Steelmaking
(cid:129)
Subir Biswas Debasish Sarkar
Introduction to Refractories
for Iron- and Steelmaking
SubirBiswas DebasishSarkar
RefractoryTechnologyGroup, DepartmentofCeramicEngineering
R&DandScientificServices NationalInstituteofTechnologyRourkela
TataSteel(India) Rourkela,Odisha,India
Jamshedpur,Jharkhand,India
ISBN978-3-030-43806-7 ISBN978-3-030-43807-4 (eBook)
https://doi.org/10.1007/978-3-030-43807-4
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SubirBiswasdedicates thisbooktotheloving
memory of his Parents & Parents in Law.
&
Debasish Sarkar dedicates this book with a
great sense of Devotion to “Lord Krishna”.
Preface
Despite several classic literatures including books, journal papers and internet
resources,extensivedemandmotivatedtofulfilthegapinbetweenbookishknowl-
edge and shop-floor experience, and thus we decided to write this textbook for
studentsandprofessionals.In-depththoughtprocessinstigatedtomakeanexcellent
linkinbetweenfundamentalconceptsofrefractoriesandtheirjudicioususeofiron
andsteelmaking,primefocusofthisbook.So,itprovidesabridgebetweenceramist
andmetallurgistintheperspectiveofmanufacturingofironandsteelforbothsmall-
andlarge-scaleindustries.Itcoversbasicunderstandingonrefractoryselectionand
operationalprocesstomitigatetheproductioneffort.Inthiscontext,theentirebook
has been divided into 12 chapters, starting from “Refractories for Iron and Steel
Plant” (Chap. 1) followed by “Iron and Steel Making Process” (Chap. 2); “Blast
FurnaceRefractory”(Chap.3);“HotStoveandHotAirCarryingSystem”(Chap.4);
“Refractory Practice in EAF” (Chap. 5); “Refractory for Hot Metal Transport and
Desulfurization”(Chap.6);“BOFRefractory”(Chap.7);“RefractoryforSecondary
Refining of Steel” (Chap. 8); “Refractory in Ladle Flow Control and Purging
System” (Chap. 9); “Refractory for Casting” (Chap. 10); “Modern Refractory
PracticeforCleanSteel”(Chap.11);and“AdvanceMaterialDesignandInstallation
Practices” (Chap. 12).We believe that suchconciseliteratureiseffectively helpful
for a wide range of community including students, academia, researchers, novice
graduate trainees, senior managers, raw material processing, refractory manufac-
turers, refractory procurement personalities and last but not least iron and steel
manufacturers.
Chapter 1
Refractoriesaretheessentialliningmaterialsforworkinginterfacesandbackupzone
offurnacesthroughoutthemanufacturingofironandsteel,inspecificsequentialand
consecutiveoperationofforming,holding,mixingandtransportinghotmetal,liquid
steel and slag. Despite refractory–metal direct interactions, refractory has to
vii
viii Preface
successivelyexperiencehightemperatureandcorrosiveenvironmentthroughflues,
stack or shaft and ducts. Prior to consider the refractories, recent market trend,
designing parameters including predominant mechanical and thermal behaviour
areexplicitlydiscussedtoprovideabetterinsightofthesubject.Inthisconsequence,
thischapterdealswiththeclassificationanddescriptionofacidic,neutralandbasic
refractoriesfordifferentenvironmentandapplicationzoneforironandsteel-making
processes. Modern class of both shaped and unshaped refractories are highlighted
startingfromrawmaterialstoinstallationpractice.Refractorycorrosionmechanism
influenced by blast furnace slag, primary and secondary steel-making slag are
analysedinordertounderstandanddevelopnext-generationrefractories.
Chapter 2
Withextensivechangingintheoperatingpracticeduetostringentcontrolinproduct
quality, introduction of new product mix and demand for high productivity, it is
indeed to upgrade the refractory quality to cope up with the changed environment
andrefractorylifeimprovement.Hence,startingwiththemasterplan,itwasdecided
toprovideabriefintroductiononmodernironandsteel-makingpracticealongwith
background of refractory choice to amalgamate the relation of refractory perfor-
mancewithchangedescalatingdemandonsafeperformance.Assmallblastfurnaces
havebeenclosedandreplacedbylargesizefurnaces,open-hearthsteelmakinghas
been replaced by high productive basic oxygen furnaces (BOF), RH (Rurhstahl
Heraeus)—degasser is the most popular device for making ultra-low carbon steel.
Additionalcompositionadjustmentbysealedargonbubblingwithoxygenblowing
(CAS–OB) has started to operate in many integrated and large size steel plant to
produce high quality alloy steel, the operating processes of those equipment have
beendiscussedindetail.
Chapter 3
Blastfurnaceislikelytocontinueasthemostefficientroutetoproducepigironfor
its high productivity and cost optimization, for many years to come. Although a
smallpartofironmakinghasbeensupplementedbyalternate iron-makingprocess
likedirectreducediron(DRI)andsmeltingreduction;however,thereplacementof
blast furnace for steel making is a distant dream. Thus, the refractory for modern
blast furnace including cast house refractories is a critical issue and is discussed.
Different refractory maintenance practices prolong campaign of blast furnace life
with improved productivity, and thus their key features are enrolled. Starting from
thereductionofcokeratetoeffectivehotmetalthroughrunnerisachallengingtask
to the operator in the mind of production cost reduction and in turn, efficiency of
blastfurnaceisanalyzed.
Preface ix
Chapter 4
Hotstoveisathermalheatregeneratortoproduceandsupplyconstanthotairtoblast
furnace. The present demand of increased hot metal productivity through blast
furnacerouterequireshighhotblasttemperaturemorethan1200(cid:1)C,anditrequires
to optimize and upgrade the quality and design of refractory. Thus, the design of
stoveandtheircheckershaveundergonemajorchangesanddemandsininstallation
of superior quality refractories. Advantages in changed design and upgrade refrac-
toryqualityfromaluminadometosilica,installationofceramicburnersareextrav-
agantly explained in this chapter. Latest development in stove design is top
combustionstovethatcandeliverhotairmorethan1300(cid:1)C;itisobviousthatthis
operational feature has economic benefit over the conventional one. Detailed dis-
cussionhasbeendoneoncritical refractory applicationinthosetypeofstovesthat
eventuallyhelptogenerateknowledgeonhowonecanuseeffectivelyhotblastmore
than1300(cid:1)Cforaslargeas5000m3blastfurnace.
Chapter 5
Owing to several advantages including flexibility to produce several grades steel,
precise control, cleaner environment and minimum installation space, many mini
steel plants are producing steel through electric arc furnace (EAF) route. This
protocol is benefited to use sponge iron and higher share of scrap utilization. EAF
supports 35% high quality alloy steel production around the globe. Different con-
structional and operational features, side wall and bottom/hearth refractory proper-
ties and refractory design for bottom tapping are discussed in the perspective of
effective steel processing. Despite the use of three carbon electrodes in EAF, only
one electrode-based direct current (DC) arc furnace is highlighted. Refractory
corrosion mechanism in the presence of different impurities and subsequent slag
interaction are discussed through relevant phase diagrams in order to select the
refractory depending on steel compositions. Eventually, the state-of-the-art operat-
ingpracticeandrefractoryperformancesaresummarized.
Chapter 6
Continuous steel production demands uninterrupted iron supply for steel vessels.
Limited60–80-tonhotmetalladlehasseveraldisadvantages,andthushighcapacity
up to 300-ton torpedo ladle is being introduced to overcome the hot metal ladle
limitations.Herein,explicitlyfocusedonthedesignaspects,competitiveearlydays
andrecentrefractorylining,plausiblerefractorydeteriorationfactorsandoperational
influence on the refractory performance to operate the torpedo ladle effectively.
x Preface
Torpedo ladle refractory development and lining modules for higher campaign,
effect of insulation refractories, refractory maintenance protocols, and future chal-
lengesareencounteredtoimprovetheworkingenvironment.Despitetorpedoladle,
desulphurization in hot metal ladle and in situ process reactions with refractories,
andwearmechanismsarediscussedtofulfiltheknowledgegap.
Chapter 7
IsitBOFa“heart”ofanysteelsector?Ifyes,itismandatetotakeextracaretokeep
it healthy through refractory management, lining practice and effective operational
protocols.Inthisbackdrop,thischapterconcentratesontherefractorydesigningfor
the vessel and tap hole sleeve, and analyse probable wear mechanism through
ternaryphasediagram.Influenceofgaspurgingandslagsplashingontherefractory
lifeofdifferentzones,followedbyzonalliningconceptandroleofantioxidantare
alsobeingdiscussedsystematically.Topicsofthischapterconcernsonstate-of-the-
art refractory maintenance practice to prolong campaign life and optimization of
cost. Importance of protective slag coating on refractory performances, break-
through in achieving vessel life >20,000 heats by introducing slag splashing and
its influence in refractory performance have been explained in detail. MgO-C
refractoryliningwearisaninevitablecircumstanceandisdiscussedinconsideration
of refractory–slag interaction, reduction of MgO, metal infiltration with respect to
critical pore diameter, thermal stress and spalling phenomena, impact caused by
charging and mechanical erosion and abrasion. Basic philosophy has been
highlighted to improve the MgO-C refractory for BOF lining. Herringbone vessel
relining and maintenance practice by gunning and patching are emphasized to
improvetheBOFlininglife.
Chapter 8
Modern steel ladle is used not only to merely transport liquid steel from BOF to
caster,butalsotoactasareactorvesselwhererefiningofsteeltakesplacetoreduce
impurities, carbon, alloy addition and killing (Al, Si, bi-metal) of steel to reduce
oxygenandothergasses;thiscomprehendsthenecessityandcriticalroleofrefrac-
tories.Substantialmodificationanddevelopmenthavebeenbroughtintotherefrac-
tory quality to eliminate carbon (C) and oxygen pick-up into steel from refractory
liningforladlefurnace(LF)andCAS–OBprocesses.Thus,refractorydesigninsteel
ladles, energy saving issues, variation of thermal conductivity with respect to
conventionalgraphiteandnanocarbon,thermalstress-assistedcracksandrefractory
failurearediscussed.RH–Degasserisinlimelighttoproduceultra-lowCandhigh
alloyed steel with an efficient productivity. Most suitable refractory practice has
beensuggestedinconsideration ofslag–refractory interaction that eventuallyfacil-
itateprolongladlelifeandhighqualitysteel.
Preface xi
Chapter 9
Continuousstrivetowardsnewtechnologyintroducedreliableflowcontrolsystems
thatenablesafeandprolongtappingliquidsteelfromladletotundishwithconsistent
andhighcastingrate.Thus,synchronizationofoperationalparameters,appropriate
refractoryandanalysisofprobablefailureareessentialandencountered.Erosionof
boreandcorrosionofslidingsurfaceoftheslideplates,radialcrackingofplatesand
metal leakage are the most critical issues as addressed with mention of optimize
refractoryqualityofplatesandnozzlestoprolongcastingtime.Inordertohomog-
enousthemoltensteel,gaspurgingisanimportantaspectandthusdifferenttypesof
purgingplugs,theirdesign,refractoryqualityandtheeffectofcastingsequenceshad
also been discussed. Thermal-stressed failure and premature wear that may reduce
theoperationalsafetyandpromoteshop-floorsafetyhazardsarealsohighlighted.
Chapter 10
Continuouscasting(con-cast)demandsuninterruptedproductlengthwhereasin-got
processispopularforbatchprocess.Inmodernproductionprotocol,in-gotcasting
processislimitedandmorethan90%ofglobalsteelproductionfollowscontinuous
castingofslab,bloom,billet,thinslab,etc.Abriefunderstandingincludingmould,
pouring, choice of refractory and their failure, advantages and disadvantages of
in-gotcastingarediscussed.Inspiteofbatchprocess,exhaustivecon-castinspecific
operationalfeatures,andrefractorydesignandfailuresaredeliveredintheperspec-
tiveofminimizingcastingdefectsandhigheryieldoffinishedsteel.Tundishisthe
indispensable component in the con-cast process, and it is the refractory lined last
vessel before solidification of molten steel in the mould, in which different refrac-
tories in hot face and in backup for easy de-sculling are described. Causes of
clogging, usage of anti-clogging refractory materials in sub-entry nozzle and other
“black refractories” with latest design of inert gas purging in SEN had been
mentioned.
Chapter 11
Ductilityfacilitiesreformingbutelasticmodulusprovidesthestrengthofsteel.Itall
depends on constituents and phases in steel. The previous discussion emphasizes
steel production is a multi-step process that has to pass through the exhaustive
environment and thus possibilities of inclusions despite targeted compositions.
This drawback reduces the steel performance, and therefore modern amenities
demand clean steel for an extensive range of applications. An excellent choice of
new class of modern refractory is required to avoid contamination and maintain
