artículo grupo 6

8/10/2019 Artculo Grupo 6

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Bauxite based brick Chamotte basedbrick

Al2O3 ~73 ~58

iO2 ~26 ~36

aO 0.2 0.3

iO2 2.7 2.!

2O3 !.! !.#

Alkalis 0.3 !.3

ate Ser%ice time o& li'ers (mo'ths) Sam*le t+*e ,ocatio' (dista'ce to outlet -m)A'al+ses

*er&ormed

/a+ 2006 $e*osit 0 !0 20 1"

Available online at www.sciencedirect.com

SciVerse ScienceDirect

our'al o& the 4uro*ea' Ceramic Societ+ 32 (20!2) !5!!528

. else %ier. comlo cate9 eurceramsoc

4xte'ded studies o& de:radatio' mecha'isms i' the re&ractor+ li'i': o& arotar+ kil' &or iro' ore *ellet *roductio'

es*er St9er'ber:a;Joh' C. acce*ted 7 a'uar+ 20!2

A%ailable o'li'e 2 "ebruar+ 20!2

Abstract

Cha':es o%er a *eriod o& 8 +ears i' the chemical com*ositio' a'd mor*holo:+ o& de*osit a'd li'i': materials i' a *roductio' rotar+ kil' &or iro' ore

*ellet ma'u&acture are described. he &olloi': ha%e bee' studied? to t+*es o& re&ractor+ brick used as li'i': material> de*osited chu'k materials

&rom the li'i':> the i'teractio' @o'es betee' de*osits a'd li'i':s. /or*holo:ical cha':es at the de*ositli'i': i'ter&ace a'd the acti%e chemical

reactio's are established. ,ar:er hematite :rai's i' the de*osit material (550 m ) *rimaril+remai' at the ori:i'al de*ositli'i': i'ter&ace. he

remai'der *e'etrates &issures %oids a'd brick 9oi'ts &orms a lami'ar structure ith coru'dum &rom the bricks a'd mi:rates i' :rai's i' the li'i':

material. otassium *e'etrates more dee*l+ i'to the bricks tha' hematite resulti': i' the &ormatio' o& kalsilite leucite a'd *otassium alumi'a

hich co'tribute to de:radatio' o& the li'i':.

D20!2 4lse%ier ,td. All ri:hts reser%ed.

Keywords*B. 4lectro' microsco*+> C. Corrosio'> $. A,O3> $. /ullite> 4. e&ractories

Introduction

he *elletisi': o& iro' ore as a burde' material &or blast &ur

'aces has bee' used commerciall+ si'ce the earl+ !50s. o

mai' *rocesses are used toda+ duri': such *roductio'? the tra%

elli': :rate a'd the :ratekil' *rocess.!I' the :ratekil' *rocesshich is studied here the :rate is a *reheater a'd the kil' is

a rotati': &ur'ace li'ed ith re&ractor+ bricks. he re&ractor+

li'i': de:rades o%er time throu:h ex*osure to hi:h tem*er

atures a'd a corrosi%e e'%iro'me't reEuiri': re*laceme't at

re:ular i'ter%als. $e:radatio' mecha'isms i' rotar+ kil's are

com*lex si'ce se%eral di&&ere't mecha'isms o*erate simulta'e

ousl+. he mai' source o& de:radatio' is residue &rom *ellet*roductio' hich to:ether ith &l+ ash &rom coal bur'ed to heat

the kil' &orms de*osits o' the li'i': that accumulate i' chu'ks.2

"i:. ! shos such de*osits i' the kil' studied i' this ork (FF2,oussa%aara Fiiru'a%aara ,imited (,FAB) Firu'a Sede')

; Corres*o'di': author. el.? G#6 20 22#705.+-ail address*[email protected](. St9er'ber:).

05522!H see &ro't matter D 20!2 4lse%ier ,td. All ri:hts reser%ed.

doi?!0.!0!69.9eurceramsoc.20!2.0!.0!2

obser%ed duri': a *roductio' sto*. Adhesio' o& de*osits o' the

re&ractories has also bee' obser%ed at other iro' ore *ellet *ro

ductio' sites a'd i' di&&ere't t+*es o& kil'> hich a**ears to be

related to the Eualit+ a'd com*ositio' o& the bur'er &uel used.3

he &ormatio' a'd locatio' o& the de*osits i' the kil' %aries

but i' :e'eral there is more de*ositio' o& material i' the armer

@o'e closest to the bur'er. he de*ositio' ca' reach a thick'ess

u* to 30 cm> ith *eaks *rotrudi': like stalactites ith le':ths

u* to ! m. Ioe%er some @o'es i' the kil' ca' be ithout a'+

de*ositio'. A thi' la+er o& de*ositio' is co'sidered *rotecti%e

as it i'sulates a'd loers the li'er tem*erature a'd is *rotecti%e

a:ai'st ear. Jhe' this la+er :ros too thick mecha'ical actio'

occasio'all+ causes &allout o& hea%+ chu'k &ormatio's that ca'cause ex&oliatio' o& the li'i': creati': a 'e hot &ace here

*ellet residues a'd &l+ ash o'ce a:ai' come i'to co'tact ith

&resh li'i': material a'd are able to de*osit i' chu'ks.

he kil' studied here rotates clockise (obser%ed &rom the

outlet) at a**rox. 2r*m a'd is tilted 3K to the hori@o'tal *la'e

such that the *ellets tra%el more easil+ toards its outlet throu:h

a helical mo%eme't. "i:. 2 shos the desi:' o& the kil'.


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u'e 2008 #8 Brick 30 1$

u'e 2008 #8 72 Brickde*osit 0 30 S4/

u'e 20!0 $e*osit 0a6 !2 25 33 1"

u'e 20!0 !# 72 6 Brick 6 !2 25 1$u'e 20!0 !# 72 6 Brickde*osit 6 !2 25 S4/ O/


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ollectio' +ear 2006 2006 2006 20!0 20!0 20!0 20!0 20!0ista'ce to outlet (m) 0 !0 20 0 6 !2 25 33

e2O3 0.3! !.55 88.27 #.#2 6.66 #.83 0.!8 2.#e3O# 2.22 2.22 2.35 0.# 0.76 !.05 3.!! !.#!

iO2 2.3 2.!! 3.8 2.60 !.!8 2.!5 3.3! 3.28

/2O3 0.55 0.5# !.0 0.#6 0.20 0.## 0.82 0.83aO 0.52 0.37 0.55 0.#5 0.23 0.36 !.3! 0.75

/:O 0.5# 0.#8 0.63 0.5! 0.52 0.58 0.5# 0.55

=a2O 0.!38 0.!00 0.202 R0.050 R0.050 R0.050 R0.050 R0.050

F2O 0.088 0.072 0.!53 0.02 0.028 0.07! 0.!02 0.07/'O 0.07 0.07 0.07 0.08 0.08 0.08 0.!0 0.08

iO2 0.2! 0.!7 0.20 0.! 0.!8 0.! 0.! 0.20

Q2O5 0.! 0.!8 0.!7 0.!0 0.!30 0.!80 0.!70 0.!0

2O5 0.060 0.0#6 0.07! 0.060 0.023 0.0#6 0.073 0.073otal oxides 7.83 7.! 8.38 7.0 7.02 7.07 7.#6 7.##

ul*hur 0.00!5 0.076 0.0!2! 0.0!27 0.0266 R0.00!0 0.002! 0.003#

a"i:. ! was obtai'ed at this locatio' o' this occasio'.

!522 .% St/ern0erg etal% .ournal of the +uro$ean 2era-ic Society )" 3"41"5 1(191("8

able 3Chemical com*ositio's (tL) o& the de*osit materials collected i' the *roductio' kil'.


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co'&irmed *eaks corres*o'd to coru'dum a'd mullite i'cludi':

traces o& a'dalusite (Al2O3SiO2) a'd cristobalite (SiO2).

%"%"% fter years in service

"i:. # shos the li'i':de*osit i'ter&ace i' a sam*lecollected

&rom the outlet o& the kil' (to the ri:ht i'"i:. ! ,here bauxite based bricks ha%e ser%ed as li'ers &or # +ears. he hematite

"i:. 3. S4/ micro:ra*hs shoi': (a) a li'i':de*osit i'ter&ace sam*le col

lected 6 m &rom the outlet o& the kil' u'e 20!0 a'd (b) a *art o& the de*osit

material i' (a) ith a hi:her ma:'i&icatio'. I hematite C coru'dum.

(hite :rai's marked I) &ormi': a disti'ct i'ter&ace ith the

remai'i': brick. he hite arros i' "i:. # mark a crack a**roximatel+ *arallel to the li'i':de*osit i'ter&ace. rai's o& mullite

are marked / coru'dum is marked C. (his co'%e'tio' is used

herea&ter.)

"i:. 5(a) a'd (b) are e'lar:eme'ts o& the areas markedith black a'd hite &rames i' "i:. #. $islod:ed coru'dum:rai's (the dark :rai's i' "i:. 5(a)) are released b+ erosio'he' the :rai' bou'daries become corroded i' the li'i':

a'd mi:rate i'to the de*osit material surrou'ded b+ hematite

:rai's. =ote also the 'eedles o& hematite &ormed closest to

the sur&ace i'side the coru'dum :rai' (marked ith hite

arros i'"i:. 5(a)). Iematite a'd coru'dum are isomor*housa'd ha%e bee' obser%ed to &orm a solid solutio' at ele%ated

tem*eratures.8The &i'er i'terlocked mullite structure (marked< i'"i:. 5(b)) loses its i'terlocki': as it tra's&orms to rodlikecr+stals (marked


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.% St/ern0erg etal% .ournal of the +uro$ean 2era-ic Society )" 3"41"5 1(191("8 !523

"i:. 5. S4/ micro:ra*hs shoi': (a) dislod:ed coru'dum :rai's (dark :rai's)

mi:rated throu:h the de*osit material a'd (b) mullite a::re:ate tra's&ormed i'

co'tact ith *otassium. =ote the di&&ere'ce i' ma:'i&icatio' i' the ima:es.

I hematite C coru'dum < *rimar+ mullite these are *hases detected i' the

sam*le but i' co'ce'tratio's less *romi'e't tha' leucite a'd

coru'dum.

%)%"% fter 8 years in service

"i:. !0(a)(d) shos the de*ositli'i': i'ter&ace i' sam*lescollected 25 m &rom the outlet o& the kil' here the chamotte

based bricks ha%e ser%ed as li'ers &or 8 +ears. Iematite is the

domi'a't *hase i' the de*osit material (dark i' the O/ micro

:ra*h a'd hite i' S4/ micro:ra*hs)."i:. !0(a)shos homaterial &rom the de*osits has *e'etrated &issures (arro to le&t

i' the micro:ra*h) a'd 9oi'ts (arro to ri:ht i' the micro:ra*h).

Iematite &illed 9oi'ts are #00800 m broad hile hematite

&illed &issures are !00200 m i' idth."i:. !0(b) shos hothe :rai's o& hematite ha%e started to si'ter resulti': i' :rai'

:roth a'd a more homo:e'ous la+er o& hematite at the i'ter&ace

(marked ith arros). Clusters o& hematite hich ha%e mi:rated

throu:h the li'i': are &ormed dee*er i' the li'i':. hese clus

ters :i%e the li'i': a reddish colour"i:. !0(a). he materiali' the bo'di': *hase betee' the hematite :rai's that mi:rated

throu:h &issures a'd 9oi'ts a**ears to be o& a 'o'cr+stalli'e

mor*holo:+ ("i:. !0(!) a'd (d)). his bo'di': *hase exhibitshi:h co'ce'tratio's o& *otassium (abo%e !0tL) a'd sodium

(~3 tL) ith traces o& sul*hur a'd *hos*horus.

$i&&racto:rams obtai'ed &rom a brick sam*le collected at this

locatio' ('ot sho') i'dicated that 'o 'e *hases had &ormed

com*ared ith as&abricated brick. A ma9orit+ o& co'&irmed

*eaks corres*o'd to coru'dum a'd mullite i'cludi': traces o&

cristobalite a'd Euart@ (both SiO2).


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!52# .% St/ern0erg etal% .ournal of the +uro$ean 2era-ic Society )" 3"41"5 1(191("8

"i:. 6. (a) Back scattered S4/ micro:ra*h o& *arts o& "i:. #, a'd (b) Al (c) Si (d) "e (e) =a (&) F shos 4$S ma**i':s o& the corres*o'di': area.

Discussion

his *a*er deals ith di&&ere't de:radatio' mecha'isms act

i': o' the bricks ser%i': as re&ractor+ li'ers i' rotar+ kil's at

iro' ore *ellet *roductio'. he discussio' is *rese'ted i' terms

o& the mecha'isms o*erati':.

(%1% +ffect of $otassiu- on the -icrostructure of the lining

he e&&ect o& *otassium o' mullite a::re:ates i' the li'

i': is to cause the a::re:ates to lose their i'terlocki': &orm?

the mullite tra's&orms to 'eedlelike &ormatio's i' the li'i':

(see' i' "i:. 5(b)). hese structures are also obser%ed b+


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.% St/ern0erg etal% .ournal of the +uro$ean 2era-ic Society )" 3"41"5 1(191("8 !525

"i:. 7. (a) a'd (b) S4/ micro:ra*hs shoi': li'i':de*osit i'ter&ace o& sam

*les collected !2 m &rom the outlet o& the kil' u'e 20!0. Arro marks i

de*leted @o'e I hematite C coru'dum.

mm. otassium *e'etrates more dee*l+ a'd i' lar:er amou'tstha' sodium i' the li'i': material e%e' i& their oxides (F2O a'd

=a2O) are *rese't i' similar co'ce'tratio's i' collected de*osit

materials (0.!0.2 tL). his is i' a:reeme't ith =arita et al."#

ho obser%ed that *otassium as &ou'd i' co'ce'tratio's &i%e

times as hi:h i' the &irecla+ based li'i': (hich is com*ara

ble i' com*ositio' ith the chamotte based li'er used i' this

"i:. 8. S4/ micro:ra*h shoi': a de*ositli'i': i'ter&ace sam*le collected

30 m &rom the outlet o& the kil' u'e 2008. I hematite C coru'dum.

"i:. . (a) $i&&racto:ramrecorded o'abrick sam*le that has ser%ed as re&ractor+

li'er &or 6 +ears i' the kil' (collected 3 m &rom the i'let o& the kil' u'e 2008)

a'd (b) di&&racto:ram recorded o' a brick sam*le i' its &abricated co'ditio'.

stud+) i' a blast &ur'ace.


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!526 .% St/ern0erg etal% .ournal of the +uro$ean 2era-ic Society )" 3"41"5 1(191("8

"i:. !0. (a) O*tical micro:ra*h shoi': a de*ositli'i': i'ter&ace sam*le here the arro to le&t marks a &issure a'd the arro to ri:ht marks a brick 9oi't (b)

S4/ micro:ra*h shoi': de*ositli'i': i'ter&ace here hematite has mi:rated i'to the li'i': (c a'd d) S4/ micro:ra*hs hematite &illed &issures. I hematite

C coru'dum. All sam*les collected 25 m &rom the outlet o& the kil' u'e 20!0.

he *e'etratio' o& de*osit material i'to &issures a'd 9oi'ts

acts like a :lue i' the brick 9oi'ts such that the bricks are si'tered

to:ether a'd act as a mo'olithic li'i':. his is *robabl+ o'e

o& the reaso's that the li'i': could ser%e as lo': as 8 +ears

i' o'e locatio' (collected 25 m &rom the outlet i' u'e 20!0).

=e%ertheless the @o'e o& iro' *e'etratio' is 9ust a &e mm a'dthe co'ce'tratio's o& iro' co'tai'i': *hases ere still too lo

to be detected b+ 1$ a'al+sis. Ioe%er a hi:h co'ce'tratio'

o& cristobalite is still *rese't hich is si:'i&ica't &or abrick

that has ser%ed as li'er &or 8 +ears at a locatio' here &l+ ash

&alls.

(%)% +ffect of titaniu- o6ide on lining $ro$erties

ita'ium oxide i'clusio's ere obser%ed i' the bulk o& the

li'er "i:. 7(a). Ioe%er a @o'e ~!00 mi' idth closest to thede*osit as de*leted o& these i'clusio's *ossibl+ b+ mi:ratio'

throu:h the li'i': toards the hematite i' the de*osit. /ore

o%er iro' oxide a'd alumi'a &orm a lami'ar structure (as see'

i' "i:. 3(b)) here it a**ears that hile *otassium di&&uses &romthe iro' oxide i'to the alumi'a tita'ium mi:rates &rom the alu

mi'a @o'e a'd di&&uses i'to the iro' oxide lamella. his mi:ht

be the dri%i': &orce &or the &ormatio' &or this lami'ar structure.

Se*aratio' o& tita'ium &rom alumi'a a'd i'stead &ormatio' o&

a solid solutio' betee' tita'ium a'd iro' oxide is i' a:ree

me't ith *re%ious ork.8%'e reaso' &or this is that coru'dumdoes 'ot dissol%e tita'ium i' its lattice.!7The se*aratio' o& tita'ium oxide &rom alumi'a rich re:io's i' the li'i': b+ mi:ratio'

a'd di&&usio' co'tributes to a' i'creased excha':e o& material

betee' li'i': a'd de*osit.

(%% +ffect of varia0le conditions on lining $ro$erties

$e:radatio' occurs b+ di&&ere't mecha'isms at di&&ere'tlocatio's i' the kil'. he outlet o& the kil' here the hi:h alu

mi'a bricks ser%e as li'er is ex*osed to hi:her tem*eratures

hereas the i'let o& the kil' co'tai'i': a chamotte based li'er

is ex*osed to hi:her alkali co'ce'tratio's resulti': &rom the &l+

ash &rom the bur'er. a'd

&i'all+ erosio' (dislod:eme't o& *articles de*letio'). Simi

lar descri*tio's are re*orted i' seco'dar+ steelmaki':20alimere:e'erati': &ur'ace2!ablast &ur'ace!#!o**er *roductio'22

a'd duri': the *roductio' o& stai'less steel.23

Je *ro*ose that %a*orised *otassium *e'etrates %oids &is

sures a'd brick 9oi'ts here it is e'tra**ed b+ liEuids co'de'ses

a'd di&&uses throu:h the bulk reacti': ith the li'i': material

a'd 'ucleati': i' the brick bulk *rimaril+ as &elds*athioid mi'

erals a'd also as Al2O3. his is e'ha'ced b+ sodium hich

loers eutectic tem*eratures. Iematite &rom the de*osit material

starts to react ith coru'dum &rom the brick. O'e o& the dri%i':

&orces &or this is the excha':e o& tita'ium. he brick de:ra

datio' is caused b+ co'curre'tl+ acti%e *rocesses o& chemical

reactio's a'd mi:ratio' o& :rai's &rom the re&ractor+ li'i': i'to

the de*osit material a'd %ice %ersa.

Conclusions

T otassium *e'etrates the sur&ace o& li'er bricks i' muchhi:her co'ce'tratio' tha' sodium to a de*th o& se%eral mm.

T he *rese'ce o& *otassium causes the &ormatio' o& seco'dar+

mullite arou'd the a::re:ates o& *rimar+ mullite hich is a

corrosi%e mecha'ism that *romotes de:radatio' o& the li'i':.

T hases such as kalsilite leucite a'd *otassium alumi'a

are &ormed as a co'seEue'ce o& *otassium mi:ratio' hich

co'tribute to the de:radatio' o& the li'i':.

T rai's o& hematite ith si@es betee' 5 a'd 50 m remai' *ri

maril+ at the ori:i'al i'ter&ace betee' the li'i': a'd de*ositmaterial.

T Some hematite *e'etrates &issurescracks %oids a'd brick

9oi'ts some &orms a lami'ar structure ith coru'dum &rom

the bricks a'd some mi:rates i' :rai's or clustered :rai's

throu:h the li'i': material.

T 4xcha':e o& tita'ium oxide &rom the li'i': i'to the de*osit

material is o'e o& the dri%i': &orces that creates a lar:er co'

tact area betee' li'i': a'd de*osit at the hot &ace a&&ecti':

de:radatio'.

T $e:radatio' is 'o'u'i&orm alo': the kil' althou:h the

tre'ds abo%e are obser%ed.

T $e:radatio' is caused b+ simulta'eous chemical reactio's

&i'all+ resulti': i' the mi:ratio' o& eroded :rai's &rom theli'i': i'to the de*osit material.

Acknowledgements

he authors are :rate&ul to ,FAB &or hel* ith chemical

a'al+sis a'd to F'ut ,i'dmark SAAB (S%a**a%aara Akeri

,imited) &or collectio' o& sam*les. O'e author .S. is also

:rate&ul &or &i'a'cial su**ort &rom I9almar ,u'dbohm

esearch

Ce'tre (I,C).

References

!. Uha': V "e': 1u Uha': V Va': . 4'er:+ a'd exer:+ a'al+ses o&

a mixed &uel&ired :ratekil' &or iro' ore *ellet i'duratio'. +nergy 2onvers

Manage20!!>52(5)?206#7!.

2. ia': Ie N a' / ,i I "a' 1I Vua' ,S. "ormi': mecha

'isms o& ri':s i' rotar+kil' &or oxidi@ed *ellet. 28(2)?32##.

6. $e,ucia / Jol&e I. e&ractories to co'tai' &luori'ated aste streams.

20(5)?##5#.7. St9er'ber: A'tti /, =ordi' ,O Ode' /. $e:radatio' o& re&rac

tor+ bricks used as thermal i'sulatio' i' rotar+ kil's &or iro' ore *ellets

*roductio'.$$l 2era- Technol200>6(6)?7!726.

8. St9er'ber: ,i'dblom B Jikstrom A'tti /, Ode' /. /icrostruc

tural characteri@atio' o& alkali metal mediated hi:h tem*erature reactio's

i' mullite based re&ractories. 2era- :nt20!0>36(2)?733#0.

. o'ceb+ / Co'sta'tiCare+ F "isherJhite /. Subsolidus *hase rela

tio'shi*s i' the s+stem "e2O3 AWO3XiO2 betee' !000K a'd !300 KC.

. - 2era- Soc200#>86(6)?7580.

!0.


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!528 .% St/ern0erg et al% .ournal of the +uro$ean 2era-ic Society )" 3"41"5 1(191("8

!2. ,ee J 6#(2)?!03!7.

!#. =arita F O'o+e Satoh V /i+amoto / a'i:uchi F Famata'i S et al.

4&&ects o& alkalis a'd @i'c o' the ear o& blast &ur'ace re&ractories. :S:.

!8!>2!(!2)?83#5.

!5. Scudeller, ,o':o 4 Qarela . otassium %a*or attacki're&ractories o& the

alumi'asilica s+stem.. - 2era-Soc!0>73(5)?!#!36.

!6. "orsmo S4. Oxidatio' o& ma:'etite co'ce'trate *oders duri': stora:e

a'd dr+i':.:nt . Miner &rocess2005>75(!2)?!35X##.

!7. $as F Choudhur+ $as S. he AlOYi (alumi'umox+:e'tita'ium)

s+stem.. &hase +=uili02002>23(6)?52535.

!8. "arris Alle' . Alumi'ous re&ractories alkali reactio's. :ron Steel +ng

!73>50(2)?677#.

!. Bouchetoua /, 3!(7)?!005.

20. verseas!3>!3(#)?305.

2!. /al+she%

artículo grupo 6

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