VLCL

VLCL

VT LIU CHU LACc vn chnh: Thnh phn no l nhiu nht trong sn phm Tm hiu v thnh phn Nguyn liu sn xut K thut sn xut Tnh cht v ng dng, phm vi ng dng Phng php nh giCHNG 1: VT LIU CHU LA DINATDi nat l loi VLCL c 93%SiO2, sn xut t qung ca quc v cht lin kt l vi hoc cht khc, nung nhit m bo quc bin i thnh tridimit v cristobite1. SiO21.1. S bin i th hnh ca SiO2 v tnh cht ca chng a. QuartzC hai dng th hnh : quartz v quartz quartz : y l dng th hnh bn vng nhi thng, ph bin trong thin nhin. Khi nung n 573 n chuyn thnh quartz v km theo gin n.quartz : tn ti trong phm vi 573-870. 870, ht quartz c kch thc no v phi c mt cht khong ha mnh th n chuyn chm dn thnh tridimite. Trong thc t sn xut gch dinat u dng cht khong ha v quartz iu kin nghin mn n chuyn thnh tridimite qua pha trung gian metacristobalite 1200-1470, nhng mnh nhit trn 1300. Dng tridimite l dng n nh nht m ta mun c trong gch dinat. Nu khng c ph gia nng chy vi vai tr cht khong ha th metacristobalite s chuyn ha thnh cristobalite.b. Tridimite C 3 dng th hnh tn ti t nhit thp n nhit cao l , , .

Khi nng nhit ln qu 1470 th tridimite chuyn chm sang cristobalite. Nu nung nhanh n nhit trn 167010 th tridimite chuyn thnh thy tinh nng chy Qua hnh v ta thy rng tridimite l tinh th bn vng v n nh nht. Vvy sn xut sn phm dnat phi lm sao to c nhiu tridimite nht.c. Cristobalite. C hai dng th hnh l Cristobalite (tn ti nhit cao), Cristobalite ( tn ti nhit thp). Hai dng th hnh nay c mt khc nhau rt ln vi Cristobalite (2.22g/cm3) v Cristobalite (2.34g/cm3), nn dn ti bin i th tch ca chng rt ln. y l l do v sao ngi ta khng mun c nhiu Cristobalite trong dinat v chng d gy nn v, nt sn phm khi lm ngui hay nng nhit .d. Thy tinh quartzThy tinh quartz c hnh thnh bng cch nng chy nhanh ca quartz 1600 , ca tridimite 167010 v ca Cristobalite 1723.Khi lm ngui nhanh cht nng chy ny thu c thy tinh quartz, thy tinh ny c rt nhiu c tnh qu nh bn sc nhit , chu la, bn ha, tnh cht quang hc. c bit l c h s gin n nhit rt thp, nh hn 20 ln so vi thy tinh xy dng v 6 ln so vi thy tinh pyrex.Do ta c nhn xt sauS bin i th hnh lun km theo s bin i trng lng ring dn n bin i th tch. S thay i th tch ny quyt nh ton b qu trihf nung v s dng dinat. V th tch khn n nh l nguyn nhn lamf sn phm c bn nhit thp. bn nhit cng thp khi s bin th hnh cng nhanh, th tch thay i cng nhiu.2. Nguyn liu sn xut VLCl dinat2.1. Cht khong haNh ni trn th nh s c mt ca cht khong ha m qu trnh chuyn ha t quartz sang tridimite c thc yCht khong ha ch yu to cht nng chy nhit thp. Cht nng chy ny c nht nh, thm t tt nht l phi tan c Cristobalite tao c tinh th tridimite bn vng trong sn phm dinat, xen k gia cc tinh th y l pha thy tinh v mt s pha tinh th khc.Cht khong ha mnh nht l Na2CO3 v K2CO3, tuy nhin ngi ta khn dng v n h thp nhiu tnh cht sn phm nhit cao.Ph bin ngi ta hay dng l Cao, FeO, di khi MnO. Trong thc t sn xut ngi ta dng ng thi CaO v FeO lm cht khong ha, th khi cu t chnh l FeO, cn vi ch l cht h tr, t l tt nht gia CaO v FeO l n . Vi dinat dng xy l cc ha khng dng FeO m dng MnO v FeO trong mi trng kh s li xc tc cho hin tng tm than (2CO CO2+C), i vi trng hp ny tt nht dng 2-3% CaO hoc 2% hn hp CaO v MgO vi t l 1:1 n 1:2.Dng CaO lm cht khong ha di dng vi sa tng tnh ng khung ca phi liu, phn phi u ph gia lin kt cc ht quatzit nghin kh, lm cho cc vin thnh phm t c cng trc sau khi sy, xc tin qu trnh tridimit ha. Cao d iu ch, ly t voi nung bnh thng.Cht khong ha l oxit st thng cho vo phi liu di dng vy st, x nu qung v cha nhiu FeO, Fe2O3 khng dng do to im tecti cao hn nhiu v tc dng khong ha km hn nhiu.2.2. Nguyn liu sn xut dinatTrong sn xut dinat ngi ta thng dng cc nguyn liu cha SiO2 nh ct quc, sa thch, quactzit sn xut. Ct qut l sn phm phn hy ca qung ni cha qut nh hoa cng do tc dng ca kh quyn, gi, s thay i nhit Cc ht ct quc tch t qua nhiu th k c thm t bng nc c cha cc tp cht mn nh t st, vi, thch cao. Cc tp cht ny phn phi u gia cc ht cc, lin kt cc ht li thnh qung rn hn, bn hn gi l sa thch hay cc kt. Khi ch p sut ln, cc kt bin thnh mt loi bin cht l quaczit.Qutzit c hai loi: quaczit xi mng ( nu lng cht lin kt trong quczit nhiu 30-75% ), qutzit tinh th (cc ht quc tip xc vi nhau chc ch hn v lin kt vi nhau bng cc rng ca ht v c tr lng nhiu hn qutzit xi mng)2.2.1. Tnh cht k thut ca qutzita. Tc chuyn ha khi nungQutzit tinh th c tc chuyn ha chm, cn qutzit xi mng ty thuc vo lng xi mng v thnh phn ca n c th chuyn ha chm, trung bnh v nhanh. trnh t do chuyn ha nhanh , ta kt hp 2 loi qutzit vi nhau.b. xpTheo xp c 4 loi sau

SttTn nhm ht nc xp biy kin

1Rt c0.51.2

2c0.5-41.2- 4

3Xp1.5-44.3-10

4Rt xp410

c. Thnh phn ha hcThng thng dng loi c SiO2 95%, ngoi ra cn c CaO, MgO, Na2O, K2O, Al2O3, c bit c hi nht l Al2O3 v kim v n h thp chu la ca qutzitd. chu la sn xut dinat yu cu qutzit c chu la 1750. Loi 72% c 2 pha bn vng hn c l mulit v corun Trong phm vi thnh phn c Al2O3 t 72-78%, mulit to thnh dung dch rn vi Corun, pha lng ch xut hin 1850 v thnh phn ng vi im nng chy l 79%Al2O3 + 21% SiO2Kt lun: Nu tng hm lng Al2O3 ( bt u t VLCL bn axit) s tng nhi chu la v nhit mm ca cc vt liu chu la alumosilicat. Tuy nhin tnh cht ca VLCL khng ch ph thuc vo hm lng Al2O3 m cn nhiu nhn t khc na. Nhn chung lng cht lng ca VLCL bn axit tng ln chm hn so vi samot, nn ng lng tng i dc hn. Trong thc t sn xut ngoi hai cu t ch yu l Al2O3 v SiO2 cn c cc tp cht, chnh cc tp cht ny vi hm lng 2-5% cc oxt nh : Fe2O3, CaO, MgO, Na2O, K2O lm tng lng pha lng to thnh v gim cc ch tiu k thut ca VLCL.2. Nguyn liu sn xut VLCL samotL t st v cao lanh chu la2.1. Ngun gc2.2. Thnh phn ha v thnh phn khongTrong thin nhin khng khi no gp cao lanh hay t st c thnh phn ng dng AS2H2 ( 39,5% Al2O3, 46,6% SiO2, 13,9% H20) m thng ln cc tp cht khc. Thng thng : SiO2 chim n 70% hoc hn, dng quartz, chng s lm gim do v chu la, tng kt khi, mt vi trng hp lm t t st khi nung nhit cao.Al2O3 tong t st ( khi nung ) loi tt cao hn 40% ( loai t st cao bazo); loi bazo c 30-40%, loi bn axit 15-30%, lo axit 95% Al2O30. Nguyn liuNguyn liu sn xut VLCL cao alumin thng dng cc qung thin nhin hay nguyn liu nhn to.Cc nguyn liu ch yu l qung thuc nhm silimanit, hydrat nhm v nhm k thut.Vic la chn nguyn liu ph thuc vo tnh cht v k thut ca sn phm1.1. Khong thuc nhm silimanit Rt ph bin trong thin nhin v c gi tr trong cng nghip Gm: silimanit, andaluzit, disten (kianit) v diumterit Ba khong u u c cng thc chung l Al2O3.SiO21.2. Hy drat nhm Cng thc chung: Al2O3.n H20 Gm 3 loi phn bit nhau bi cu trc v hm lng nc lin kt ha hc1. Hydracgilit: Al2O3.3 H201. Bomit: Al2O3. H201. Diaspo: Al2O3.H20Khi t nng s xy ra s bin i khng thun nghch t dng ny sang dng khc theo s 250-340 0C 450-550 0C 950-1200 0C - Al2O3.3 H20 Al2O3.H20 Al2O3 Al2O3 Hydracgilit Bomit 450-500 0C - Al2O3.H20 Al2O3 Trong thin nhin, thng gp qung boxit, l khong tng hp tt c cc hydrat nhm, ch yu l hydracgilit v bomit. Ngoi ra boxit cn c cc to cht: oxyt v hydroxyt st, quarzt, quarzit, caolinit. Hm lng Fe2O3 trong boxit t khi < 2-3% thng >5%. iu y lm hn ch dng boxit trong cng nghip sn xut VLCL cao alumin.1.3. Nhm k thutNhm k thut c sn xut bng gia cng ha hc qung boxit nn c tinh khit caoC 3 dng th hnh: Al2O3. vl dng tinh khit. Dng ch to ra do c mt ca tp cht.Trong nhm k thut khong ch yu l Al2O3 nm trong giai on chuyn tip thnh Al2O3 v cn li mt t hydrat nhm (hydracgilit v bomit). Khi t nng n 1200 0C th Al2O3 Al2O3.1.4. Corun in nng chyL nguyn liu lm vt liu mi, gm 2 loi Loi trng: Al2O3 98%, sn xut bng cch nu chy nhm k thut trong l in Loi thng: sn xut bng cch nu chy boxit, Al2O3 = 91-97% ty theo lng hp cht trong boxit, c bit l Fe2O3 v SiO2 Thnh phn khong ch yu l a Al2O3 v mt t b Al2O3 do boxit c nhiu tp cht. Lng tp cht cng nhiu lng b Al2O3 cng nhiu.

2. K thut sn xut2.1. Sn phm sn xut t nhm silimanit u im ca khong ny: khi t n nhit mullit ha th qu trnh to mullit tin hnh hon ton, khng ph thuc cc iu kin gia cng nh nghin trn.. D thnh lp qui trnh sn xut hn. V vy sn xut sn phm cao alumin t disten phi tin hnh nung s b chng thnh Smt ti kt tinh. Sn xut sn phm cao Alumin t nhm silimanit dng cht kt dnh ch yu l t st nghin mn lm giu. Tuy nhin ch dng mt lng nh m thi (10-15%) v t st lm gim Al2O3v tng tp cht d chy trong sn phm . Tt nht l dng t st nhiu nhm v tinh khit. Qui trnh sn xut tng t sn xut sn phm nhiu samot:Cht lm gy l silimanit ,andaluzit hoc dten nung s b nghin mn .Cht kt dnh (10-15%) dng t st chu la caoAl2O3 (40%). Thnh phn ht phi bo m sn phm c mt cao nht , c ht ln nht 1-2mm. p lc nn 1000kG/cm2, nhit nung 1500-15500C. S dng : lm thng thp v nu thy tinh2.2. Sn phm t hidrat nhm Nu dng qung boxit phi nung s b kh nc lin kt ho hc cng nh kt khi s b sn phm , sau em nghin mn . Nu dng Diaspo th khng cn nung s b Cht lin kt cng dng cht kt dnh 10-15% , nhit nung 15000C Tnh cht sn phm Al2O3 60-65% (ln hn sn phm t silimanit) Tp cht nng chy : 3,5-4% Nhit chu la 1800-18500C. Nhit kt thc bin dng 1650-17000C Sn phm t boxit v diaspo cha Al2O3 nhiu hn so vi sn phm t nhm silimanit . Tng s tp cht nng chy v xp cao hn 1 t . V th tng hm lngAl2O3 ln 10% cng nh km theo tng nhit bt u bin dng ln 1 t.2.3. Sn phm t nhm k thut T nhm k thut c th sn xut ra sn phm mullit(70-75%Al2O3) , mullit corun (78-95%Al2O3) v corun(>95%Al2O3) a. Sn phm mullit v mullit corunK thut sn xut mullit v mullit corun tng t nh k thut sn xut sn phm nhiu samot : Dng samot mullit corun kt khi rt c vi 15-20% t st do kt dnh. sn xut mulit corun ta tin hnh nh sau: Nghin nhm k thut mn cng vi 15-20%t st do , ng vin , nung . t st chu la y l 1 cu t tng hp mullit trong sn phm , ng thi ng vai tr cht lin kt nhm k thut trong cc vin th .Nhit nung cc vin th thnh samot mullit corun khong 1400-15000C ( qa trnh mullit ho hon ton ), cn n kt khi th phi n nhit 1500-16500CSamot mullit corun kt khi phi c ht nc 3%. Nghin mn t c ht : Ht ln nht 2-5mm ; ht trung bnh 0,5-0,088mm; ht nh 20000C ( nhit nng chy ca MgO nguyn cht 28000C )C hai loi VLCL manhdi : Loi vin v loi bt. Loi vin xy tng l , loi bt dng m l.1. Nguyn liuNguyn liu thng dng l Manhdit MgCO3 , mt s ni khng c manhdi th dng MgO ly t nc bin.

1.1. ManhditL khong cha 47,62%MgO v 52,98%CO2Gm 2 loi : Manhdit tinh th v Manhdit v nh hnh Manhdit tinh th c to ra do tc ng ca vi hoc lmit vi dung dch cacbonat axit manhdi theo phn ng : CaCO3 + Mg(HCO3)2 MgCO3 + Ca(HCO3)2 (dd) CaMg(HCO3)2 + Mg(HCO3)2 2MgCO3 + Ca(HCO3)2 (dd) Manhdit v nh hnh l sn phm phn hu cc khong silicat manhdit nh : Serpentin , livin theo phn ng : 3MgO. 2SiO2. 2H2O + 3CO2 3MgCO3 + 2SiO2 + 2H2O 2MgO. SiO2 + 2CO2 3MgCO3 + 2SiO2 Tp cht ch yu trong manhdit l Fe2O3 ,SiO2, CaO, Al2O3. Trong CaO l tp cht c hi nht.Yu cu : Manhdit sau khi nung phi c MgO 85% i vi bt luyn kim v 91% i vi gch , CaO 2-3% , SiO2 + Fe2O3 5%1.2. MgO ly t nc binTrong nc bin cha 0,2% MgO nhng ngun nc bin v tn MgCl2 + MgCa(OH)4 2Mg(OH)2 + CaClSn xut bng phng php ny c nhng kh khn sau: Lng nc bin cn dng ln Thc hin qu trnh hyrat ho hon ton lmit rt kh Phi dng lng CaCl2 ln Kh lc c MgO u im: Tn dng c lmi v ngun nc bin C th iu chnh hm lng MgO trong sn phm ph hp vi yu cu k thut Hm lng MgO tng i cao >90-95% Nu dng phng php trn tch MgO t nc t l nc d sau khi kt tinh mui n rt kinh t.2. Qa trnh ha l khi nung2.1. Qu trnh ha l v thnh phn khong Nu sn xut t manhzit , khi nung s tin hnh phn hu : MgCO3 MgO + CO2 - Q Phn ng bt u 4000C , nhanh 6400C . Tc phn hu manhzit ph thuc vo lng tp cht , cu trc v mt manhzit . Nu nguyn liu ban u sn xut t nc bin th phn ng u tin khi nung l : Mg(OH)2 MgO + H2O - QPhn ng ny tin hnh mnh 4300C2.2. nh hng ca thnh phn khongThnh phn khong chnh l Periclaz MgO, c chu la rt cao ( 28000C ). C th b hydrat ho theo phn ng : MgO + H2O Mg(OH)2 . Phn ng ny xy ra khi , sy hoc trn vi nc ng thi lm tng th tch ln hai ln. V vy cn phi phi liu trnh nt n sn phm sau ny. Kh nng hydrat ho ca MgO ph thuc nhit nung, mn v nhit hydrat ho: Nu nung nhit thp ~11000C, periclaz rt hot ng v sn phm lc gi l manhdi badic, chng ng rn vi dung dch MgCl2, CaCl2, MgSO4.. nhit thng. Nu nung nhit cao ~ 1500-16000C periclaz kt tinh tt hn v ta c manhdi kt khi, cng ng rn vi dung dch trn nhng nht 600CNgoi ra cn c cc khong sau CaO t do : Rt d b hydrat ho to thnh Ca(OH)2 gy nt n v ph hu sn phm MF ( manhdi ferit MgO.Fe2O3 v manhdi vustit MgO . FeO ) : s to thnh dung dch rn vi MgO c tc dng tt cho qu trnh ti kt tinh periclaz lm tng qu trnh kt khi C2F ( dicanxi ferit ) : C tc dng kt khi tt nht nhng lm gim nhit bin dng di ti trng v chu l ca vt liu . Cn phi hn ch . C4AF tng t C2F CMS : Lm tng qu trnh kt khi nhng l khong d chy ( Nhit nng chy 14600C )lm gim nhit bin dng di ti trng v tng co khi nung . Khong c hi M2S ( forterit ) : lm tng nhit bin dng di ti trng ( do nhit nng chy cao ) nhng c lin kt forsterit th vt liu phi nung nhit cao > 16000C C3S v C2S : u c nh hng khng tt n qu trnh kt khi . C3S khi lm ngui n 1150-12500C s b phn hu C3S C2S + CaO t do . CaO t do c nh hng khng tt nh nu trn . Cn C2S khng n nh do khi lm ngui s c s bin i th hnh t C2S C2S km theo hin tng tng th tch 10% gy t sn phm. 3. K thut sn xut3.1. Sn xut sn phm Manhedia. Nguyn liu Dng manhdi kt khi tt : MgO 90-92% ; CaO 2,5 %; SiO2 4% ; MKN 0,6%. Mun sn xut sn phm mt cao , cho vo phi liu 1,1 0,3% ph gia TiO2 S sn xut

b. Chun b nguyn liu Thnh phn ht tt nht: Ht 2-0,8mm : 45-55% Ht 0,8-0,088mm: 5-15% Ht 800kG/cm2d. Sy sn phm Sau khi p, vin mc c cng khng cao lm:15-20kG/cm2, chuyn vo l phi cn thn, phi xp nghing v tha tng b mt sy v thng gi tt Qu trnh sy kh phc tp do qu trnh hyrat ho MgO vn tip tc tin hnhe. Nung sn phm Sn phm manhdi khi nung hu nh khng c s bin i a hnh no c nn khng c cc giai on co gin c bit 1100-12000C: Bt u xut hin pha lng ng vi im Otecti ca MgO, CaO, Al2O3, SiO2 (~11570C). Sn phm lc u kt khi do ti kt tinh tp hp cc khong 1450-15000C: Lng pha lng tng, qu trnh kt khi tng. nhit max 15000C hoc 16000C, cng vin mc rt thp Giai on lm ngui, khi trong vt liu cn pha lng c th lm ngui nhanh nhng khi sn phm trng thi gin phi lm ngui chm4. Tnh cht v lnh vc ng dng4.1. Tnh cht Nhit chu la >23000C Nhit bin dng di ti trng khng cao lm: 1500-15500C bn nhit: lm ngui bng khng kh 4-9 ln, lm ngui bng nc 1-2 ln. Nguyn nhn: do s chnh lch ln gin n nhit gia Periclaz (1,35.10-5) vi cht lin kt Silicat (2-3.10-5) v do moun n hi ln.4.2. Lnh vc s dngCh yu dng trong l in, l nu thp, cc l luyn kim mu. Loi Mannhdi bn nhit dng lt zn nung l quay ximng v vm l mactanh (thay gch Crm manhdi). Ch : nhit cao gch manhdi khng c t tip xc vi gch samt c v n s to thnh hp cht cordierit (2MgO2Al2O35SiO2) d chy (t0nc=14250C)3Al2O3.1SiO2 + MgO 2MgO.2Al2O3.5SiO2 Mulit peniclas cordient

CHNG 6VLCL CRM-MANHDI, CRMITVLCL Crm manhdi (Cr-Mg) l sn phm sn xut t 2 nguyn liu crmit v manhdi kt khi. Khong ch yu trong sn phm ny thuc loi nhm khong Spinen vi cng thc chung R2+O, R3+2O3. (R2+ l Mg2+, Fe2+; R3+ l Cr3+, Fe3+, Al3+...)1. Nguyn liu cromitTu theo hm lng Cr2O3 chia qung crmit lm 4 loi Qung ngho:Cr2O3 50%Cromit sn sut vlcl yu cu: Cr2O3=35-40%,2. K thut sn xut VLCL cromitQung cromit qung dunit qung manhedi basic

p th p th bunke

Nghin mn nung nh lng

Sng bunke Bunke nghin bi keo SSB

nh lng my khuy bm My trn bnh xe

Nn Sy Nung

Phi liu gm: qung cromit, ph gia manhedi basic ( 9%), qung unnit (6%), qung unit l olivine M2S Trong qung crmit c serpentin l khong khng chu la phi cho vo 9% manhdi bazic nung 10000C hp vi serpentin thnh cht lin kt Forsterit chu la cao, ng thi hp vi Fe2O3 thnh manhdiferit chu la 3MgO2SiO22H2O + MgO = 2(2MgOSiO2) + 2H2O (Serpetin) (manhdibazic) (forsterit) MgO + Fe2O3 = MgOFe2O3 Tnh cht: L loi gch trung tnh, n c th tip xc vi gch axit (inat) v gch baz (manhdi) ngay nhit cao. khong 17000C m khng c tc dng g ng k ng dng: Dng xy lp ngn cch gia 2 loi gch baz v axit. V d gia inat v manhdi. Nhng crmit khng th xy tip xc vi samt v nhit cao chng tc dng vi nhau to cht c chu la thp3. Vt liu chiu la crommanhedi3.1. S cng ngh sn xutManhedi kt khi keo kt dnh cromit Nghin mn ( ht 0.8-1) p nghin

nh lng trn phi liu nh lng

Nn Sy

Nung 3.2. Phi liuQua hnh trn ta thy c 2 loi t l phi liu tt nht Crmit:Manhdi = 30:70. Ta c sn phm bn nhit l gch Cr-Mg. Gch Cr-Mg bn nhit cn c gi l gch Mg-Cr v lng manhdi kt khi nhiu hn thng c dng xy vm l Martin, bn hn v t b phng rp hn loi th hai Crmit:Manhdi = 65:35. Sn phm c nhit bin dng di ti trng cao3.3. To hnh v sy3.4. Nung3.5. Tnh cht v ng dng Tnh cht Cng c hc tng i cao 200-400kG/cm2 Nhit bin dng di ti trng khng cao lm 1450-15500C bn ho cao bn nhit tng i cao ng dng: c s dng rng ri trong cng nghip luyn kim, xy xy vm l mactanh, lt l in nu thp, l nu ng, lt zn nung l quay xi mng Gch Cr-Mg c s dng cng vi gch manhdi xy tng l mactanh ch khng tip xc vi thp, khng lm bn thp do crm ca gch. xy gch Cr-Mg thng dng va xy l manhdi kt khi nghin mn. Tt hn c l dng nhng tm thp mng dy 1,5-2mm xy, khi nung nhit cao, cc tm thp ny s b oxi ho v to vi MgO ca gch thnh manhdiferit (t0nc= 17500C) hn cc vin gch li vi nhau rt chc.

CHNG 7 VT LIU CHU LA CCH NHITMc ch ca s dng VLCL cch nhit: Gim thp mc tiu tn nhin liu H nhit mi trng, c ct trng bng tnh cch nhit.VLCL cch nhit tha mn 2 yu cu: Nhit tch ly nh khi gim trng lng th tch v tng xp dn nhit gim khi xp tng, kch thc l xp gim1. Phn loiCch nhit ( vt liu nh) hin nay dng rng ri gm 3 loi Loi cch nhit thp: Nhit lm vic