Lub ladle slag kab yog qhov chaw uas cov hlau molten tuaj rau hauv kev sib cuag nrog huab cua. Tam sim no,Magnesia carbon cibfeem ntau yog siv rau kev tsim kho ntawm ladle slag kab. Vim qhov sib txawv ntawm qhov kub thiab qhov muaj nyob ntawm qhov chaw muaj pa oxygen, qhov kev yaig ntawm qhov no yog qhov nrawm dua li ntawm lwm qhov chaw. Tsis tas li ntawd, qhov tipping thiab slag tawm ntawm cov hlau molten thaum ua haujlwm ua rau muaj kev puas tsuaj loj rau cov kab slag. Yog li ntawd, cov kab ladle slag yog ib qho ntawm cov khoom uas muaj kev saib xyuas ntau tshaj plaws.
Lub neej ntawm ladle slag kab yog feem ntau cuam tshuam thiab txwv los ntawm peb yam: sab nraud ib puag ncig, refractory zoo thiab masonry txoj kev.
1. Sab nraud ib puag ncig
Lub ladle yog ib qho khoom siv rau kev tau txais cov hlau molten thiab ua haujlwm nchuav. Qhov kub ntawm cov hlau molten feem ntau yog nyob ib ncig ntawm 1500 degree. Thaum cov kab ladle slag tuaj rau hauv kev sib cuag nrog huab cua ntawm qhov ntsuas kub no, cov tshuaj tiv thaiv oxidation muaj zog yuav tshwm sim. Tsis tas li ntawd, qhov sib txawv ntawm qhov sib txawv ntawm qhov sib chwv ntawm cov hlau molten thiab huab cua kuj muaj kev cuam tshuam zoo heev rau cov kab ladle slag. Qhov sib txawv ntawm qhov kub thiab txias yuav hnyav heev rau qhov thermal stability ntawm lub ladle slag kab [20]. Thaum tau txais thiab pov tseg cov haujlwm tas li, lub refractory yuav ua rau qee qhov kev tawg. Yog li ntawd, nyob rau hauv ib puag ncig sab nraud, oxidation ntawm qhov kub thiab txias muaj kev cuam tshuam zoo rau kev yaig ntawm kab slag. Nyob rau tib lub sijhawm, qhov kev hloov pauv loj hauv qhov kub thiab txias ua rau muaj kev xav tau siab ntawm thermal stability ntawm cov ntaub ntawv refractory. Nyob rau hauv kev sib cuam tshuam ntawm melting poob thiab vau ntawm cov ntaub ntawv refractory, lub ladle slag kab yog yooj yim puas, thiab ces steel infiltration tshwm sim.
LF refining slag yog ib qho yooj yim ua rau oxidation thiab decarburization ntawm magnesia carbon cib. LF slag muaj cov viscosity tsawg ntawm qhov kub thiab txias, muaj zog permeability nyob rau hauv decarburization txheej, thiab muaj ib tug siab solubility nyob rau hauv magnesium oxide. Nyob rau tib lub sij hawm, lub slag yog ib qho yooj yim rau nkag mus rau hauv lub grain ciam teb ntawm periclase kom dissociate magnesia xuab zeb hais, raws li qhia nyob rau hauv daim duab 2 (SA yog slag nyob rau hauv daim duab; TA yog qhov sib tshuam ntawm peb daim). Yog li ntawd, kev pab cuam lub neej ntawm LF slag kab magnesite carbon bricks yog qhov tsawg. Shen et al. systematically kawm txog kev puas tsuaj mechanism ntawm ladle magnesium carbon bricks nyob rau hauv lub LF refining txheej txheem, qhia tias me me MgO grain aggregates yog yooj yim eroded los ntawm high-kub slag. Tom qab yaig, cov slag yuav txuas ntxiv nkag mus rau sab hauv ntawm MgO aggregate raws periclase grain ciam teb, nws thiaj li ua rau cleavage ntawm periclase aggregate.
2. Refractory zoo
Currently, magnesite carbon bricks are mainly used for ladle slag lines. Both traditional magnesia carbon bricks and low-carbon magnesite carbon bricks, which are currently widely used, mainly use flake graphite as their carbon source. Flake graphite is generally selected from -197, -196, etc., that is, the particle size is greater than 100 mesh and the purity is higher than 97% or 96% (mass fraction). The binder is a thermosetting phenolic resin. During the carbonization reaction, the self-chain segments undergo cross-linking reactions to form a network structure that can form a mechanical interlocking force between magnesia sand particles and graphite. Graphite is the main raw material for the production of magnesia carbon refractory bricks, mainly due to its excellent physical properties: ① non-wetting of slag, ② high thermal conductivity, and ③ low thermal expansion. In addition, graphite does not melt with refractory materials, and graphite has high refractoriness. It is precisely because of this characteristic that mag-c bricks are selected for slag lines with harsh operating environments [24]. For low carbon magnesia carbon bricks (mass fraction of carbon ≤8%) or ultra-low carbon magnesite carbon bricks (mass fraction of carbon ≤3%), it is difficult to form a continuous network structure due to the low carbon content, so the organizational structure design of low carbon magnesia-carbon bricks is relatively complex. On the contrary, the organizational structure design of high carbon mag-carbon bricks (mass fraction of carbon>10%) yog qhov yooj yim.
Vim tias qhov cuam tshuam ntawm magnesite carbon bricks rau ya raws thiab kev cuam tshuam ntawm kev xaiv cov qauv, kev ua haujlwm ntawm magnesia- carbon bricks yuav cuam tshuam rau qee yam. Tom qab magnesia carbon bricks yog damp, cov qauv yuav xoob, thiab dej khiav tawm ntawm qhov kub thiab txias los tsim ntau yam khoob, uas yuav muaj kev cuam tshuam tsis zoo rau lub thermal stability thiab corrosion kuj ntawm cov cib no, thiab muaj peev xwm tiv nrog molten steel. kuj yuav qaug zog heev. MgO-C yog rhiab heev rau thermomechanical abrasion vim hais tias lub thermal expansion coefficient ntawm MgO muaj ib tug siab reversibility. Lub binder ntawm magnesia carbon cib kuj yog ib qho tseem ceeb uas cuam tshuam rau qhov zoo ntawm magnesia carbon cib. Ntau dhau los yog tsawg dhau los yuav cuam tshuam rau kev ua haujlwm ntawm magnesia carbon cib. Cov binder me me dhau lawm yuav ua rau cov hmoov ntawm magnesia carbon cib kom xoob thiab yooj yim ntxuav thiab tev tawm; Cov ntaub nplaum ntau dhau yuav ua rau lub thermal shock stability thiab refractoriness ntawm magnesia carbon cib kom deteriorate, thiab ntau yam teeb meem yuav muab ntxiv rau cov hlau molten.
Thaum lub ladle tau txais cov hlau molten los ntawm lub converter, nws yuav tau nrog ib tug loj npaum li cas ntawm slag. Qhov qis melting point 2CaO·SiO2 nyob rau hauv lub slag dissolves rau hauv MgO grain ciam teb thiab reacts chemically nrog cov kab impurity ntsiab nyob rau hauv MgO txheej, uas plays lub luag hauj lwm tseem ceeb nyob rau hauv lub dissolution ntawm magnesia refractory cov ntaub ntawv. Los ntawm qhov kev xav ntawm converter slag, kev tshawb fawb txog kev txhim kho ntawm magnesia carbon refractory cib feem ntau tsom rau magnesia xuab zeb, antioxidants thiab microstructure.
Tsis tas li ntawd, qhov sib ntxiv ntawm cov tshuaj antioxidants rau magnesia carbon cib kuj cuam tshuam rau lawv qhov zoo. Txhawm rau txhim kho oxidation tsis kam ntawm magnesia-carbon bricks, ib qho me me ntawm cov khoom ntxiv feem ntau yog ntxiv. Cov additives muaj xws li Si, Al, Mg, Al-S, Al-Mg, Al-Mg-Ca, Si-Mg-Ca, SiC, B4C, BN thiab Al-BC thiab Al-SiC-C series additives. Lub luag hauj lwm ntawm additives feem ntau muaj ob yam: ntawm ib sab, los ntawm ib tug thermodynamic taw tes ntawm view, thaum ua hauj lwm kub, additives los yog additives reacts nrog carbon los tsim lwm yam tshuaj. Lawv txoj kev sib raug zoo nrog cov pa oxygen ntau dua li cov pa roj carbon monoxide, thiab lawv tau oxidized ua ntej carbon, yog li tiv thaiv carbon. Ntawm qhov tod tes, los ntawm qhov kev xav ntawm kev xav, cov tebchaw tsim los ntawm cov tshuaj tiv thaiv ntawm cov tshuaj ntxiv nrog O2, CO lossis carbon hloov cov microstructure ntawm cov khoom siv refractory, xws li nce ntom, thaiv qhov hws, thiab cuam tshuam qhov diffusion ntawm oxygen thiab Cov khoom siv tshuaj tiv thaiv [28] Tam sim no, Al hmoov yog tsuas yog siv nyob rau hauv magnesia carbon cib los tiv thaiv carbon oxidation. Txawm hais tias Al muaj peev xwm tiv thaiv oxidation muaj zog, thaum kub siab, Al reacts nrog C thiab N2 los ua Al carbon thiab nitrogen tebchaw. Ntawm lawv, Al carbide yog ib qho yooj yim rau hydrate nyob rau hauv cov txheej txheem los ntawm qhov kub thiab txias mus rau qhov kub thiab txias, uas ua rau cov voids nyob rau hauv lub magnesia carbon cib, uas ua rau cov qauv kom loosen thiab tawg.
3. Masonry txoj kev
Magnesium carbon bricks nyob rau hauv lub ladle slag kab feem ntau txais yuav qhuav masonry (ncaj qha stacking bricks yam tsis muaj hluav taws cov av nkos bonding) thiab ntub masonry (siv cov av nkos ua ke nrog refractory cib). Qhov zoo ntawm cov masonry qhuav yog tias nws txo qhov cuam tshuam ntawm cov av nkos. Nyob rau hauv qhov kub thiab txias, vim yog cov khoom sib txawv ntawm mag-c cib thiab cov av nkos hluav taws kub, qhov sib txawv ntawm qhov thermal expansion yog vim qhov kub thiab txias, uas yog ib qho yooj yim los tsim qhov khoob ntawm qhov chaw sib cuag. Qhov tsis zoo ntawm txoj kev no yog tias cov cib tsis tuaj yeem lav tau 100% nyob ze. Nyob rau tib lub sijhawm, thaum magnesia carbon bricks nthuav dav vim cua sov, tsis muaj chaw rau buffering ntawm cov cib, uas ua rau cov cib yuav tsum tau nyem thiab tawg; los yog vim kev nthuav dav ntawm cov cib, tag nrho lub nplhaib ntawm slag kab yog nqa tag nrho, thiab lub zog loj extrusion ua rau lub phaj phaj deform, thiab cov khoom siv refractory poob kev tiv thaiv thiab ntxuav thiab tev tawm, uas ua rau ntau dua. hem rau qhov zoo ntawm cov kab slag.
Txoj kev ntub dej masonry zoo ib yam li txoj kev masonry hauv cov tsev, tab sis nws yog nruj dua nyob rau hauv cov kev cai. Qhov zoo ntawm txoj kev no yog tias nws tuaj yeem zam qhov khoob uas yuav tshwm sim hauv cov masonry qhuav. Nyob rau tib lub sijhawm, cov av nkos hluav taws tsis muaj zog ntawm qhov kub thiab txias. Thaum cov magnesia carbon bricks nthuav dav vim yog cua sov, lawv tuaj yeem ntws los hloov mus rau cov kev hloov pauv ntawm qhov sib txawv ntawm cov cib, dispersing lub extrusion quab yuam ntawm cib, yog li zam lub cim ntawm qhov khoob. Qhov tsis zoo ntawm txoj kev no yog tias kev siv cov av nkos hluav taws ua rau cov qauv ntawm cov kab slag tsis ruaj khov thiab ua rau muaj kev nyuaj ntawm masonry. Yog tias cov av nkos hluav taws tsis sib npaug, tseem yuav muaj qhov sib txawv ntawm cov cib.
