耐火砖的损坏机理
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Wear Mechanisms in cement rotary kilns 水泥回转窑中耐火砖的损耗机理CementICTM •R. Krischanitz•March 08refractory performance Process 操作工艺kg/l -Ovality 椭圆度-Deformed kiln shell 筒体变形sulfates, alkali carbonates, (alkali sulfates and calcium chlorides以硫酸盐形式有机化合物存在于粘土夹层和长石中CaAl2Si2O8alternative fuelsAlternative fuels tend toincrease the input of wearrelevant elements into thesystem!替代燃料会加大有害元素的输入量！Kiln cycles 窑系统内(有害元素)的循环Enrichment of volatile compounds (Cl, K2O, Na2O, SO3) by evaporation / condensation between rotary kiln and preheater 在回转窑和预热器之间，挥发性化合物(Cl, K2O, Na2O, SO3)会不断的蒸发/凝结，循环富集。
With ASR > 1, the alumina bricks of the preheating zone are exposed to alkali attack 当ASR碱硫摩尔比 > 1时，在预热带的高铝砖会受到碱侵蚀Cl-: highly volatile formation of large cycles - extraction only via by-pass Cl-具有高度的挥发性，形成更大的循环- 只能通过旁路系统排出 Na2O, K2O: extraction as def. compound Alk2SO4 or in solid solution in Belite and Aluminate Na2O, K2O可以特定的化合物形式排出如AlK2SO4或固溶在贝利特或铝酸盐中 SO4: extraction as def. compound Alk2SO4 or in solid solution in Belite, (CaSO4 rare, high volatility) SO4可以特定的化合物形式排出如Alk2SO4 或固溶在贝利特中(较少生成 CaSO4,具有高挥发性)11 39 Wear MechanismsSO2K2O, SO3, Cl-K2O, SO3K2O, SO3, Cl-Kiln cycles 窑系统内(有害元素)的循环12 39Wear MechanismsAlkaline salt infiltration 碱盐渗透 influence of alkali/sulphur ratio 碱硫摩尔比的影响alkali/sulphur ratio 碱/硫摩尔比 reaction partners 参与反应的化合物 >1 alkali surplus 碱/硫摩尔比>1, 碱多 Free Na2O, K2O,non basic lining, chrome spinel 存在游离的Na2O,K2O, 非碱 性砖衬，铬尖晶石会受侵蚀 formation of nepheline corrosion of chrome spinel 形成霞石,铬尖晶石受侵蚀 ~ 1 (alkali sulphates) 碱/硫摩尔比~ 1 (硫酸碱) saturated compounds e.g. K2SO4 饱和的化合物, 如K2SO4 infiltration without reactions, densification of microstructure 没有反应的渗透，火砖 微观结构密实化 < 1 sulphate surplus < 1 硫酸盐多 free SO3 basic lining 存在游离的SO3，碱性 砖衬受侵蚀 corrosion of CS brick bonding 火砖的硅酸钙结合相 受侵蚀leads to 导致Balanced alkali/sulphur ratio ASR 碱/硫摩尔比ASRASR ~0,8 to 1,213 39 Wear MechanismsNa 2O K 2O Cl + − 94 71 = 62 SO3 80Wear process alkaline salt infiltration 损耗过程:碱盐渗透14 39Wear MechanismsAlkaline salt infiltration 碱盐渗透Chemical analysis 化学分析:MgO Al2O3 SiO2 CaO MgO Al2O3 SiO2 CaO 81,90% 9,41% 1,55% 3,22% 77,90% 7,46% 0,32% 0,62% MgO Al2O3 SiO2 CaO K2O Na2O SO3 Cl K2O Na2O SO3 Cl 2,01% 0,26% 2,15% 0,05% 7,04% 0,45% 7,79% 0,05% K2O Na2O SO3 Cl 0,26% 0,05% 0,52% 0,05%88,90% 8,72% 0,42% 0,78%densification of the microstructure and loss of thermo-mechanical brick properties (flexibility)火砖微观结构密实化，失去了热机械强度(弹性) crack formation at the interface between infiltrated and not infiltrated brick area 火砖在受渗透区域和未渗透区域之间的界面形成了裂缝 15 39 Wear MechanismsCorrosion of brick bonding 火砖陶瓷结合的腐蚀结 构 溃 散结 构 溃 散 裂 纹 原 始 结 构16 39 Wear MechanismsCorrosion of calcium-silicatic brick bonding 硅酸钙类火砖陶瓷结合的腐蚀2Ca2SiO4 + SO3 + MgO Ca3Mg(SiO4)2 + CaSO4 Ca3Mg(SiO4)2 + SO3 + MgO 2CaMgSiO4 + CaSO4 CaMgSiO4 + SO3 + MgO Mg2SiO4 + CaSO4 The corrosion of the calcium-silicatic brick bonding leads to a severe loss of the bricks bonding strength. The new formed phases are present as isolated particles within the pores and do not contribute to the brick bonding. 硅酸钙类火砖陶瓷结合的腐蚀导致火砖陶瓷结合强度严重的丧失。
新形成的 相孤立地存在于火砖孔隙中，没有结合强度。
The consequences are crack formation and finally spalling of hot face brick parts. 其结果是火砖形成了裂缝，最终火砖热面剥落下来。
17 39Wear MechanismsASR 碱硫摩尔比> 1:Alkali attack on non basic bricks 碱对非碱性砖的侵蚀Physical attack 物理侵蚀: - Deposition of alkali compounds in the open pores (densification of microstructure)碱类化合物在火砖敞开的孔隙中沉积下来(火砖微观结构密实化)Chemical attack 化学侵蚀: ΔV up to + 36% 体积膨胀量可达+ 36% - Incorporation of alkali oxides into glassy phase up to saturation (fireclay bricks)碱的氧化物结合成玻璃相达到饱和(粘土砖)- Reaction with cristobalite, quartz and mullite at T > 600°C, formation of orthoclase (KAS6),albite (NAS6), leucite (KAS4) and nepheline (NAS2) at T > 930°C: Volume increase up to 36% 在T > 600°C时和方英石(KAS4)，石英以及莫来石反应，形成正长石(KAS6), 钠长石(NAS6), 白 榴石(KAS4)以及在T > 930°C时形成霞石(NAS2) ：体积可增大36%。
-Formation of β-alumina (KA11) and K2O.Al2O3 at T 1000-1050°C: Volume increase up to 20%在T 1000-1050°C时形成β-氧化铝 (KA11) ：体积增加20%- Spalling of shells even at small temperature changes due to the increased thermal expansionof the reaction layers in comparison to mullite. 和莫来石相比，反应层的热膨胀率高，即使很小的温度变化，火砖表皮(反应层)即会剥落。
18 39 Wear Mechanismsα nepheline 霞石 ~ 3 α mullite莫来石ASR > 1 碱硫摩尔比> 1: Alkali attack on non basic bricks 碱对非碱性砖的侵蚀19 39Wear MechanismsExamples of alkali spalling 碱爆的示例⇐Alkaline spalling of andalusite bricks in the cooler front wall after 1 month.使用1个月后，冷却机前墙，红柱石的碱爆Alkaline spalling of castables ⇒ 浇筑料的碱爆20 39Wear Mechanisms熟料液相渗透Increased clinker melt due to unfavourable clinker composition or overheating of the kiln feed. Clinker melt infiltration is observed only at the hot face, mostly adjacent to a thick clinker coating. The affected brick microstructure is severely densified and the matrix heavily corroded. Often also a coagulation of the matrix and the formation of coarse pores can be observed. The loss of thermo-mechanical properties leads to crack formation and finally spalling. 因配料不当或窑喂料过烧而产生了过多的熟料液相。
