Effect of Reduction Atmosphere on Properties of High Chrome Bricks

The high chrome bricks specimens were prepared by firing at 1 350,1 450 and 1 550 ℃ in carbon embedded condition and at 1 700 ℃ in air,respectively. Effects of firing atmospheres （carbon embedded and air） on bulk density,apparent porosity,cold crushing strength,and slag penetration resistance of high chrome bricks were researched in order to improve physical properties and corrosion resistance of high chrome bricks and to prolong the service life in slagging coal gasifier. The results show that with temperature rising,the apparent porosity of specimens decreases and the bulk density increases; the cold crushing strength of the specimens carbon embedded fired at 1 450 ℃ is the highest,reaching 214 MPa; carbon embedded condition is beneficial to reducing the sintering temperature and improving the microstructure; the specimens carbon embedded fired at 1 450 ℃ perform better slag penetration resistance than the specimens fired at 1 700 ℃ in air.

The Effect of Sintering Temperature on Microstructure of High Chrome Bricks

The microstructure of high chrome bricks made at different sintering temperature are analyzed by SEM . The results indicate that the sintering temperature of high chromebricks has an optimum range , it is not the higher, the better, The high chrome bricks made at this -sintering temperature have the moderate crystal six in the matrix and of dense structure. The closed bonding structure could be obtained between grains and matrix and no crackle occurred.The high chrome bricks with this microstructure have the best dynamic properties.

Damage Mechanism of High Chrome Bricks for Opposed Multi Nozzle Gasifier and Their Improvement

To reveal the damage mechanism of high chrome bricks for opposed multi nozzle gasifier with expanded diameter,the chemical composition and the morphology of a used high chrome brick were researched using XRF,SEM and EDS,and the properties of the high chrome bricks were improved by adding ultra fine alumina,alumina-chrome-iron oxide synthetic material with spinel structure,and chromium metal.The results show that(1)the high chrome brick is seriously damaged by the chemical dissolution of chrome as well as the chemical reactions at the slag/brick interface,the slag penetration and the structural spalling;(2)FeO in the slag reacts with Cr_(2)O_(3)in the brick to form a FeCr_(2)O_(4)layer on the particle surface thus leading to spalling;CaO reacts with SiO_(2)and Al2O3 in the brick forming a metamorphic layer of low melting point materials;due to the different thermal expansion coefficients of the metamorphic layer and the original brick,cracks appear and continue to expand and deepen under multiple temperature and pressure fluctuations thus leading to spalling of brick layer;(3)the improved brick has decreased apparent porosity,increased bulk density and compressive strength,and better thermal shock resistance compared with the original brick;after one cycle of on-site application,the furnace lining surface is smooth and flat with little damage,indicating that the improved high chrome bricks basically meet the working condition requirements of the opposed multi nozzle gasifier with expanded diameter,however,the final effects need to be evaluated in detail after the whole furnace service.

Study on Microstructure and Slag Corrosion Mechanism of High Chrome Bricks for Gasifier

Research was focused on slag corrosion mechanism of high chrome bricks used for different types of gasifier by comparing the structure of high chrome bricks for petroleum coke gasifier and water-coal slurry gasifier with slag corroded testing brick and water coal slurry gasifier through Scanning Electron Microscope （SEM） examination and X-ray diffi＇action. Results show that for high chrome brick used for petroleum coke gasifier, corrosion is mainly caused by Cr2O3 in the brick and V2O5 in molten slag and liquid phase generation at low temperature; for high chrome brick used for water-coal slurry gasifier, corrosion is caused by dissolution of Cr2O3 in molten slag and corrosion of ZrO2. For LIRR-HK95 brick, it performs better petroleum coke corrosion resistance than the others due to the optimal composition and structure.

Development and Application of High-Performance Magnesia-Chrome Bricks for RH Degasser

The paper analyses the wear mechanism of magnesia-chrome bricks for snorkel of RH degasser. High-performance magnesia-chrome bricks with good resistance to molten slag and infiltration resistance have been manufactured by means of reasonable fabricating technology. The application results of the developed magnesia-chrome bricks at 300t RH degasser of Baosteel indicate that the lining life has been increased up to 150 heats.

Chemical Corrosion Mechanisms of Magnesite-chrome Bricks by Converter Slag

The corrosion resistance of four kinds magnesitechrome bricks against converter salg was investigated by static crucible slag tests. The microstructures of the asdelivered and tested refractories were analyzed by means of SEM and EDS. The results showed that： Different magnesite-chrome bricks have different slag resistances. Generally, the slag resiantance sequence is as follows： rebounded fused magnesite-chrome brick 〉 semi-reboun- ded magnesite-chrome brick 〉 direct-bonded magnesitechrome brick 〉 silicate bonded magnesite-chrome brick. Slag reacts with the periclase of magnesite-chrome refractories, which results in the dissoving of periclase in fayalite slag. However, the complex spinels have superior slag resistance.

Effects of Firing and Operating Atmospheres on Microstructure and Properties of Phosphate Bonded Cr_2O_3-Al_2O_3-ZrO_2 Bricks

The microstructure and properties of phosphate bonded Cr2O3 - -Al2O3 - ZrO2 specimens fired in air or coke bed were investigated firstly. Then property change of the Cr2 O3 - Al2 O3 - ZrO2 bricks after secondary treat- ment in simulation environment was studied. Finally, corrosion resistances of the Cr2 O3 - Al2 O3 - ZrO2 bricks in air and simulation environment were compared; and microstructure of on-site used Cr2O3 - Al2O3 - ZrO2 bricks in slagging gasifiers was analyzed. The results show that the atmosphere has significant effect on the mi- crostructure and properties of the phosphate bonded Cr2O3 -Al2O3 -ZrO2 bricks. As the specimens are fired in air, the phosphate forms a composite solid solution with Cr2 O3 and Al2 O3, therefore, strength of the speci- mens is enhanced. For specimens fired in coke bed, a certain amount of gases are generated owing to the re- duction of phosphate and part of Cr2 O3, which results in the increasing number and size of the pores, bad interfa- cial bonding between Cr2O3 aggregates and matrix as well as low strength of the specimens. During service process in reducing atmosphere, the phosphate binder and part of Cr2O3 in edge of the specimens are also re- duced, leading to significant increase of number and size of the pores in the edge of the specimens; as a result, inreducing atmosphere, the specimens show much worse corrosion resistance than in air.

Slag Resistance of Magnesite-chrome Brick Impregnated with Chrome-bearing Sols

Cr2O3 has eminent slag corrosion resistance. So, the magnesite -chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world. After chromebearing sols being prepared by sol-gel method, single sol （ Cr（ OH）3） and mixed sol （ Mg（ OH）2 - Cr（ OH）3） were impregnated into magnesite - chrome bricks by vacuum impregnation. The corrosion resistance of the impregnated bricks to silicon steel slag was studied by porosimetric analysis and fractal dimension calculation. The results showed that the corrosion resistance of impregnated magnesite -chrome brick was better than that of the unimpregnated brick and the brick impregnated by MgSO4 solution, and the one which has surface-treated by Mg（ OH）2 -Cr（OH）3 sol was the best, mainly because of lower apparent porosity, smaller pores diameter and their smoother inner sarface.

Discussion on Wear Mechanism of High Chrome Brick Used in Coal Slurry Gasifier

The microstructure and phase composition of high chrome brick used in coal slurry gasifier has been analyzed by means of SEM and Energy Spectrum. The results indicate that the used brick can be divided into different zones as slag-adhered zone, reaction zone, penetration zone and unaltered zone. The phase composition and microstructure are different and cracks occurred in different degree at these zones. A dense ring belt was formed with complex spinel (Mg,Fe)(Cr,Al,Fe 2O 4) in the reaction zone near the hot face. The wear mechanism of the brick during its employment has been discussed. It is considered that the reaction and penetration of coal slag and strong reductant bring about the composition change of the brick and destroys its original network inlayed structure and consequently result in its structure spalling and weakening strength, which is the main wear mechanism of the brick and followed by temperature fluctuation and high mechanical impact of flowing fluid with high-speed.

Analysis of Spent High Chrome Brick in Slagging Gasifier

Wear of the spent high chrome brick in slagging gasifier was studied. The result shows that erosion and spalling are the m, ain wear mechanism of high chrome brick and the CaO content of coal slag is crucial to wear of high chrome brick.

Corrosion of Magnesia-chrome Brick by Smelting Reduction Slag with Iron Bath

Effects of FeO content （0, 5%, 10%, and 15% in mass, respectively ） in lab-synthesized smelting redttc- tion slag with iron bath and test temperature （1 450, 1 500, 1550, anti 1 600 ℃ ） on corrosion am,amount and microstructure of fused rebonded magnesia - chrome brick with 26.02 massqc of Cr2O3 were researched by rotary cylinder method. The results show that ： （ 1 ） the corro- sion amolult of magnesia -chrome brick by slag without FeO is higher than that by the slag with 5% FeO, and the vorrosion amount increases when FeO content increa- ses from 5% to 15% ; （2） the test temperature is one of the important factors affecting the slag corrosion resist- ance of magnesia - chrome brick, and the corrosion of smelting reduction slag to brick increases with the temperature rising.

Service Results and Analysis of Fully Co-clinkered Magnesite-Chrome Brick in Slagline Area of VOD Vessel

Operating condition and service results of several tested bricks in slagline area of the VOD vessel are described. It has been shown that the fully co-clinkered magnesite chrome brick is superior, followed by two-stage calcined magnesite-dolomite brick , prereacted magnesite-chrome brick and one-stage calcined magnesite-dolomite brick. Chemical and petrological examination were carried out by conventional analysis and optical microscope respectively. The reason of damage of the tested bricks are discussed and described as follows : (1) MgO in brick is erased and dissolved by slag to destroy structure of the direct bond ; (2) slag penetrating into the brick and then reacting with it to form various belts leading to spatting ; (3 ) reducing action of reducing agents ; (4) vaporization of some composition in the brick at high temperature under vacuum causes reducing weight and increasing porosity and (5 ) serious ma-chanic abrasion. Therefore, some opinions on increasing lining life of VOD vessels are suggested.

铜冶炼侧吹炉用镁铬质耐火材料损毁机制

为了保证新工艺下侧吹炉的安全稳定运行,采用扫描电子显微镜、能谱仪分析了铜冶炼侧吹炉渣线部位侧墙镁铬砖的侵蚀损毁机制。结果表明:1)位于渣线处的镁铬砖由于受到铜锍、熔渣的交替冲刷、渗透作用,难以形成稳定的挂渣层,造成镁铬砖渗透-侵蚀-剥落的持续循环,导致该处的镁铬砖蚀损最为严重;而渣线上部镁铬砖的蚀损程度较小,原因是铜锍在渣线上部镁铬砖中的渗透作用明显减弱,镁铬砖热面形成稳定的尖晶石及橄榄石相致密层,可以一定程度上阻挡熔渣和铜锍的进一步渗透及侵蚀。2)铜锍虽然在镁铬砖中仅沿气孔和晶界渗透,并不参与侵蚀反应,但其渗透后包裹于基质颗粒或晶粒周围,破坏了镁铬砖的直接结合,破坏原镁铬砖的稳定结构,降低镁铬砖对熔渣及铜锍的抗侵蚀性。3)铜锍主要沿铬铁矿颗粒周围以及析出富铁尖晶石的方镁石晶间渗透,不利于镁铬砖抵抗SiO_(2)-FeO熔渣的渗透与侵蚀。

The State-of-art of Magnesia-chrome Refractories for P-S Converter in China's Non-ferrous Industry

The state-of-art of magnesia-chrome refractories from direct-bonded magnesia chrome brick to fused-grain rebounded magnesia chrome brick for P-S converter is dis-cribed. The Cr2O3 content of the brick is continually increased with the reduction of the impurity content of brick , the pre-synthetic raw material it applied and the operating condition of convener is optimized so that the service life of convener is largely enhanced.

HIsmelt工艺熔融还原炉用耐火材料的抗侵蚀性研究

为促进HIsmelt工艺的进一步发展和应用,根据HIsmelt工艺熔融还原炉(SRV)的特点,利用静态坩埚法对比研究了SRV渣在1 500℃下对铬刚玉砖、微孔刚玉-莫来石砖、刚玉-莫来石砖、刚玉-尖晶石砖的侵蚀。结果表明:1)铬刚玉砖抗SRV渣渗透侵蚀能力最强,因为FeO与铬刚玉砖中的Al_(2)O_(3)和Cr_(2)O_(3)反应生成高熔点物,抑制炉渣的渗透和侵蚀。2)微孔刚玉-莫来石砖中镁铝尖晶石与钙铝黄长石的生成在侵蚀层形成保护层,阻止SRV渣的渗透侵蚀,在3种无铬材料中,表现出最优的抗侵蚀性。3)刚玉-莫来石砖中由于大量钙长石的形成产生的缝隙造成渣的不断渗入,使得熔渣对砖的侵蚀较严重。4)刚玉-尖晶石砖中原位生成粒径小、活性高的尖晶石晶粒,能有效吸收熔渣中的铁离子形成镁铝铁复合尖晶石,阻挡SRV渣的侵蚀。

水煤浆加压气化炉耐火材料损毁原因探析

为了探析水煤浆加压气化炉耐火材料的损毁原因,采用X射线荧光光谱分析(XRF)测试仪器研究了高铬耐火砖使用前后不同部位、不同工况下的氧化物组成及铬含量,结果表明:气化炉拱顶砖、筒体砖、下渣口砖侵蚀机理各不相同;高温条件下原料煤的熔渣与耐火砖表面进行反应、渗透,从而引起耐火砖的组分变化及强度改变,在气化炉内部残炭、灰渣颗粒的空间行为、壁面沉积、流场运动等共同作用下会导致耐火砖剥落;气化炉在运行过程中开停车、负荷波动等异常工况会加速耐火砖的侵蚀。

铜冶炼PS转炉风口区镁铬砖侵蚀机理的探究

为提高铜冶炼PS转炉风口区镁铬质耐火砖的使用寿命,对PS转炉风口区的镁铬残砖进行理化性能分析、化学成分分析和显微形貌分析,探究铜锍、粗铜和炉渣对镁铬砖的侵蚀机理,得出以下结论:铜锍和粗铜在以开口气孔、晶界及微裂纹为主要途径的渗透过程中造成镁铬砖的侵蚀,而炉内SO_(2)/SO_(3)气氛引起的结构疏松以及生产中因热震形成的裂纹,又加剧了铜锍和粗铜的继续渗透,从而引起镁铬砖的结构剥落和热剥落,这是导致风口区镁铬砖损坏的主要原因;炉渣渗透到镁铬砖后,与方镁石固溶体发生化学反应,导致方镁石溶解于硅铁系炉渣中,而镁铬砖中的铬精矿具有良好的抗渣性。因此,一方面,在选择耐火材料时应综合考虑其化学成分、结构致密性和抗热震性;另一方面,在实际生产中应通过均衡生产减少因温度剧烈波动而造成的热震作用,改变炉渣成分以减弱炉渣与耐火砖中方镁石的反应。

铁浴熔融还原炉长寿化技术研发与实践

HIsmelt熔融还原工艺具有工艺流程短、原料适用性强、产品纯净度高等特点,因采用较高的二次燃烧率,使得熔渣中含有较高的FeO含量,易侵蚀炉缸耐材。结合山东墨龙HIsmelt商业化工厂的技术研发与实践,介绍了该HIsmelt工厂建设情况和熔融还原工艺特点,并重点对耐火材料研发、炉衬结构优化和冷却装置创新方面进行了分析。结果表明:采用铝铬砖提高了耐材渣线区域的抗侵蚀能力,更加适合炉内的冶炼环境;渣区冷却器的设计增强了耐材上部炉渣的冷却强度,有助于减轻炉渣对耐材的侵蚀;虹吸出铁的工艺操作,使得熔融还原炉出铁工艺更加灵活可靠。耐火材料使用寿命的提高,对于熔融还原炉长期安全、稳定和高效运行具有重要意义。

RH炉和水煤浆加压气化炉中含铬耐火砖的应用与损毁机理

RH炉和水煤浆加压气化炉中均广泛使用了含铬耐火砖,分别为镁铬砖和铬铝锆砖,评述了这两种含铬耐火砖在相应高温炉中的应用和损毁机理。RH炉用镁铬砖研究进展包括RH炉及镁铬砖的发展、镁铬砖的损毁机理、镁铬砖的改性研究等三个方面。水煤浆加压气化炉用铬铝锆砖研究进展包括水煤浆加压气化炉及铬铝锆砖的简介、铬铝锆砖的损毁机理等两个方面。最后对RH炉用镁铬砖和水煤浆加压气化炉用铬铝锆砖的应用和研究进行了展望。