Influence of Nano-Al_2O_3 on Properties of Magnesia Chrome Refractories

Magnesia chrome bricks were prepared with fiLsed MgO- Cr2 O3 synthesized material, fused magnesite and ：hrome ore as main starting materials. Nano-Al2O3 was tdded into refractories （ 2% , 4% and 6% in mass ） ;ubstit,ting for Al203 micropowder. After m＆ing and ;haping, the bricks were fired at 1 550 ℃, 1 600 91℃, t 650 ℃ and 1 750℃, respectively. The microstruc-ure , sintering property, mechanical properties, thermal ;kock resistance and shtg resistance of the specimens with he addition of nano-Al2O3 were investigated. The results indicate that the performance of brick with 4 mass% of nano-Al2O3 is greatly improred afier firing at 1 650 ℃.

Effects of Chrome Oxide Concentrate Powder on Properties of Magnesia Composite Materials

The magnesia composite materials were prepared using fused magnesia, used magnesia chrome bricks, magnesium aluminate spinel, alumina powder and chrome oxide powder as starting materials. In order to improve the performance of magnesia composite material, the influence of chrome oxide concentrate powder on the properties of magnesia composite material was re-searched. The apparent porosity, bulk density, cold crushing streugth, linear expausion and thermal shock resistance of the specimens were determined. The results show that adding chrome oxide concentrate promotes the formation of the composite phases of three kinds of spi-nel, which is beneficial to the thermal shock resistance.The magnesia chrome spbwl can not be .[brined at high temperatures theoreticalby, but can dissolve in the mag-nesia composite material. Comprehensively, the optimal addition of chrome oxide concentrate is 10. 0 mass% for the magnesia composite materials.

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.

Effect of Magnesia-Chrome Synthetic Materials on Magnesia-Alumina-Chrome Ramming Mixes

Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumina spinels. Their physical properties were tested and microstructures were analyzed. The results show that the ramming mixes made of different raw materials bring about different microstructures and properties although the mixes have the same chemical composition, binder content and aggregate size composition.

Magnesia-Chrome Refractories for Flash Furnace

The rapid development of our country' s heavy non-ferrous metallurgical technology and the revolution in new type of heavynon-ferrous metallurgical furnace have imposed more critical demand on the refractory materials ,i.e. high quality and long service life. This paper presents the domestic status of the refractories for flash furnace , briefly describes the wear of the refractory used, andit is considered that the domestic in refractories for flash-furnace can be surely realized.

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.

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.

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。

Influence of in situ formed spinel in bonding phase on mechanical properties and air permeability of magnesia-chrome porous purging materials

Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel smelting.However,practical applications of magnesia-chrome porous purging materials are stil hampered by the poor scouring resistance to molten steel and unstable air permeability owing to their low mechanical properties and uncontrollable pore structure.Therefore,the particle-packing type magnesiachrome porous purging materials reinforced by in situ formed spinel were prepared using fused magnesia-chrome particles and Al powders as major raw materials.The results show that in situ formed spinel solid solutions in bonding phase led to the decreased median pore size and increased pore surface fractal dimension from the reactions between Al powders and magnesia-chrome particles and along with high-temperature sintering,bonding between magnesia-chrome particles and the resultant mechanical properties of materials were greatly elevated.Besides,the results of air permeability tests and polynomial ftting indicated that the formation of spinel solid solutions was the main contributing factor for controllable air permeability,and pressure drop of porous purging materials was positively correlated with surface fractal dimension of pores.Moreover,the as-prepared porous purging materials added with 6 wt.%Al powders obtained the maximum cold crushing strength(54.2 MPa)and hot modulus of rupture(12.9 MPa)with median pore size of 24.06μm and ftting non-Darcian permeability coefficient of 0.97×10^(-6)m.

Research and Application of New Non-burned Periclase-magnesia Alumina Spinel Bricks

To meet the needs of environmental protection and promote the application of chromium-free refractories for RH refining furnaces, research on application of new non-burned periclase-magnesia alumina spinel bricks was carried out. Through laboratory research and field application, it is concluded that the non-burned periclase-magnesia alumina spinel brick can replace magnesia-chrome material, and its service life is equivalent to that of the magnesia-chrome material with reduced cost.

Development and Application of Chrome-free Refractory Materials for RH Degasser

The research progress and industrial application of chrome-free refractories for RH degasser were introduced in the paper.It is proved that unburned magnesia-spinel refractories used for RH throat and snorkel in Baosteel have longer service life compared with traditional direct bonded fused magnesia-chrome materials.The new developed chrome-free unburned magnesia-spinel composite can fully meet the present demand for RH operation and can be applied extensively for RH processing.At present,instead of chrome-containing materials,chrome-free refractories have been applied widely for RH in Baosteel.Super low carbon MgO-C material with high mechanical properties at mild and high temperatures can be an alternative chrome-free material for RH.

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。

铜冶金用镁铬耐火材料抗渣性的研究现状

这是一篇冶金陶瓷材料领域的论文。镁铬质耐火材料由于具有优异的高温强度和抗渣性,并且具有良好的使用性能,被广泛应用于炼铜工业。本文从理论上综述了铜冶金用镁铬耐火材料侵蚀机理的研究现状,并明晰了炉渣温度、原料物性如品位和Cr_2O_(3)的含量以及添加剂因素影响镁铬耐火材料抗渣性的作用机制,最后依据研究现状总结了提高镁铬耐火材料服役寿命的主要途径,为未来镁铬耐火材料的结构设计和性能调控提供指导与帮助。

铜熔渣对不同型号镁铬砖的侵蚀特性研究

结合扫描电子显微镜-能谱仪(SEM-EDS)、X射线显微分析仪、X射线光电子能谱(XPS)及Factsage热力学模拟计算,考察了铜熔渣碱度对镁铬砖的侵蚀影响。结果显示:铜熔渣熔炼过程中会渗透进炉砖小孔,与三氧化二铬反应生成六价铬酸盐侵蚀炉砖;镁铬砖侵蚀速率随铜熔渣碱度的增加而降低;镁铬砖含铬增加及配入添加剂A可降低铜渣对镁铬砖侵蚀。

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。

RH精炼炉用无铬耐火材料的研究现状和发展趋势

镁铬砖由于具有良好的抗热震性和良好的抗渣性,而被广泛应用于冶炼、水泥等高温炉上。自上世纪80年代起,铬公害问题已受到人们的关注,于是开发替代镁铬材料的环境友好型无铬耐火材料成为当今研究的热点。针对当前无铬耐火材料存在的问题,总结了各种无铬耐火材料的研究现状,并讨论了无铬耐火材料未来发展趋势和研究方向。

宝钢RH精炼炉用耐火材料无铬化的实现

介绍了宝钢RH炉内衬耐火材料无铬化工作及取得的成果,重点涉及下部槽、环流管和浸渍管部位无铬材料的开发应用过程。近年来,在RH槽体内壁上不断尝试了烧成镁尖晶石锆、刚玉-尖晶石和不烧镁尖晶石等材料,最终实现了以不烧镁尖晶石砖为主体,结合部分刚玉-尖晶石浇注料整体浇注浸渍管的方案,实现了对RH浸渍管、环流管、下部槽和中上部槽等部位整槽镁铬质耐火材料的替代。工业应用试验表明,RH精炼炉的寿命业绩和成本消耗均获得进步,至2012年底,宝钢炼钢厂全面实现了RH精炼炉用无铬耐火材料的工业化应用。

镁锆砖和镁铬砖的抗RH炉渣侵蚀性对比

为取代RH炉用镁铬材料,以电熔镁砂为主原料,分别加入单斜锆、脱硅锆、单斜锆与脱硅锆的混合粉、锆英石制备了ZrO2质量分数分别为15%和20%的镁锆砖,并利用静态坩埚法对比研究了镁锆砖和镁铬砖的抗RH炉渣侵蚀性。结果表明:对于Al2O3含量高且碱度(CaO/SiO2比)大的RH炉渣,镁锆砖抗侵蚀性能优于镁铬砖的;镁锆砖的侵蚀机理是砖中的ZrO2与渣中的CaO迅速反应,形成高熔点物相CaZrO3,能堵塞砖中的孔隙而形成致密保护层,从而阻止钢渣对镁锆砖的进一步侵蚀;而镁铬砖的侵蚀机理是渣中的Al2O3、Fe2O3等R3+和镁铬尖晶石中Cr3+交换,渣与砖反应生成的镁铝尖晶石和镁铁尖晶石使得材料变性,同时由于体积效应使镁铬材料鼓胀开裂,从而导致镁铬砖的严重侵蚀。

Mg对Cr_2O_3/Al_2O_3催化剂及其丙烷脱氢性能的影响

制备了不同Mg含量的Cr2O3-MgO／Al2O3催化剂，考察了Mg含量对Cr2O3／Al2O3催化剂丙烷脱氢反应性能的影响，并通过低温N2吸附-脱附，XRF，XRD，NH3-TPD，H2—TPR，SEM等手段对催化剂进行了表征。结果表明：MgO的加入能提高丙烷脱氢反应中的丙烯选择性，主要原因是MgO的加入使载体表面酸量减少，调变了催化剂中Cr价态的分布，并使cr晶粒变小，更好地分散在载体上；Cr2O3-MgO／A1zO。催化剂中Cr2O负载量（w）为18％时，MgO负载量（ω）为1％～2％较为适宜，催化剂的性能可达到最佳，在反应条件下3h内，丙烷平均转化率为33％，丙烯选择性为93％。

纳米Fe_2O_3对镁铬耐火材料烧结及力学性能的影响

在镁铬耐火材料中添加纳米Fe_2O_3,研究了它对镁铬耐火材料烧结性能与常温力学性能的影响。结果发现,在相同的工艺条件下,加入1％(外加)的纳米Fe_2O_3即可使镁铬砖的烧成温度降低150℃左右,并在相同烧成温度下能使试样的常温抗折强度和耐压强度大幅度提高。分析认为,在镁铬耐火材料中添加少量纳米级Fe_2O_3,可促进MgO-FeO固溶体中Cr^(3+)和Al^(3+)含量的提高,增强镁铬砖的直接结合程度,从而提高其力学性能。