Research of Lignin Modified Phenol Formaldehyde Resin Bonded Magnesia Carbon Bricks

In order to reduce the cost and to improve the low temperature bonding strength of phenol formaldehyde resin（ PF）,the lignin modified phenol formaldehyde resin（ LPF） was synthesized using calcium lignosulfonate as a partial replacement of phenol,and sodium hydroxide as catalyzer. Then the magnesia carbon bricks were prepared using the LPF as binder. Different process conditions of LPFs such as calcium lignosulfonate additions（ 10%,20%,30%,40% and 50%,in mass,the same hereinafter）,catalyzer additions（ extra added,1%,2%,3%,4% and 5%） and reaction times（ 1,1. 5,2,2. 5 and 3 h） were investigated. Effects of prepared LPFs on properties of magnesia carbon bricks（ baked at 200 ℃ for 24 h） were researched in order to modify the synthesizing conditions of LPFs. Cold physical properties and hot modulus of rupture of magnesia carbon bricks bonded by LPF and by traditional PF after baked at 200 ℃ for 24 h and fired at 1 200 ℃ for 3 h were compared,respectively. The results show that the optimal synthesizing conditions of LPF for preparing magnesia carbon bricks are 30% calcium lignosulfonate,1% catalyzer,and 2 h reaction time. The magnesia carbon bricks bonded by the optimal LPF achieve：（ 1） the bulk densities 2. 84 g · cm- 3and 2. 82g·cm- 3,apparent porosities 9. 6% and 14. 6%,moduli of rupture 17. 8 MPa and 6. 4 MPa,crushing strengths72. 3 MPa and 48. 7 MPa,after baked at 200 ℃ and1 200 ℃,respectively;（ 2） the hot modulus of rupture7. 3 MPa after fired at 1 400 ℃. The above properties are better than those of the magnesia carbon brick bonded by PF.

Magnesia Carbon Bricks

1 Scope This standard specifies the classification, technical requirements, test methods, quality appraisal procedures, packing, marking, transportation, storage, and quality certificate of magnesia carbon bricks.

Magnesia Carbon Brick

1 Scope This standard specifies the classification, technical requirements, test method, inspection rules, marking, packing, transportation and storage of magnesia carbon brick.

Synthesis of Magnesium Aluminate Spinel-corundum Composite with Waste Slide Plate and Magnesia Carbon Brick

Magnesium aluminate spinel -corundum composite was prepared with waste slide plate and magnesia carbon brick. Microstructure and sintering ability of as-prepared magnesium aluminate spinel -corundum composite were investigated with XRD, SEM, and DSC/TG. With the addition of waste slide plate increasing or synthesis tem- perature rising, the bulk density of the specimen increases and the apparent porosity decreases, but the crystallinity of the specimen decreases and the magnesium alaminate spinel phase increases. The obtained composite contains 72% spinel and 26% corundum. Primary phase and secondary phase are bonded by glass phase. The results show that it is feasible to synthesis magnesium aluminate spinel - corundum material with waste slide plate and magnesia carbon brick.

Development of a Thermoplastic Magnesia Carbon Brick ——“A Cold Process Flexible System”

Conventional resin bonded MgO-C bricks, which are manufactured via cold mixing process, harden and attain brittleness during carbonization of resin due to the formation of isotropic glassy carbon. They do not exhibit thermo-plasticity, which can facilitate the release of huge amount of stresses generated during preheating or in operation. On the contrary, pitch bonded MgO-C bricks, show better pyro-plasticity due to formation of an anisotropic and graphitized coke structure during carbonization of pitch. Hence, pitch bonded bricks show a superior structural spalling resistance in comparison to resin-bonded bricks. One of the drawbacks of pitch-bonded bricks is that the manufacturing requires a hot mixing process and hot pressing facility. This paper describes how a combination of above two processes was optimized to make a MgO-C brick via cold process. These bricks exhibit a low Modulus of Elasticity and thereby facilitate release of stresses during operation. Normal coal tar pitch is considered as an environmental hazard due to the presence of polyaromatic hydrocarbons like benzopyrene B [ a ] P. So, a special binder with a low B[ a ] P was selected, which is eco-friendly in nature. Such bricks were made in our plant in China and supplied to an integrated steel plant in Europe for their ladle. The bricks supplied have given encouraging life.

Effects of B_4 C and Si Antioxidant on Oxidation Resistance of Low-carbon MgO-C Brick

Low-carbon MgO - C specimens with dimension of Ф6 mm × 36 mm were prepared using fused magnesia, flake graphite and carbon black as main starting materials, thermoplastic phenolic resin as binder, hexamethyl ene tetramine as curing agent, Si powder （ w （Si） 〉 80%, particle size 〈0. 074 mm） and B℃ （ d90 =36. 5 μm ） as antioxidant, pressing under 200 MPa and drying at 200 ℃ for 24 h. The oxidation resistance tests were conducted at 600 ℃ , 1 000 ℃ and 1 400 ℃ for 2 h, respectively. Effects of B4C and Si antioxidant on oxidation resistance of low-carbon MgO - C brick were studied by comparing the areas of the decarburized layers. The results shaw that： （1） When Si powder addition is 3%, at 600 ℃ and 1 000 ℃, the specimens with 0. 5% B4C perform good oxidation resistance; at 1 400 ℃, the oxidation resistance of the specimens is improved with the addition of B4C increasing, and that of the specimen with 0. 7% B4 C is the best. （2） When B4C addition is 0. 5%, at 600 ℃ and 1 000 ℃ ,the oxidation resistances of the specimens with 3% and 5% Si powder are similar, which are better than that of the specimen with 1% Si powder; and at 1 400 ℃ , the oxidation resistance of the specimens is improved obviously with the addition of Si powder increasing, and that of the specimen with 5% Si powder is the best. （3） Bused on the results, it is believed that the low-carbon MgO - C brick with 0. 5% B4C and 3% Si powder performs the best oxidation resistance.

Aluminum and Activated Alumina Powder Additions on Microwave Synthesis of Al_(4)SiC_(4)

Aiming at improving the properties of magnesia carbon materials,silicon aluminum carbide(Al_(4)SiC_(4))containing materials were prepared using industrial aluminum powder,silicon carbide powder,and graphite as raw materials,and activated alumina powder as an additive,mixing thoroughly,pressing into cylinders and then firing at 1200℃for 30 min in a carbon embedded atmosphere by the microwave method.The effects of the aluminum powder addition(20%and 24%,by mass)and activated alumina powder addition(0,3%,5%and 7%,by mass)on the microwave synthesis of Al_(4)SiC_(4) as well as the effect of the obtained Al_(4)SiC_(4) containing material on the properties of magnesia carbon bricks were studied.The results show that:compared with the samples with 20%aluminum powder,those with 24%aluminum powder generate more Al_(4)SiC_(4).With the activated alumina powder addition increasing from 0 to 7%,the amount of Al_(4)SiC_(4) generated increases first and then decreases.Compared with the sample without activated alumina powder,the samples with activated alumina powder show lower bulk density and higher apparent porosity.With the activated alumina powder addition increasing from 3%to 7%,the bulk density of the samples increases first and then decreases,while the apparent porosity of the samples shows an opposite trend.The optimal additions are 24%aluminum powder and 5%activated alumina powder,and Al_(4)SiC_(4) synthesized in this sample has a hexagonal plate structure.With the synthesized Al_(4)SiC_(4) containing material added,the magnesia carbon brick has slightly increased cold modulus of rupture,basically the same modulus of elasticity and improved oxidation resistance.

高精炼比模式下钢包渣线镁碳砖的研制及应用

为提高MgO-C砖使用寿命,在分析了国内某钢厂210 t精炼钢包在高精炼比冶炼模式下的渣线MgO-C砖损毁机制的基础上,以97级电熔镁砂、鳞片石墨、富镁尖晶石微粉、抗氧化剂(Al粉+Si粉)和酚醛树脂为原料制备镁碳砖,研究了以不同量(加入质量分数分别为0、3%、6%)的富镁尖晶石微粉等量替代电熔镁砂细粉对试样物理性能、抗氧化性、抗渣性的影响。结果表明:与未添加富镁尖晶石微粉试样相比,添加3%(w)富镁尖晶石微粉时,试样的力学性能、抗氧化性和高温抗折强度都有明显提升,线膨胀率有一定下降;但随着富镁尖晶石微粉加入量增加至6%(w),试样的综合性能呈现下降趋势。将加入3%(w)富镁尖晶石微粉的镁碳砖应用在钢包渣线上,在高精炼比冶炼工况条件下,镁碳砖“馒头状”熔损和竖缝等问题得到明显改善。

Properties of Phenolic Resins——CarboresP Binders for Magnesite Carbon Refractories

An environmental friendly carbonaceous material- carboresP （one of the Carbores series materials） was investigated for the production of MgO-C refractories in laboratory scale and field tests. The MgO-C specimens were produced with different CarboresP contents. The bulk density （180℃ × 48h）, CCS, apparent porosity （1000℃ ×3h ） and hot modulus of rupture （1400℃ ×0. 5h ） were tested and contrasted. The appropriate amount of carboresP was 1.0%. The amount of metallic additions can be partially substituted （reduced to 1.5% ）. The microstructure of resin-carboresP binder is anisotropic structure with high oxidation resistance and good thermal-shock stability. The Stress/strain curve indicates that the characteristic length, （LCH） of MgO-C brick with resin/CarboresP bonding has been improved, which means the MgO-C bricks have good mechanical flexibility and stresses absorbability. Field tests were done in slag line of a 40t LF-VD refining steel ladle using Resin/CarboresP bonded ＂ MT-14A MgO-C bricks. The result shows that the MgO-C bricks by ＂soft bonding＂ have good physical properties and excellent workability during production of the bricks . In contrast with traditional MgO-C brick used for secondary refining furnaces, the spalling tendency of the bricks could be reduced significantly. The average lining life of the resin/ CarboresP bricks has increased by 18. 4% comparing with the pure resin-bonded types.

A Review on Some Applications of Magnesia in Current China Refractories Industry

Magnesia-based refractories hold a big share in the total refractories output in China because of abundance of magnesite resource. In this paper a short review has been focused on the current and future new use of magnesia in the production of magnesia-based products including low carbon MgO-C bricks, MgO- CaO bricks, MgO-based castables, MgO-CaO-Fe2O3 ramming mix and MgO-CaO-C bricks for low carbon steelmaking and clean steel making, magnesite ball for slag splashing, MgO-CaO-ZrO2 for sintering and transfering zones of cement kiln and MgAlON for special use in the steel industry.

The Effect of Graphite Particle Size on Properties of Low Carbon MgO-C Composite Materials

The effects of graphite granularity on the properties of low carbon MgO-C based materials have been investigated in the work. Large crystal fused magnesia, natural flake graphite with different particle sizes and anti-oxidant were adopted as raw material for preparation of specimens. However, the results show that the physical properties, oxidation resistance and thermal shock resistance of low carbon MgO-C materials with content of 4.0wt% graphite are improved obviously through the use of special and suitable size graphite. The excellent performance achieved was considered as a result of microstructure modification of MgO-C materials. Therefore, it is suggested that both fine and micro grade natural flake graphite used for production of low carbon MgO-C bricks.

Effects of Resins with Different Molecular Structures on Properties of MgO-C Bricks

Resins PFG-4 , PFG-8 and a reference resin （resin A） were used as binders of MgO - C bricks, effects of the resins with different molecular structures on wettability of magnesia, on physical properties, mechanical properties, oxidation resistance and thermal expansion properties of MgO- C bricks were researched. The results show that the microstructures of solidified resins with different mo- lecular structures are different, which have obvious effect on the cold mechanical properties of MgO - C brick, but little effect on the oxidation resistance, thermal perform- ance and expansion properties.

Properties,Performance and Quality Control of Recycled MgO-C Bricks

Properties, section structure and service results of recycled MgO-C bricks and new MgO-C bricks for ladle slag line of Baosteel were analyzed and compared, and the measures of improving stability and quality of recycled MgO-C bricks were summarized. The results show that： （1） High quality recycled MgO-C materials can be produced by scientific, meticulous and strict management for every process such as dismantling furnace, selection, removing impurity and slag, stacking and homogenization ; （2） Using high quality recycled materials and reasonable production technique, recycled MgO-C bricks with better properties and service efficiency than those of new MgO-C brick can be produced; （3） Service efficiency of recycled MgO - C bricks is good because of its high density, good oxidation resistance and reasonable structure.

电炉炼钢过程渣线镁碳砖侵蚀机理研究

针对宝钢电炉冶炼过程中,炉衬渣线镁碳砖耐火材料侵蚀严重导致电炉炉龄偏低的问题,通过对镁碳砖耐火材料侵蚀微观结构的观察及钼丝炉内炉渣侵蚀镁碳砖试验,得知FeO x·MnO·MgO相是镁碳砖耐火材料溶解到炉渣后形成的主相,渣中FeO、MnO具备了溶解MgO能力,炉渣中FeO x含量偏高是导致镁碳砖耐火材料侵蚀严重的主要因素;电炉炉渣体系内,炉渣碱度对镁碳砖耐火材料侵蚀影响不明显。钼丝炉内炉渣侵蚀试验表明:温度越高,镁碳砖耐火材料侵蚀越严重;高温段保温时间对侵蚀影响不大;渣线镁碳砖耐火材料进行冷热交替试验后,镁碳砖耐火材料侵蚀相对严重。根据试验结果,采取降低炉渣FeO x含量、缩短冶炼过程炉与炉之间间隔时间等措施,炉壁镁碳砖耐火材料侵蚀得到缓解,电炉中期炉龄稳定提升到450炉以上。

镁砂品级对镁碳砖显微结构和组成的影响

为了对镁砂原料和役后镁碳砖更合理的利用,研究不同品级镁砂对镁碳砖显微结构和组成的影响。首先,进行热力学计算,确定了镁碳砖中MgO、SiO_(2)和FeO与石墨的反应温度,然后分别以96.5、97.5、98.5电熔镁砂和99高纯鳞片石墨为原料,以PF-5323型热固性酚醛树脂为结合剂,压制成型后在埋碳气氛下经不同温度热处理,得到不同品级镁碳砖,测其对常温性能的影响并借助SEM和EDS对其进行显微结构分析,研究镁碳砖显微结构和组成的变化规律。结果表明:随着镁砂原料品级的提高,镁碳砖体积密度增大,显气孔率降低,常温强度升高,显微结构更为致密。镁碳砖经高温热处理后,材料体系发生自耗反应,使二氧化硅、氧化铁含量降低,C/S比变大,自耗反应程度随着品级的提高而降低。有害成分的减少会对镁碳砖有提纯效果,可使低品级镁砂应用于更为苛刻场合,提高资源利用率。985镁碳砖相比于965镁碳砖而言有优异的性能表现,但是跟975镁碳砖相比差异不大,而且98.5镁砂价格昂贵,再加上废弃镁碳砖回收利用率较低,高档镁砂不足以发挥其全部价值,不利于节约资源,保护环境。

电炉渣线砖侵蚀机理及研究进展

电炉渣线磨损是电炉最大的耐火材料问题。本文结合实际生产情况,分析了电炉渣线部位的侵蚀机理,介绍了电炉渣线砖的研究进展及延长电炉渣线寿命的措施。

120 t双水口LF精炼钢包生产实践

针对双水口全精炼钢包内衬严重侵蚀,影响钢包安全使用、制约生产顺行的现状,对双水口全精炼钢包寿命提升进行研究。通过开发应用钢包内衬复合砌筑、精炼喷粉调渣、电极溅渣补包等技术手段,使双水口全精炼钢包寿命大幅提升,一次包龄由35.9次提高到53.7次。

低碳镁炭砖及其研究进展

分别就导热性、抗热剥落性能、抗氧化性、抗渣侵蚀性能等几个方面综述了低碳镁炭砖的研究进展 ,并讨论了影响这些性能的一些因素。指出了低碳镁炭砖亟待解决的问题是提高其抗热剥落性 ,抑制碳的氧化 ,提高材料的抗渣侵蚀性。最后指出 。

防氧化剂TiN和Al对MgO-C砖性能的影响

以3～1 mm、＜1 mm、＜0.088 mm的电熔镁砂和＜0.15 mm的鳞片石墨为原料,热固性酚醛树脂为结合剂,分别加入0.5%、1%、2%、4%的含碳TiN或2%的Al粉为防氧化剂,制备了镁碳砖试样,并与无防氧化剂的试样对比进行抗氧化性和抗渣侵蚀试验.结果表明：添加Al粉试样的抗氧化性能最好,TiN的次之,未加防氧化剂的最差;添加TiN试样的抗渣性能最好,无防氧化剂的次之,添加Al粉的最差.镁碳砖中引入适量TiN后明显提高抗渣侵蚀性能的原因是：TiN氧化生成TiO2时产生的体积膨胀堵塞气孔,阻止熔渣侵入;TiO2与渣中的CaO反应生成3CaO·TiO2,提高渣的粘度.综合各项性能,TiN的最佳加入量为2%.