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.

The Properties of the Carbonated Brick Made of Steel Slag-slaked Lime Mixture

The properties of the carbonated brick made of steel slag-slaked lime mixture such as strength, drying shrinkage, water absorption and soundness were mainly investigated. The experimental results indicate that, after carbonation, the strength of the brick increases, its drying shrinkage reduces, and its soundness becomes eligible. The optimal slaked lime/steel slag（SL/SS） ratio for the carbonated brick is 0.2 and the asprepared brick meets the requirements of the Chinese standard for MU20-grade building bricks, additionally, it also demonstrates prominent environmental benefits. The XRD and pore structure analyses indicate that the excellent properties of this carbonated brick are attributed to the formation of carbonate crystals and the dense structure due to the carbonation.

Effect of Ti(C,N) on Properties of Low-carbon MgO-C Bricks

The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XRD and SEM analysis together with EDS. The results showed that Ti （ C, N） distributed in the matrix of lowcarbon MgO - C brick uniformly after being treated at 1 600 ~C for 3 h in coke powder bed, and Ti （C, N） and MgO formed a solid solution. After the treatment at 1 600 ℃ for 3 h in coke powder bed, the bulk density and cold crushing strength of low-carbon MgO - C brick with Ti （ C, N） decreased, and the apparent porosity and linear change rate of specimens increased. The oxidation resistance of low-carbon MgO - C brick with Ti（ C, N） was superior to that of low-carbon MgO - C brick with no additives, but inferior to that of low-car- bon MgO - C brick with Al powder. The slag resistance of the specimen with Ti （ C, N） was excellent as well.

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.

CFRP-聚合物砂浆加固震损构造柱约束砖砌体墙试验研究

为研究斜向碳纤维布条带或斜向聚合物砂浆条带与外覆角钢组合的加固方式对震后砌体结构的加固效果,对模拟经过地震作用的三面带构造柱约束砌体墙片进行抗震加固,并进行拟静力试验。三面砌体墙均采用角钢外覆加固,面层采用不同方式处理。研究结果表明:采用碳纤维布-聚合物砂浆条带的加固方式能很好地恢复震损墙体的承载能力和变形能力;碳纤维布条带在限制裂缝开展以及提高震损结构延性方面有一定贡献;面层采用斜向聚合物砂浆条带加固的震损墙体延性和承载力均较低。工程实际应用中,建议考虑两种材料的复合加固形式。

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.

高炉炉缸侧壁碳复合砖残余厚度和热面处保护层厚度传热模型分析

山东泰山钢铁集团有限公司(简称泰钢)1号高炉自2019年10月开炉投产以来,炉缸热电偶温度基本保持较低的温度。通过建立一维稳态传热模型计算碳复合砖的残余厚度和热面处保护层的厚度。结果表明,炉缸底部侧壁的碳复合砖侵蚀量较少,炉缸铁口中心线附近碳复合砖侵蚀量较多,高炉炉缸区域未出现“象脚状”侵蚀。高炉炉缸内保护层的厚度随着高度的增加而增大,富铁保护层易在铁口中心线以下形成,富渣保护层易在铁口中心线以上形成。碳复合砖中的主要成分氧化铝几乎不与铁水发生反应,而二氧化硅会与铁水发生反应。铁水渗透进入碳复合砖的临界孔隙为2.030μm,远大于其平均孔隙0.238μm,因此,采用碳复合砖有利于抵抗铁水的侵蚀。

鱼雷罐内加废钢对耐材影响分析

对某钢厂25#鱼雷罐的耐材渣样进行分析,结果表明:25#鱼雷罐罐内残留渣成分与高炉渣成分相差较大,尤其MnO含量较高。通过扫描电镜分析可知,MnO、CaO等对铝碳化硅炭砖的骨料和基质熔损较大。25#鱼雷罐锥体出坑与此罐运转过程中,罐内局部渣铁成分发生巨大变化,其对铝碳化硅炭砖熔损较快,导致局部出坑。

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。

焦炉炭化室用后硅砖的分析研究

为了解焦炉炭化室硅砖在使用中的损毁机制,对使用了40多年的JN43型侧喷式焦炉炭化室的硅砖进行取样分析,对样品的外观、理化性能、物相组成、显微结构等进行了分析研究。分析发现:1)用后的焦炉炭化室上、中、下3个不同部位的硅砖从炭化室到燃烧室方向,都形成了颜色、质地显著不同的层带;2)煤中的焦油组分对炉墙砖产生了很强的渗透作用,而煤中氧化物组分对炉墙砖的渗透轻微;3)炉墙在高温作用下发生烧结,体积总体呈收缩趋势;4)炉墙燃烧室侧约1/3炉墙厚度内的砖中方石英和石英相消失,鳞石英晶粒显著长大,较多开口气孔变成了闭气孔,线膨胀率降低;5)炉墙靠炭化室侧约1/2炉墙内石英和方石英部分鳞石英化,造成该区域线膨胀率降低。

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.

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.

Eco-Friendly Smokeless Al_2O_3-SiC-C Brick for Hot Metal Ladle

Hot metal transfer ladles were historically lined with high alumina refractories because of compatibility of high alumina refractories with the highly acidic slag, which is transferred .from the iron making plant along with hot metal. With the introduction of higher capacity ladles, technological advancement in the process and increased productivity, calls for a higher campaign life of hot metal ladles, which could not be performed by ordinary high alumina refractories. Resin bonded Al2O3- SiC-C （hereinafter ASC ） bricks gradually developed which at present taking place replacing the conventional refractories. Considerable work has been carried out in developing the ASC refractory to reach the present state. However, for higher capacity ladles still there is a lot of scope for improvement. The present paper deals with the newly developed ASC bricks, which was used in 165 ton capacity hot metal ladles in one European plant and has given a substantial increase in performance. But, the customer was not fuUy satisfied since the brick was reported to produce smokes during preheating of the ladle. In the subsequent supply the smoke generation problem was taken care by adjusting the binders and additives and eco-friendly bricks were re-engineered and supplied to the same plant, which also performed splendidly and created all time record in their plant history.