转炉热态自流修补料用结合剂的研究

研究了 3种以焦化副产品为原料制取的结合剂对转炉热态自流修补料烧结性能的影响。讨论了不同结合剂与不同性质沥青相配合时修补料的烧结强度指数及烧损率的变化。结果表明 :当采用重苯为原料合成的结合剂时 ,可以使修补料的烧结强度指数大于 80 % ;结合剂的最佳加入量为 4%。     

环保型(水系)转炉自流热修补料的研制

为了提高转炉寿命,降低炼钢成本,通常采用转炉溅渣护炉和大面热修补方法对转炉内衬进行维护。但转炉溅渣法存在两个缺点:1)修补后使用寿命短,要求维护频率高,溅渣护炉料消耗量大;2)修补的面积较大,不能够对熔损严重的凹坑或凹槽进行修补。而转炉内衬的损毁是不规则的,由于废钢加入和出钢等因素对于转炉的前后大面及炉底的破坏要较其他部位严重得多,因此需要采用热态自流修补料(大面修补料)对这些部位进行修补。热态自流修补料应当具有高温流动性好,烧结时间短,使用寿命长等优点。目前,许多钢厂使用的都是以镁砂、沥青和添加剂组成的热态自流修补料。这种材料在高温下会产     

新型转炉热补料的研究与应用

转炉装料侧、出钢侧、出钢口和炉底受高温作用及钢水与钢渣的化学侵蚀作用,装料侧还受到兑铁水和废钢的机械作用,从而造成局部损坏,导致停炉修补,严重影响炼钢生产。 热态修补料是对炉衬损毁部位进行修补以延长其使用寿命的必需材料。对热态修补料的要求是:高温流动性好,烧结时间短,与母体砖粘结性好。用于转炉装、出料侧(简称“大面”)及出钢口等部位修补的“焦油砂”修补料,存在烧     

出铁沟高温自流修补料的研制与应用

对高炉出铁沟易出现开裂现象作了分析,研究了临界颗粒粒度、结合剂和悬浮剂的种类对高温自流修补料性能的影响,开发出了Ａｌ２Ｏ３ＳｉＣＣ质自流修补料     

水结合大面补炉料在转炉上的应用

检测转炉用焦油结合和水结合修补料的高温流动性、烧结时间等性能,并将实际使用情况分析比较,水结合大面补炉料性能良好,解决了焦油结合修补料烧结时间长,劳动强度大,作业环境差等问题,在转炉使用中取得了较好的效果。     

铝粉加入对MgO-C热投射料的影响

MgO－C热投射料由烧结镁砂、沥青和强化流态剂组成。这种具有适当的流动性和硬化特性的投射料用于转炉，实践证明是有效的C据了七ikabut。uO。rsea。报道，RyusyuRefractoriesCo．．1。id研究了铝粉的加入对该材质热投射料性能的影响。用选定颗粒尺寸的烧结镁砂加沥青和作为流化剂的。乙内酸胺混合，制备两种试样。一种不加铝粉，另一种加5％铝粉替代MgO细粉。做投射料在投射时环境温度（1000～1300℃）与其硬化时间及强度关系的试验。试验表明。1200℃以上，加铝粉的MgO－C热投射料硬化时间缩短，且粘附强度提高。铝粉加入对MgO-C热…     

基于废旧镁碳砖的转炉热态修补料的研制与应用

为了回收再利用废旧镁碳砖,进一步提高耐火资源的利用率和附加值,以废旧镁碳砖颗粒、MS95烧结镁砂细粉、改性沥青为主要原料制备转炉热态修补料,分别研究了改性沥青(加入质量分数7%~21%)、Al粉(1%、2%和3%)和Al+B_4C复合粉(Al粉加入质量分数分别为1%、2%和3%,B_4C粉加入质量分数为0.5%)加入量对转炉热态修补料性能的影响,并选择最佳配方,进行了工业试验。结果表明:1)单独引入改性沥青19%(w)作为结合剂时,转炉热态修补料的铺展性能和强度均较好;2)同时添加3%(w)的Al粉和0.5%(w)的B_4C粉,与单一使用Al粉作为添加剂相比,可以显著提高试样的耐压强度和抗氧化性;3)以废旧镁碳砖为主要原料生产的转炉热态修补料具有铺展性好,补炉附着性强,烧结速度快,使用寿命长的优点,能满足转炉补炉要求,且优于现场使用的修补料。     

新型转炉热补料的研究与应用

1　前言长期以来 ,科研工作者已研制出一种“焦油砂”修补料进行转炉装出料侧 (简称“大面” )出钢口的修补。但是“焦油砂”修补烧结时间长、耐用性差 ( 70～ 90ｍｉｎ ,修补一次可使用 1～ 3次 ) ,而且“焦油砂”需将焦油和镁砂加热混合而成 ,生产工艺比较复杂。本研究针对“焦油砂”存在的弊端 ,研制出一种新型大面修补料 ,其特点是 :补炉料生产不需要热态加工 ,烧结时间短 ( 4 0～ 60ｍｉｎ) ,耐用性强 (修补一次可至少使用 8炉次 ) ,且成本低。2　实验研究2 .1　原料、结合剂及外加剂实验所用主要原料为镁砂 (化学组成见表 1 ) ,改性高…     

环保型转炉大面修补料的研制和应用

采用高纯镁砂、中档镁砂、镁白云石合成砂三种混合镁砂配料,以高温改性沥青、酚醛树脂等为结合剂,多元醇为助流剂,配以少量润湿剂,研制成了一种环保型转炉大面热态修补料。在转炉上的实际使用证明,该修补料高温流动性好,硬化时间短,强度高,使用寿命较长(平均寿命超过30炉),环保性好。     

高温投射修补料流动性的改善

1 前言 对转炉部分损毁部位进行修补,以谋求转炉的正常操作和延长炉子的使用寿命。作为其手段使用了各种类型的高温修补料。其中高温投射修补材料对转炉装料侧墙、炉底和出钢侧墙的修补非常有效,大多采用沥青和酚醛树脂的浆状烧结材料。 但是,沥青系修补料所需烧结时间很长,酚醛树脂系材料又存在时效变化等问题。 基于以上原因,调查和研究了沥青粉的特性对流动性的影响。另外,还研究了付与沥青流动性的添加剂的效果。进而依据这些研究结     

A simple mix design method for self-compacting concrete

This paper proposes a new mix design method for self-compacting concrete (SCC). First, the amount of aggregates required is determined, and the paste of binders is then filled into the voids of aggregates to ensure that the concrete thus obtained has flowability, self-compacting ability and other desired SCC properties. The amount of aggregates, binders and mixing water, as well as type and dosage of superplasticizer (SP) to be used are the major factors influencing the properties of SCC. Slump flow, V-funnel, L-flow, U-box and compressive strength tests were carried out to examine the performance of SCC, and the results indicate that the proposed method could produce successfully SCC of high quality. Compared to the method developed by the Japanese Ready-Mixed Concrete Association (JRMCA), this method is simpler, easier for implementation and less time-consuming, requires a smaller amount of binders and saves cost.     

FORMULATION OF INJECTION MOLDING BINDER SYSTEMS

A polyethylene and three ethylene vinyl acetate (EVA) copolymers were evaluated to determine the best mix of binder components. The effect of plasticizers and processing aids was investigated. One weight percent of silane coupling agent was added to improve the ceramic and binder mix stability. These mixes were evaluated from the Brabender torque data and capillary viscosity. A limited number of molding experiments were also performed. The results showed that polyethylene and EVA copolymers with a melt index of around 25 are the most suitable binders, that plasticizers improve the flowability of the mix; and that processing aids containing a double bond and amines reduce viscosity and improve moldability. Combining plasticizers, processing aids and a small concentration of an appropriate coupling agent results in a low primary binder concentration. EVA mixes have shown better flow and moldability.     

Hydraulic Alumina Binder for Extrusion of Alumina Ceramics

The present work describes the effect of hydraulic alumina (HA) as a new inorganic binder on extrusion of alumina ceramics. The addition of a small amount of HA imparted significant flowability and rigidity to the extruded alumina. Under optimum processing conditions such as amounts of HA and water, and curing period, alumina rods and tubes were successfully extruded using a single screw extruder. Sintered specimens have achieved a relative density of 97% after sintering at 1600°C for 2 h. Dense alumina samples prepared using organic and inorganic binders had similar mechanical properties, that is, Young's modulus >380 GPa and H _v>2000. These results suggest that HA is a new kind of inorganic binder applicable to the extrusion of ceramics.     

A study on the applicability of vibration in fresh high fluidity concrete

The introduction of superplasticizers (Sp) in the production of concrete has produced highly flowable mixtures with enhanced viscosity. In cases of optimum flowability and viscosity, for example self-compacting concrete (SCC), no vibration is necessary for placement. However, such ideal conditions are not practically easy to achieve and deviations are possible. This paper reviews the results of a study to investigate the vibration of such high fluidity concrete. Two criteria were used to characterize the fresh mix, that is, slump flow and V-funnel time (V-time). Firstly, the feasibility of vibration on such mixes was studied. Then, the significance of flowability and viscosity was determined. Next, the relationship between workability and its segregation tendency was investigated. Finally, concrete mixes that missed SCC criteria were vibrated. Three different scenarios of vibration were concluded: namely, mix that accept vibration freely, mix that required controlled vibration and mix that needed prior treatment of viscosity enhancing agent (VEA) before vibration.     

UHP电炉用新型干式打结料的应用

介绍了超高功率 (UHP)电炉干式打结料的侵蚀机理、技术要求及新型UHP电炉干式打结料的改进要点 ,以及研制的UHP电炉新型干式打结料在钢厂的实际应用情况。应用结果表明 :该打结料的开始烧结温度较低、烧结速度较快 ,能在较短的时间内形成高强度致密层 ;在使用过程中仅需简单热补或根本不用修补 ,大大缩短了炉子维修时间 ,降低了能耗 ;使用寿命较长。     

Polycrystalline cubic boron nitride sintered with Ti(C,N)-W-Al mechanically alloyed binders

The structural changes in Ti(C,N)-W-Al mechanically alloyed (MA) binders and the sintering mechanism of PcBN were investigated by XRD, SEM and TEM techniques. The elastic properties of PcBN compacted were determined by ultrasound technique. Tungsten was efficiently dissolved in Ti(C,N) by mechanical alloying, forming homogeneous binders during sintering. Opposite strain effects were induced in the binders than in PcBN particles. Dissolution of W in Ti(C,N) enhanced the fracturing of the cBN particles and the formation of the nanostructured binder pools by increasing the hardness of binder particles. Poisson's ratios and Young's moduli of the new PcBN products were higher than the reference product. Micro-Vickers hardness of sintered products increased with milling time of the binder powder. Slightly higher hardness values were achieved when Al powder was mechanically alloyed with Ti(C,N) and W powders than when it was attrition milled with MA Ti(C,N)-W.     

Chemical factors that influence the performance of mine sulphidic paste backfill

Sulphide-rich tailings from four Canadian mines were sampled (Mines A1, A2, B and C) to prepare several different paste backfill mixtures. The sulphur grade within these tailings samples range from 5 to 32 wt.%. The binders used were Portland-cement-based binders, fly-ash-based binders and slag-based binders with proportions ranging from 3 to 6 wt.%. The study was carried out in two stages. Stage I allowed us to understand the effects of binder type, binder proportion and tailings properties on compressive strength development of paste backfill during the course of curing time. It was pointed out that for high sulphide tailings, neither the slag-based binders nor the fly-ash-based binders were effective, whereas the sulphate-resistant-based binder (mix of Type I [TI] and Type V [TV] Portland cements) gave good long-term strength. However, the slag-based binders gave the best strength for low and medium sulphide-bearing tailings for which the Portland- and the fly-ash-based mixtures have a relatively low strength. Stage II allowed us to study the early stage strength acquisition of the various mixtures. It was found that the chemical composition of the mixing water plays a role on the mechanical behavior of certain cemented backfills.     

High-alumina refractory castables bonded with novel alumina-silica-based powdered binders

In recent years, nano-binders (mainly colloidal suspensions) have been proposed as alternative materials for applications that require CaO-free refractory lining or improved mechanical behavior at intermediate temperatures (700?°C<?T?<?1200?°C). Despite the benefits of these suspensions, nano-bonded castables usually present limited green mechanical strength and different on site logistics to handle the liquid. Considering the availability of novel alumina-silica-based powdered binders, this work investigated the role of submicron alumina and SioxX®-Zero (both supplied by Elkem company) on rheological and mechanical properties of vibratable high-alumina castables, aiming to identify whether they can be suitable options to replace colloidal silica suspensions. Cold and hot mechanical strength and apparent porosity in the range of 110–1400?°C, cyclic thermal shock resistance, creep tests and hot elastic modulus of the designed formulations were evaluated. According to the results, SioxX®-Zero-bonded compositions presented good flowability levels and their sintering process started around 800?°C. Adding boron carbide to the same formulations resulted in transient liquid sintering of the silica-containing refractories, which allowed the development of compositions with improved thermo-mechanical performance in the 600–1400?°C temperature range. Furthermore, the submicron alumina-bonded samples presented fast sintering, resulting in E values close to 200?GPa (the highest value so far registered in our lab for a coarse grain size formulation) after one heating-cooling thermal-cycle up to 1400?°C.     

酚醛树脂注塑固化成型及流动特性的研究

考察了辊压工艺及酚醛树脂的邻对位比值(O／P)对酚醛注塑料的成型时间及流动性的影响。结果表明注塑料的辊炼温度及时间对其成型时间及流动性有明显的影响，其中流动性受影响的幅度随树脂O／P值的不同而差别较大。O／P值愈高，流动性随辊压温度或辊压时间的增加而降低的趋势愈明显，成型时间随辊压温度或辊压时间的增加而缩短，但缩短的幅度受树脂O／P值改变影响较小。在不同O／P值酚醛树脂注塑料的各自最佳辊压工艺的条件下，影响注塑料成型时间的最关键因素是酚醛树脂的O／P值，O／P值愈高，成型时间愈短，而O／P值对注塑料的流动性的影响不明显。