高炉富氢冶炼时渣-焦界面的润湿行为

高炉富氢冶炼后焦炭的气化反应行为发生了较大变化,改变了渣-焦界面润湿性,这对高炉的透气、透液性有着重要影响。利用渣-焦界面接触角测定试验研究了不同条件对渣-焦界面润湿性的影响规律,利用激光共聚焦显微镜对焦炭表面的三维形貌进行表征并分析了渣-焦界面作用机理。结果表明,随着焦炭与H₂O反应时间的增加,焦炭表面孔隙率逐渐增大,熔渣在焦炭表面的润湿驱动力增强,使熔渣与焦炭表面的接触角、界面张力和界面反应速率均随之降低,界面黏附功增大,熔渣在焦炭表面的润湿性改善。随着熔渣碱度的降低以及w(FeO)的增大,熔渣与焦炭表面的接触角和界面张力降低,界面反应速率和界面黏附功增加,熔渣在焦炭表面的润湿性改善;碱度在1.1～1.3变化时渣-焦界面润湿性变化幅度相对较小,w(FeO)由5%增加至10%时润湿性改善最明显;熔渣碱度降低以及w(FeO)增大均使熔渣对焦炭表面的溶蚀作用增加,使焦炭表面孔隙率和孔隙深度均明显增大,大气孔增多,熔渣对焦炭的黏附作用增强,不利于高炉生产。     

钛渣与焦炭界面性质的研究

为揭示钛渣粘结焦炭的实质,用测定接触角的方法研究了炉渣与石墨和TiN的润湿性,结果表明,钛渣(不论还原与否)和普通渣都能强烈润湿TiN,但都不润湿焦炭,钛渣润湿焦炭在于渣-焦界面处沉积有反应生成的Ti(CN)的作用。     

铁焦性能的影响因素及富氢高炉使用铁焦的探讨

铁焦是一种新型碳铁复合炉料,相比普通焦炭,其具有高反应性,能降低高炉热储备区温度,提高工作效率。铁焦的性能受制备原料的种类、配比和工艺参数等因素的影响。对于高炉富氢冶炼,因其铁矿石还原及成渣过程改变,需要加速初渣熔化和金属铁渗碳过程;而铁焦的气化反应温度低,有利于碳黑的析出和促进金属铁的渗碳,因此将铁焦代替部分焦炭应用于富氢高炉冶炼可以发挥铁焦和氢气的双重节能减排优势。系统讨论了制备因素对铁焦性能的影响,并探讨了铁焦在富氢高炉应用的可行性和优势。结果表明,铁矿粉对铁焦的反应性具有正向催化作用,加入一定配比的黏结剂可使铁焦结构致密,炭化温度会影响铁焦金属化率,适当的炭化时间可提高铁焦抗压强度和反应后强度。部分铁焦代替焦炭应用于富氢高炉,在发挥其高反应性作用的同时,还可以保护焦炭,加速铁水的渗碳过程并改善高炉的透气性。建议深入探索铁焦在富氢高炉内的反应行为和性能演变特点,并结合富氢高炉对铁焦的性能要求和制备铁焦的影响因素,研究适用于高炉富氢冶炼的铁焦制备技术,以推动高炉低碳冶炼技术的实施。     

浅谈高炉风口喷吹熔剂

根据高炉的炉料平衡,对典型高炉不同区域内的炉渣碱度进行计算。分析结果显示,在大喷煤条件下,传统的高炉配料方式导致炉内渣碱度变化很大,减少了高炉内气 液 固相共存区,降低了高炉下部的透气性。通过风口向炉内喷吹石灰粉来平衡喷煤灰分的碱度,可实现减少炉腹渣量、减缓炉内渣碱度波动、提高软熔带、扩大三相共存区、增加下部透气性、提高煤粉燃烧性、保证高炉顺行和提高高炉产量。     

兰炭替代部分焦炭对焦炭层透液性的影响

为探究高反应性兰炭替代部分焦炭加入高炉的可行性,文章通过对气化后的焦炭和兰炭进行冷、热态透液性试验,获得液体在焦床中的流动速度、滴落量及滞留量。结果表明,在高炉上部气化阶段,高反应性兰炭对焦炭有一定的保护作用。在冷态滴落实验中,小粒径燃料条件下,随着兰炭比例的增加,液体滴落速度变缓,滴落量降低16.8%。当兰炭粒度增加至20~23 mm时,液体滴落量增加约20%;热态炉渣滞留实验中,大粒径条件下炉渣滞留量降低近50%,透液性变好。综合考虑高炉上部燃料的气化和高炉下部透液性,加入少量大粒径高反应性兰炭,可减少焦炭的气化损失,相对保持焦炭的强度,稳定炉料的透液性,达到节约优质冶金焦资源的目的。      

高炉使用铁焦的㶲分析

 中国钢铁生产主要以高能耗和高排放的高炉-转炉长流程为主,节能减排压力较大。因此,积极研发高炉低碳炼铁技术,促进高炉工序CO₂减排尤为重要。铁焦是将含铁原料加入适宜的煤中,经焦化或炭化后成型的新型碳铁复合炉料,其高反应性可以显著降低热储备区温度、降低碳消耗,高炉使用适量的铁焦可实现一定程度的节能降碳。基于现场生产数据,采用㶲分析理论,建立高炉使用铁焦的㶲平衡模型,探索铁焦添加量对高炉物料消耗及能量利用效率的影响。结果表明,高炉使用铁焦后,炉内间接还原得到发展,碳利用率提高,炉内灰分量降低,冶炼单位生铁的碳素消耗和炉渣量均会降低,与未使用铁焦相比,高炉使用114 kg铁焦后,吨铁碳素消耗降低25.95 kg,渣量降低11.28 kg。此外,铁焦内部的金属铁仅需熔化,节省还原所需的㶲量,焦炭和鼓风带入㶲会显著降低,因此高炉冶炼吨铁消耗的总㶲量降低,同时,炉内传热也得到改善,内部㶲损失有效降低,与未使用铁焦相比,高炉使用114 kg/t铁焦后,目的㶲效率由46.14%提高至48.87%,热力学完善度由87.46%提高到88.02%。在此条件下,高炉吨铁的内部㶲损失降低192.63 MJ,实现节能6.57 kg(标煤)。     

莱钢高炉风口取样研究

通过风口取样,对莱钢1#1 080 m3高炉风口区域焦炭、碱金属以及炉渣成分的变化情况进行了详细的检测分析。结果表明,在高炉结瘤操作时,高炉风口区焦炭粉化严重,死料柱的透气性与透液性差,风口焦炭碱金属含量增加;高炉炸瘤后,随着喷吹煤比的增加,风口焦平均粒度有减小趋势;风口焦样粒度沿高炉径向向炉缸中心减小;风口边缘渣碱度比靠近中心渣碱度低。     

COREX熔融气化炉中块煤裂化现象

COREX流程主要使用块煤作为燃料,但仍需要加入一定比例的焦炭来支撑熔融气化炉内炉料,保证炉况顺行.块煤裂解形成的半焦和焦炭在熔融气化炉内的劣化程度对煤气流的透气性、渣铁的透气透液性和炉缸热量的分布等影响较大.利用风口取样技术取出风口焦试样,进行粒度分布研究、显微结构分析、透气性指数计算和热态性能测定,发现风口焦试样中大于10mm的较大颗粒多为入炉焦炭劣化所致,小于10mm的小颗粒多为块煤裂解所致；认为块煤挥发分热解后的产物会加剧焦炭的溶损反应,且块煤裂解半焦的反应后强度不及入炉焦炭,半焦在炉内的劣化是影响渣铁透气透液性的主要因素；最后结合对试验结果的分析,给出了降低COREX流程能耗的一些措施.     

神户钢铁公司开发成功高炉中心控制技术

高炉下部存在着炉芯焦炭层(以往被作dead man“死铁层”,温度高达1500～1800℃),该层的透气性和透液性的好坏对高炉炉况和炉体寿命影响很大。由于炉芯焦炭层处在高炉下部,所以无法控制它的透性和透液性。神户钢铁公司材料研究所钢铁技术中心对高炉炉芯结构进行了研究,他们发现炉芯焦炭层是由高炉中心下降的焦炭充填而成     

渣相组分对高炉炉缸死焦堆滞留率的影响

 为明确高炉炉渣组分对死焦堆中炉渣静态滞留率的影响,采用自行设计的炉渣穿焦试验装置模拟高炉炉渣穿过炉缸死焦堆的过程,探究不同二元碱度(w(CaO)/w(SiO₂))、镁铝比(w(MgO)/w(Al₂O₃))对炉渣滞留率的影响。试验结果表明,随着碱度的增加,炉渣穿过焦炭层的能力增强,滞留率降低;当炉渣镁铝比较低时,炉渣滞留率较高,当镁铝比为0.50～0.55时,滞留率出现最小值,当镁铝比较高时,由于渣焦间润湿性变好,“液桥”间炉渣滞留量增大,滞留率存在上升趋势;渣焦间润湿性较差。炉渣穿过焦炭层的过程主要为物理传输过程,但炉渣仍存在着向焦炭内部渗入的现象,渣焦界面发生反应生成SiC,该反应产物可改善渣焦界面润湿性。     

超大型高炉风口焦炭取样分析研究

为恢复炉况及探讨超大型高炉冶炼规律,对首钢京唐公司高炉进行了风口焦炭取样分析,研究了其入炉焦炭热强度与焦炭反应性、焦炭冷强度与焦炭耐磨强度之间的关系;探明了风口焦炭的粒度、劣化度及渣铁滞留量;探索了渣铁滞留量与渣铁体积、风口焦炭粒度、煤比及炉渣二元碱度的关系;分析了炉缸径向焦炭粒度分布、风口前高透气性区长度、炉缸透气性等;根据上述研究结果,提出了高炉操作建议并得到应用。实践结果表明:风口焦炭取样分析可以作为高炉操作调整的重要参考。     

高炉风口焦炭的形貌与冶金行为

 为了研究焦炭在风口区域的劣化过程,获取高炉风口区及风口区边缘焦炭样品,利用显微分光光度计和扫描电镜对焦炭与氧化性气体、炉渣和铁水的反应界面形貌与生成物进行了检测,分析了焦炭在风口区的冶金行为。研究结果表明,氧化性气体会以消耗碳元素方式侵蚀焦炭基质,炉渣则会进入焦炭气孔和裂纹中,通过反应、冲蚀和挤压气孔壁的方式瓦解焦炭。铁水主要通过渗碳作用侵蚀焦炭,残留的灰分会覆盖气孔壁表面,阻碍化学反应进行。风口区的焦炭已经高度石墨化,呈现大量片状石墨结构,微观结构的改变导致焦炭强度降低,最终瓦解粉化。焦炭内部的灰分、炉渣颗粒会与炉渣融合,形成终渣。     

Steady heat transfer in melt-irrigated blast-furnace zone

The steady heat transfer in the irrigated zone of the blast furnace is considered, taking account of the filtration of hot metal and slag through the coke bed. In this zone, the fluxes of coke, hot metal, and slag are heated simultaneously and exchange heat with one another, by both convection and radiation. Convection ensures heat treatment between the gas and all the batch materials and also between the slag and coke, since the slag running through the coke partially covers its surface. Radiant heat transfer develops among the coke, hot metal, and slag. It is more intense at higher temperatures. The heat transfer among the coke, hot metal, and slag in the irrigated zone of the blast furnace has a considerable influence on the temperature field in this zone. To calculate the heat transfer at the shoulder and hearth, information is required regarding the distribution of the thermal effects of direct reduction of iron, silicon, and manganese over the height of the irrigated zone and the proportion of the coke surface covered by slag.     

Carbon Transfer in the Lower Zone of a Blast Furnace

In this paper results from an investigation focused on coke/iron reactions occurring in the hearth of a blast furnace, below the slag layer, are presented. In this region, as coke dissolves in the iron there is the potential for a mineral layer to form and persist at the coke/iron interface and inhibit the rate of coke dissolution. Key findings of the investigation include that the composition of the mineral layer was principally composed of oxides of aluminium and calcium, present as various calcium aluminates and that the morphology of the layer profoundly affected the rate of carbon transfer. Follow‐up up studies on the kinetics of carbon transfer focussed on how the wetting and interfacial characteristics of iron on the calcium aluminates would affect iron penetration of the mineral layer are also reported and discussed as was a new material, called coke analogue, that could be used in the study of real industrial coke. Analysis of the wetting behaviour of liquid iron on alumina and the calcium aluminates investigated indicated that iron wetting of the mineral layer was not a key parameter in coke dissolution in iron for the coke composition studied. The brief details given for the coke analogue indicated that it did replicate coke dissolution behaviour in iron, though more experimental work is required to fully understand and exploit the potential of this material.     

高炉内铁?焦界面的渗碳润湿行为研究

高炉内铁水渗碳过程是影响冶炼效率及未饱和铁水对炉缸炉衬侵蚀的重要因素。本文通过高温真空润湿性测试装置模拟了高炉炉缸区的铁水渗碳反应,分析了不同碳质量分数（3.8%、4.3%、4.8%）的Fe?C熔体与质量分数为99.9%的石墨基体在高温下界面间的润湿反应,同时利用扫描电镜（SEM）和能谱仪（EDS）研究了渗碳界面的微观形貌及渗碳距离。结果表明:界面接触角随着Fe?C熔体中碳含量的增加而变大;熔化过程中,接触角随着反应时间延长而减小,并最终趋于稳定;4.8%碳质量分数的Fe?C熔体中由于含碳量已至饱和,处于不润湿状态。扫描电镜分析显示,Fe?C熔体与石墨基体的接触界面形成了“球帽状”凹陷,凹陷半径与体积随碳含量的增加而减小。能谱线扫描分析显示,随着Fe?C熔体中初始碳含量的增加,石墨基体中的碳素溶解量减少,渗碳效果变差,良好的润湿性有利于碳的传质。通过计算表面能发现,石墨基体中碳素溶解进入Fe?C熔体后,有效减小了两者之间的表面能,使得表面张力减小,接触角在熔化期间递减。      

Flow of molten slag and iron at 1500 °C to 1600 °C through packed coke beds

The blast furnace dripping zone is of great importance to the mass transfer of elements such as sulfur, carbon, and silicon, to and from the liquid metal phase. To understand mass transfer in the dripping zone, not only mass-transfer reactions and kinetics should be known, but the flow phenomena and process dynamics should be understood as well. The flow of hot metal and slag in the dripping zone was studied in experiments, in which liquid slag and metal trickled through a packed coke bed at 1500 °C to 1600 °C. The results indicate that slag and iron flow concurrently in a funicular type of flow. The iron flows through the core of the voids in the bed and is enveloped by slag, which flows filmwise in between the coke and the iron. This mode of flow allows for a large contact area between slag and iron, through which mass can be transferred. While flowing, the liquid can only pass and access a void, if and when the fluid capillary pressure at the void neck can be overcome. As a result, liquid droplets collect into rivulets. These rivulets flow down, along the accessible voids, using only a part of the available volume. The residence times of the fluids in the bed depend partly on the length of the pathway and are a function of the bed structure, the void neck distribution, and the stochastics of the flow. During flow, slag may react with coke, thus changing the distribution of the slag composition, and its sulfur capacity. In addition, the residence time distribution of the slag and the liquid holdup change as a result of these reactions. Holdup and residence time distribution of the liquids as measured in the experimental setup could not be modeled quantitatively, most likely due to the doubly distributed nature (in space and in time) of the model parameters, induced by reactions between slag, coke, and liquid metal.     

氯元素在高炉软熔滴落带分配规律

为了解氯元素在软熔滴落带的分配规律,对高炉内氯元素的反应行为进行热力学分析,同时研究了氯元素入炉量和炉料碱度对氯元素在高炉软熔滴落带渣、铁及焦炭中分配规律的影响。结果表明:随着入炉氯元素含量的增加,软熔滴落带铁和渣中的氯元素含量均不断增加,且渣中氯元素含量的增加幅度大于铁中氯元素含量的增加幅度。随着入炉氯元素含量的增加,软熔带总特征值(S值)逐渐减小,透气性逐渐增强,焦炭中的氯元素含量逐渐降低。随着入炉炉料碱度的增加,软熔滴落带铁中的氯元素含量无明显变化,渣中的氯元素含量增加,焦炭中的氯元素含量的大小主要受软熔带透气性的影响。     

Falling Angle of Fe-C-Based Alloy Droplet on Coke and Graphite

The hold-up of molten pig iron and slag melt in the coke packed bed of blast furnace (BF) causes a decrease of void between coke lumps and inhibits gas permeability. Smooth dripping of those liquids in the coke bed is desirable to keep the productivity of BF. Herein, the conditions for smooth flowing of molten iron on coke surface are calrified, and the falling angles of Fe-C and actual pig iron droplets on coke and graphite are measured at high temperature. It is found that Fe-C droplet easily slids down on coke because of small falling angle, and the falling angle of actual pig iron is even smaller, while those droplets adhere to a graphite substrate. The carbon in iron has only a small effect on the static contact angle with coke, but has a great influence on the falling angle. From the viewpoint of the roughness of coke surface, the variation of static contact angle and falling angle is discussed.