煤中氢对含碳球团还原的影响

针对含碳球团还原过程中的煤种选择问题,研究了烟煤和无烟煤挥发分中氢对含碳球团还原的作用以及温度、加热速度对氢还原过程的影响。结果表明,含碳球团中煤热解产生的氢对铁氧化物有还原作用。由于煤中挥发分的热解析出温度与氢还原铁氧化物的还原温度不一致,氢在还原初期迅速放出,导致氢的还原作用率低;提高温度和加热速度可提高煤中氢的还原作用率和挥发分的利用率。综合考虑,含碳球团实际生产选择煤种时,应选择反应性好的无烟煤。     

高炉喷吹混合煤的燃烧特性及动力学分析

利用热重分析天平,研究非等温燃烧条件下无烟煤、贫煤与高挥发分烟煤的混合煤试样的燃烧特性及其反应动力学参数。考察了不同配比混合煤试样的挥发分初析温度、着火温度、最大燃烧速率和燃尽特性等燃烧特征参数,求出了反应的动力学参数活化能Ea和指前因子A。研究结果表明：随着烟煤配入量的增加,混合煤的挥发分初析温度、着火温度和燃尽温度...     

鞍钢高炉喷吹煤粉合理配煤的试验研究

实验室研究及工业试验结果表明，高炉喷吹烟煤和无烟煤的混合煤的综合效果优于喷吹单一烟煤或无烟煤，研究结果还表明，在鞍钢生产条件下，对于１０００ｍ＾３级高炉，当煤比为１００ｋｇ／ｔ左右、不富氧或低富氧率时，混合煤的挥发分含量宜控制在１８％左右，当煤比进一步提高后，混合煤的挥发分含量应适当提高。     

煤中挥发分对热解过程的行为影响分析

较高的还原温度易造成结圈,使回转窑直接还原铁工艺发展受限,为此,需研究低温条件下煤中还原性气体释放和铁矿石的还原过程。通过热重分析仪-傅里叶红外光谱仪-质谱仪(TG-FTIR-MS)联用方法分析不同挥发分煤的热解特性和铁矿石还原过程。结果显示,高挥发分煤在热解过程中具有更加优越的反应活性,随着挥发分的提高,煤中还原性气体的释放温度更低,释放含量更高。整个热解过程中有机气体主要为CH₄、CH3+碎片、苯、甲苯以及同系物;无机气体为SO₂、CO、CO₂、H₂O。高挥发分煤种的还原性气体CO释放温度较低。此外,热解过程中,高挥发分煤种表观活化能更低,热解过程更容易进行;相较于无烟煤,采用烟煤还原铁矿石时还原反应进程更快,还原过程更加彻底。为此,采用高挥发分煤种进行煤基还原将会为有效降低煤基还原温度提供新思路。     

煤种对含煤球团还原速度的影响

研究了在１２２３￣１４７３Ｋ的氮气氛中３种不同挥发分煤粉的粒度、铁精矿粉粒度、温度及碳－氧摩尔比对含煤球团还原速度的影响。发现降低煤粉或铁精矿粉粒度，提高温度或碳－氧摩尔比可提高含煤球团的还原速度，且这４种因素对还原速度的影响程度随煤种挥发分的降低而增大。分别采用以碳气化反应、气相内扩散、界面反应为控制环节而得出的表达含煤球团反应过程的速度方程处理本研究数据，发现３种速度方程（４种表达形式）均能较     

喷吹炭化煤与铁矿粉混合物时炭化煤的燃烧

用实验室规模的试验装置和数学模型对带氧气套管的喷嘴喷吹粉状炭化煤和铁矿物的混合燃烧和熔化现象进行了研究。在炭化煤粒喷入后，观测到铁矿粉在燃烧室内被熔化和凝聚。试验表明，熔化的铁矿粉已被凝聚过程中的固体碳所还原。通过适当形式的奈维－斯托克方程和煤燃烧动力学，对流体流动、传热和炭化煤的燃烧行为已经数学模型化。对图示流线及燃烧室内局部温度及煤气成分的分布做了计算。     

热重分析仪测定煤、焦成分

介绍了利用热重分析仪测定煤、焦中水分、灰分、挥发分及固定碳的方法、实验条件、操作要点等。用TGA501热重分析仪测定烟煤、无烟煤和焦炭的成分，结果比较准确。     

高炉喷吹烟煤与无烟煤时煤气量变化的分析

高炉喷吹烟煤时吨铁煤气量比喷吹无烟煤时减少，其主要原因是由于烟煤中氧含量一般都大大高于无烟煤中的氧含量，它可以代替鼓风中的氧，使随鼓风一起入炉的Ｎ２量减少，另外由于煤中氢含量也高于无烟煤中的氢，使直接还原度降低，也使吨铁煤气量降低。     

基于混料设计的高炉喷吹煤配煤结构优化研究及应用

为解决太钢高炉喷吹煤配煤成本和煤粉质量相悖的问题,运用混料设计中极端顶点法进行试验设计,建立多指标响应优化模型。结合太钢煤种性能特点,以无烟煤、清徐煤、府谷煤、兰炭粉作为混料的4种因子,将混合煤的配煤成本、固定碳含量、挥发分、灰分、硫分和发热量等指标进行优化分析。在当前价格体系下的研究结果表明,当无烟煤、清徐煤、府谷煤、兰炭粉的比例为18∶36∶34∶12时,配煤成本和煤粉质量综合效益最优。本研究应用于太钢配煤现场生产中,取得煤粉固定碳质量分数高于72%、燃料比降低10 kg/t、配煤成本降幅显著的效果。     

不同烟煤还原红土镍矿最佳粒度的实验研究

以含Ni1.93%、Fe14.25%的红土镍矿为对象,分别采用A、B两种烟煤作为还原剂,研究了焙砂的主要矿物组成和不同烟煤粒度对镍矿预还原的影响。结果表明:焙砂中大多数镍铁合金呈分散状态,晶粒细小,铁氧化物呈星点状弥散状态。对于挥发分较低的烟煤,粒度越小,气化速度越快,越有利于镍矿的预还原;但对于挥发分较高的烟煤,适当增加大粒度的比例可以提高挥发分挥发的温度,充分利用挥发分促进镍矿的预还原。     

Direct Reduction of Mixtures of Manganese Ore and Iron Ore

This paper presents recent results of direct reduction investigation of different combination of blends of manganese ore, iron ore and coal at the Department of Ferrous Metallurgy (IEHK) of RWTH Aachen University. A mixture of iron and manganese ore in a ratio of 75/25 is a good raw material for steelmaking of high Mn‐alloyed grades. The experimental studies consisting of reduction of (a) fine material and (b) agglomerated material (briquettes) were carried out in the range of 1273 to 1673 K. The behaviour of combined reduction of manganese ore and iron ore and the employment in the direct reduction on a coal and gas basis for production of steels with high Mn content were investigated. It was found that a high metallization degree for Mn can be reached at 1273 K with the reduction of manganese ore by hydrogen‐containing gas. Addition of carbon monoxide to the reducing gas retarded the reduction process. The addition of coal to manganese ore and iron ore blends increased the degree of reduction. The results of carbothermic reduction of briquettes consisting of a mixture of manganese ore and iron ore combined with coal as reducing agent show that a high temperature, a low Mn/Fe ratio and a high Fe₂O₃ content have a favourable effect on the degree of reduction. In order to obtain a high degree of metallization, the temperature should be higher than 1473 K. The reduction of briquettes at higher temperatures (up 1573 K) has shown a molten phase and the separation of slag and metal.     

MECHANISMS OF REDUCTION OF IRON ORE/COAL AGGLOMERATES AND SCIENTIFIC ISSUES IN RHF OPERATIONS

Laboratory studies of chemical kinetics and heat transfer in the reduction of iron ore/carbon (coal) mixtures in various forms are reviewed. Therefore, the rate-limiting steps, which are of critical importance in process development, may be identified or suggested for a given set of conditions. Commercial operations using rotary hearth furnace (RHF) for the reduction of iron ore and waste oxide recycling by heating chemically self-sufficient agglomerates and related technical issues will be reviewed and discussed. The development of the next generation of processes based on ore/coal agglomerates, which would have very significant economical and environmental advantages, will be presented and discussed.     

Reduction and Carburization of Iron Oxide by Carbonaceous Materials

The iron nugget making process, where mixtures of iron ore powder and pulverized coal are made to heat rapidly, is regarded as a new ironmaking process. Since the iron carburization reaction is an especially important step from the viewpoint of energy saving in this process, the purpose of this study is to reveal the carburization mechanism of reduced iron formed during the heating process of the mixtures. Fe₂O₃ and H₂‐CO‐CO₂ gas mixture were made react with each other to simulate the formation of iron ore and the generation of coal gas from coal during the heating process. An electric resistance furnace was used to heat the samples. A cut surface of the quenched iron product was observed by microscopy. Carbon content in the iron was analyzed after reduction and carburization of Fe₂O₃. It is considered that there are many possibilities in the real process to carburize the reduced iron during the heating process, such as carburization with CO formed by coal combustion, solution loss reaction, and direct carburization with coal. It was observed in the present work that the carbon content in the reduced iron became the highest as Fe₃C was formed during the heating process. Therefore, it became clear that the key technology for production of pig iron containing high carbon was to control the formation of Fe₃C in the heating period of the mixture. The carburization mechanism was discussed in this study based on these experimental results.     

铁矿-煤球团和空气在并流条件下的还原实验研究

在管式电炉内,进行了铁矿－煤球团和空气在并流条件下还原实验研究。结果表明：铁矿－煤球团能够被还原并获得较高的金属化率,还原后的球团被再氧化先是脱碳反应抑制了金属化率的进一步升高,然后是金属铁的氧化使金属化率降低。     

冷压成型用煤的粘结性

分析了成型用煤粘结性对冷压成型和型煤炭化工艺的作用,讨论了主体煤粘结性和配粘结用煤对型煤和型焦的强度及热性质的影响。主要结论是：(1)型煤强度主要取决于所用粘结剂的质和量,与煤本身的粘结性无关,型焦的强度和热性质主要受成型用煤的粘结性和所用粘结剂的相互作用的影响;(2)有弱粘结性的低挥发分主体煤特别是贫瘦煤是制备强度高,热性质好的冶金型焦和铸造型焦的优质原料。     

CHARACTERIZATION OF PROPERTIES AND REDUCTION BEHAVIOR OF IRON ORES FOR APPLICATION IN SPONGE IRONMAKING

Studies on the chemical and physical properties, and the reduction behavior (in coal) of hematite iron ores procured from 10 different mines of Orissa, were undertaken to provide information for the iron and steel industries (sponge iron plants in particular). The majority of the iron ores were found to have high iron and low alumina and silica contents. All these iron ores were free from the deleterious elements (S, P, As, Pb, alkalies, etc.). The results indicated lower values of shatter and abrasion indices, and higher values of tumbler index in all the iron ore lumps except Serazuddin (previous) and Khanda Bandha OMC Ltd. For all the fired iron ore pellets, the degree of reduction in coal was more intense in the first 30 min, after which it became small. Slow heating led to higher degree of reduction in fired pellets than rapid heating. All the iron ores exhibited more than a 90% reduction in their fired pellets in 2-h time interval at a temperature of 900°C. Iron ore lumps showed a lower degree of reduction than the corresponding fired pellets.     

HIsmelt熔融还原主反应器能质流转模型构建与验证

 HIsmelt熔融还原炼铁工艺以铁矿粉和煤粉作为原料,流程中不需要烧结、球团和焦化,与高炉炼铁流程相比具有降碳减排等优势。明晰能质流转过程对HIsmelt熔融还原炼铁实际生产具有指导意义。基于物料平衡、热平衡方程,对输入和输出HIsmelt主反应器物质和能量进行平衡计算,建立能质流转模型,并结合FactSage中Equilib模块计算的各元素在渣铁两相间的质量分配比及实际生产数据对其进行修正。该模型可以计算原料和燃料成分、矿煤质量比、二次燃烧率、热风氧含量等参数对铁水温度、炉渣成分、热风量、煤气量等主要冶炼指标的影响。其次依据该模型,进行了物料平衡、热平衡计算,依据实际生产数据对模型计算结果进行了验证,结果表明该模型与实际生产数据契合度较高。探究了矿煤质量比对冶炼的影响,矿煤质量比为1.39～1.45时,矿煤质量比降低0.1,会使二次燃烧率降低0.23%,进而造成煤气化学能的利用率降低,同时需要更多的热风使煤粉燃烧,热风量和煤气产生量增加,可以通过适当提高热风氧含量以提高二次燃烧率并使煤气量降低来改善;矿煤质量比降低0.001,会使铁水温度升高3.76 ℃,有利于铁水后续的加工处理,但铁水温度升高使铁元素在铁液与渣中的比值降低,使炉渣FeO质量分数升高0.026%,增加铁损,可通过降低富氧热风喷吹量来降低铁的氧化量,从而降低铁损。     

从含铌铁矿中提铌及制铌铁的新方法

针对我国包头现有高炉－转炉－电炉－电炉提铌工艺存在流程长,成本高,铌损失率大且只能生产含铌１３％－１５％铌铁的情况,提出包头铌资源选冶新思路;用ＣＯ－ＣＯ２混合气体选择性热还原含铌铁矿,９０％以上的铁的被还原为金属铁,铌矿物不被还原。