直接还原技术的进展与展望

直接还原是一种以气体、液体燃料或非焦煤为能源,使用球团矿、块矿、粉矿在固态下进行还原生产金属铁的炼铁工艺技术.对国内外直接还原技术的研究情况进行了介绍和评述,表明发展直接还原技术将有较大的市场需求.重点介绍了转底炉法,该技术规模化生产尚未到达成熟的阶段,但具有良好的发展前景.     

浦项FINEX熔融还原工艺技术研究

韩国浦项（POSCO）在COREX熔融还原工艺基础上，成功的开发了FINEX熔融还原炼铁工艺技术，并于2007年4月10日开工点火，设计产能150万妇，通过50天的验证，装置运行一切正常。FINEX工艺的基本原理是用四段流化床代替COREX装置的还原竖炉，流化床内还原气体和粉矿直接接触进行还原，还原后的热矿粉进入熔融气化炉。使用FINEX工艺，能够直接利用粒度小于8mm的粉矿，同时能够直接使用煤粉。COREX装置的熔融气化炉被用来对还原获得的海绵铁热压块进行最后还原和熔炼，也作为FINEX的煤气发生器，原来的还原竖炉用作为FINEX装置的贮料仓和加料仓。     

FINEX炼铁工艺

<正>FINEX是一种直接用粉矿和非炼焦煤粉冶炼铁水的新工艺,由浦项制铁与西门子奥钢联公司联合开发。FINEX采用气基还原技术,以低成本的粉矿和煤粉为原燃料,通过多级流态化床反应器对粉矿进行直接还原,铁水质量与高炉铁水相差无几。但FINEX工艺可省去焦化、烧结和球团工艺,减少     

直接还原炼铁技术的最新发展

直接还原炼铁工艺根据还原剂不同分为气基与煤基.目前已获得工业应用的气基直接还原流程主要有使用球团矿或块矿的Midrex法和HyLⅢ法,以及直接使用粉矿的Finmet法.已获得工业应用的煤基直接还原流程主要有回转窑工艺和转底炉工艺,转底炉有使用球团矿的,也有直接使用粉矿的.对各种直接还原流程的工艺特点和应用情况进行了分析比较,并评述了其最新发展趋势,结合国内情况提出了一些建议.     

预还原球团铬矿冶炼轴承钢试验

一、我国铬矿资源缺乏。用于生产络铁的铬矿要求以块矿为主,搭用少量粉矿。块矿和粉矿价格相差悬殊,一般差30～40元/吨。浙江省冶金研究所完成了“粉矿代替块矿生产铬铁”而研制预还原球团铬矿的课题。为了扩大预还原球团使用面,用预还原铬矿作为铁合金代替部分铬铁,直接加入含铬钢种进行炼钢,对降低炼     

新铁源—直接还原铁制造技术综述

着眼于能够取代高炉法的未来铁源发展趋势，回顾了直接还原生产的工艺技术，以小型轧机对钢铁需求量为基础，高生产率直接还原铁已经被炉体尺寸的扩建和高温提炼所确立，在交替变换的铁源领域中，新技术的发展是与旋转炉缸和含碳团矿连带在一起的。含碳团矿在1300－1400℃温度范围内的旋转炉缸中，经过10分钟就可被还原，含碳矿和旋转炉缸技术还考虑到下一世纪的废物回收。     

铁帽型含金复合矿煤基直接还原过程中铁氧化物的行为

对铁帽型含金复合矿煤整直接还原过程中铁氧化物行为进行了研究，并用粉晶X-射线衍射对其反应机理进行验证。结果表明：直接还原过程中，不仅包括铁氧化物的还原相变，同时还存在铁氧化物同其它氧化物之间的固相反应。     

低品位镍矿直接还原-磁选富集工艺半工业试验研究

为充分利用红土镍矿,详细阐述了低品位镍红土矿直接还原-磁选富集工艺技术。通过半工业试验,探讨研究了影响低品位红土镍矿冶直接还原-磁选富集的主要工艺技术参数,证明了该工艺处理低品位红土镍矿的可行性,实现了低品位红土镍矿的有效利用。     

熔融还原炼铁新工艺的展望

熔融还原炼铁新工艺与传统的高炉冶炼工艺相比，它具有缩短流程、直接用煤和粉矿等独特的优点，经世界各国研究开发已形成了一定的生产能力，现正在寻求新的突破。     

预还原烧结矿生产工艺

传统上说，烧结矿的还原是在高炉中间接还原。因此，高炉中烧结矿的还原行为受到还原平衡的控制。然而，由于采用了新开发的工艺，除了可以使用粉矿外，在烧结机上还可以通过还原剂同步进行直接还原，从而使得还原不受一氧化碳i--氧化碳气体反应平衡的限制。     

Development in smelting reduction processes

Corex process is a smelting reduction process to produce hot metal of blast-furnace quality. Coal is used instead of coke, and this replacement makes production costs of hot metal decrease. Iron ore reduction and melting is separated into two steps: in a melter gasifier reducing gas is generated and melting energy is produced by coal gasification; iron ore is reduced in a shaft furnace. Due to this separation, a great variety of untreated coals can be used. The Corex process is designed to operate under elevated pressure, up to 5 bar. Reducing gas is generated in a fluidized bed by partial oxidation of coal. After leaving the melter gasifier, the gas is mixed with cooling gas to obtain a temperature suitable for direct reduction, i.e. approximately 850–900°C. The fines captured in a hot cyclone are re-injected into the gasifier. Reducing gas is fed into the reduction furnace and ascends through the iron burden according to the counterflow principle. The hot DRI having a temperature of 800–900°C is continuously charged into the melter gasifier, where further reduction is effected and melting occurs. Hot metal and slag drop to the bottom of the melter-gasifier. Analogous to blast-furnace practice hot metal and slag are discharged by conventional tapping.     

Analysis of Material and Energy Consumption of Corex C3000

The first Corex C3000 unit has been built at Baoshan Iron and Steel Corporation, China, and some improvements compared with C2000 have been made. On the basis of material and heat balances, an analysis of material and energy consumption in the Corex C3000 smelting reduction process was conducted and the calculated consumption of lump ore and pellets, coal rate, oxygen consumption are compared with the target values of C3000. Regarding the heat balance calculation, the main factors affecting the energy consumption of C3000 are analysed, and the effective utilization of the sensible heat of top gas and molten slag, as well as the calorific heat of the export gas can be considered to realize lower energy consumption. In addition, the effects of metallization in the reduction shaft and oxidation degree of the gas produced in the melter‐gasifier on the Corex performance are discussed.     

Energy Consumption in Smelting Reduction

The concepts of theoretical gas utilization ratio, smelting heat of iron ore and effective calorific value of coal were introduced in this work. The practical gas utilization ratio and the gas consumption in the shaft of a reduction unit for smelting reduction were discussed. The Corex process was optimized and the energy consumption was minimized according to the relationship of gas production in the smelting unit and the degree of iron ore reduction in the reduction unit. It was proven that the most important factor for saving energy in smelting reduction process is to use coal with suitable effective calorific value for the smelting heat of iron ore.     

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.     

Reduction behaviour of agglomerated iron ore nuggets by devolatisation of high-ash,high-volatile lignite coal for pig iron production

High-quality coking coals all over the world are gradually approaching extinction. These days, steel industries are trying to focus more on the utilisation of non-coking grades of coal. The present work involving high-ash, high-volatile lignite coal can be used indirectly in iron-making processes. Direct use is not possible due to low amount of carbon and high value of ash. High ash content leads to huge sulphur content, and this leads to high cost involvement in secondary processes. On the other hand, huge amount of iron ore fines are generated during mechanised mining, sizing, screening, transportation, beneficiation and sintering processes. Iron ore nuggets are formed from inferior quality iron ore fines using suitable binders with the applied pressure. Mechanical properties of iron ore nuggets are also assessed through shatter and abrasion test. A furnace was designed, to indirectly utilise high-ash, high-volatile lignite coal, for pre-reduction iron ore nuggets. Iron ore nuggets were partly reduced by CO, H₂ and fine carbon produced from volatilisation of coal. Optimized pre-reduced nuggets, having high mechanical stability was directly charge in the raising hearth furnace for pig iron production.     

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。     

微波加热含碳氧化锰矿粉固态还原过程中硫的分配

在rC∶rO原子摩尔比为1.06、rCaO∶rSi O2分子摩尔比为1.27的条件下,通过电子探针面扫描成分分析,对微波加热含碳氧化锰矿粉固态还原过程中硫的分配进行了研究。结果表明:加热温度为1 000~1 300℃时,88%~96%的硫分配于气相中,锰铁金属化物中的平均硫含量为0.002%~0.017%;随着微波加热温度的提高和保温时间的延长,锰铁金属化物中的含硫量与含铁量呈负消长的关系,而与含锰量呈正消长的关系;提高微波加热温度和延长保温时间,有利于进一步改善含碳锰矿粉的气化脱硫效果。与传统冶炼方法相比,微波加热含碳锰矿粉以气化脱硫为主,并可以获得良好的脱硫效果。     

Modelling novel coal based direct reduction process

Abstract

The present paper develops a one-dimensional model of a novel coal based iron ore direct reduction process. In this process, a mixture of iron ore, coal fines and small amount of binder is made into pellets and these are placed in a bed. Air is forced upward through the pellet bed and provides oxygen for the volatiles and part of the coal in the pellets to be burnt. Initially the pellet bed is heated from the top. As the temperature of the top level of pellets increases, they start to evolve pyrolytic matter which is ignited and, as a consequence, the pellets at lower levels in the bed are heated. In this way, a flame propagates downward through the bed. The iron ore reacts with the gases evolved from the coal (including volatiles) and carbon in the coal and undergoes reduction. The model presented in the article simulates the processes occurring in the solid and gaseous phases. In the solid phase, it uses a novel porous medium model consisting of porous pellets in a porous bed with two associated porosities. The model includes equations for energy balance, reactions of iron oxide with carbon monoxide and hydrogen, coal pyrolysis and reactions between the gas components in the voids. The model shows that a rapidly increasing temperature front can travel downward through the bed if the air is supplied for long enough. The predictions of the modelling are discussed and compared with observations obtained from an experimental rig.     

COREX竖炉还原热模拟研究

介绍了由煤气发生炉，煤气加热炉和还原竖炉组成的Ｃｏｒｅｘ竖炉还原热模拟装置，用木炭或用原煤加少量木炭的为原料，Ｏ２和ＣＯ２为气化剂，产生还原煤气，将铁矿石还原成金属率达９０％以上的海绵铁的过程。描述了不过程中竖炉内的温度分布，熔剂分解和不同炉料结构时的海绵铁粒度组成和金属化率等试验情况，讨论了还原煤气的成分，温度，流量，还原时间以及炉料结构等对海绵铁金属化率的影响。