矿壳矿煤球团预还原试验研究

论述了矿煤球团用铁精矿及添加剂包壳的优点。研究了矿煤球团的配碳量、用铁精矿包壳时添加剂的种类和数量、还原温度、升温速度及气氛等因素对预还原球团强度和金属化率的影响。     

攀枝花低硅钛精矿还原试验研究

以攀枝花低硅钛精矿为研究对象,研究氧化温度和时间对钛铁矿物相结构和还原的影响,同时对预氧化钛铁矿不同温度和时间下还原失重率和金属化率变化情况进行分析。研究结果表明:钛精矿的氧化在较短时间内可完成,随着氧化温度的升高,钛精矿主要物相变化过程为FeTiO_3→Fe_2O_3+TiO_2→Fe_2TiO_5+Fe_2O_3+TiO_2;在钛铁矿的还原过程中,还原温度和时间对钛铁矿还原的金属化率影响较大,在还原温度大于1 300℃,时间大于8 h后变化不明显;显微结构分析发现,高温还原后金属铁扩散发生聚集,形成球形和棒状金属铁颗粒,其尺寸大约为10μm。     

高铝铁矿和高锰铁矿共还原行为的研究

高铝铁矿和高锰铁矿是两种储量丰富但又极难分选的铁矿资源,实现铁、锰、铝的高效综合利用具有重要意义.本文研究了这两种铁矿石工艺矿物学,考查了单矿种及两者的混合矿种的直接还原行为及还原过程中的矿物组成演变,揭示了相应的还原机理.结果表明:高铝铁矿难还原,其机理为经还原后仅部分铁氧化物转化为金属铁,其余的铁与铝、硅矿物形成难还原的铁橄榄石和铁尖晶石;高锰铁矿易还原,其中的铁氧化物大部分被还原成金属铁,锰氧化物与铝、硅矿物结合形成锰尖晶石和锰橄榄石,促进了铁氧化物的还原.而且在相同还原条件下,高锰铁矿球团金属化率比高铝铁矿高30个百分点,前者还原性明显优于后者.两种矿进行共还原,当高锰铁矿配比达到60%时,球团金属化率就可大于90%.锰氧化物的存在对高铝铁矿石中铁氧化物的还原具有显著的促进作用.     

LiCl催化剂对含铌铁矿粉氢气选择性还原的影响

在自制的扩散床底供气管式电阻炉内进行实验,研究了添加LiCl催化剂对H2选择性还原白云鄂博含铌铁矿粉中铁氧化物的影响。发现含铌铁矿粉中加入LiCl催化剂后对还原反应有促进作用,还原度和金属化率明显提高,铁氧化物几乎全部被还原为金属铁。改变催化剂的加入比率（质量分数）分别为2.14%、1.71%、1.43%、1.00%、0.71%、0.43%,结果表明,70g含铌铁矿粉中添加质量分数为0.71%的LiCl催化剂的催化效果最好,且杂质含量相对较少,其还原度达到95.82%,金属化率达93.73%。     

金属化球团防止再氧化研究

研究了转炉尘泥和精矿含碳球团在氧化性气氛下还原，冷却和贮存过程中的再氧化问题，提出了有效防止氧化的措施，高温（大于１２００℃）、快速（１０－２０ｍｉｎ）还原得到的金属化率大于９０％扔金属化球团，采用炉内冷却、埋煤粉中、放密封罐内、炉内冷却至９００－１０００℃后出炉冷却四种都是有效的，干燥清洁的室内存是简单有效贮存海绵铁的方法。     

金属化球团的理论与实践(上)

本文对国外铁矿石直接还原的发展概况和生产实践进行了综合述评;对国内发展铁矿球团直接还原的远景,以及试验和半工业性试验结果也作了简要论述。文中着重对铁矿球团直接还原的热力学基础,主要方法的特点,对球团矿的质量要求,还原剂种类和要求,防止金属化球团的再氧化,对金属化球团质量要求和应用等问题,分别进行了分析和讨论。     

回转窑预还原-氧煤燃烧熔分炼铁技术分析

针对高炉炼铁存在工艺流程长、焦炭依赖度高、环境污染大等问题,提出了一种回转窑预还原-氧煤燃烧熔分炼铁新工艺。该工艺具有原料适应性广,不需要消耗焦炭,污染物排放少,适合冶炼特殊铁矿资源等特点。通过建立数学模型,对该工艺进行了数值模拟。计算结果表明,回转窑预还原炉料的金属化率、熔分炉煤气的氧化度和鼓风氧含量对冶炼工艺煤耗和氧耗影响较大,煤粉和氧气消耗随着预还原炉料金属化率的升高,熔分炉煤气氧化度的增大和鼓风氧含量的升高而降低。该工艺对冶炼特殊铁矿资源具有显著优势,可以弥补高炉冶炼的不足,对降低燃料消耗和减少CO_2排放具有重大意义。     

铁矿——煤球团还原度的测试方法

提出了用失重法测试快速加热时铁矿—煤球团还原度的方法。计算还原度的公式为：Ｒ＝４７ＭＯ（ΔＭΣ－ｆｖ，ｗＭＯｐｃ）×１００，％在１０５０～１２５０℃快速加热条件下的实验证明，该法的测试结果与定时取样化学分析结果进行比较，取样点的绝对误差基本小于５％，平均绝对误差基本小于３％。     

矿——煤球团内的还原反应

铁矿－煤球团内挥发分的还原作用可以忽略，碳的还原反应可以用一个均相非基元反应ＦｅｘＯｙ＋Ｃ＝ＦｅｘＯｙ＋ＣＯ表示，碳的还原反应按Ｆｅ３Ｏ４→ＦｅＯ→Ｆｅ逐级进行时，存在一个Ｆｅ３Ｏ４→ＦｅＯ和ＦｅＯ→Ｆｅ同时进行阶段。     

攀枝花钛精矿直接还原过程的研究

研究了攀枝花钛精矿球团的氧化规律和温度、时间、还原剂数量等对不同氧化率的球团外配碳直接还原效果的影响。在相同条件下与原矿球团相比,外配碳球团的金属化率有明显的提高,并且随球团氧化度的升高而增加。在还原剂配比合适时。再增加还原剂的用量。对还原球团金属化率的影响不显著。但往钛精矿球团内加入少量的碳,却可以显著提高还原球团的金属化率。     

Reduction Behaviour of Iron Ore–Coal Composite Pellets in Rotary Hearth Furnace (RHF): Effect of Pellet Shape,Size, and Bed Packing Material

Reduction of iron ore–coal composite pellets in multi-layers at rotary hearth furnace (RHF) is limited by heat and mass transfer. Effect of various parameters like pellet shape, size, and bed packing material that are supposed to influence the heat and mass transfer in the pellet bed, have been investigated, on the reduction behaviour of iron ore–coal composite pellets at 1250 °C for 20 min in a laboratory scale RHF. Reduced pellets have been characterised through weight loss measurement, estimation of shrinkage, porosity, and qualitative, quantitative phase analysis by XRD. A significant difference in the degree of reduction is observed layer-wise in the pellet bed with the variation in pellet shape and size. Pellet bed without any packing material or packed with coal have demonstrated higher degrees of reduction compared to the pellet bed packed with graphite and sand.     

降低柳钢生铁成本的探讨

分析柳钢铁水成本构成,从近期使用的原料(烧结矿、球团矿、块矿)和燃料(炼焦煤、喷吹煤)两方面探讨降低铁水生产成本的措施。     

Reduction of boron-bearing iron ore concentrate/coal composite pellet and kinetics analysis

Ludwigite is a complex iron ore containing boron and it is the most abundant boron resource in China. Boron-bearing iron ore concentrate is an intermediate product of the ore dressing process of crude low-grade ludwigite and extracting boron from it has great influence on the total boron yield. Pre-reduction of the boron-bearing iron ore concentrate is one of the important steps of the pyrometallurgical boron and iron separation process. In the present work, non-isothermal and isothermal reduction of boron-bearing iron ore concentrate/coal composite pellet was performed. The evolution of reaction fraction, carbon consumption, off-gas evolution, phase composition and microstructure were systematically revealed based on reduction experimental results in conjunction with X-ray diffraction, scanning electron microscope-energy dispersive spectrometer and electron probe micro analyzer analysis. The kinetics of the reduction of the composite pellet was also analysed. The reduction mechanism changed at a temperature around 1150°C. The rate of carbon gasification in the composite pellet during the reduction decreased mainly due to the chemical inhibition by B₂O₃ on the electron transfer.     

Composite Pre-Reduced Pellet (CPR) — A New Way for Fines Utilisation

Composite pre-reduced pellet has a metallised core encased in a sintered shell of iron ore. It is produced under oxidizing atmopsphere and degree of reduction obstained is as high as 91%. Non-coking coal, charcoal, coke and char fines are used as reducing agent. The physical properties of this pellet make it suitable for use in blast furnace/steelmaking processes.

In this paper an attempt has been made to present a review of the work done in this area as well as ore: coal mixed pellet. The effect of process variables like, temperature, time, Fe₂O₃/C ratio, heating rate and heating conditions on degree of reduction has been discussed. Attempt has also been made to judge the suitability of the pellet for use in iron and steel industries.     

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。     

硫在含碳球团内的转化行为

为了研究含碳球团还原产品中硫含量过高的问题和出路,笔者借鉴高温法定硫的原理,设计了一套分析测定装置,首次系统地研究了铁精矿配加烟煤、无烟煤和生石灰等原料之后的含碳球团在不同温度、时间条件下硫的分解转化行为,得出了煤种、CaO含量、温度和时间等条件对产品硫含量的影响趋势,分析揭示了试验现象与脱硫反应之间的规律,并对含碳球团的工艺选择与环保的关系进行了相应的论述.     

球团配加赤铁精矿的试验研究

利用球团模拟试验炉对配加10%～50%的赤铁精矿进行了试验,试验条件：干燥温度600℃,时间10 min;预热温度900℃,时间20 min;强氧化性气氛,焙烧30 min。结果表明,生产强度〉200 kg/个的球团矿,赤铁精矿配比30%以下时,需要的最低焙烧温度为1 180℃;35%时,最低为1 200℃;40%～50%时,则最低为1 220℃以上。赤铁精矿配比从10%增加到50%,可使球团矿的铁品位增加约0.7%、SiO2含量降低1%;还原度及低温还原120粉化率相差不大。同时,进行了配加煤粉、焦粉、有机黏结剂和PT粉的探索试验,试验表明,添加物对降低焙烧温度和提高球团矿强度有较好的作用,配加3%的PT粉,赤铁精矿配比30%球团矿的焙烧温度可降低50℃以上。     

冷固球团矿热态强度变化规律的研究

西方研究了几种铁精球团矿在煤基回转窑直接还原过程中热态强度变化规律。结果表明：添加“复合粘结剂”铁精矿冷固球团矿在还原过程中抗压强度下降幅度和强度低谷区宽度上于预热球团矿，水泥冷固球团矿和氧化才矿，其热态强度能满足工业生产加转窑的要求，适于做回转窑直接还原炉料。     

添加熔剂对球团矿还原膨胀率的影响

在鞍钢现场的原料条件下,向铁精矿中添加含CaO、MgO等熔剂并研究其对原膨胀率的影响。结果表明:CaO恶化球团的还原膨胀性能,MgO能够很好地降低球团的膨胀率,并随着熔剂配比的增加而降低。当熔剂配比为1%时,镁石球团还原膨胀率指标最低,为11.83%,且比基准球团低1.2%;石灰石球团还原膨胀率指标最高,为14.93%且比基准球团高出1.93%。     

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.