铁矿球团还原膨胀机理及影响因素的研究进展

 铁矿球团在还原过程中通常会伴随体积的膨胀,如果发生异常膨胀或恶性膨胀则会严重妨碍炼铁生产的顺行。开展铁矿球团还原膨胀机理和影响因素研究,有利于制备出低还原膨胀率球团,改善高炉运行状况。从物相转变、铁晶须生长、还原反应速率以及碳沉积等方面归纳了引发铁矿球团还原膨胀的机理。指出了生产工艺制度、熔剂、杂质元素以及还原气氛等因素对球团还原膨胀产生造成的影响,并针对不同影响因素的还原膨胀抑制方法进行了简要评述。     

某低品位铁矿回转窑还原结圈物特性及其形成机制

回转窑结圈一直以来是制约煤基回转窑直接还原工艺发展的重要因素,以某低品位铁矿回转窑还原结圈物为研究对象,深入研究回转窑结圈物的特性及其形成机制.从结圈物的宏观形貌、物化性能、软熔特性和微观结构入手对某低品位铁矿球团回转窑结圈物的特性进行分析,并结合热力学相图、化学物相及能谱分析研究了结圈物的形成机制.结果表明:结圈物由熔融物包裹球团形成,接近窑壁,其熔融包裹物增多,结圈物中MFe、CaO含量明显增大,软熔温度越低;由球团粉末中FeO与SiO₂形成的铁橄榄石及煤灰带入的CaO而形成的钙铁辉石低熔点相是造成结圈的主要原因;低熔点相的存在同时也促进了金属化球团间铁晶粒的相互扩散与迁移,从而加剧了结圈现象.     

高炉使用含碳复合炉料的原理

 高炉炼铁正朝着高产、低污染、低能耗的方向发展,为了实现这一目标,包括高炉使用含碳复合炉料等一些革新的炼铁技术已经被提出或实际应用。铁焦、热压含碳球团是将铁矿粉和煤粉按一定比例混合后制成的新型含碳复合炉料。研究结果指出,含碳复合炉料相比于传统的高炉炉料（烧结矿和球团矿）具有高温强度高、还原性能好以及原料适应性强等优势。阐明了高炉使用含碳复合炉料的基本原理,介绍了铁焦制备的工艺流程及应用情况,重点进行了热压含碳球团制备工艺流程、冷态冶金性能、高温冶金性能、高炉使用热压含碳球团等试验研究,最后利用多流体高炉数学模型对高炉使用热压含碳球团操作进行了模拟研究。研究表明,高炉使用一定量的含碳复合炉料可以降低热空区温度,增加产量,降低焦比,高炉热利用效率明显提高,操作性能得到有效改善。     

浅谈水钢炼钢区域葫芦吊维护与升级

随着钢铁工业的发展,钢铁企业为了生存、发展,都在原有设备的基础上不断做大产能,降低成本。在做大产能的同时,无形中就加大了区域内行车作业率,系统生产对设备稳定的容错能力极端减少,突显了行车的检修、维护工作的重要性,怎样保证行车大型备件的及时、安全吊装,已成为当前行车维护检修面临的一大难题。     

碳包覆不同形貌纳米铁氧化物的还原分析

为了抑制铁矿粉在还原过程中铁晶须的生长,采用水热炭化法对球状、棒状2种不同形貌的纳米氧化铁进行了碳包覆,并用热重法对碳包覆铁氧化物的还原行为进行了研究.同时,采用场发射扫描电子显微镜(FE-SEM)分析了铁氧化物、碳包覆铁氧化物还原后样品的形貌.结果 表明,与普通铁矿粉相比,纳米氧化铁还原温度大幅降低;升温速率越小,越...     

Comparative functioning of dihydro- and tetrahydropterins in supporting electron transfer, catalysis, and subunit dimerization in inducible nitric oxide synthase

The nitric oxide synthases (NOS) are the only heme-containing enzymes that require tetrahydrobiopterin (BH4) as a cofactor. Previous studies indicate that only the fully reduced (i.e., tetrahydro) form of BH4 can support NO synthesis. Here, we characterize pterin-free inducible NOS (iNOS) and iNOS reconstituted with eight different tetrahydro- or dihydropterins to elucidate how changes in pterin side-chain structure and ring oxidation state regulate iNOS. Seven different enzyme properties that are important for catalysis and are thought to involve pterin were studied. Only two properties were found to depend on pterin oxidation state (i.e., they required fully reduced tetrahydropterins) and were independent of side chain structure: NO synthesis and the ability to increase heme-dependent NADPH oxidation in response to substrates. In contrast, five properties were exclusively dependent on pterin side-chain structure or stereochemistry and were independent of pterin oxidation state: pterin binding affinity, and its ability to shift the heme iron to its high-spin state, stabilize the ferrous heme iron coordination structure, support heme iron reduction, and promote iNOS subunit assembly into a dimer. These results clarify how structural versus redox properties of the pterin impact on its multifaceted role in iNOS function. In addition, the data reveal that during NO synthesis all pterin-dependent steps up to and including heme iron reduction can take place independent of the pterin ring oxidation state, indicating that the requirement for fully reduced pterin occurs at a point in catalysis beyond heme iron reduction.     

Characteristics of coal required for superior performance of Corex ironmaking

Abstract

The Corex smelting reduction process was developed as an alternative to the blast furnace and consists of two reactors: the reduction shaft and the melter gasifier. Coal rather than coke is used for heat generation, production of reducing gases and to maintain adequate bed permeability; hence, coals have to meet certain physical, chemical and especially high temperature properties for stable process operation and high iron outputs. Statistical analysis was employed to investigate the influence of coal properties on Corex performance, and laboratory coal characterisation studies were correlated with plant performance. This paper details these coal characteristic studies and highlights the coal blend properties required for superior plant performance.     

Some Aspects of the Melting and Dephosphorization Mechanism of Hydrogen-DRI

To meet the future environmental challenges, hydrogen direct reduced iron (H-DRI) is expected to constitute the principal material for virgin steel production. For an efficient value chain, knowledge of the melting mechanism and dephosphorization mechanism of H-DRI is needed. The in situ melting behavior, the melting mechanism, and the dephosphorization mechanism during heating of H-DRI are investigated experimentally at 1773 and 1873 K. It is found that the melting rate of H-DRI varies with the reduction degree (91–99.5%), increasing with decreasing reduction degree. An autogenous slag forms during heating and flows through the pores of the H-DRI, thus increasing its effective thermal conductivity. The fraction of filled pores varies with reduction degree explaining the difference in melting rate. At this stage, the dissolution of apatite is initiated and completed upon melting of the metal phase. A gradual reversion of phosphorus from the autogenous slag to the liquid metal is observed after complete melting. The rate of reversion is discussed based on the properties of the H-DRI, for example, reduction degree and carbon addition.     

甲醇/乙醇-氢气还原铁矿石制备Fe3C研究

鉴于工业上成功采用CH₄-H₂系和CO-H₂系气体作为还原剂制备Fe₃C, 尝试以甲醇作为碳源, 同氢气共同还原铁矿石制备Fe₃C.试验考察温度、氢还原时间、甲醇量对碳化铁率的影响.采用扫描电镜分析、XRD测试等手段研究产物的物相组成.结果表明:在反应温度700 ℃, 无水甲醇量高于60 mL, 氢还原时间120 min的试验条件下, 达到高效生产Fe₃C的目的.该工艺方法流程简单, 操作条件温和, 具有广阔的应用前景.在此基础上, 用乙醇代替甲醇, 研究其还原效果.      

Recovery of Iron From High-Iron Red Mud by Reduction Roasting With Adding Sodium Salt

 Red mud is the waste generated during aluminum production from bauxite, containing lots of iron and other valuable metals. In order to recover iron from red mud, the technology of adding sodium carbonate—reduction roasting—magnetic separation to treat high-iron red mud was developed. The effects of sodium carbonate dosage, reduction temperature and reduction time on the qualities of final product and the phase transformations in reduction process were discussed in detail. The results showed that the final product (mass percent), assaying Fe of 90.87% and Al2O3 of 0.95% and metallization degree of 94.28% was obtained at an overall iron recovery of 95.76% under the following conditions of adding 8% sodium carbonate, reduction roasting at 1050 ℃ for 80 min and finally magnetic separation of the reduced pellets by grinding up to 90% passing 0.074 mm at magnetic field intensity of 0.08 T. The XRD (X-ray diffraction) results indicated that the iron oxides were transformed into metallic iron. Most of aluminum mineral and silica mineral reacted with sodium carbonate during the reduction roasting and formed nonmagnetic materials.     

中国钢铁工业碳达峰及低碳转型路径

 2020年中国宣布将提高国家自主贡献力度,二氧化碳排放力争在2030年前达峰。钢铁工业作为典型的资源、能源密集型行业,是率先落实碳达峰的重要行业。分析了钢产量、生产结构、节能减排技术和碳税等因素对中国钢铁工业碳排放的影响程度。研究表明,不同的钢产量达峰时间将对钢铁工业的碳达峰产生不同影响,技术和生产结构因素也将对中国钢铁工业产生重要影响。地方区域是落实国家碳达峰任务的责任主体,对京津冀及周边地区、长三角地区、汾渭平原和两广地区4个具有不同钢铁生产特点的重点区域碳排放进行研究,并分析了区域达峰方案。加快调整产业结构、推广低碳技术、改变能源结构、推进产业间耦合和加强碳资产管理等方面制定钢铁工业低碳转型路径,对实现中国钢铁工业碳排放早日达峰和碳中和有重要意义。     

我国直接还原铁生产的现状

近年来，我国直接还原铁的生产有了重大进展，建设中的、试运行的和已投产的共有７０多个直接学原铁生产线，直接还原铁的质量也逐步提高。到２０００年，我国直接不失生产能力预计将达到５０－６０万ｔ／年。     

攀钢—高炉炉况失常后恢复期间的调查及分析

自1995年11月起，攀钢—高炉炉况一直不太稳定，生产水平波动较大，尤其是1996年3月下旬炉况再次恶化，为了尽快使之恢复正常，攀钢炼铁厂组织了炉况恢复攻关。在一高炉炉况恢复期间，对其进行了跟踪调查，据此进行了分析讨论。     

COREX熔融还原炼铁煤气利用方向研究

文中介绍了ＣＯＲＥＸ副产煤气的状况，比较了在一个紧凑式钢厂中ＣＯＲＥＸ副产煤气用于发电，制造海绵铁与生产甲醇三种设计方案的经济效益，生产甲醇短期效益较好但市场风险很大，发电投资最小但效益最小；生产海绵铁市场广阔，效益居中。     

基于不同炼铁工艺的铁矿石低温还原粉化特征

 为改善铁矿石在炉内的低温还原粉化性能以适应多样的炼铁生产条件,以炼铁生产常用的烧结矿、球团矿以及块矿为研究对象,通过控制还原气体成分和温度的方式,考察并比较了不同种类铁矿石在高炉炼铁工艺和COREX非高炉炼铁工艺2种煤气条件下的低温还原粉化行为。试验结果表明,相同的还原气氛和温度条件下,烧结矿、球团矿以及块矿的还原粉化形式、程度有较大差异,而各类铁矿石对煤气性质、温度变化的敏感性也各不相同。这对更为全面地考察和评价不同类型铁矿石的低温还原粉化特征,进而改善铁矿石冶金性能和优化炼铁工艺参数具有一定的实用性和参考价值。     

Research on deadman state during tapping process

In this paper, a deadman state model is established. According to the actual operation parameters of 5500?m³ blast furnace (BF) in Shougang Jingtang United Iron and Steel, the influence of taphole depth, deficient iron amount and salamander depth on deadman state is discussed. Meanwhile, the relationship between deadman state and differential pressure of BF is analysed. The results show that deadman of 5500?m³ BF is floating during regular production and the range of floating height is 0.23–0.30?m. When the mud mushroom cannot be formed or cracks during tapping process, the range of floating height is 0.38–0.45?m. The upward movement of deadman can result in the reduction of coke size and porosity, which is one of the key factors that causes holding hot blast.     

基于CSC方法的钢铁行业节能减排技术潜力分析

为了研究中国钢铁行业的节能减排潜力,以35项钢铁行业先进节能减排技术为研究对象,建立节能供应曲线(Conservation Supply Curve,简称CSC)模型,分析影响钢铁行业的节能减排收益、成本效益以及钢铁生产流程工序层面的节能减排潜力因素。结果表明,这35项技术全部应用可实现3.01 GJ/t的节能量以及398.22 kg/t的CO2减排量。将结果与第十三个五年计划推广技术作对比,在当前情况下,约有50%的推广技术并不符合成本效益;运用CSC模型进行了钢铁生产流程工序层面的节能减排潜力研究,得到各个工序的节能量和减排量,并据此分析了各项技术未来的发展趋势和应用前景。     

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.     

低碳高炉炼铁新技术及在安钢应用的可行性

为贯彻国家节能减排精神,实现“低碳炼铁、节能减排、实现清洁生产”的目标,在不断完善传统节能减排方法(如大喷煤和高风温等)的基础上,还需要进一步开发应用各种新技术和新措施。本文简要介绍了钢铁生产过程CO2的排放情况,重点阐述了高炉系统的CO2的产生及排放现状。同时介绍了为降低CO2排放,高炉炼铁新的研究应用热点,包括高炉...     

Effects of Reducing Gas on Swelling and Iron Whisker Formation during the Reduction of Iron Oxide Compact

The effects of different types of reducing gas on swelling and iron whisker formation during the reduction of iron oxide compacts were investigated. The compacts sintered in air at 1273 K were reduced at 1173 K in different reducing atmospheres. The results indicated that catastrophic swelling can happen in CO but not when H₂ is present in the reducing gas mixture. Scanning electron microscope (SEM) micrographs showed that catastrophic swelling was caused by a large amount of long iron whiskers formed during the reduction. The presence of N₂ and CO₂ in CO changed the amount of long iron whiskers and its distribution, which determined the extent of swelling.