赤褐铁矿磁化焙烧矿物组成和物相变化规律

磁化焙烧—磁选工艺是有效处理难选弱磁性氧化铁矿的最有效方法之一,所得到的铁精矿性质与天然磁铁矿性质具有较大的差别。反浮选结果表明,人工磁铁矿和天然磁铁矿在浮选性能方面具有较大的差异,采用XRD(X-ray diffraction)、显微镜测试技术观察磁化焙烧矿物组成和物相变化,原矿中硅以碎屑石英和硅质泥岩形式存在,焙烧后有部分硅质泥岩,还有部分石英是被铁矿包裹,分布较原矿分散,即磁化焙烧形成的磁铁矿有一定的包裹、充填和浸染现象,具有不完整的晶体结构,分布分散,矿石内部组织结构的不均匀程度增加。原矿有用矿物主要以Fe2O3形式存在,脉石矿物主要是石英;焙烧后铁矿物的赋存由Fe2O3转变成Fe3O4为主,并掺杂Fe2O3,FeO,Fe,矿物组成发生变化,矿物不均匀性增强。焙烧物中还出现高铁橄榄石和铁硅酸盐峰,一部分橄榄石和硅酸盐矿物进入反浮选精矿,造成铁损失。     

Mechanism of sintering and fracture of superfluxed iron-ore sinters

Mineral formation in the binders of a commercial sinter with a basicity of 1.6 at the Magnitogorsk Metallurgical Integrated Works has been found to be determined by the crystallization of two morphological forms of high-iron aluminosilicoferrite (namely, dendritic and lamellar forms) from the melt. In a sintering zone, an association of dendritic aluminosilicoferrite crystals and dicalcium silicate Ca₂SiO₄ forms in high-calcium melt regions separated from magnetite grains. This association leads to the fracture of the finished product as a result of the phase transformation of Ca₂SiO₄ from the β into the γ modification during sinter cooling. Lamellar aluminosilicoferrites forming in high-iron sinter volumes serve as a high-strength binder for ore grains.     

三水铝石型高铝褐铁矿粉烧结液相生成特性

 烧结矿依靠液相黏结未熔颗粒获得强度,因此铁矿粉与CaO反应生成液相的能力对保证烧结矿质量非常重要。采用高温综合热分析仪（TG-DSC）对塞拉利昂高铝铁矿粉配加CaO的液相生成特性进行了研究。试验结果表明：提高CaO的配比,可以增加液相生成量,液相生成峰值温度基本稳定在1 209 ℃左右;随着矿粉粒度逐渐减小,液相生成量一直减少,同时,液相生成峰值温度先降低后增加,当粒度为0.074～0.180 mm时,液相生成温度最低;熔剂粒度的增加可增加液相生成量,同时初始液相生成温度显著提高;与生石灰（CaO）相比,采用石灰石（CaCO3）做钙源可以降低液相生成温度、增加液相量;与其他种类的矿粉对比表明,高铝铁矿粉其液相生成温度最高,反应性最差,Al2O3含量一般的澳大利亚褐铁矿的液相生成温度相对较低,高品位磁铁矿的液相生成温度最低,反应性良好。烧结杯试验表明,随着塞拉利昂铁矿配比的增加,成品率从78.37%逐渐降低到73.36%,烧结矿的转鼓强度由60.5%逐渐下降到49.6%,该高铝矿的配加比例应控制在混匀矿的20%以内。     

典型钒钛磁铁矿的烧结基础特性

 近年来,钒、钛和铬等重要金属的价格飞涨,钒钛磁铁矿资源的高效开发利用,不仅能缓解铁矿石资源的短缺问题,还能很好地解决重要金属的供需矛盾,有利于中国钢铁工业的可持续发展。通过微型烧结设备对国内使用量较大的5种典型钒钛磁铁矿的烧结基础特性进行了系统研究,同时使用XRD和SEM-EDS对精矿粉的物相组成进行了分析。研究表明,钒钛磁铁矿的基础特性与其化学成分和物相组成的联系紧密,低钛型钒钛磁铁矿的主要物相为磁铁矿,烧结基础特性的综合评价指数相对较好,其中CJ矿的最好,而高钛型钒钛磁铁矿的主要物相为磁铁矿和钛铁矿,它们的烧结基础特性均很差。总体来说,钒钛磁铁矿的烧结基础特性普遍较差,在使用过程中应尽可能与烧结基础特性较好的铁精矿搭配。     

MgO对烧结矿CaO-Fe2O3系初期液相生成的影响

为了研究MgO对烧结过程中CaO Fe2O3系初期液相生成的影响及作用机理,通过DSC研究了不同MgO含量试样在升温过程中液相生成的变化,并通过XRD确定液相生成前MgO对矿物组成的影响。结果表明,试样中MgO含量的增加使得升温过程中初期液相生成量减少,但是初期液相的生成温度没有明显变化。MgO对初期液相的抑制分为两种方式,一种为MgO与Fe2O3反应生成含镁磁铁矿,另一种为MgO添加导致CaFe2O4分解。这两种方式都使CaO含量升高,促进了高熔点矿物Ca2Fe2O5和含镁磁铁矿的生成,导致液相量降低。通过研究MgO对初期液相生成的影响,为烧结矿中合理添加含镁熔剂提供理论基础。     

Influence of Alumina on Iron Ore Sinter Properties and Productivity in the Conventional and Selective Granulation Sintering Process

Iron ore sinter constitutes a major proportion of blast furnace burden. Hence, its quality and consistency have a significant impact on blast furnace performance. Iron ore fines are the main source for sinter, and the chemical composition of the iron ore fines, together with the thermal conditions that blends are subjected to, plays an important role in forming the primary melt during the sintering process and accordingly determines the sinter structure and quality. Therefore, considerable importance has been placed on the chemical composition and consistency of iron ore fines, particularly in terms of alumina content. Due to depletion of high grade iron ore resources, alumina content in the iron ore fines is expected to increase gradually. Ore with higher alumina content is usually expected to be detrimental in forming the sinter matrix, if sintered alone, due to the low reactivity of alumina bearing minerals and the high viscosity of primary melts. The selective granulation process is a new sintering process for high alumina iron ore fines, and can eliminate the adverse effects of ‘hard to sinter’ or ‘unsuitable – for ironmaking’ ores. In the present work laboratory sintering experiments have been carried out with iron ore fines of different alumina level (2.00 to 5.46 mass‐%) to know the influence of alumina on mineralogy, productivity, physical and metallurgical properties of sinter prepared by the conventional and the selective granulation process. With increasing alumina content in sinter of both the conventional and selective granulation process, the fractions of hematite and of silico‐ferrites of calcium and alumina (SFCA) as well as the pore phase increased whereas the magnetite and silicate phases decreased. With increase in alumina content sinter productivity and tumbler index (T.I.) decreased, and metallurgical properties like sinter RDI and reducibility improved. However, sinter of the selective granulation process showed better results compared to the conventional process.     

富氧条件下高精粉配比对烧结指标及冶金性能的影响

为了深入研究富氧条件下磁铁矿配比对烧结矿烧结指标和冶金性能的影响,采用烧结杯试验、还原和软熔设备研究了不同磁铁矿配比下的烧结指标、还原性、低温还原粉化与软熔特性。试验结果表明,随着磁铁矿粉配比由0提升到56.4%,小于10 mm粒级烧结矿所占比例下降,大于40 mm粒级烧结矿所占比例有较大的波动,烧结料面富氧后成品烧结矿所占比例增加;垂烧速度由22.35 mm/min下降到15.87 mm/min,成品率先由73.88%升高到79.08%,后又下降到77.49%,利用系数在矿粉A配比为32.4%时达到最高,转鼓指数由59.26%上升到76.09%,收缩率和烧损随着矿粉A配比提高显著降低;富氧和增加磁铁矿配比共同导致烧结时间延长和转鼓指数的提升,随着矿粉A配比由0增加到56.4%,烧结矿的还原性由88.51%下降到82.13%,烧结矿的低温还原粉化指数由74.70%升高到了80.75%,软熔温度上升,软熔区间有下移趋势,且软熔区间变窄,滴落速度整体上呈现出下降趋势,熔滴滴落量降低,熔滴特性的变化主要是由于烧结矿中w(MgO)/w(Al₂O₃)提...     

2种氧分压下铁矿粉烧结高温熔体的流动行为

铁矿粉烧结高温熔体的流动行为,对烧结矿强度的改善有重要影响,而其受到烧结料层内氧分压的深刻影响.以7种铁矿粉为研究对象,在实验测定2种氧分压下高温熔体流动行为的基础上,通过FactSage热力学计算、XRD矿相分析法及矿相数点法探究其影响机制.结果 表明,当高温保持段的氧分压从0.1 kPa升高至21.0 kPa,高温...     

Model of Iron Ore Sintering Based on Melt and Mineral Formation

A model of iron ore sintering was built with consideration of fuel combustion,catalysis of sinter mixture as well as formation of melt and mineral,which was verified via sintering pot tests and showed a good fit to the experimental results.The effect of bed depth on temperature was reflected by the residence time in high-temperature zone,rather than the top value of the temperature,which was weakened by melt formation as well as hematite decomposition.Moreover,the effect of bed depth,fuel content and distribution on sintering process was different,which was reflected by temperature profiles and the rule of calcium ferrite formation.The formation of melt as well as magnetite was a process which was decided by kinetic factors,while the formation of calcium ferrite was related to fuel blending conditions,which is determined by thermodynamics when the fuel ratio inside sinter granules is low or fuel content is high,otherwise,it is determined by kinetics.     

TG-DSC法对莱钢进口铁矿粉烧结性能的研究

采用TG-DSC法对进口铁矿粉添加生石灰的烧结性能进行了研究。实验结果表明,此法可以表征铁矿物烧结过程中发生的物理和化学变化,弄清了添加8．45％生石灰后巴西MBR粗粉、澳大利亚库利安诺宾粗粉和哈默斯利粗粉在烧结过程中产生液相的初始温度、主体矿物熔化温度,以及结晶与凝固温度。三者相比,库利安诺宾粗粉和巴西MBR粗粉比哈默斯利粗粉更有利于低温烧结。实验还发现,铁矿物在熔化和凝固中分别伴随着赤铁矿分解—磁铁矿氧化过程,铁酸半钙存在对磁铁矿氧化有抑制作用。     

褐铁矿在烧结工艺中的优化配置

为了探究全进口矿条件下褐铁矿在烧结工艺中的合理配置,实现褐铁矿的高效利用以进一步提铁降本,针对S钢铁公司500 m2大型烧结机实际原燃料条件,基于试验用铁矿粉的常规理化性能和高温烧结基础特性开展了不同褐铁矿配比的烧结杯试验研究,结合Factsage 7.1热力学软件,模拟计算了不同褐铁矿配比条件下的黏附粉含量和理论液相生成量及性能,并采用矿相显微镜分析了烧结矿的显微结构,探明了褐铁矿与赤铁矿和磁铁矿的优化搭配规律。研究表明:澳大利亚褐铁矿具有粒度粗、矿化能力弱,同化温度低、黏结相强度差、吸液性强的特点,当褐铁矿质量分数由45%增加至55%时,提高磁铁精矿OD矿的质量分数至15%,同时降低OC矿质量分数至10%,烧结矿转鼓强度和低温还原粉化性能等指标达到最优,这是由于一方面提高磁铁精矿配比不仅具有增加黏附粉比例、改善液相生成数量和性能的作用,而且可以均匀液相分布,消除过熔现象;另一方面,增加磁铁精矿配比可以改善烧结料球的粒度组成,减少褐铁矿吸液量,提高烧结矿强度。因此,在高褐铁矿配比条件下,增加适宜的磁铁精矿配比有利于稳定烧结矿质量,全面改善烧结矿性能。      

Sintering behaviours of iron ore with flue gas circulation

Flue gas circulation is an important method for energy conservation and pollutant emission reduction in iron ore sintering. In this paper the effects of flue gas recirculation ratio on sintering of different iron ores including haematite, magnetite and limonite were studied by illustrating the variation of sinter bed temperature, atmosphere and mineralisation characteristics of different types of iron ores induced by the circulation. It shows that the proper flue gas circulation ratios for haematite, magnetite and limonite are 37, 30 and 25%, respectively. For magnetite ore, preheating and high consumption of oxygen in combustion zone caused more silicate minerals and less acicular calcium ferrite, thereby lowering sinter tumbler strength. As for haematite ore, the rapid change of temperatures of combustion, melting and solidification zones leads to elevated combustion efficiency and increased formation of acicular calcium ferrite, which enhances the sinter strength. When using limonite ore as the main raw material, high oxygen consumption, lower maximum temperature of sintering bed, higher cooling rate and larger porosity of sinter are observed.     

高配比磁铁精矿烧结技术的研究进展

 随着传统高品位铁矿石资源的日趋枯竭,烧结用铁矿石资源已经从赤铁矿类型逐渐转变为复杂综合的铁矿类型。但某些铁矿石的杂质和烧损较高,细粒级比例较多,严重影响了烧结性能和烧结矿质量,如烧结矿品位、强度和固体燃耗等。磁铁精矿具有含铁品位高、杂质低的特点,而且在氧化时能够释放出大量的热量。配加磁铁精矿不仅可以改善烧结矿质量,而且还具有减少烧结燃料消耗的潜力。然而,大多数磁铁精矿是经过处理后的铁矿粉,其粒度非常细,会对烧结料层透气性产生很大的负面影响,从而影响烧结过程,不利于烧结生产率的提高。在调查了磁铁精矿烧结特性的基础上,回顾和评论了高配比磁铁精矿烧结技术的最新进展,包括添加剂技术、原料预处理技术、预造块技术、复合烧结技术、气体燃料喷吹技术、双层预烧结技术等。通过分析烧结料层的透气性和控制烧结过程中的化学反应,论证这些新技术在高配比磁铁精矿烧结中的潜力,期望充分发挥磁铁精矿的优点,改善100%磁铁精矿或高配比磁铁精矿烧结混合料的烧结性能,为高生产效率条件下生产出优质低耗的烧结矿提供理论依据和技术方案。     

SiO2对CaO-Fe2O3熔体结晶矿物组成及显微结构的影响

摘要：由于近年来低品位铁矿石的使用量增加,导致烧结过程中SiO2含量升高。SiO2是烧结矿中主要的脉石成分,其含量的变化与烧结矿最终质量密切相关。运用X射线衍射、光学显微镜和SEM-EDS方法研究了SiO2对CaO-Fe2O3熔体结晶矿物组成及显微结构的影响。研究结果表明,随着SiO2含量的增加,CaO-Fe2O3-SiO2熔体结晶产物中CaFe2O4(CF)含量减少而富铁铁酸钙(SFC)含量增加,CaFe2O4和SFC分别以块状和板条状析出,SFC的晶体结构随着SiO2含量的增加从Ca36Fe144O25-2向SFCA-I转变;当SiO2的质量分数超过3.0%时,椭圆状的Ca2SiO4（C2S）从熔体中结晶,其含量随SiO2含量的增加而增加,另有大量圆点状玻璃相分布于铁酸钙基体表面。     

铁矿粉液相流动性的主要液相生成特征因素解析

烧结矿是我国高炉炼铁的主要原料,烧结矿质量将直接影响高炉冶炼及炼铁工序的经济技术指标.因此,基于铁矿粉的高温特性进行优化配矿从而改善烧结矿的产质量对于炼铁工序节能增效具有十分重要的现实意义.铁矿粉的液相流动性是非常重要的烧结高温特性指标,适宜的液相流动性可以使烧结矿获得较高的固结强度.本文模拟实际烧结黏附粉层中铁矿粉颗粒与钙质熔剂质点的接触状态,采用FastSage热力学计算和微型烧结可视化试验方法研究了固定CaO配比条件下铁矿粉的液相流动性及其主要的热力学液相生成特征影响因素.研究结果表明,采用固定CaO配比与固定碱度的熔剂配加方式下,铁矿粉的液相流动性规律明显不同.铁矿粉的液相生成量是影响其液相流动性的最主要液相生成特征因素,液相生成量越多则铁矿粉的液相流动性指数越大.铁矿粉液相流动性的配合性机制是基于其液相生成量的线性叠加原则.脉石矿物含量将在一定程度上影响铁矿粉的液相流动性,随着SiO₂含量的升高铁矿粉的液相生成量减少,从而导致液相流动性指数显著降低;而Al₂O₃含量增加,液相流动性指数略有升高.      

碱度对钒钛烧结矿强度和烧结过程的影响

在新的配矿条件下，研究了碱度对承钢钒钛磁铁烧结矿的强度、矿物结构和烧结过程的影响。结果表明：在大量使用澳矿时，综合考虑烧结矿碱度对承钢烧结过程、高炉炉料结构和高炉冶炼过程的影响，烧结矿碱度控制在1．9左右比较适宜。     

铁矿石高温烧结基础特性评价方法的国外研究进展

 随着全球优质铁矿石日益减少、资源禀赋变差,国内外钢厂普遍面临着烧结原料供应不稳定、铁矿石性质波动大、原料结构频繁变化等问题,对烧结生产、高炉冶炼和产品质量产生了极大的不利影响。因此,开展铁矿石烧结性能评价研究具有重要的现实意义。铁矿石烧结基础特性可分为冷态特性和高温特性两大类,前者主要包括铁矿石的化学成分、粒度组成、矿物学特性等常温性质,后者主要包括铁矿石的同化性能、液相生成特性等高温成矿行为及实际烧结性能。概述了国外关于铁矿石高温烧结基础特性评价方法的研究进展,系统归纳了不同研究机构提出的评价指标和试验方法。已有研究表明,现有基于团块烧结法的评价方法虽然对铁矿石不同的烧结行为分别进行了深入研究,但未能在其与铁矿石的实际烧结性能之间建立起准确可靠的关系,主要原因在于,对影响铁矿石实际烧结性能的最关键因素把握不准,同时对烧结过程的模拟性有待提高。因此,揭示铁矿石基础特性与其烧结性能的内在联系,首要前提在于必须深入研究和把握“铁矿石-制粒物料-烧结矿”不同阶段物料性质的传递规律,查明影响铁矿粉烧结过程的主要因素,这对找准高温烧结基础特性研究的切入点具有十分重要的意义。     

Structural and morphological changes during reduction of hematite to magnetite and wustite in hydrogen rich reduction gases under fluidised bed conditions

Abstract

During the reduction of iron ore fines structural changes in particles have a significant influence on the rate of reduction. Investigations regarding porosity, specific surface area and mean pore diameters in the reduction of hematite with hydrogen rich reducing gases were performed by mercury porosimetry. Morphological changes were examined by metallographic analyses of polished sections in reflected light. In the magnetite equilibrium phase, significant influence of temperature on structural parameters and sintering effects were found.

For wustite phases, the influence of temperature was less pronounced. For the reduction of hematite to magnetite and magnetite to wustite topochemical phase growth and microporous product layers were observed. In the single step, reduction of hematite to wustite progressive conversion and significant increase in the mean pore diameter were found. The results presented in this work are of high importance for understanding the reaction kinetics of iron ore fines and essential for modelling heterogeneous reactions.     

矿石特性对CaO Fe2O3系熔体渗透性的影响

在烧结过程中维持一定数量的熔体对烧结矿的产品率和强度非常重要。熔体通过粘结层快速展开而获得烧结矿固相粘结相的微观结构。实验研究了不同矿石特性对CaO·Fe2O3熔体渗透行为的影响。渗透性测试可用来观察最初熔体的扩展情况。实验主要通过矿石中二氧化硅、三氧化铝的质量分数，以及脱水后的矿石表面形态，来分析熔体在矿石间的渗透行为。实验结果表明，随矿石中二氧化硅、三氧化铝和结合水量的增加，CaO·Fe2O3熔体对矿石的渗透行为受到抑制。     

矿石特性对CaO Fe2O3系熔体渗透性的影响

在烧结过程中维持一定数量的熔体对烧结矿的产品率和强度非常重要。熔体通过粘结层快速展开而获得烧结矿固相粘结相的微观结构。实验研究了不同矿石特性对CaO·Fe2O3熔体渗透行为的影响。渗透性测试可用来观察最初熔体的扩展情况。实验主要通过矿石中二氧化硅、三氧化铝的质量分数,以及脱水后的矿石表面形态,来分析熔体在矿石间的渗透行为。实验结果表明,随矿石中二氧化硅、三氧化铝和结合水量的增加,CaO·Fe2O3熔体对矿石的渗透行为受到抑制。