烧结混合料水分的自动化控制

本文对比国内烧结水份控制的各种策略，提出了莱钢烧结水份控制的实现方法和改进方案。     

烧结混合料水分测量过程控制方法

水分是影响钢铁行业烧结过程的重要因素之一,它起着黏结、润滑和导热等重要作用。混合料烧结过程中,上层烧结料中的水分在升温过程中蒸发成水蒸气。随着抽风,水蒸气开始在下层冷料表面冷凝形成过湿层,过湿层的透气性很差,阻碍燃烧过程和传热过程。     

高性能超细、纳米硬质合金及其制备过程中的关键技术问题

介绍了超细、纳米硬质合金的国内外研究、生产以及市场情况,主要应用领域,硬度、抗弯强度、断裂韧性、热硬度、热导率等力学、热物理性能和使用性能特点,湿磨过程中的研磨与分散、混合料制备过程中的控氧、粉末成形、烧结过程中WC晶粒长大的控制和粉尘控制等合金制备过程中存在的关键技术问题以及解决这些问题的主要途径.     

烧结自动化智能控制技术探讨

钢铁行业需要大量铁矿石，然而，天然富矿越来越少，高炉不得不使用贫矿，但贫矿直接人炉，不论在经济还是在操作上都是不合理的。本文主要针对烧结厂配料系统的现场工艺、控制要求和过程特点，采用先进的自动控制技术完成了烧结配料自动化控制系统的设计，达到了对配料过程变量的实时检测，工艺流程的实时监控，过程参数的实时控制。     

高铝矾土和煤矸石合成矾土基莫来石料的研究

按照莫来石料的化学组成要求,以高铝矾土和煤矸石为基料,需要时加入少量的活性Al2O3微调成分,配成多组混合料,将混合料分别经磨细、过滤、烘干、成型、干燥、煅烧工艺后,测定合成料的性能.结果表明:采用此工艺方法可制备出莫来石料,加与不加烧结助剂试样的烧结温度分别为1600℃和1700℃,莫来石料的显气孔率分别为1.0%和2.5%以下,体积密度分别为2.75g·cm-3和2.87g·cm-3以上,并具有较高的荷重软化温度,分别为1590℃和1600℃.     

国际先进陶瓷材料研究现状

先进陶瓷材料指用精制高纯人工合成的无机化合物为原料，采用精密控制工艺烧结而制成的高性能陶瓷，又称为高性能陶瓷、高技术陶瓷、精细陶瓷或特种陶瓷，是相对于传统陶瓷材料而言的。发达国家非常重视先进陶瓷材料的研发，美国、欧盟对先进陶瓷在军事、航空航天等领域的应用兴趣浓厚；日本在先进陶瓷材料的产业化方面占据世界领先地位。本对重点国家在先进陶瓷领域的研究进展进行介绍，并简单介绍我国在本领域的研究布局，以期对我国陶瓷领域的发展有所裨益。     

射频导纳料位仪在烧结混合料槽料位测量中的应用

介绍了射频导纳料位仪在烧结混合料槽料位测量中的原理及优势,设备安装的注意事项及仪表的标定调试.     

难熔金属材料先进制备技术

介绍了现代烧结技术(微波烧结、放电等离子烧结、选择性激光烧结)、先进高纯材料制备技术(电子束精炼、区域熔炼、等离子弧熔炼)、近净成形技术(3D打印、金属注射成形、高能喷涂成形)和抗氧化技术(涂层、复合材料等)4类先进制备技术。阐述了基本原理、技术优势、国内外研究现状及其在难熔金属材料制备方面的初步应用,并指出难熔金属材料的制备正在向着更高纯度、更高抗氧化性能及近终成形方向发展。最后提出了采用先进技术制备高性能难熔金属材料亟待解决的一些突出问题:从实验室走向实际应用还需要大量的的试验和基础研究数据;需要进一步提高难熔金属单晶纯度、扩大单晶品种和规格;近净成形件完全代替传统锻件要先解决内部组织和缺陷的控制、综合力学性能的调控等;高温抗氧化时长需进一步提高。     

烧结配混系统优化方案

经过配混系统的优化后,"水碳"得到稳定,混合料温度得到明显提升,为烧结的各项指标的提高做足贡献。     

利用放电等离子烧结技术制备粒径可控的多孔铝

利用放电等离子烧结技术（SPS）制备了粒径可控的多孔铝，具体的方法为：以铝粉和食盐为原料，首先烧成为块体，再利用溶解法，将造孔剂食盐熔解掉。利用反溶液法研究了控制造孔剂食盐颗粒大小的方法，制备出粒径可控的食盐颗粒（粒径控制范围为5～20μm）。通过系统研究SPS烧结工艺（烧结温度、压力等）及铝粉与食盐配比、粒径配比等关系，获得的多孔铝的孔隙率可达69.41％，最小孔径为5μm左右。     

LIGGGHTS and EDEM application on charging system of ironmaking blast furnace

Chemical reactions between gas and raw material are determined by burden distribution, especially radial distribution of pellet/sinter and coke in blast furnace. An appropriate control of burden distribution is required to yield a smooth operation with effective performance and an appropriate gas flow at the wall. This paper studies two different DEM packages application for charing system of ironmaking blast furnace. The simulations (EDEM 2.2.1 and LIGGGHTS 3.4.0) based on the discrete element method (DEM), are validated using mass fraction distribution in the trajectory of pellet flow and burden distributions of pellet on a horizontal plane. The results show that good agreements are found among EDEM, experiment and LIGGGHTS. Furthermore, reducing shear modulus of material can increase calculation speed of DEM.     

永磁铁氧体烧结过程应力场有限元分析

利用有限元法对永磁铁氧体材料烧结过程的瞬态应力场进行了数值模拟分析,讨论了温度场变化对铁氧体磁瓦内部热应力的影响,得出磁瓦在烧结过程中的等效应力分布云图,结合分布图与热传导方程讨论了磁瓦烧结开裂问题中产生边裂和角裂的原因.同时分析了升温速率对应力场的影响,该分析结果反映了升温速率对磁瓦内部热应力最大值的影响规律.模拟结果为磁瓦烧结工艺制度的制定提供理论依据.     

永磁铁氧体烧结过程温度场有限元分析

利用有限元分析法对永磁铁氧体材料烧结过程温度场进行了数值模拟研究,得出铁氧体磁瓦在烧结过程的不同传热方式下、不同烧结阶段的温度分布规律,得出了烧结过程对流传热为主的低温阶段与辐射传热为主的高温阶段的分界温度.同时对对流为主的低温阶段的模拟结果进行了实验验证,得出模拟结果与实验结果定性符合.模拟结果为磁瓦烧结工艺制度的制定提供理论依据.     

Simulation of the pressure drop across granulated mixtures using a coupled DEM – CFD model

The sinter process converts mixtures of iron ore, iron ore fines and fluxes into a fused aggregate (sinter) that is used as burden material in the blast furnace. The rate of this process is predicted by measuring the pressure drop across the green granulated mixture before ignition. A lower pressure drop corresponds with a higher permeability resulting in a higher sinter rate. The addition of fine material, such as concentrate or concentrate agglomerated into micropellets, to the sinter mixture affects the pressure drop. This study numerically predicts the pressure drop over several granulated mixtures in order to reduce the number of experimental measurements. The pressure drop was studied both experimentally using a pot grate and by coupled DEM (Discrete Element Method) – CFD (Computational Fluid Dynamics) simulations. The validation of the model was performed by comparing the measured and numerical values of the pressure drop across glass beads 3 and 6?mm in diameter respectively. The simulation of the pressure drop was extended to granulated mixtures that contain 0–40% concentrate or micropellets. DEM was also used to numerically simulate iron ore granules and relate their mechanical behaviour to particle size distribution, shape, friction coefficient, Young’s modulus and adhesion force.     

Failure Analysis of Wear Block of Crush Deck Used in Sinter Plant

Failure analysis of wear block used in the crush deck of a Sinter Plant was carried out. Crush deck acts as a platform to transfer the hot sinter cake from sinter machine to crushing unit. Hot sinter cake with a temperature around 800 °C falls on the crush deck from the discharging end of rotating sinter machine. This investigation consists of visual observation, chemical analysis, characterization of microstructures, energy dispersive spectroscopy, and measurement of hardness. Analysis revealed that this is an iron-based material with Cr–Ni alloying with higher hardness and lower toughness, which was due to improper microstructure. Microstructure revealed a large number of primary carbides along with needle-shaped carbides, which drastically reduce the toughness of the material. Application point of view the wear block should have optimum combination of toughness and wear resistance at elevated temperature; however, analyses showed the actual wear block had with higher wear resistance and lower toughness. This was reflected in the undesirable microstructure observed during metallographic study. It was thus concluded that the component failed before a proper life cycle was achieved due to poor material properties. Based on the failure analysis suitable heat treatment process was recommended. Metallurgical study carried out on the suggested material, showed significant improvements in material property. Trial of recommended wear block was taken at the plant level and life of the recommended material improved twice than that of previous one.     

烧结质量的计算机在线检测

对于烧结这类高度复杂的动态系统，提出了利用图象序列和动态模式识别的思想。把图象序列的特征量和质量相结合，很好地解决了烧结质量的在线检测，为最终实验复杂生产系统的自动控制探索出一条新的途径。     

Surface behaviour of magnesium chloride-coated iron ore sinter

The coating of sinter particles with magnesium chloride rendered a less reducible material at low temperature, and simultaneously enhanced mechanical strength. The joint use of scanning electron microscopy (SEM) and energy dispersive analyses of the X-rays (EDAX) emitted by the solid revealed the magnesium atoms to be almost uniformly distributed on the sinter surface. However, X-ray photoelectron spectroscopy (XPS) provided an extremely useful tool for understanding the chemical reaction, largely confined to the surface, when the sinter was heated at high temperatures. A model which assumes solid-state reaction between MgO and Fe₂O₃ to form a surface spinel-like MgFe₂O₄ compound has been proposed to describe that process in both salt-coated sinter and salt: physical mixture sinter preparations.     

Cu—1C—1Cd粉末复合体致密化过程的研究

系统地研究了Ｃｕ－１Ｃ－１Ｃｄ粉末复合体制备过程中,原始粉末状态,压制压力,烧结温度等工艺参数对材料相对密度的影响。结果表明,原始粉末的差异对制备工艺的全过程均产生规律性的影响。压制压力对压坯密度的影响符合粉末冶金材料的一般压制规律,在烧过程中,镉和孔隙扩散对烧结密实化过程起着重要作用。     

A case study on the fracture of sinter machine pallet axles

A sinter machine produces sinter at 1200–1400 °C to supply raw materials for blast furnace ironmaking. The sinter machine is composed of a series of pallet cars which are constrained on rails. Each pallet car has four axles which connect the pallet car and four running rollers. In sinter production, the pallet axles experience periodic thermal expansion and periodic load changes under high temperature, high moisture, corrosive atmosphere and heavy dust. After serving for about seven years, pallet axles of one of ArcelorMittal sinter machines started breaking, causing unscheduled production delay. The fracture of the axles is in the orientation of top and bottom, and the cracks are deeper in upper portions than in lower portions of axle cross sections. The axles have been studied through chemical analysis, strength analysis, stress analysis, lifetime analysis via deterministic mechanics and lifetime distribution analysis. It has been found that the axles are breaking in fatigue-crack mechanism. The fatigue cracks are resulted from effect of thermal expansion on net tensile stress of the axles. Considering harsh working environment and dynamic loading, lifetime analysis, using deterministic mechanics, indicates that originally installed pallet axles are approaching the end of their lifetime. Weibull distribution function can very well describe lifetime distribution of pallet axles. Accordingly, about 50% of originally installed axles will be gone before next two and half years, and more than 90% of them will break before next six and half years. An intelligent replacement strategy is recommended. In a scheduled maintenance time, carefully inspect all axles using ultrasonic crack detectors, and replace those axles whose expected lifetime is shorter than next scheduled maintenance date. To replace steel SAE 1045 with steel SAE 4040 for fabricating new pallet axles may significantly increase lifetime of the new pallet axles.     

Experimentelle und numerische Untersuchungen zur Kennzeichnung von Sinterteilen mittels gezielt eingebrachter Fremdpartikel

Experimental und numerical investigation on the marking of sintered parts by the targeted application of particles Sintered parts from steel as well as light metal alloys are becoming popular in many industrial sectors due to their advantageous product properties. Beside the good utilization of raw material and the variability in alloying the sinter technology offers the opportunity to mark parts in a unique and invisible manner. Spheric particles are used as information carrier. A quadratic 4x4 matrix with a maximum of 16 particles is placed inside a sinter part for first experiments. The defined places and number of particles result in an identification number. After sintering process the two materials are inseparably connected. The readout of the data is realized with x‐ray or computer tomography due to different physical properties of the particles and the powder material.