图像技术在球团方面的应用及未来发展方向

<正>图像技术在球团中的应用集中在成品球团矿平均粒度在线检测、球团矿还原膨胀测定和回转窑生产氧化球团时窑内温度的在线监测等。图像技术在球团生产的应用还不是很广泛,目前仅局限于成品球团矿平均粒度检测、球团矿还原膨胀测定以及回转窑内部球团和烟气温度测定。未来发展方向应该更多地着眼于整个球团的     

基于Segment Anything的堆叠球团粒度检测

球团的合理粒度分布对其质量至关重要。通过深入研究现有方法,针对球团粒度检测中不完全分割和过度分割等问题,提出了Pellet-SAM(PelSAM)分割方法。该方法继承于Segment Anything(SAM)结构,主要操作是冻结图像编码器和提示编码器的相关参数,并在图像编码器上添加轻量级的空间和通道适配器及微调掩码解码器,使用标记的球团分割数据集对网络进行训练,从而实现对球团图像的准确分割。由于分割后的球团轮廓呈现类圆形,为了便于计算球团直径,先采用最小二乘法对分割后的球团轮廓进行圆拟合;再应用小孔成像原理,结合摄像头和球团表面的距离及摄像头的焦距等因素计算比例系数,然后利用该系数计算图像中球团颗粒的实际大小;最后根据球团颗粒的实际大小将球团粒度分布划分为4个范围,即小于8、[8,12]、(12,16]以及大于16 mm,其中[8,16] mm的为合格球。试验结果表明,该方法在球团分割数据集上取得了96.8%的准确率,比UNet和DeepLabv3方法分别提高了21.0和12.6个百分点。在实际工厂环境下,该方法计算得到的球团粒度分布与人工筛分测量的结果相近,最大误差仅为1.74个百...     

基于小波变换的球团矿图像边缘检测

球团粒径及其分布是衡量球团矿质量的重要指标。球团矿图像的边缘检测对基于数字图像处理的球团粒径自动检测具有重要意义。但是，由于成像中的噪声及球团图像的无背景等特点，使得球团图像的边缘检测比较困难。本文利用小波变换系数模局部极大值来检测球团图像的边缘，取得了较好的效果。     

煤粉粒度对预热含碳球团抗压强度的影响

为了弄清含碳球团配煤粒度对球团抗压强度的影响规律,研究了配加不同粒度煤粉的含碳球团在中性气氛中预热至不同温度后的抗压强度。结果表明:当温度小于1 000℃时,煤粉粒度对含碳球团的抗压强度影响不大,而当温度大于1 000℃后,煤粉粒度对含碳球团的抗压强度有显著影响;当配加煤粉的粒度介于0.074~0.106mm时,含碳球团还原后的抗压强度最高,煤粉粒度过细或过大都不利于球团强度的提高;在高温还原过程中,煤粉粒度越细含碳球团的还原速率越大,金属化率越高。     

铁矿石烧结技术的最新发展（三）

烧结生产率和料层透气性有直接关系，因此也和粒度组合有关。评述了影响制粒过程和粒度组成的因素，如矿石粒度分布、水分、添加剂等。介绍了在主制粒流程前，根据粒度矿物或化学成分对某些原料进行预制粒或单独处理的设想。描述了代用制粒系统，如日本钢管公司的球团烧结工艺和振荡制粒。由于混合料布到台车上会发生粒度偏析，因此布料技术受到很大重视。评述了如强化筛分布料器和条筛式布料器的新发展。     

化工铬渣冷固球团的制备及性能研究

利用化工铬渣制备用于还原解毒的冷固球团，研究铬渣粒度，粘结剂种类和数量、添加剂种类和数量对球团成球性能及球团强度的影响，提出了铬渣冷固球团制备的最佳配比。     

冷却方式对球团矿冶金性能的影响

随着钢铁工业的不断发展，竞争日益激烈，促使高炉冶炼必须采取相应的措施增产、降耗。球团矿含铁量高、粒度均匀、冷强度高、还原性好，可节焦增铁，降低生产成本。目前，国内铁矿球团生产以竖炉为主，为了追求产量，各生产厂家都努力提高生产率，但球团冷却这一重要工艺环节往往被忽视，极大地影响了球团的质量。     

含碳球团还原机理研究

在１２２３－１４７３Ｋ的Ｎ２气氛下研究了石墨粉粒度、铁精矿粉粒度、温度、碳含量地含碳球团的速度的影响，结果表明，石墨粉和铁精矿粉粒度越小，还原温度和碳含量越高，含碳才还原速度越大，基于碳气化反应、气相扩散和界面反应和含碳球团的速度方程均能较好地处理本研究的数据，根据Ａｒｒｈｅｎｉｕｓ方程计算出的碳敢化反应和界面反应活化能分别为２２７．７和２９４．１４ｋＪ／ｍｏｌ；计算出的气相扩散为限制环节的含碳球     

含铁固体废弃物冷固球团强度的影响因素

为提高冷固球团强度，以含铁固体废弃物为原料，研究了黏结剂、原料含水的质量分数、成形压力、原料粒度和干燥制度等因素对冷固球团抗压强度和落下强度的影响。结果表明，配加不同黏结剂制得的冷固球团强度明显不同，且当黏结剂配比由1%增加至5%时，冷固球团的强度随之增加；冷固球团的强度先随原料含水质量分数的增加而增加，当原料含水质量分数增加至8%后，冷固球团的强度随着原料含水质量分数的增加而降低；冷固球团的强度先随成形压力的增加而增加，当成形压力增加至13 MPa后，冷固球团的强度随着成形压力的增加而降低；适宜的原料粒度组成会使冷固球团强度得到增强，干燥制度也对冷固球团的强度有一定影响。     

粒度对熔剂性球团冶金性能及矿相结构的影响

为提高熔剂性球团质量,解析不同粒度条件下球团性能的变化规律,本文以唐钢新区带式焙烧机球团生产线为研究对象,通过投笼造球试验和冶金性能检测等方式,分别对8.0～10.0、10.0～12.5、12.5～16.0、16.0～20.0 mm 4种粒度条件下球团冶金性能和矿相结构进行研究。结果表明：随着熔剂性球团粒度的逐渐提高,球团抗压强度从1 767 N/P提高至3 606 N/P,1 h还原度从78.5%降低至47.8%,还原膨胀指数略有降低,整体维持在12%以下,低温还原粉化指数(>6.3 mm)从87.8%降低至66.5%,低温还原粉化指数(>3.15 mm)从95%降低至87.2%,低温还原粉化指数(<0.5 mm)变化幅度较小,约为4%;随着熔剂性球团粒度的逐渐提高,气孔率降低,从38.93%降低为31.4%,液相率略有降低,固相比例显著提高,从41.05%提高至58.41%,致密度提高但液相率降低可能使得原本存在的链接状态失去效果,侧面减弱了熔剂性球团的低温还原粉化性能。因此,在熔剂性球团生产过程中应控制合适的球团粒度,改善熔剂性球团性能和微观结构,以便有利于高炉...     

Heating and melting of wustite pellets in liquid slag

The melting behaviour of the metallized, porous wustite pellets immersed in liquid slag, as well as the influences of the metallization ratio, pre-heating temperature of the pellet and slag temperature were examined in this work by means of an X-ray imaging system. The internal structure of the pellets after having been immersed in slag was checked by optical microscope and EPMA. The adoption of digital image processing improved the image analysis dramatically and, as a result, some important phenomena, such as solid slag shell forming and melting, slag penetration, wustite component dissolution as well as the influence of experimental conditions, were quantified.     

X-ray microtomography for characterisation of cracks in iron ore pellets after reduction

Abstract

This work presents a method, based on X-ray microtomography and three-dimensional (3D) image analysis, of characterising and quantifying crack distribution in iron ore pellets. The aims have been to verify the method and to determine to what extent crack propagation contributes to the decrease in compressive strength that occurs during reduction at 500°C as haematite transforms into magnetite. Raw materials known to cause disintegration problems were selected in order to promote crack propagation. Pellets displayed crack lengths of sizes roughly corresponding to half the pellet diameter already before reduction and, during reduction, a further crack propagation of ～50% occurred. Through estimations by finite element analysis of the crack size and the pellet geometry, it has been possible to determine that this crack growth most likely is a mechanism that contributes to the decrease in compressive strength. The decrease of ～90% that was experimentally determined to occur after 30 min of reduction is, however, too large to be explained by crack propagation alone. The study shows that the proposed techniques allow 3D imaging of iron ore pellets and characterisation of cracks. The scans are non-destructive and can be carried out repeatedly, which allows a specific sample to be studied at different stages during a process. Through future use of the proposed method, our aim is to reach a deeper understanding of the mechanisms behind low temperature disintegration of iron ore pellets and the performance of LKAB olivine pellets inside the blast furnace.     

Influence of CaO-SiO2-Al2O3 Ternary Oxide System on the Reduction Behavior of Carbon Composite Pellet: Part I. Reaction Kinetics

The reduction behavior of composite pellets comprising of hematite, synthetic graphite, and several oxide binder systems was investigated in a laboratory-scale horizontal tube furnace. Three oxide binder systems using silica-rich, alumina-rich, and conventional blast furnace slag compositions were selected to examine the effect of oxide chemistry on the reduction behavior of pellets. Compositional differences in the CaO-SiO₂-Al₂O₃ ternary system were confirmed to influence the reactions occurring in composite pellets during the reduction of iron oxide. An in situ visualization approach was used to observe the oxide/iron/carbon interactions at high temperatures from 1623 K to 1773 K (1350 °C to 1500 °C). The off-gas composition was measured by means of an infrared analyzer to determine the pellet reaction rates. Changes in physical appearance during the in situ reaction experiments demonstrated a strong correlation between the oxide composition and internal reactions. Moreover, the mechanical properties of pellets were investigated by measuring compressive strength to understand the relationship between physical properties of pellets and the associated oxide binder systems selected for this study.     

Characterisation studies on swelling behaviour of iron ore pellets

At JSW Steel Limited (JSWSL), pellets form the major part of the iron-bearing feed to corex and blast furnace. JSWSL produces low-basicity pellets ((CaO/SiO₂) – 0.40 to 0.50). The quality of the pellet is affected by the raw material chemistry (gangue content), flux proportion and their subsequent heat treatment to produce the fired pellets. The raw material silica, limestone addition, i.e. basicity – CaO/SiO₂ of pellet decides the mode, temperature and the amount of melt formed. The properties of the pellets are, therefore, largely governed by the form and degree of bonding achieved between ore particles and also by the stability of these bonding phases during the reduction of iron oxides. In the present study, laboratory pelletisation experiments have been carried out to know the effects of silica and basicity on the microstructure and swelling behaviour of pellets during reduction. Phase analysis was carried out using image analyser, and chemical analysis of oxide and slag phases was carried out using SEM–EDS. From the laboratory studies, it was observed that the swelling index of the pellets decreased with an increase in silica content due to the decrease in porosity. The presence of higher silica in pellet hinders the reduction step of haematite to magnetite at lower temperatures. Pellets with basicity range 0 to 0.1 exhibited lower swelling index due to the formation of high melting point fayalite phase and also at this basicity range the structure is held together by the seam-like compounds between Fe₂O₃ and SiO₂ primarily at high silica content. Higher swelling index was observed at the basicity range 0.3 to 0.7 due to the presence of low melting point calcium olivines (1115°C) between fayalite (FeSiO₄) and dicalcium silicate (Ca₂SiO₄). Low melting point slag phase enhances the swelling index of the pellets. Swelling index of the pellets considerably dropped between the basicity range 0.9 to 1.1 due to the formation of calcium ferrite phases with a close pore structure.     

煤粉燃料球团生产中链篦机结渣物成因分析

对以煤粉为燃料的链篦机-回转窑法铁矿球团生产中链篦机预热段生成的结渣物进行了XRD、显微结构及扫描电镜能谱分析,发现其矿相组成主要是铁氧化物以及少量含镁铝固溶体。为查明链篦机结渣物形成机理,开展了温度及煤灰残碳量对结渣物形成影响的模拟焙烧试验。结果表明,焙烧物的物相中有含残碳的煤灰,其物相组成、显微结构与实际结渣物组成物相类似,证实链篦机喷煤补热燃烧过程中煤灰中的残碳可使结渣混合物体系生成含亚铁相的硅铝酸盐类低熔点化合物,是导致链篦机结渣物形成的主要原因。     

Effect of CaO on the reduction behaviour of iron ore–coal composite pellets in multi-layer bed rotary hearth furnace

The effect of CaO on the reduction behaviour of iron ore–coal composite pellets has been studied in a laboratory scale multi-layer bed rotary hearth furnace at 1250°C for 20?min. Reduced pellets have been characterised through weight loss, porosity measurement, phase analysis by XRD, and morphology study by SEM. The addition of CaO to the composite pellets showed different effects at different carbon levels. For higher carbon-containing pellets (C/Fe₂O₃ molar ratio at the upper stoichiometric level of 3), the addition of CaO increased the extent of reduction for all three layers significantly up to a certain limit (4?wt-%); and thereafter the degree of reduction is decreased with a further increase in CaO percentage in the pellets. For low carbon-containing pellets (C/Fe₂O₃ molar ratio of 1.66), the addition of CaO to the pellets did not show any beneficial effect.     

Fundamental Study on New Method of Reducing Iron Ore-Coal Pellet in Cocurrent Shaft Furnace

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Left ventricular shape analysis from three-dimensional echocardiograms

Cystic fibrosis patients require pancreatic enzyme supplements to aid food digestion. It is suspected that incorrect delivery of this enzyme may result in both significant malabsorption and the development of strictures in the proximal colon caused by the high-dose supplement reaching this region before the food. Investigations into the drug's delivery were performed using dual-isotope imaging; a method was developed to directly label the enteric-coated enzyme pellets with 111In, re-applying the enteric coating afterwards, and this was then ingested with a pancake meal labelled with 99Tcm-tin colloid. Consecutive image data, acquired over a period of > or = 4 h using a dual-headed gamma camera, were analysed to assess intestinal transit. In-vitro stability checks on these labelling techniques were encouraging, showing < 2% 99Tcm and < 7% 111In elution over 90 min in hydrochloric acid. In 5 of the 12 patients studied to date, the pellets were seen to pass through significantly faster than the food, with a mean difference in 50% gastric emptying time of greater than 93 min. The mean absolute difference in emptying time for all 12 patients was > 67 min. Thus, a technique has been developed to effectively radiolabel pancreatic enzyme pellets, and analysis of dual-isotope images using this preparation, together with radiolabelled solid food, has demonstrated significant differences in the transit of these two substances through the gastrointestinal tract of some cystic fibrosis patients.     

铁精矿冷固球团矿煤基回转窑直接还原新工艺

铁精矿冷固球团矿煤基回转窑直接还原新工艺的关键技术包括复合粘结剂及相应的配套实用技术,提出了含复合粘结剂的生球强度界面作用力综合模型,冷固球团矿强度的粘结膜机理,含复合粘结剂的冷固球团矿催化还原体积反应机制及全窑高温快速还原热工制度。