共查询到19条相似文献,搜索用时 899 毫秒
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以酒钢高炉瓦斯灰、转炉OG泥、转炉二次除尘灰和自产铁精矿为主要含铁原料制备复合球团开展直接还原试验。通过利用马弗炉模拟平铺料式隧道窑焙烧过程开展基础性试验研究,考察焙烧温度、焙烧时间、球团配比等条件对金属化球团金属化率、抗压强度的影响,结果表明:金属化球团金属化率和抗压强度指标均随焙烧温度的提高和焙烧时间的延长而升高,综合考虑金属化率和抗压强度指标,球团在焙烧温度1 200℃、焙烧时间100 min时是比较适宜的;不同瓦斯灰配入量条件下试验结果表明,球团金属化率随瓦斯灰配入量的增加而升高,抗压强度随瓦斯灰配入量的增加而降低。在此基础上,利用30 m平铺料式隧道窑装置开展了直接还原半工业验证试验,最终取得金属化球团铁品位73.51%、金属化率88.76%、抗压强度平均2 328 N、脱锌率95.10%的试验指标,金属化球团抗压强度等各项指标均满足酒钢高炉或转炉用料要求,说明通过平铺料式隧道窑处理冶金含铁尘泥复合球团在技术上是可行的。 相似文献
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为了解决常规加热煤基直接还原的反应时间长、还原温度高、产品质量差等问题,基于微波加热特性结合直接还原理论提出了采用微波加热进行氧化球团煤基直接还原的新工艺。通过采用扫描电镜、能谱分析仪和显微硬度计等检测手段对常规加热和微波加热煤基直接还原过程进行了深入研究,探究氧化球团微波加热煤基直接还原过程微观机制。研究结果表明,微波加热不仅改变了球团矿的微观结构和能量分配,而且在某种程度上表现出微波加热的“非热效应”,常规加热时,在还原温度1050℃下还原150 min,球团金属化率仅为89.38%;氧化球团煤基直接还原过程采用微波加热,从室温上升到1050℃后再等温14 min,球团金属化率达到92.67%。 相似文献
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黏结剂在冷固结球团中必不可少,目前广泛使用的冷固结球团有机、无机黏结剂如CMC、膨润土和水泥等均会在高温下失效,导致球团高温强度严重下降,因此,寻找一种高温强度良好的黏结剂是目前需要解决的问题。采用新型黏结剂制备冷固结球团,通过XRD和SEM-EDS等对新型黏结剂球团制备原料及球团性能特征进行分析,同时探讨黏结剂对球团冷态抗压强度及高温强度的影响及其作用机理。试验结果表明,黏结剂以流动状态存在于冷固结球团中,可有效吸附或包裹铁矿粉颗粒,增加黏结剂配比可同时提高球团的冷态抗压强度及高温抗压强度;在高温还原性气氛下焙烧冷固结球团,由于发生还原反应,球团金属化率提高,铁矿粉颗粒间空隙增大,导致球团强度下降,焙烧时间为30~90 min时,球团金属化率及抗压强度变化趋势最明显;焙烧初期,球团抗压强度不会发生快速下降,且焙烧结束后球团强度仍可保持为100 N/个左右。 相似文献
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摘要:通过对不同温度、不同兰炭配入量的内配兰炭赤铁矿球团进行FeO含量检测和矿相结构分析,得出兰炭在赤铁矿球团焙烧过程中的作用机制。结果表明:兰炭含量较低时,主要发生燃烧反应,不利于赤铁矿向磁铁矿转变,且气孔率增大使球团抗压强度降低;兰炭含量过高,还原反应占主导,大量Fe2O3被还原为Fe3O4,甚至被还原为FeO,随之形成铁橄榄石;兰炭燃烧放热过多使球团内部熔化,导致球团抗压强度大幅降低。最终选择适宜的兰炭配比为1.5%,焙烧温度为1300℃,焙烧时间为18.5min,空气流量为3.2L/min, 抗压强度为2708.8N。 相似文献
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一、概述竖炉是国外用来焙烧铁矿球团的最早设备,即所谓第一代球团焙烧装置。竖炉焙烧球团法具有结构简单、投资少、热效率高、操作维护方便等优点。1960年以前,竖炉球团产量占世界球团总产量的70%(图1)。但由于第二代、第三代球团焙烧装置的相继出现,且其优越性明显超过竖炉装置,到1971 相似文献
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Influence of microwave heating on the microstructures of iron ore pellets with coal during reduction
Iron ore oxidised pellets as the burden of blast furnace present many advantages, such as uniform size, high iron grade and high physical strength. A comparison of the iron ore oxidised pellets with coal (out-proportioning) by conventional heating and microwave heating was carried out in this paper. Microstructure transformations during reduction process were investigated by optical microscopy and scanning electron microscope with energy dispersive spectrometry analysis. Micro-hardness of metallic iron phase formed in the reduction was tested with digital micro-hardness tester. The influences of microwave heating on reduction degree, morphology, iron phase and gangues were investigated, respectively. The results show that reduction time can be greatly shortened by microwave heating even at lower temperatures. The fine cracks generated, as the pellets were heated by microwave, were irradiated due to the selectivity of microwave heating. Densification of the metallic iron phase and the separation of the iron and gangues were both found to be enhanced by microwave heating. 相似文献
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WANG Zhao-cai CHU Man-sheng LIU Zheng-gen CHEN Shuang-yin XUE Xiang-xin 《钢铁研究学报(英文版)》2012,19(10):7-12
After taking into account the conditions of the domestic iron resources and the non-coking coal resources, the process of coal gasification-shaft furnace is an effective way to develop direct reduction iron in China. The following tasks are very critical to choose suitable process of shaft furnace and gasification, including the production of oxidized pellets with excellent comprehensive properties as well as the study of the reaction behavior and mechanism of swelling. The results showed that the oxidized pellets of using domestic magnetic iron concentrate as raw materials have favorable comprehensive properties, including higher mechanical strength both before and after reduction, faster reduction rate and lower reduction swelling index (RSI). All of these properties can meet the shaft furnace yielding requirement. When the temperature was below 1223 K, the pellets′ RSI was lower than 20%. With increasing of the content of H2 in atmosphere, the pellets reaction rate accelerated, crushing strength enhanced and RSI decreased. The RSI dropped to 10.26% at 1323 K in 100% H2 atmosphere, and it is up to 39.88% in 100% CO atmosphere. The iron grains mainly presented in platelike when pellets were reduced by H2, however, in CO atmosphere the iron grains were precipitated in flocculent. The whisker shape of iron grains and heating effects of reduction reaction are the major factors leading to the poor pellets strength and increase of RSI. Appropriately controlling the temperature and increasing the ratio of H2 to CO in atmosphere are good for dropping the RSI. 相似文献
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铁精粉在预热、焙烧过程中会伴随着热量的变化,这一行为会影响球团矿的抗压强度。为探究熔剂中CaCO3分解对熔剂性球团强度的影响机理。通过TG-DSC分析技术,研究铁精粉、不同铁精粉混合、铁精粉与熔剂混合交互作用下的热量变化规律,以及热量变化对球团矿抗压强度的影响,建立热量变化与焙烧温度的匹配关系。通过调节焙烧温度、焙烧时间使熔剂性球团达到普通酸性球强度。结果表明,铁精粉之间的交互作用并不明显;在700~850 ℃铁精粉与石灰石粉发生交互作用,磁铁精粉的氧化反应对石灰石的分解有一定的促进作用,TG曲线的试验值较理论值出现前移;石灰石分解行为对磁铁矿球团氧化固结的抑制作用明显,可以通过延长焙烧时间使熔剂性球团达到普通酸性球强度;在提高焙烧温度后,熔剂性球团强度明显增强,相较于普通酸性球团增加约50 N/个(球)。 相似文献
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Cold-bonded composite pellets, consisting of iron ore fines and fines of noncoking coal or char, were prepared by steam curing
at high pressure in an autoclave employing inorganic binders. Dry compressive strength ranged from 200 to 1000 N for different
pellets. The pellets were heated from room temperature to 1273 K under flowing argon at two heating rates. Rates of evolution
of product gases were determined from gas Chromatographie analysis, and the temperature of the sample was monitored by thermocouple
as a function of time during heating. Degree of reduction, volume change, and compressive strength of the pellets upon reduction
were measured subsequently. Degree of reduction ranged from 46 to 99 pct. Nonisothermal devolatilization of coal by this procedure
also was carried out for comparison. It has been shown that a significant quantity (10 to 20 pct of the pellet weight) of
extraneous H2O and CO2 was retained by dried pellets. This accounted for the generation of additional quantities of H2 and CO during heating. Carbon was the major reductant, but reduction by H2 also was significant. Ore-coal and ore-char composites exhibited a comparable degree of reduction. However, the former showed
superior postreduction strength due to a smaller amount of swelling upon reduction.
Formerly Graduate Student, Department of Metallurgical Engineering, Indian Institute of Technology, Kanpur, India 相似文献
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我国钒钛磁铁矿资源丰富,但综合利用难度大,现有工艺仍存在一些问题,工艺流程还有待完善和革新。气基竖炉直接还原-电炉熔分新工艺为钒钛磁铁矿资源清洁高效综合利用提供了新途径。以含钒钛的铁精矿为原料制备氧化球团,模拟气基竖炉直接还原条件,研究了还原气组分和温度对球团的还原进程、还原膨胀以及还原强度的影响。结果表明:以钒钛铁精矿为原料,配加1%膨润土,在1 250℃下焙烧20 min后,所制备氧化球团性能良好,具有较高的抗压强度。在恒定还原气组分(纯H2、H2/CO=2.5、H2/CO=1、H2/CO=0.4和纯CO)和温度(850、900、950和1 000℃)下,钒钛铁精矿球团还原速率快、还原膨胀率小(<20%),可满足气基竖炉直接还原工艺要求。煤制气-气基竖炉直接还原凭借其能耗小、环境友好、单机产能大、产品质量好等优点,将在钒钛磁铁矿资源高效清洁综合利用领域得到发展。 相似文献
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节能减排是钢铁工业目前面临的重要挑战,而废塑料作为一种可再生清洁能源和还原剂替代焦粉、无烟煤等化石燃料在炼铁工业中已经获得大量关注。把废塑料、褐铁矿粉、无烟煤以及黏结剂混合制取含碳球团,在管式加热炉内做直接还原实验。废塑料在高温下裂解释放热量,为球团的预热和直接还原提供外加热源。同时,与无内配塑料含碳球团对比,内配废塑料的含碳球团孔隙率增大,这样有利于反应中还原气体的传质,从而促使含碳球团的还原率随之提高。对影响含碳球团直接还原的因素如C/O摩尔比、还原时间、内配废塑料种类及其质量分数进行实验研究。实验结果表明:在实验设定条件下,含碳球团直径10mm,还原温度1 350℃,内配质量分数为4%的聚碳酸酯(PC)在还原时间6min时,球团孔隙率最高,达74%;此时还原率最高,达98.89%。含碳球团还原体系在反应过程中,内配一定比例的废塑料,可以缩短还原时间,降低还原温度,提高球团的还原效率。 相似文献
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The mechanism of improving compressive strength of magnetite pellet by adding boron-bearing iron concentrate was studied. Boron-bearing iron concentrate and magnetite were mixed, pelletized and roasted under differ ent roasting conditions. Then, compressive strength of pellets was tested, and polished sections of the roasted pellets were analyzed from the perspective of mineralogy. Finally, the effects of different proportions, roasting temperatures and roasting time of boron-bearing iron concentrate on the compressive strength of magnetite pellets were investigated and explained. 相似文献