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在日本铁矿烧结中每年排放约32MtCO2,占总排放量的2.6%。由于烧结废气中含有一定量的CO,因此如果焦粉能够完全燃烧就可减少其消耗量。为明确焦粉在烧结过程中的燃烧机理,目前的研究主要是基于焦粉在铁矿石、石灰石和氧化铝等各种烧结物料颗粒间的位置对其着火温度和燃烧速率的影响。对粗焦粉颗粒来说,铁矿石和石灰石的附着会降低其着火温度,加快燃烧速率。除焦粉和石灰石形成的复合小球状颗粒外,细焦粉颗粒则会黏附于其他物料颗粒表面或者与其他物料颗粒共存形成的复合颗粒,既不会改变焦粉的着火温度,也不会改变其燃烧速率。石灰石对加快焦粉燃烧速率似乎具有催化作用。 相似文献
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为了明确高炉富氢冶炼条件下焦炭的气化行为,利用高温模拟试验研究了高炉内φ(H2)对焦炭气化反应和孔隙结构的影响,得到了不同φ(H2)下矿石的还原与焦炭气化反应的关系、焦炭气化最严重的温度区间及焦炭微观孔隙结构的变化。研究结果表明,矿石的还原度和焦炭的失重率在升温过程中都逐渐增加。随着φ(H2)的增加,焦炭的气化率增加幅度最大的温度区间逐渐向低温区移动,主要由于随着φ(H2)的增加,矿石的还原反应逐渐趋向于在低温区进行,使得其在高温区产生的可供焦炭气化反应的CO2和H2O的总量降低;φ(H2)由5%增加至10%时,焦炭的气化率增加幅度最大;随着φ(H2)的增加,焦炭的平均壁厚逐渐降低,孔隙率、比表面积及总孔容都逐渐增加;焦炭大孔所占比例逐渐增加,焦炭气孔壁的薄壁结构所占比例逐渐增加。 相似文献
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快速失重法测定富矿粉,焦粉的水分 总被引:1,自引:0,他引:1
人重水分测量装置确定了富矿粉和焦粉的极限失重温度。在两者的极限失重温度(300℃,450℃)下进行了水分测量,含有6.65%朱分的富矿粉,测定时间为5min;含有2.25水分的焦粉,测定时间为2.75min。 相似文献
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摘要:为了研究铁矿粉对铁焦炭化过程中体积膨胀 收缩机制的影响,采用高温热台显微镜、Image pro plus软件、扫描电镜、XRD等先进的表征手段解析了不同铁矿粉及其添加量对铁焦成焦过程的宏观体积、微观结构和矿物组成的影响。研究结果表明,随着铁矿粉添加量的增加,铁焦炭化过程中的体积收缩量逐渐减小。相同铁矿粉添加量时,铁矿粉种类对铁焦炭化过程中的体积演变影响较小。炭化过程中铁焦内含铁矿物由Fe2O3逐渐还原为金属Fe,但不同铁矿物还原后在铁焦内的分布规律有所差异。 相似文献
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In recent years an intensive work has been carried out to decrease the coke losses of the blast furnace through mixing small‐sized coke called “nut coke” in the iron ore burden layers. In order to clarify the influence of nut coke on the pellets reducibility, industrial iron ore pellets were reduced with and without nut coke participation under different temperatures and atmospheres. Isothermal and non‐isothermal reduction tests under simulating blast furnace conditions were performed using an experimental laboratory rig. Furthermore, reflected light microscopy, scanning electron microscopy and X‐ray technique were applied to characterize the microstructure and different phases developed in the origin and reduced pellets. Pellets reduced isothermally without nut coke participation exhibited reduction retardation (RR) at elevated temperature (≥1373 K) whereas the presence of nut coke had a positive effect of preventing such phenomena. The non‐isothermal reduction of pellets showed that, as the amount of nut coke in pellets bed increased, the reducibility of pellets increased, too. The rate controlling mechanism of pellets and pellets‐nut coke mixtures was predicted from the correlation between apparent activation energy calculations and microstructure examination. 相似文献
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A mathematical model is developed to estimate the radial distribution of the ore‐to‐coke ratio in the blast furnace shaft on the basis of molar flow and energy balance equations. It utilizes the radial temperature distribution of the gas measured above the burden surface to estimate the thermal flow ratios in concentric rings of the shaft, and from this the ore‐to‐coke distribution under the assumptions that a thermal reserve zone of a given temperature exists in the furnace. The model, which also predicts the radial distribution of temperature and pressure in the shaft, has been evaluated on measurements from an industrial blast furnace and verified by comparing the results with temperatures from an in‐burden probe. 相似文献
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��쿣���ʤ������������������ 《钢铁研究学报》2015,27(11):14-20
A theoretical coke rate calculation model was established based on the traditional engineering method with the consideration of the combustion of pulverized coal, oxygen enrichment, blast humidity and other factors. A coefficient, measuring the amount of heat load with the change of furnace carbon, is proposed to establish the calculation method of heat loss. The theoretical coke rate and appropriate direct reduction rate of some large- scale blast furnace are calculated based on this model. Then the effects of different factors, including blast temperature, blast humidity, top temperature, iron ore grade, ash content and sulfur content of coke, carbonate flux consumption, silicon content of hot metal, direct reduction rate and slag rate, on coke rate were analyzed. The results show that the theoretical coke rate is 277. 15kg/t and appropriate direct reduction rate is 0. 34. The iron ore grade, ash content of coke, silicon content of hot metal and direct reduction rate have significant influences on coke rate. In addition, the calculation values in this model are lower than those of traditional model, which means the degrees of the factors affecting coke rate decrease nowadays. 相似文献
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The mathematical model of minimum safety factor that investigated the collapse trends of coke layer under different charging parameters was established firstly on the basis of the slope stabilization theory in soil mechanics, and then the model of burden profile after coke collapse was improved by adopting the predetermination of quadratic curve and energy correction methods. The research will provide theoretical evidences for describing the coke profile more accurately and technical direction for choosing suitable charging parameters of blast furnace. The results show that: it is helpful to improve the stability of coke layer with increasing chute inclining angle and length of the coke flat; when the main falling point of ore moves toward furnace wall or the coke flat is wider, the curve radian of burden profile after coke collapse becomes smaller; the ore to coke ratio distribution agrees with the gas top temperature measurement well under considering coke collapse comparing with the result of ignoring coke collapse. 相似文献
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当前低碳高炉冶炼条件下使得炉内焦炭层变薄,恶化了料柱的透气透液性,焦炭在炉缸高温区石墨化过程中产生的焦粉是导致该现象出现的主要原因之一.为了研究焦炭在高炉下部的石墨化过程对其在炉缸内的冶金性能影响,研究了1100~1500℃不同温度下焦炭的石墨化度改变;同种焦炭石墨化程度与焦炭反应性及反应后强度之间的关系;不同石墨化度焦炭与碱金属侵蚀之间的关系;观察并分析了试验后不同焦炭试样的微观形貌.结果表明,随着温度的升高,焦炭石墨化程度加深,且温度每升高100℃,焦炭石墨化度约提高1.8倍,层间距d002值约降低2%,微晶结构层片直径La值约提高3%,层片堆积高度Lc值约提高15%;焦炭的表面气孔减少,特别是大气孔减少,焦炭表面镶嵌组织减少,各向同性组织增多,焦炭的结构有序化程度增强.随着焦炭石墨化程度的加深,焦炭的反应性逐渐减小、反应后强度逐渐提高,焦炭表面的劣化情况减弱,生成的大气孔减少,气孔壁破坏趋势减弱.碱金属对焦炭的反应性有促进作用,使焦炭的反应性提高,反应后强度降低.而焦炭的石墨化对焦炭的碱侵害具有一定的抵抗作用,降低了焦炭表面的劣化程度. 相似文献
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The present work aims to study the high‐temperature strength of coke. Mechanisms of disintegration were evaluated using basket samples charged into LKAB's experimental blast furnace prior to quenching and dissection. Coke charged into basket samples was analysed with CSR/CRI tests and compared with treated coke from the blast furnace. Results from tumbling tests, chemical analyses of coarse and fine material, as well as light optical microscopy studies of original and treated coke have been combined and evaluated. The results indicate a correlation between the ash composition and the CSR values. Differences in the texture of the coke were noted with light optical microscopy, and a significant change in the coke texture during the CSR/CRI test conditions was found. The results suggest that the main reaction between coke and CO2 took place in isotropic areas, which was especially pronounced in coke with a low CSR. Signs of degradation were apparent throughout the coke pieces that have undergone CSR/CRI testing, but were less observable in coke reacted in the blast furnace. The results indicate that reaction with CO2 is generally limited by the chemical reaction rate in the CSR/CRI test, while in the blast furnace the reaction is limited by the diffusion rate. Coke degradation is therefore mostly restricted to the coke surface in the blast furnace. 相似文献