Gasification of iron coke and cogasification behavior of iron coke and coke under simulated hydrogen-rich blast furnace condition

To explore the iron coke application in hydrogen-rich blast furnace,which is an effective method to achieve the purpose of low carbon emissions,the initial gasification temperature of iron coke in CO_(2) and H_(2)O atmosphere and its cogasification reaction mechanism with coke were systematically studied.Iron coke was prepared under laboratory conditions,with a 0-7wt%iron ore powder addition.The properties of iron cokes were tested by coke reactivity index(CRI)and coke strength after reaction(CSR),and their phases and morphology were evolution discussed by scanning electron microscopy and X-ray diffraction analysis.The results indicated that the initial gasification temperature of iron coke decreased with the increase in the iron ore powder content under the CO_(2) and H_(2)O_((g))atmosphere.In the 40vol%H_(2)O+60vol%CO_(2) atmosphere,CRI of iron coke with the addition of 3wt%iron ore powder reached 58.7%,and its CSR reached 56.5%.Because of the catalytic action of iron,the reaction capacity of iron coke was greater than that of coke.As iron coke was preferentially gasified,the CRI and CSR of coke were reduced and increased,respectively,when iron coke and coke were cogasified.The results showed that the skeleton function of the coke can be protected by iron coke.

K_2CO_3 catalysis on the reactivity of top charged coke and stamp charged coke

The catalysis of K2CO3 on the reactivity of top charged coke and stamp charged coke from Pansteel in China was studied. The coke reaction index of the stamp charged coke was 1%-2% higher than that of the top charged coke. Under the catalysis of K2CO3, the coke reaction index of both cokes approximately increased by 4%, 6%, 10% and 6% at 900, 1000, 1100 and 1200℃, respectively. The reactivity of the K-enriched stamp charged coke was 1%-2% higher than that of the K-enriched top charged coke below 1100℃. However, only negligible differences were found in the temperature zone between 1100 and 1200℃. Scanning electron microscopy images illustrated that pores in the top charged coke were smaller and equally distributed, while relatively more big pores exist non-homogenously in stamp charged coke. Due to the different processes in production, the stamp charged coke was more porous and most of the pores tended to be applanate. Cracks were observed in the microstructure of the stamp charged coke during the carbon solution reaction, implying the inferior quality of the stamp charged coke to the top charged coke at high temperature. Diffusion of K during the carbon solution reaction was studied by the energy dispersive spectrometry. It is found that K gradually spreads into the center of lumpy coke with the rising of temperature and is equally distributed on the edges of pores at 1200℃. Besides, oxidation reactions of functional groups become faster with the catalysis of K.content

Effect of Coke Reaction Index on Reduction and Permeability of Ore Layer in Blast Furnace Lumpy Zone Under Non-Isothermal Condition

Reasonable control on CRI（coke reaction index）is one of the key factors for BF（blast furnace）low-carbon smelting.However,there are contrary opinions.One is increasing CRI to improve reaction efficiency in BF and the other is decreasing CRI to suppress coke degradation in furnace.Different methods are adopted to realize effective catalysis（increasing CRI）and passivation（decreasing CRI）of coke.Simulation tests of coke in BF lumpy zone under gradual temperature rising have been done.Effect of CRI on gas composition,ore reduction,burden column permeability and heat reserve zone′s temperature under non-isothermal condition are studied.Then combined with iron making calculations,a novel BF operation suggestion is proposed as coke nut with small size be catalyzed and mixed with ore while skeletal coke with large size be passivated and separately charged into BF.

CO_2 Gasification Characteristics of High and Low Reactivity Cokes

In order to effectively utilize the high reactivity coke, the gasification characteristics of high and low reactivity cokes were investigated at 1100 ℃. Low reactivity coke A and high reactivity coke B were chosen and charged into the reaction tube in two methods. The results indicated that the mass loss ratio of high reactivity coke in mixed cokes was more significant than that of single high reactivity coke in the middle stage of reaction. Nevertheless, the mass loss ratio of low reactivity coke in mixed cokes was less than that of single low reactivity coke. It was mainly attributed to gas diffusion and internal reaction of coke. When high and low reactivity cokes were mixed, the practical average mass loss ratio was nearly the same as the weighted average. The microscopic structures of coke indicated that with the increase of reaction time, the external and internal layers of low reactivity coke reacted more uniformly with CO2, whereas the reaction degree of external layer of high reactivity coke was obviously higher.

不同条件下焦炭的高温反应行为及热态性能评价

针对某钢铁企业四种捣固焦,研究了不同条件下焦炭高温气化反应行为,从不同角度评价焦炭热态性能。结果表明,在国标条件下,四种焦炭的CRI和CSR分别在21%~31%和54%~68%范围内。随着焦炭反应性的升高,气化溶损反应开始温度和激烈温度均降低,且两者分别在887~948℃和1315~1423℃范围内。随着溶损率的增加,焦炭C和D的固定溶损率反应后强度均降低,且前者大于后者,但两者差值明显低于国标条件下的差值。高炉实际运行结果显示,在其他条件不变的情况下,使用焦炭C和D时高炉技术经济指标相差不大。采用高温下固定溶损率反应后强度和平均反应速率评价焦炭的热态性能更符合炉内情况,推荐的检测条件为温度1200~1400℃、固定溶损率为20%~30%。

不同制样方法对焦炭反应性及反应后强度稳定性的研究

焦炭反应性样品制样方式主要有传统的手工制样和机器制样两种,不同的制样方法制出的焦炭颗粒不同,分析了不同焦炭颗粒的稳定性。通过实验研究,得出全自动机械制样焦炭反应性结果稳定,符合实验要求。

全自动焦炭反应性及反应后强度检测系统的研发与应用

焦炭作为高炉冶金中重要的燃料,其检测指标反应性(CRI)及反应后强度(CSR)对高炉的冶炼炉况、铁水产量及成本具有重要影响。传统的焦炭反应性、反应后强度检测过程通常依赖于实验室手工操作,耗时长且容易受到人为因素的干扰。为降低人为因素干扰,提高检测效率和准确性,提出了一种基于视觉、机器人等自动化技术的焦炭反应性及反应后强度的全自动检测方法,同时介绍其在冶金工业中的应用。

Effects of Additives on Sulfur Transformation,Crystallite Structure and Properties of Coke during Coking of High-sulfur Coal

High-sulfur coal, as an alternative coal source, has a relatively high proportion in coal reserves. However, the feature of high sulfur content, which can cause environmental pollution and poor quality of molten iron, restrains its utilization in coking industry. Coking experiments of high-sulfur coal with Fe2O3, La2O3 and CaO as additives were carried out in order to fix the sulfur in coke. The effects of additives on sulfur distribution, crystallite structure, surface morphology and properties of coke were investigated. The results indicate that CaO can be used as sulfur-fixing agent in coking process, and CaS is the main mineralogical phase of the sulfur-contained mineral constituents in coke. Fe2O3 and La2O3 facilitate the conversion of CaO to CaS. The additives mainly influence the crystallite height and the average interlayer spacing doo2 of coke. The addition of La2O3 increases the value of the crystallite height while the addition of CaO and Fe2O3 decreases it. CaO leads the pores of coke to increase with its physical action and agglomerating characteristic. Fe2O3 and C can form （Fe,C）, resulting in the pulverization and erosion of the pore wall. La2O3 makes the coke surface become more compact and thinner. The reactivity of coke increases with the decrease of crystallite height and crystallite layer number.

高炉富氢热储备区矿焦匹配关系模拟研究

通过建立高炉热储备区CO、H_(2)混合气体还原FeO矿球未反应核模型,探究煤气利用率与温度的关系,进而得到不同H_(2)含量时,矿球还原性与焦炭反应性的匹配关系。结果表明:①还原性气体全为CO时,对于单一种矿球来说,随着热储备区温度的降低,煤气利用率受动力学和热力学共同作用,呈现升高后降低的趋势,有一个煤气利用率最大值;②富氢时,对同一种矿球来说,随着H_(2)含量的增加,在温度为950~1000℃时,煤气利用率整体升高,煤气利用率最大值对应的温度也升高;③矿球还原性越高,匹配的焦炭反应性越高,H_(2)含量增加1%,焦炭反应性指数需降低0.42%。

对焦炭反应性和反应后强度规范性试验方法的研究

通过对焦炭反应性和反应后强度规范性试验方法的研究,探讨了焦炭在热反应炉内以不同试验方式下所带来不同的反应性(CRI)和反应后强度(CSR),并对其进行了分析和比较,得出焦炭CRI和CSR与摆放方式的关系、每层焦炭CRI和CSR的关系以及焦炭CRI和CSR与摆放高度的关系。

焦炭高温抗压强度研究

采用可调气氛高温抗压试验机研究了焦炭的高温抗压强度。在高炉实际反应程度范围内,焦炭抗压强度与失碳率LC呈直线关系。失碳率的影响随温度的升高而减弱。抗压强度与温度的关系也可以用直线来进行描述。讨论了高炉内温度和失碳率对焦炭强度的综合影响以及焦炭强度在高炉内的分布规律。结果表明,焦炭抗压强度在燃烧区外可降低70%以上。

高炉块状带焦炭强度模拟研究

重点研究焦炭在高炉块状带内的抗压强度与温度和反应程度的关系。使用1台热模型对高炉块状带进行了模拟研究,1台可调气氛高温抗压试验机对所获焦炭试样进行了抗压强度检验,得到了焦炭在实际温度下的反应后抗压强度分布。在高炉间接还原区内,焦炭抗压强度随温度的升高而直线下降,在高温区内强度下将更为严重。焦炭失碳率是影响其强度的主要因素,在高煤比条件下应采用高反应性煤种并保留适量未燃煤,以保护焦炭强度。

焦炭搭配对高炉块状带含铁炉料还原的影响

为了探索高、低反应性焦炭搭配对高炉块状带含铁炉料还原的影响,通过模拟高炉块状带温度场和气体成分条件,研究了搭配不同比例的高反应性焦炭对含铁炉料静态还原的影响规律。结果表明,在温度为900℃和CO体积分数为32.5%的条件下,随着高反应性焦炭比例的增加,料层中Boudouard反应的发展程度加剧,固体物料温度降低。当高反应性焦炭质量配比为50%时,含铁炉料还原度提高9.13%。因此,高、低反应性焦炭的合理搭配有望能降低高炉冶炼的能耗。

高炉用焦炭热强度指标要求及检测方法

高炉冶炼通常要求焦炭具有较低的反应性和较高的反应后强度.但焦炭反应性过低不利于提高高炉反应效率.本文对焦炭在高炉内消耗机理进行了分析,认为高炉炉身焦炭消耗量与铁矿石直接还原度相关,炉身消耗的焦炭量是比较稳定的,现有焦炭热强度评价方法存在不足.为了避免焦炭反应过度,应调整焦炭热强度指标的测定方法,如改变反应气氛或根据焦炭失重量确定反应时间,使测定结果能够合理反映炉内焦炭消耗的规律.

提升焦炭反应性对高炉块状区域含铁炉料还原的影响

在CO/CO2/N2体积比为33/12/55,温度为900℃和分层布料条件下,以5种具有不同反应性的焦炭为还原剂,对含铁炉料进行还原试验研究。结果表明,即使在叉子曲线理论还原平衡点以下,高反应性焦炭也可还原出金属铁。随着焦炭反应性增强,焦炭气化速率加快,含铁炉料颗粒周围的CO体积分数逐渐升高,料层压差略有升高,含铁炉料的还原度逐渐增高。配加高反应性焦炭可促进高炉热保存带含铁炉料的还原,提高进入软熔带区域炉料的金属化率。

高炉用焦炭的高温抗压强度

采用可调气氛高温抗压试验机研究焦炭的高温抗压强度。在高炉实际反应程度范围内,焦炭抗压强度与失碳率呈近似直线关系。失碳率对强度的影响随温度升高而减弱,抗压强度也随温度升高而降低。在此基础上,从理论上分析了高炉用焦炭的破碎机理。

工艺参数对热压铁焦抗压强度的影响

热压铁焦是一种新型含碳复合炉料,高炉使用铁焦有助于降低热空区温度、减少CO_2排放.研究了工艺参数对热压铁焦抗压强度的影响,并分析其作用机理.研究结果表明,在一定范围内,铁焦抗压强度随着铁矿粉配比增加先增加后降低,在矿粉配比15%时取得较大值3 490.89 N;随着烟煤配比的增加而提高;随着热压温度的提高而提高,在热压温度350℃时取得较大值4 305.50 N;随着炭化温度的提高先降低后提高;随着炭化时间的增加先提高后降低,在炭化时间4 h时取得较大值3 518.80 N.从抗压强度角度考虑,热压铁焦合适的制备工艺参数为10%~15%铁矿粉,60%~70%烟煤,热压温度300~350℃,炭化温度1 000~1 100℃,炭化时间2~4 h.

高反应性铁焦制备及其强度研究进展

我国钢铁产量与优质焦煤资源、环保形势的矛盾日益突出,优化炼铁工艺,实现高炉降碳减排刻不容缓。提高碳利用率是降低高炉焦比、减少CO_(2)排放的有效措施。铁焦作为一种有望实现工业化应用的铁碳复合炉料,其高反应性可降低高炉热储备区温度,提高炉身工作效率,从而提高碳利用率,因此受到广泛关注。综述了铁焦的发展历程和研究进展,比较了不同铁焦制备工艺的特点和获得铁焦的性能。煤直接配加铁矿粉制备铁焦工艺投资成本小,利用现有焦炉设施即可实现,但需严格控制炼焦炉温度,否则会降低焦炉寿命;热压法铁焦制备工艺可大量使用弱黏结性煤或非黏结煤,制备的铁焦具有较高的反应性和反应后强度,已实现工业化生产和应用;而冷压法制备工艺能进一步降低炼焦能耗,但铁焦产品的强度需优化。炼焦过程中加入煤中的含铁矿物均被还原为金属铁,其氧化反应催化了铁焦在高炉内的气化。针对铁焦强度劣化,提出在制备过程中添加含甲苯、乙苯、邻二甲苯和长支链烷烃等类胶质体的解决方法,为炼制满足高炉要求的高强度-高反应性铁焦提供了可行途径。研究表明,铁焦与含铁炉料混装的布料方式既能实现高炉降碳减排,又不影响高炉透气透液性;铁焦的反应性与反应后强度的协同优化、铁焦在高炉内的递变行为和铁焦对高炉能耗影响是未来的重点研究方向。

40kg捣固小焦炉配煤试验研究与生产效果分析

在缺少主焦煤的情况下,为寻找生产二级冶金焦的最优配煤比,降低炼焦生产成本,依据炼焦配煤研究理论,通过采用40 kg捣固小焦炉,以气煤、1/3焦煤、瘦煤为原料煤进行了配煤试验研究,成功试验出生产二级冶金焦的最优配煤质量比:众维精煤25%、音西原煤15%、新兴原煤40%、榆树沟原煤20%。生产实践结果表明,采用此配煤比生产的冶金焦抗碎强度M40达到79.9%,耐磨强度M10达到8.0%,焦炭热反应性CRI为50%,反应后强度CSR为42%,吨全焦配煤成本下降143.26元,降幅达15.06%。

基于偏最小二乘回归的焦炭热性质非线性预测模型

针对基于煤质指标预测焦炭热性质建模过程中易出现的多重共线性问题,提出应用偏最小二乘回归对焦炭热性质进行预测的建模思路。考虑到煤质指标与焦炭热性质之间复杂的非线性关系,采用拟线性化处理的方法,将煤质指标的一次效应、二次效应及交互效应作为模型输入,建立焦炭热性质预测的偏最小二乘回归模型;基于拟线性化处理的非线性偏最小二乘回归和线性偏最小二乘回归对焦炭热性质预测实例进行分析。研究结果表明:基于偏最小二乘回归方法建立的焦炭热性质预测模型是有效可行的;非线性偏最小二乘回归模型的预测精度明显比线性偏最小二乘回归模型的预测精度高。