Study on softening melting characteristics of iron bearing material in oxygen blast furnace

The softening melting characteristics of sinter, pellet and mixed ore in oxygen blast furnace and traditional blast furnace were studied by using load softening and dropping equipment. It is found that, compared with the traditional blast furnace under the softening starting temperature of sinter, pellet, and their mixture decreases, the softening ending temperature increases in oxygen blast furnace atmosphere. Under the condition of oxygen blast furnace, the dropping temperature of sinter decreases, the dropping temperature of pellets and their mixture increases, and dropping zone becomes narrow and even disappears. Through the analysis of the data of the soft melting process, it is found that the mixed ore has a certain interaction effect in the oxygen blast furnace atmosphere, which improves the gas permeability of the charge.     

氧气高炉含铁炉料软熔特性研究

摘要：以烧结矿、球团矿及其混矿为研究对象,利用荷重软化滴落设备,分别探索了氧气高炉和传统高炉条件下烧结矿、球团矿、混合矿软熔特性。研究发现,与传统高炉气氛相比,在氧气高炉气氛下烧结矿、球团矿、混矿软化开始温度降低,软化结束温度升高,烧结矿滴落温度降低,球团矿与混矿滴落温度升高,并且熔滴区间减小甚至消失。通过对软熔过程相关数据分析,发现在氧气高炉气氛下混矿有一定的交互作用,提高了炉料透气性。     

高炉冶炼钒钛磁铁矿合理炉料结构的研究

合理的炉料结构是高炉冶炼钒钛磁铁矿最重要的内容之一.本文基于现场生产条件,在保证炉渣二元碱度、焦比、煤比等不变的条件下,进行不同碱度钒钛烧结矿和不同球团比例的综合炉料软熔滴落的试验,研究了高炉冶炼钒钛磁铁矿的合理炉料结构.结果表明,随着综合炉料中烧结矿碱度的提高和球团比例的增加,综合炉料的软化开始温度T4基本不变,软化终了温度T40升高,软化区间（T40-T4）变宽;综合炉料的熔化开始温度TS逐渐升高,熔化终了温度TD逐渐上升,熔化区间TD-Ts明显收窄,综合炉料的透气性能明显改善;同时初铁中V、Cr含量增加,V、Cr收得率明显提高.因此,在一定的范围内,提高综合炉料中钒钛烧结矿的碱度和球团比例,有利于高炉冶炼钒钛矿合理炉料结构的形成.     

鼓风条件及块矿比例对炉料软熔性能的影响

为了研究不同鼓风条件下块矿比例对高炉含铁炉料软熔性能的影响,计算模拟了3种鼓风条件下的温度和气体含量并使用高温熔滴炉研究了块矿比例对含铁炉料软熔性能的影响,进而进行综合炉料结构优化的分析。结果表明,富氧、加湿鼓风条件下,氢气含量增加,能有效降低炉内最大压差,窄化熔融区间,改善炉内透气性;富氧、加湿鼓风条件下,块矿比例的增加虽然会导致炉内最大压差和软熔区间的增大,但是最大压差的绝对值仍远小于基准条件下的最大压差值,软熔带宽度也小于基准条件下的宽度。可以得知,在富氧和加湿鼓风条件下适当增加块矿比例,综合炉料软熔性能仍然优于基准条件,且能降低高炉生产成本,对于炉料结构是一种有效的优化措施。     

Softening and Melting Behavior of Ferrous Burden under Simulated Oxygen Blast Furnace Condition

The softening and melting behavior of sinter,pellet and mixed burden was researched through high temperature reaction tests under load simulating traditional blast furnace(T-BF)and oxygen blast furnace(OBF)conditions.The results indicated that compared with T-BF,the softening zone of sinter and pellet became wide,but the melting zone became narrow in OBF.The permeabilities of both sinter and pellet were improved in OBF.Under the condition of OBF,the temperature of softening zone of mixed burden was increased by 63 K,but the temperature of melting zone was decreased by 76 K.Therefore,the permeability of material layer was significantly improved.This was mainly caused by the change of the melting behavior of pellet.In addition,the quality of dripping iron in OBF was much better than that of T-BF.     

氧气高炉块矿与烧结矿软熔过程交互作用

 以不同预还原度的块矿及块矿与烧结矿的混合矿为研究对象,利用单颗粒荷重软化试验装置,考察了氧气高炉及传统高炉还原气氛对块矿及混合炉料软熔性能的影响。研究发现,高还原势的氧气高炉条件下,含铁炉料还原度的提高导致其颗粒内部铁相数量增加,低熔点渣相数量减少,块矿的软熔性能与传统高炉条件相比有所改善。同时,通过对软熔过程相关数据及炉料颗粒微观结构的分析,发现氧气高炉条件下,块矿-烧结矿混合炉料在界面上发生了交互作用;由于铁相数量的增加及渣相的减少,不同渣相的接触时间被推迟,接触的渣量也减少,导致相对于传统高炉条件,氧气高炉条件下发生交互作用的温度升高,其作用强度减弱。     

炉腹煤气中氢气含量对炉料软熔性能的影响

 在实验室条件下研究了提高炉腹煤气中氢气含量对含铁炉料软熔性能的影响。研究结果表明：随着氢气含量的提高,含铁炉料的软化开始温度先增加后降低,软化终了温度升高,软化区间先变宽后变窄,熔融开始温度、滴落温度升高,熔融区间变窄,炉料透气性明显改善。增加炉腹煤气中氢气含量有利于高炉冶炼。     

邯钢高炉低烧比炉料结构的优化

鉴于环保压力的影响,高炉应减少烧结矿的使用,多使用相对清洁的球团矿和块矿进行高炉冶炼。为配合酸性炉料的大比例加入,需要提高烧结矿的碱度。然而,随着烧结矿碱度的提高,高炉炉内压差升高,透气性恶化,高炉相应生产质量指标难以提升。为了避免烧结矿碱度过高所带来的问题,提出了新的技术思路,即将烧结矿中碱性熔剂取出直接加入高炉,选择适宜的球团矿种类、适宜碱度的烧结矿配加一定量的石灰石与一定比例块矿组成高炉炉料结构。研究结果表明,与综合炉料中直接加入碱度为2.3的烧结矿相比,外配石灰石的方式所组成的综合炉料熔滴性能更优,炉料透气性得到了改善。在熔滴性能满足高炉要求的情况下,通过外配石灰石的方式,炉料结构中烧结矿比例可以降低至47%左右。     

Study on the interaction behaviour between lump and sinter under the condition of oxygen blast furnace

This research report describes the influence of the reducing atmosphere of oxygen blast furnace (OBF) and traditional blast furnace (TBF) on the softening and melting behaviour of lump and lump-sinter mixed burdens assessed by using the softening and melting test. The results reveal that in the OBF atmosphere, the softening and melting properties of lump ore is improved compared with that of the TBF, since the development of reduction degree increased the quantity of the iron phase in the burden particle, and decreased the quantity of slag phase with low melting temperature. In addition, the analysis on the microstructure of burden particles revealed that the interaction effect also occurred at the interface between lump and sinter particles in OBF case. Meanwhile, the scanning electron microscope images shows that the interface is still distinguishable when the samples of OBF case reached 60% contraction ratio (1379°C), whereas in the case of TBF, the interface almost disappeared above 40% contraction, and became completely undistinguishable at 60% contraction ratio (1290°C). This illustrates that, under the OBF condition, the starting temperature of interaction is raised, and the effect intensity is weakened.     

Mixed burden softening and melting phenomena in blast furnace operation Part 2 – Mechanism of softening and melting and impact on cohesive zone

Abstract

The present work was designed to improve the current understanding of the softening and melting (SM) mechanism of ferrous materials and to identify their potential impact on the cohesive zone in the blast furnace (BF). The lump ore, direct reduced iron (DRI) and hot briquetted iron (HBI) were individually subjected to industrial trials and their results were compared with those obtained in the laboratory (SM) tests described in first part of the present paper. The difference between melting and 10% bed shrinkage temperature obtained from the results of laboratory and industrial tests was compared and it was found within 10% limits. The SM temperatures were also correlated to the basicity, gangue and flux contents of the mixed burden. The liquid slag mass fraction was computed using FactSage software and compared with the deformation of the burden bed. These results indicated presence of a small amount of liquid at temperatures close to the softening temperature of the burden suggesting that the deformation of solid phases is the primary cause for softening of the burden. The melting of the mixed burden is dependent on the melting point of DRI and melt exudation occurs close to the meltdown of the burden. The impact of ferrous burdens on the cohesive zone was predicted on the basis of experimental results which indicated DRI/HBI is an excellent blast furnace feed material to improve the productivity and decrease the coke rate in the BF.     

烧结矿碱度变化对软熔滴落性能影响的试验研究

介绍了改善烧结矿软熔滴落性能对强化高炉冶炼的重要性,并通过试验系统研究了烧结矿碱度变化对软熔滴落性能的影响。试验结果表明:对于高碱度烧结矿来说,随着碱度升高,开始软化温度、开始熔化温度均呈现下降趋势,滴落温度升高,软熔区间、熔化区间均变宽,初渣熔点升高,整体性能呈现变差趋势。     

矿焦混装对钒钛矿综合炉料软熔滴落的影响

 为提高高炉冶炼钒钛磁铁矿水平,系统研究了矿焦混装对高炉综合炉料软熔滴落性能和V、Cr在渣铁中迁移规律的影响,并进行了理论分析。试验过程中烧结矿和球团矿所占比例不变。研究表明,矿焦混装对高炉综合炉料的软化区间、熔化区间、滴落率和透气性等软熔滴落性能参数有显著影响。随着混装率提高,软化区间[t40－t4]稍微变宽;熔化区间[tD－tS]逐渐变窄,软熔带变薄且位置下移;熔滴性能总特征值明显减小,综合炉料透气性能显著改善;渣铁滴落率先增加后减少;V、Cr在初铁中的收得率先升高后降低。因此,一定程度的矿焦混装有利于改善钒钛磁铁矿高炉冶炼综合炉料的软熔滴落性能,其混装率以25%为宜。     

Impact of Sinter Basicity and Alumina on Softening Melting Behavior in Blast Furnace

Softening–melting (SM) experiments have been carried out by using sinter basicity (CaO/SiO2) 1.74 to 2.09 and alumina content 2.90 to 3.39%. The objective of the work is to find the relation between sinter basicity and alumina on SM temperature range, so that we can improve the furnace performance. The increase in basicity of sinter from 1.74 to 2.09 at alumina 2.90 decreases softening start temperature and increases melting finish temperature. Thus, there is a rise in the SM temperature range from 192 to 245 degree Celsius (°C) which increases the gas flow resistance and reduces the permeability across the cohesive zone and deteriorating furnace performance, whereas on the other hand, with an increase in basicity from 1.74 to 2.09 at alumina 3.39, it decreases both softening start temperature and melting finish temperature. Thus, there is a decrease in the SM temperature range from 230 to 220 °C, which shows slight improvement in gas flow resistance.     

浅谈高炉风口喷吹熔剂

根据高炉的炉料平衡,对典型高炉不同区域内的炉渣碱度进行计算。分析结果显示,在大喷煤条件下,传统的高炉配料方式导致炉内渣碱度变化很大,减少了高炉内气 液 固相共存区,降低了高炉下部的透气性。通过风口向炉内喷吹石灰粉来平衡喷煤灰分的碱度,可实现减少炉腹渣量、减缓炉内渣碱度波动、提高软熔带、扩大三相共存区、增加下部透气性、提高煤粉燃烧性、保证高炉顺行和提高高炉产量。     

Fundamental research on iron coke hot briquette – A new type burden used in blast furnace

In order to improve blast furnace efficiency, reduce CO₂ emission and accelerate energy utilisation, a new preparation process of iron coke hot briquette (ICHB) based on the raw materials conditions in China, a new type blast furnace ironmaking burden, was experimentally investigated in this paper. The new preparation process was researched and optimised through single factor experiment and orthogonal experiment. Meanwhile, the reactivity and the post-reaction strength of ICHB prepared under the optimised conditions were tested and the effect of ICHB on the thermal performance of conventional coke was researched. In addition, softening and dripping properties of mixed burden with optimised ICHB charging was simultaneously investigated. The results showed that the optimised preparation parameters of ICHB include 15% iron ore, 65% bituminous coal, 350°C hot briquetting temperature, 1100°C carbonisation temperature and 4 hours carbonisation time. The reactivity and the post-reaction strength of ICHB prepared under the optimisation conditions are 62.4 and 10.6%, respectively. ICHB has protective effect on conventional coke and the protective effect is more obvious with 10% ICHB adding. With the increase of ICHB charging ratio, softening interval T₄₀–T₄ of mixed burden is widened while melting interval T_D–T_S (namely cohesive zone) is narrowed. Additionally, the permeability of mixed burden becomes better and dripping ratio is first increased then decreased. The suitable charging ratio of ICHB in mixed burden is about 30%.     

烧结矿碱度对综合炉料交互反应的影响

以不同碱度的烧结矿及烧结矿与块矿的混合矿为研究对象,利用荷重软化熔滴装置,考察了烧结矿碱度对综合炉料软熔性能及不同炉料间交互作用的影响。研究发现:随着烧结矿碱度增加,炉料结构中块矿的质量配加比例提高,炉料间的交互作用增强,主要表现为综合炉料软化开始温度及熔融开始温度降低,混合炉料的透气性得到改善。炉料结构的变化使矿物间的交互反应随着烧结矿碱度的提高而增强,进而导致液相成分发生改变,降低了初渣物相熔点,而烧结矿碱度过高时会恶化料柱的透气性。同时通过扫描电子显微镜?能量色散谱仪(SEM?EDS)及X射线衍射(XRD)精修表征整个还原过程烧结矿物相变化,渣相中主要物相为浮氏体和硅酸钙,随着烧结矿碱度增加,在不同断点2CaO·SiO₂的含量呈现降低趋势,表明烧结矿还原过程生成的高熔点物相随之降低,综合炉料的液相生成温度随之降低,炉料间交互作用增强。因此,适当提高烧结矿碱度,提高块矿入炉的质量配比,利于高炉的强化冶炼。      

球团矿中MgO含量对炉料熔滴性能的影响

球团矿带入适宜的MgO可以提高炉渣的冶金性能,有利于高炉冶炼。为了探究球团矿MgO含量对高炉炉料性能的影响,在全球团冶炼的条件下,以高炉终渣成分为依据进行配料,利用高温熔滴炉检测球团矿不同w(MgO)时高炉初渣性质、炉料软熔滴落性能的变化情况。试验结果表明,随球团矿w(MgO)升高,初渣中未矿化的MgO明显增多,软化结束温度升高,软化温度区间变宽,炉料软化性能变差。当球团矿w(MgO)大于1.01%后初渣熔点升高,导致熔化特征温度升高,熔化带位置向高温区移动,熔化温度区间变窄,熔化带透气性提高;炉料的软熔带温度区间由229 ℃升高至269 ℃,软熔带增厚,炉料整体透气性变差。由于初渣中w((MgO))随之增加,初渣黏度升高,炉料最大压差和熔滴性能特征值增大。因此,在试验范围内,随球团矿w(MgO)升高,高炉炉料的软熔滴落性能恶化,渣铁分离变差,不利于高炉顺行。     

Comprehensive Evaluation of OxyCup Process for Steelmaking Dust Treatment Based on Calculation of Mass Balance and Heat Balance

Through the mass balance and thermal balance calculation for a typical OxyCup （or OxiCup） furnace process featuring a capacity of 380 kt/a of steel plant residuMs, the material flow and thermal flow diagrams were firstly obtained. Then, the performance of the main fuel in the OxyCup process, i.e. coke and carbon dust, was ana lyzed, and the results indicated that coke was mainly used as the stock column skeleton for the furnace and exothermal agent with a weak reduction ability; whereas carbon dust was mixed in the C-brick to reduce the iron oxide. In addition, the comparison between OxyCup process and traditional blast furnace process indicated that the reduction and melting processes in the OxyCup process were relatively isolated, while in the traditional blast furnace process, they were mixed with each other in the high temperature zone. Moreover, oxidizing atmosphere is necessary in part of the OxyCup furnaces to ensure the complete combustion of part of the coke, while only reducing atmosphere is al lowed in traditional blast furnaces. Finally, it was confirmed that oxygen enrichment can make a remarkable increase of the energy income and high temperature blast makes oMy a small contribution to energy income as the energy from the combustion of carbon takes up nearly 90% of the total income.     

Effect of Hydrogen Addition on Softening and Melting Reduction Behaviors of Ferrous Burden in Gas-Injection Blast Furnace

Metallurgical and Materials Transactions B - The softening and melting reduction behaviors of ferrous burden in a gas-injection blast furnace (BF) have been investigated experimentally with the...     

软熔过程中烧结矿和块矿的交互作用

 为更好地明晰块矿的软熔行为并优化其在高炉内的使用,以烧结矿和澳大利亚纽曼混合块矿为研究对象,分别就两者在软熔过程中的物理和化学交互作用进行了试验研究。通过使用中子CT扫描软熔试验试样, 发现1 450 ℃时烧结矿与纽曼混合块矿的混合炉料孔隙度要高于两者单一炉料,即两者间存在着物理交互作用;通过采用扫描电镜和电子探针分析发现,1 200～1 300 ℃温度范围内烧结矿中钙和镁扩散到了块矿中,两者发生了明显的化学交互作用。在物理和化学交互共同作用下,配加约20%纽曼混合块矿的混合炉料软熔行为得到了明显改善,且其性能相似或略好于同碱度的单一烧结矿炉料,这表明块矿和烧结矿混合后能在高炉内形成温度区间更窄、位置更低、透气性更好的软熔带。