Preparation of sinter with low reduction degradation index for COREX reduction in a high proportion

The sinter with low reduction degradation index(RDI)for COREX reduction was prepared by separated granulation sintering process.The results illustrate that the productivity and tumble index are attained to be 1.64 t m^(-2)h^(-1)and 59.25%,respectively,in pot tests under the optimal conditions.Under the reducing condition simulating COREX shaft furnace,RDI_(+6.3 mm),RDI_(+3.15 mm),and reducibility index of the sinter reach 63.05%,81.52%,and 83.65%,respectively.Compared with traditional sintering process,the productivity rose by 14.69%,and RDI_(+6.3) mm and RDI_(+3.15) mm were increased by 157.54%and 32.70%,respectively.In addition,as the proportion of sinter reached 60%,RDI_(+6.3 mm)and RDI_(+3.15 mm)of comprehensive burden were achieved to be 73.39%and 84.28%,respectively,which could completely meet the requirement of COREX shaft furnace for RDI.The mechanism was demonstrated that the more silicoferrites of calcium and aluminum and silicate phase occurred as well as magnetite,and the amount of Fe_(2)O_(3)decreased substantially in the sinter by separated granulation sintering process.Hence,the low-temperature reducing stress is restrained,with the increase in sinter strength.

Reducing process of sinter in COREX shaft furnace and influence of sinter proportion on reduction properties of composite burden

In order to reduce the materials cost of COREX ironmaking process,sinter has been introduced into the composite burden in China.This work explored the reducing process of sinter in COREX shaft furnace to clarify its reduction properties change and then the effect of sinter proportion on metallurgical performance of composite burden was investigated.The results show that the reducing process of sinter in COREX shaft furnace was basically same with that in blast furnace but sinter seems like breaking faster.Under reducing condition simulated COREX shaft furnace,sinter possessed the worst reduction degradation index(RDI)and undifferentiated reduction index(RI)compared with pellet and iron ore lumps.Macroscopic and microscopic mineralogy changes indicated that sinter presents integral cracking while pellet and lump ore present surface cracking,and no simple congruent relationship exists between cracks of the burden and its ultimate reduction degradation performance.The existence of partial metallurgical performance superposition between composite and single ferrous burden was confirmed.RDI_(+6.3)≥70%and RDI_(+3.15)≥80%were speculated as essential requirements for the composite burden containing sinter in COREX shaft furnace.

Low Temperature Reduction Degradation Characteristics of Sinter,Pellet and Lump Ore

The reduction degradation characteristics of typical sinter, pellet and lump ore were tested with the reducing gas conditions simulating two kinds of irowmaking processes. The results show that, in the same condition of gas composition and temperature, the reduction degradation degree （RDI〈3.15mm） of sinter is high, RDI〈3.15mm of lump ore is low and RDI〈3.15 mm of pellet is in the middle level. With two kinds of gas composition simulating different iron-making processes, the reduction degradation indices （RDI） of three kinds of iron ores all present the tenden- cy of ＂inverted V-shape＂ in the temperature range from 450 to 650℃, and the RDI reach the maximum value at 550℃. The reduction degradation degrees of iron ores are extended when mixing the gas with hydrogen to increase the re duction potential, and the influence extent is discrepant for different iron ores. Colligating the increase amplitude of grains in small size fraction, the influence of reducing gas on lump ore is the greatest, the influence on sinter is the second, and the sensitivity of pellet on the reducing gas properties change is relatively small. As for the degradation form, lump ore and sinter both present the degradation ,of cracking, and the distribution of small grains generated from the cracking is in the range from 03 5 to 6. 3 mm uniformly. The lump ore presents surface cracking, while sin- ter presents integral cracking. The pellet presents the degradation of surface stripping, and the proportion of grains smaller than 0.5 mm is the highest, which is up to 90% in the grains smaller than 3.15 mm.

Influence and mechanism of Indonesia vanadium titano-magnetite on metallurgical properties of iron ore sinter

In order to provide a reliable reference for utilizing Indonesia vanadium titano-magnetite(VTM) in blast furnace(BF) economically, metallurgical properties of iron ore sinter with addition of Indonesia VTM in mixed sintering materials were investigated, including low-temperature reduction degradation index(RDI), reducibility index(RI), and softening/melting properties. Additionally, influenced mechanism of Indonesia VTM on metallurgical properties of sinter was studied. It is found that adding Indonesia VTM in sintering process quickly increases the RDI of sinters, and decreases the RI from 78.02% to 68.43%. Moreover, both beginning temperature(T_4) and final temperature(TD) of softening/melting increase gradually, and cohesive zone temperature range(T_D–T_4) enlarges from 219 oC to 315 oC. As a result, the permeability of cohesive zone gets worse, which is proven by the higher maximum pressure drop(δPmax) in softening/melting experiments. It is concluded that, after comprehensively considering all metallurgical properties mentioned above, the proper proportion of Indonesia VTM in sintering process is proposed in the new raw materials conditions.

Sintered Ore Sprayed by Acid and Alkaline Waste Water Resulted From Cold Rolling

In order to prevent the powdering of a sintered ore from influencing the smooth operation of a blast furnace,the conventional way to deal with it is that the CaCl2 solution is prepared by tap water,and then the solution is sprayed onto the sintered ore for improving its RDI（low temperature reduction degradation index）.The CaCl2 solution prepared by adding acid and alkaline waste water resulted from cold rolling is sprayed onto the sintered ore to improve its RDI.The values of RDI＋6.3 and RDI＋3.15 of the sintered ore which is sprayed by the CaCl2 solution with the CaCl2 concentration of 3.5%（mass percent） are increased by 17.5% and 11.63%,but the index of RDI-0.5 is decreased by 3.1% when the spraying amount of the solution is making up 0.5% of the total sintered ore sprayed in comparison with those of the sintered ore which is not sprayed by using the CaCl2 solution.Experimental results show that after the CaCl2 solutions prepared by adding the acid and alkaline waste water are sprayed on the sintered ore,RDI of the ore can be remarkably improved and therefore another way for recycling acid and alkaline waste water can be available,by which both cost for treating waste water and cost for producing a sintered ore can be decreased and environment is free of pollution by harmful substances in the waste water.

快速烧结和低温老化对高透氧化锆半透性的影响

目的 评估快速烧结和低温老化对高透氧化锆半透性的影响。方法 利用常规烧结和快速烧结分别烧结高强氧化锆ST和高透氧化锆TT,分别进行0、5和20 h的低温老化处理后,采用Shade Eye NCC电脑比色仪在标准黑白背景下测量色彩学特征参数(L^(*)、a^(*)、b^(*)值),使用半透明参数(TP)评估材料半透明性。结果 快速烧结会降低ST的TP值,会升高TT的TP值。低温老化对TT的TP值没有影响;常规烧结的ST的TP值随着老化时间的延长降低,快速烧结组没有显著变化。结论 快速烧结会降低高强氧化锆的半透性,改善高透氧化锆的半透性。低温老化对高透氧化锆的半透性没有影响。就半透性而言,建议用快速烧结的方式烧结高透氧化锆。

高铝铁矿比例提高对烧结矿冶金性能的影响

我国钢铁行业对进口铁矿石的依存度高达80%以上,随粗钢产量的不断增长,进口铁矿石需求也不断增加,大量非主流的高铝铁矿得到应用,烧结矿Al_(2)O_(3)含量也逐渐升高。为保证烧结矿质量和高炉冶炼指标,开展了高铝铁矿比例提高对烧结矿冶金性能影响的研究。结果表明:随高铝铁矿比例提高,烧结矿Al_(2)O_(3)含量在2.25%~2.53%范围内升高,成品率与转鼓指数分别维持在82.5%和68%左右,还原度和低温还原粉化率RDI+3.15 mm分别为89.1%~93.4%和73.4%~76.9%,没有出现明显的劣化趋势;同时烧结矿荷重软熔滴落性能融滴区间逐渐下移,滴落量在Al_(2)O_(3)含量2.25%~2.39%范围内递增,在2.53%时急剧下降,且滴落渣量变化更加明显。在现有条件下提高烧结配加高铝铁矿比例,并将烧结矿Al_(2)O_(3)含量控制在2.4%以下,烧结矿质量及冶金性能可以满足高炉生产需求。

硼镁铁精粉的烧结性能试验及工业应用

为了拓展可用铁矿资源的来源途径,本文对一种含硼、镁的铁矿资源(丹东硼镁铁精粉)的烧结性能进行试验研究,并开展相关工业应用试验。结果表明:硼镁铁精粉的同化性能与杨迪粉接近,液相流动性能与PB粉接近;在现有烧结原料和工艺条件下,硼镁铁精粉等比例替代地方磁精粉,有利于提高烧结矿的成品率,降低固体燃料消耗,改善烧结矿的低温还原粉化性能。该铁精粉配比低于10%对提高烧结机利用系数和烧结矿转鼓强度有利,高于10%对上述两个指标有负面影响。工业应用试验结果表明,配加3%的硼镁铁精粉后,烧结矿的全铁品位略有降低,烧结矿中B_(2)O_(3)质量分数增加,达到0.56%;烧结矿的粒度组成得到优化,(5,10)mm和≤5 mm的粒级占比分别降低0.79%和1.29%,>40 mm的粒级占比增加3.01%;烧结机利用系数由1.60 t/(m^(2)·h)提高到1.62 t/(m^(2)·h),烧结矿转鼓强度提高2.22个百分点,低温还原粉化指数(>3.15 mm)由58.80%上升至60.29%,烧结矿产、质量指标均有明显改善。

烧结矿转鼓强度和冶金性能研究

随着钢铁行业“绿色低碳、高质量发展”政策的落地实施,高炉不仅要求烧结矿具有良好的物化性能,还要求具有良好的热态冶金性能。针对目前高炉过于强调烧结矿转鼓强度和低温还原粉化指标RDI+3.15,而忽视了还原度RI的片面要求,通过研究烧结成矿机理、矿物组成特性、黏结相系特征和形成条件,分析了FeO、碱度R、脉石成分等关键化学成分和不同铁矿粉烧结对转鼓强度及冶金性能的影响,得出了适宜的FeO含量、碱度R、MgO含量、Al 2O_(3)含量、铝硅比。同时兼顾转鼓强度、还原度RI、低温还原粉化指标RDI+3.15和软熔性能,提出了改善烧结矿转鼓强度和冶金性能的技术措施,为高炉冶炼提供综合指标优良的烧结矿。

氢基竖炉用球团生产工艺优化

竖炉用高质量球团是当前研究热点,回转窑球团产线中链篦机-回转窑-环冷机各部温度优化控制是提高球团产质水平的重要环节。介绍了链篦机-回转窑-环冷机设备优化过程以及造球工艺优化措施。首先在生产工序中缩短了干燥段,延长了预热段,同时改善了环冷机热量流通,为更好的氧化焙烧奠定了基础;在造球流程改造中,将造球盘角度统一调整为46°,旋转刮刀的转速均调整为10 r/min,旋转刮刀与底衬的距离调整为30~40 mm,造球盘落料点较之前向盘内延伸100 mm,小皮带下料点到边板距离达到43 cm,最终成球效果得到明显提升。对比工艺改进前后生产球团,其还原性能有所提升,还原膨胀及低温还原粉化指数均有所改善,其还原性能有所提升,还原膨胀率有所降低,其中1号球团还原膨胀率由12.34%降低到了7.82%,低温还原粉化指数改善明显,LTD+6.3均提高了20%左右。同时造球工艺优化为我国氢基竖炉用优质铁精矿球团提供了帮助。

配加SP10粉的烧结试验与生产实践

首钢京唐公司根据自身配矿结构特点和降本增效的实际需求,尝试开发使用新的铁矿石资源,以拓展烧结优化配矿资源选择。根据当前铁矿石价格和矿粉资源的可用性,结合烧结生产实际情况,对SP10粉进行了烧结优化配矿试验研究,分析了SP10粉对烧结技术经济指标的影响。结果表明,随着SP10粉配比由0增加至12%,烧结矿成品率、转鼓强度、烧结垂直燃烧速度及利用系数均呈现先增高后降低的趋势,其分别在SP10粉配比约4%时达到最佳值;而固体燃耗持续降低,在SP10粉配比4%时达到最小值48.94 kg/t;烧结矿粒度组成变化不明显。根据烧结杯试验结果和SP10粉的成分特点及烧结基础特性,进行了配矿工业生产实践,发现烧结矿还原度及低温还原粉化指数整体变化不大,其中低温还原粉化指数基本保持稳定,证明使用4%~7%的SP10粉替代产自澳大利亚的褐铁矿粉是可行的。

烧结矿低温还原粉化率的影响因素及预测模型

针对烧结矿低温还原粉化率传统检测方法时间滞后、过程繁杂、耗时较长等问题,本文以某钢铁厂400 m^(2)烧结机烧结矿的性能指标为研究对象,选用60组训练集进行因子分析,建立以Al_(2)O_(3)、SiO_(2)、MgO、TiO_(2)、FeO质量分数以及R、w(MgO)/w(Al_(2)O_(3))和w(CaO)/w(TFe)为自变量,低温还原粉化率为因变量的烧结矿低温还原粉化率预测模型。结果表明:影响烧结矿低温还原粉化率的主要因素是w(Al_(2)O_(3))、w(SiO_(2))、w(FeO)、R和w(MgO)/w(Al_(2)O_(3));优化后预测模型为YRDI=1.137w(FeO)+5.56w(SiO_(2))+26.44R-20.19w(MgO)/w(Al_(2)O_(3))-6.07w(Al_(2)O_(3));模型的R^(2)为99.90%,具有较高的精确度,能够快速预测烧结矿的低温还原粉化率,并能在生产中改善烧结矿质量。本文建立的预测模型可为现场烧结生产提供理论指导和技术支持。

烧结烟气半干法脱硫后SCR脱硝中温设计低温运行研究与应用

半干法脱硫+SCR脱硝是目前国内钢铁企业在烧结机烟气超低排放改造工作中常用的净化工艺,系统采用中温窗口催化剂,在使用过程中存在脱硝系统燃气消耗量大、能耗相对较高等问题。为落实“节能减排”“低碳环保”等发展思路,研究结合主流半干法脱硫+SCR脱硝净化工艺路线的技术特点,分析了半干法脱硫后SCR脱硝系统中温设计、低温运行方案的可行性,提出了优化解决方案,并结合具体项目的现场运行参数,说明该方案是可行的,即采用中温(280℃)设计的SCR脱硝系统,改装填低温(200℃)窗口催化剂运行,优化后系统运行稳定,且满足超低排放标准,高炉煤气耗量节省25%,电耗节省4%,节能降耗效果显著。

改善烧结矿低温还原粉化性能的措施

某钢铁企业结合烧结生产实际,通过分析影响烧结矿低温还原粉化率的因素,采取提高烧结矿碱度优化配矿、改善烧结工艺条件、调整烧结矿中脉石成分、规范取制样等措施,改善了烧结矿低温还原粉化性能,烧结矿低温还原粉化指标RDI+3.15mm由65.71%提高到71.12%,取得良好效果。

燃料添加方式对烧结矿冶金性能影响的研究

某炼铁厂开展烧结杯试验,研究不同燃料配加方式、不同燃料粒度组成情况下,烧结固体燃料消耗和烧结利用系数变化,成品矿质量及烧结矿还原度、低温还原粉化指数等冶金性能指标的影响,实现优化烧结生产配矿方案、提高烧结技术指标烧结矿冶金性能指标的目的。

唐钢带式焙烧机熔剂性球团矿生产实践

为适应高炉高比例球团冶炼的需求,从2021年初开始唐钢新区使用带式焙烧机生产熔剂性球团。通过改造消石灰配给设备,改变除尘灰配加方式,增加细粒铁精粉配比,降低抽干段、预热段以及焙烧段的温度,严格控制熔剂性球团矿SiO_(2)不超过3.5%及TiO_(2)含量不超过0.5%等技术措施,使得熔剂性球团矿化学成分稳定性得到明显改善,低温还原粉化RDI+6.3指标由70%左右提高到93%左右,为高炉实现35%熔剂性球团配比下的长周期稳定顺行提供了保障。

高结晶单分散银粉表征及低温烧结活性分析

采用液相还原法,通过改变纳米银晶浓度制得不同粒径的类球形银粉。采用扫描电子显微镜、比表面积分析仪、激光粒度分析仪等对银粉进行物理性能表征,并进行低温(200℃)烧结活性分析。结果表明:银粉颗粒结晶度高,单分散性好,且银粉粒径随加入的纳米银晶浓度提高呈规律性递减;样品4粒径最小,经低温烧结后银粉颗粒边界逐渐消失,烧结30 min后银粉完全烧结,形成交错联结的空间网络结构。高结晶单分散银粉的制备为HJT电池开发提供技术支撑。

改善鄂钢烧结矿低温还原粉化率的实践

2023年3月,鄂城钢铁(以下简称鄂钢)烧结矿的低温还原粉化指标显著降低,造成高炉料柱上部透气性变差,影响高炉顺行。对2022年1月-2023年3月的烧结矿低温还原粉化率变化趋势进行分析发现:配矿结构、烧结矿FeO、碱度以及烧结矿成分变化是引起烧结矿低温还原粉化指标变差的主要因素。在后续生产中,通过采取提高磁精粉比例、优化FeO控制区间和提硅降铝等措施,有效改善了烧结矿低温还原粉化率指标,满足了高炉用矿要求。

塞拉利昂块矿、矿粉在高炉生产中性能的研究

通过对塞拉利昂矿粉(块矿)物理、化学、热态性能的研究,发现塞拉利昂矿满足高炉对原料的要求。通过烧结杯试验表明,烧结矿中配加一定的塞拉利昂矿,烧结矿软化融滴性能有改善的趋势,烧结矿的低温还原粉化指数、融滴性能均可满足高炉生产要求。

钒钛烧结矿还原粉化过程的矿相分析

低温还原粉化率RDI-3.15是评价烧结矿质量的一项重要指标,它会影响高炉焦比和产量。钒钛烧结矿的RDI-3.15高达60%以上,研究认为钙钛矿是造成RDI-3.15高的主要原因,但是随着钒钛烧结矿中钙钛矿含量的大幅降低,其低温还原粉化性能并未得到有效改善。本研究应用矿相分析法对比分析了普通烧结矿和钒钛烧结矿的微观结构差别,并观察了两种烧结矿在低温还原粉化前后的结构变化;发现骸晶状赤铁矿和气孔结构是发生粉化的主要区域,而钒钛烧结矿中存在大量的气孔结构,这是导致其还原后发生严重粉化的主要原因。调整成分以提高粘结相的流动性,有利于降低气孔率和骸晶状赤铁矿含量,并增加有效粘结相,从而可减少配碳量并降低烧结温度,限制铁酸钙的分解和钙钛矿等高熔点矿物的生成,增加强度较好的交织结构的数量。