钒钛磁铁矿直接还原工艺探讨

钒钛磁铁矿的直接还原是实现钒钛磁铁矿综合利用的关键,在总结钒钛磁铁矿煤基直接还原和气基直接还原研究现状的基础上,对煤基直接还原工艺和气基直接还原工艺在钒钛磁铁矿还原上的特点进行了对比分析。在此基础上,对可以规模化实现钒钛磁铁矿高效冶炼的气基竖炉直接还原工艺进行了分析,并探讨了适合我国资源特点的钒钛磁铁矿气基竖炉直接还原工艺。     

钒钛磁铁矿的煤粉还原过程

对煤粉还原钒钛磁铁矿过程中产生的铁氧化物和钛铁化合物进行热力学分析,得出工艺还原过程中的反应热力学数据,进一步采用高温炉在还原温度1350℃、配碳比1.0、还原煤粒度小于75μm的条件下,考察还原时间对工艺指标的影响和还原过程,得出不同还原时间下产物的定量结果和物相成分.结果表明,还原时间为60min时,还原产物的全铁、金属铁、金属化率均达最大值,分别为68.60%,65.81%和95.93%,钒钛磁铁矿中铁氧化物的还原过程为Fe2O3→Fe3O4→FeO→Fe,钛铁化合物的还原过程为Fe2TiO5→Fe2TiO4→FeTiO3→FeTi2O5.     

钒钛磁铁矿深还原渣酸解实验

以钒钛磁铁矿深还原渣为原料采用硫酸法生产出了TiO2含量大于99．2％的金红石型钛白粉,主要研究了不同酸矿比、酸浓度对酸解率的影响并对酸解率较低的原因进行了分析,以找出直接还原渣硫酸浸出法的最优条件。结果表明,酸解率随着酸矿比的增加而提高,但当酸矿比高于1．65时,酸解串提高不够明显,酸解率可达到75％左右,比同样品位的钛铁矿（TiO2含量为46％-47％）酸解率低5％左右;而影响直接还原渣酸解率的原因与其中铁、镁元素的含量低有关,为了提高直接还原渣的酸解率同时又不增加除铁工序,须按一定比例混入钛铁矿。     

钒钛磁铁矿含碳球团转底炉直接还原实验研究

对转底炉直接还原钒钛磁铁矿新工艺进行了实验研究,将钒钛磁铁矿精矿粉与煤粉等混合,采用压球机压球,并用石油液化气同空气混合燃烧牛成的热烟气干燥生球,通过正交实验考察C/O、焙烧时间和焙烧温度3个因素对金属化率与抗压强度的影响,得出最优的实验方案是:C/O为1.3,焙烧温度为1330℃,焙烧时间为25-min.通过XRD分析发现在金属化率较高的球团中存在假板钛矿.     

攀枝花钒钛磁铁矿深还原渣酸解工艺研究

在攀钢开发的非高炉冶炼钒钛磁铁矿的新流程中,钒钛磁铁矿转底炉直接还原渣铁分离部分完成了工业试验,获得了含钒铁水和含二氧化钛质量分数为43%左右的深还原渣。对深还原渣的化学成分及物相特点进行了分析,系统研究了预处理、酸矿质量比、反应酸质量分数、引发温度、熟化温度等因素对深还原渣酸解率的影响,找到深还原渣的最佳酸解工艺参数,为采用硫酸法回收深还原渣中的钛奠定了基础。实验结果表明,深还原渣经预处理,其酸解率较未处理高出10%左右。预处理后的深还原渣最佳酸解条件:酸矿质量比为(1.7~1.8)∶1,反应酸质量分数为88%~89%,引发温度为100~120℃,熟化温度为220℃。     

国内钒钛磁铁矿分析方法综述

由于钒钛磁铁矿含铁、钛和钒较高,准确测定主、次元素存在一定的困难。主要叙述了近些年来国内钒钛磁铁矿分析测定方法,包括分光光度法、滴定法、极谱法、原子吸收光谱法、电感耦合等离子体光谱法、电感耦合等离子体质谱法、X射线荧光光谱法等。对这些方法的优缺点分别归纳总结并进行了评述,同时对今后的发展方向做了展望。     

色素炭黑的流态化臭氧氧化

本文通过正交试验对色素炭黑在不同条件下，采用特殊的流化床反应器，使用臭氧对炭黑进行了表面改性处理，试验得到了臭氧氧化的最佳湿度为100℃，最佳气量为0.35m^3/h，最佳反应时间为80min(O2)，并对影响因素作了阐述。     

碱度对含铬型钒钛磁铁矿烧结性能的影响

以承德建龙特殊钢有限公司现场条件为依据,通过烧结杯实验模拟碱度(R)对含铬型钒钛磁铁矿烧结性能的影响,分析了其显微结构.结果表明,随碱度提高,烧结速度先增大后减小,R=2.5时最大,为19.70 mm/min,烧损增大;R=2.7时转鼓强度最高,为63.53%;碱度提高改善含铬型钒钛烧结矿的低温还原粉化指数(RDI),R=2.7时大于3.15mm的颗粒的RDI最高,为75.09%;碱度增大生产率先增大后减小,R=2.5时最高,为1.35 t/(m2·h).R=2.1~2.5时燃耗比上升,R=2.1时最低,为43.21 kg/t.碱度提高有利于提高软化开始和软化终了温度,改善含铬型钒钛烧结矿的软化性能、矿物组成及结构,是其性能改善的内因.该矿适宜的生产碱度为2.5.     

钒钛磁铁矿钙化焙烧及其酸浸提钒

对钒钛磁铁矿精矿钠化焙烧水浸提钒和钙化焙烧酸浸提钒的效果进行对比,确定钙化焙烧-硫酸浸出提钒方法,研究了焙烧添加剂Na2CO3,CaO,Ca(OH)2和CaCO3对浸出提钒效果的影响,其中CaCO3的作用最好,确定了CaCO3添加量为10%,1 200℃焙烧时间为1h的优化焙烧条件,得到主要的含钒物相为偏钒酸钙相;偏钒...     

XRF测定钒钛磁铁矿中铁、钒、钛和硅含量

实验采用粉末压片法制样,使用能量色散X射线荧光光谱法(XRF),实现了对钒钛磁铁矿中铁、 钒、 钛和硅含量的快速测定.通过将测定值与标准值进行比较,得出最优实验条件,包括样品粒径、压力、保压时间等.所得四种元素的检出限在0.24～3.93 mg·L-1之间,相对标准偏差(n=8)在5％以下,且标准样品的测定值与标准值相...     

Geldart-B类颗粒在气固流化床中的床层膨胀与流型转变

采用理论推导和经验公式相结合方法,建立了Geldart-B类颗粒在流化床中流化过程的床层膨胀比(R)的通式,并在全取值范围内构建了床层膨胀比的收敛迭代公式。采用不同颗粒的流化实验数据对上述通式(模型)进行了验证,结果表明该模型很好地预测了床层膨胀比。进一步讨论了床层膨胀比与鼓泡流化流型变化之间的关系,给出了临界膨胀比的取值规律。有关床层膨胀比的研究结果一定程度上可有效改善流化床的监控,优化操作条件选取。     

过程工程所流化床直接还原技术研究进展

“双碳”背景下,钢铁工业亟待低碳重塑,氢气直接还原(常称为“氢冶金”)是国内外竞相研发的重要方向。流态化直接还原是过程工程所六十多年来一直坚持的研究方向。值此叶渚沛先生诞辰120周年之际,本综述回顾并概述了过程工程所在流态化直接还原基础理论和工业应用两方面所取得的一系列重要成果。基础理论方面包括颗粒间黏着力与分离力相互竞争黏结机制、聚团流化和慢速失流的发现、不同铁形貌析出机理和黏结特性,以及降低颗粒间黏结力(颗粒包覆改性、调控铁析出形貌)和增大颗粒间分离力(增强颗粒运动、增大颗粒尺寸、施加外场力)等一系列抑制黏结失流方法;工业应用方面包括100公斤/天流化床氢气直接还原、1吨/天钒钛磁铁矿流化床直接还原和千吨级钒钛磁铁矿直接还原-电炉熔分等中间试验,目前正在与鞍钢集团等单位合作开展全球首套1万吨直接还原铁/年流化床绿氢直接还原工程示范。谨以此文缅怀叶渚沛先生、郭慕孙先生等老一辈科学家,以期推动流化床直接还原基础理论和技术研发的进步,为钢铁工业低碳重塑贡献智慧和力量。要点：(1)还原过程颗粒黏结机理的揭示对突破黏结失流难题和提高还原效率具有重要的作用。(2)基于黏结机理和过程强化研究,建...     

Experimental study on the attrition and size distribution of bed material in a recirculating fluidized bed

An experimental study was performed on the attrition of the bed materials in a recirculating fluidized bed (RCFB) using Indian standard (IS) grade I sand (size between 2.0 and 1.0?mm) at ambient conditions. Experiments were performed with superficial air velocity ranging from 7.13 to 9.16?m/s, bed inventory of 7–10?kg, and a spacing of 0.085?m between the jet top and draft tube bottom. The main objective of the study was to investigate the effects of operation time on the attrition and size distribution of sand particles in a RCFB. It was noticed that the prime mode of attrition of bed materials was abrasion, not fragmentation. Reduction in the downcomer bed height was observed with increasing operation time. It indicates that attrition was significant and fines were elutriated out with the fluidizing air. Furthermore, variations in the shape, size, and harmonic diameter of particles were studied with increasing operation time. It has been observed that the coefficient of uniformity and coefficient of curvature showed increasing patterns. It specifies that particles of different size ranges and fines were formed due to attrition of particles. At the end of the operation, it was found that a significant amount of fines was elutriated with fluidizing air from the reactor.     

Nitric oxide reduction by char and carbon monoxide: Fundamental kinetics of nitric oxide reduction in fluidizedbed combustion of coal

The reduction of nitric oxide during combustion of coal char in a fluidized-bed combustor was examined with respect to two reactions : a char-catalysed reaction; and a char-consuming reaction, which control nitric oxide emissions. The relative importance of the two reactions was investigated by measuring detailed material balances for the reactions. The product distribution was explained in terms of three fundamental parallel reaction paths. Reaction rates were investigated with a fixed-bed flow reactor over the temperature range 883–1194 K, the same as the fluidized bed combustor.     

流化床内介质主要流化特性参数的研究

利用6种不同粒度的磁铁矿粉作为加重质研究流化床的流化特性。研究表明,随着颗粒平均粒径的减小,床层表面的气泡尺寸明显减小,适宜分选的气速可调范围变宽,有利于流化床分选的进行,为确定最佳的分选条件提供了依据。     

Experimental study of the inverse fluidized bed biofilm reactor

A new apparatus, the inverse fluidized bed biofilm reactor, is described. Introduction of the so called inverse fluidized bed, in which low density particles covered by a biofilm are fluidized by downflow of the liquid, allows control of the biofilm thickness and provides a high oxygen concentration in the reacting liquid. Characteristics of the reactor were studied by carrying out two important biotechnological processes: aerobic wastewater treatment by a mixed bacterial culture, and ferrous iron oxidation by the bacteria Thiobacillus ferrooxidans. The bioreaction rates per unit volume of the reactor were up to 14 times higher than those in the equivalent airlift bioreactor. The structure of the liquid flow was determined by a tracer method.     

Devolatilization and char burning of coal particles in a fluidized bed combustor

Devolatilization and char burning were studied in an electrically heated bench-scale fluidized-bed reactor at 750 to 900°C bed temperature, gas oxygen mole fractions ranging from zero to 0.21, superficial gas velocities from 0.3 to 0.7 m/s and coal particle diameters 5 to 35 mm. The coals investigated include lignite, bituminous and anthracite. The coal devolatilization and char burning times, H/C ratio histories, and particle fragmentation were measured. Statistical correlations with the operating variables were developed for the devolatilization time. A mathematical model is given for the combustion of char. Most predictions of the model agree quite well with the experimental results.     

Gasification of coal by a pilot flame in a modified fluidized bed

Coal is successfully gasified in the presence of a pilot flame in a modified fluidized bed. Except for the pilot flame, no external heat is required to operate this gasifier. The results showed that increasing the solid-to-air ratio in the feed increased the temperature and the products, carbon monoxide and hydrogen. About 95% of the volatile materials and 80% of the fixed carbon of the feed coal could be gasified by this pilot-flame gasification method. The ash could be efficiently separated during gasification by a distributor within the dead-zone collector of this gasifier.     

The use of peat granules in a fluidized bed bioreactor

This study describes the particle characteristics and fluidized hydrodynamics of peat granules. Peat granules, moistened with water, are a potential packing material in a gas–solid fluidized bed bioreactor used for treating air pollution. Information on the fluidization of wet peat granules is lacking. In order to advance this new type of bioreactor and to scale up its design for industrial use, fluidization studies of suitable packing material are required. Using abiotic experiments, three sizes of peat granules have been fluidized with air and fluidization characteristics were observed at different superficial gas velocities. Relative to other biomass particles, peat granules have a high particle density and sphericity, which contributes to favourable fluidization behaviour, without gas channelling. Fluidization experiments demonstrate that as the mean size of peat particles increased, minimum fluidization velocity increased. Increasing the moisture content of the peat granules resulted in a transition from bubbling bed fluidization to poor fluidization behaviour. Other types of moist biomass particles such as sawdust are difficult to fluidize and typically exhibit Geldart group C behaviour. In contrast, it was observed that wet peat granules could be fluidized in a bubbling bed regime, typical of group B particles.     

小型沸腾炉木柴升温空炉开车中的几个问题

分析小型沸腾炉木柴升温时的最佳投矿温度 ,局部高温或“暴涨期”高温结疤的原因及其预防措施。