宝钢含锌尘泥的循环利用工艺简介

对宝钢的含锌尘泥(转炉二次粉尘、电炉粉尘和高炉瓦斯泥)的厂内循环利用进行了研究,通过将含锌尘泥分别应用于铁水三脱、转炉造渣和电炉造泡沫渣工艺对循环利用工艺进行了试验,具体如下:将转炉二次粉尘和电炉粉尘的混合物取代烧结矿粉作为铁水脱磷剂,通过改善流动性,达到了与烧结矿粉相当的脱磷效果,在三脱处理中粉尘中的锌和铅含量得到了明显的富集,为下一步回收处理打下了基础.将转炉二次粉尘和电炉粉尘的混合物通过添加一定量生白云石和锰矿加工成冷压块,在转炉吹炼前期加入,促进了石灰的溶解,改善了前期化渣,提高了脱磷率,LT压块和矿石的耗量减少.造渣剂加入没有引起钢水的增硫明显,粉尘造渣剂的加入对钢水和炉渣成分没有影响.将高炉瓦斯泥通过添加一定量生石灰和生白云石并加工成冷压块后,在电炉熔炼期加入,强化泡沫渣操作,减少金属损失和碳粉用量.瓦斯泥压块加入后对钢水、炉渣成分和电炉的粉尘不会产生明显影响.     

A Novel Process Control Model for Extracting Vanadium Semi‐Steel in Basic Oxygen Furnace Based on Steelmaking Mechanism

A novel process control model for basic oxygen furnace (BOF) steelmaking is proposed based on metallurgy mechanism, with lower contents of carbon, manganese, silicon, and lower temperature in semi‐steel after extracting vanadium. According to mass balance and heat balance, a static control model is built up, with slagging model, temperature model, and oxygen supply model. When actual amount of oxygen supply reaches 85% of theoretical value calculated by static model, quasi‐dynamic control model is activated to predict carbon and temperature in later period of steelmaking. A steelmaking process control system for semi‐steel smelting on 120 tonne BOF is developed in a steelmaking plant in China. Based on test of three steel grades, this model acts a guide for BOF steelmaking with semi‐steel, not only providing tactic, but also pointing out a feasible method for BOF process control without sub‐lance or off‐gas analyzer.     

Decomposition,Reduction and Dissolution Mechanism of Calcium Sulfate in Iron Oxide Dust Pellet

Iron oxide dust generated during oxygen blowing in the BOF process contains a high content of iron. This iron oxide dust can be used as a material of iron source in the BOF slag reduction process or as de‐siliconisation flux or dephosphorization flux of hot metal pretreatment. One of the most practical uses of iron oxide dust is recycling as a form of pellets in the BOF considering easy application and the amount that can be recycled. In the process of making iron dust pellets cement is used as a binder that contains a lot of calcium sulfate. This calcium sulfate is reduced and dissolved in the molten metal during refining in the BOF. If the oxygen content in slag and molten steel is high enough, the reduced sulfate cannot be dissolved into molten metal and it can be removed as SO_x gas. The behaviour of calcium sulfate has been studied using of 50kg high frequency induction furnace and industrial‐scale plant tests were carried out at a 300ton BOF. The results show that for low carbon steels the evaporation of decomposed sulfate increases with increasing oxygen content in the slag while for high carbon steels the decomposed sulfate is reduced into the molten metal.     

Strength and high temperature behaviour of carbon composite pellets containing BOF fine dust

Abstract

Steel plants produce significant amounts of dust and sludge during iron and steel production. These wastes contain valuable elements, such as Fe, Cr, Ni, C, K and Na and should be handled properly to prevent them from polluting the environment. In order to utilise the BOF fine dust, the effects of the dust on cold bonded pelletising, solid state reduction and reduction melting behaviours of composite pellets made from iron ore and anthracite with added BOF fine dust were investigated at laboratory scale. The BOF dust was found to improve the cold compressive strength of the wet green carbon composite pellet, and increased with increasing dust content. Almost four times the amount of dust was needed to get the same effect on the strength of the pellet when it was used to replace bentonite. The carbothermic reduction of the composite pellet proceeded effectively at temperatures above 1200°C. The BOF dust had a positive effect on the reduction rate of the pellet, and the rate increased with increased dust content. The reduction of iron oxide was topochemical and conformed to a shrinking core kinetic model. The dust was found to improve the iron and slag melting separation rate of reduced pellets at 1400°C when its content was less than 23·11 wt-%. The liquidus temperature of the slag would decrease with the content of BOF dust increasing from zero to ～30 wt-% and then increase if the content continued to become more in the experiment. Utilising the BOF dust as the binder and flux to adjust the composition of the slag system can potentially reduce the slag ratio and production cost compared with using bentonite and limestone. This work can help to find a new process for the effective utilisation of BOF dust in a more appropriate and environmentally friendly way.     

静电布袋复合除尘器在转炉一次除尘系统的应用

静电布袋复合除尘是基于静电除尘和布袋除尘两种成熟的除尘理论而提出的一种新型的除尘技术。它结合了静电除尘器和布袋除尘器的优点,将其应用于转炉一次除尘系统能够实现处理后的转炉煤气含尘量≤10 mg/m3,除尘系统运行可靠,减少投资费用和占地面积,并对超细颗粒（如PM2.5）有较好的捕集效果,在新建和改造的转炉一次除尘项目中具有良好的应用前景。     

Dust formation in a BOF converter

Minimisation of waste and manipulation of residues to suit succeeding processes today is one of the steel works most important research areas. BOF dust is expensive to depose in landfills and difficult to recycle due to its zinc contents. The simultaneous loss of raw materials and cost increase makes it important to minimise the generation of dust. This can be done by employing better process control systems with regard to the mechanisms governing the generation. Four dust forming mechanisms can be considered in a converter: ejection of metal, ejection of slag, entrainment of charged material and vaporisation. In order to determine the importance of the four dust forming mechanisms and to characterise dust, with special emphasis to zinc, the off-gas from a 100-t BOF was sampled during twenty seven heats. The sampling equipment allows the sampling of both solid dust particles and vaporised elements. Samples from the first and the second part of blowing show significant differences both in chemical composition and in the origin of formation. The major dust formation mechanism is the ejection of metal and slag, respectively. Entrainment of solids plays an important role only during the first part of blowing. Vaporisation of elements from the bath is most important during the end of blowing. The formation of dust is influenced by process operation control, especially lance position, silica contents and time of charging of slag formers. Zinc is mostly found on the rim of ejected particles where a gradual transition of zinc oxide to zinc ferrite to iron oxide is found. At sampling temperatures of between 800 and 1000°C most of the zinc had already condensed.     

Development and use of mill scale briquettes in BOF

Generation of high iron containing wastes such as mill scale, dust and sludge are inevitable in steel making process. It is important to develop and implement processes to recycle and re-use these wastes. An attractive option is to recycle these wastes through BOF steel making process, but is not suitable for handling and efficient operation in available forms. Present work shows the briquetting of steel making wastes using various binders in a pilot scale briquetting machine. In briquetting tests, the effecting parameters have been studied for determining the best combination of binders and operating parameters. A process for briquetting mill scale in optimum combination with CRM dust and BOF dusts using an organic binder has been established. Separate indices were formulated as acceptance criterion for use of mill scale briquettes in BOF service conditions involving dynamic, crushing, abrasive and thermal loads. Subsequently, series of trials were conducted with use of mill scale briquettes as secondary coolant replacing iron ore in 130T LD converter. The present paper compares the effect of mill scale briquettes vis-à-vis iron ore on process parameters in BOF steel making and also highlights its operational advantages.     

Technique of Controlling Dust Generation during Oxygen Top Blowing in BOF

Dust generation behavior during BOF operation with minimal slag was investigated by measuring the dust concentration of the dust collecting water, and a dust generation model was proposed. In this model, the dust generation rate was expressed as a function of the carbon content in metal and the dynamic pressure at a metal surface of the oxygen top blown jet. As a result of controlling the dynamic pressure with the model, the dust generation rate during BOF operation was restrained and the oxygen blowing rate was increased by 10% to raise the productivity while maintaining the same rate of dust generation. To obtain data on the dust generation rate and clarify the behavior of the top blown jet, a new online system for measuring the dust generation rate for BOF was developed. The system enabled online continuous measurement of the dust generation rate by diluting the dust collecting water and using a colorimetric method to measure the dust concentration of the diluted dust collecting water. Application of the numerical simulation method to supersonic jets was considered and the behavior of the top blown jet was grasped in order to control the dynamic pressure. These tools were used to optimize the operating conditions and quickly evaluate the top blowing lance design under the Zero‐Slag‐Process.     

In‐Situ Measurement of CO‐ and CO2‐Concentrations in BOF Off‐Gas

Improvement of the efficiency and productivity of steelmaking requires accurate and real‐time process information to precisely adjust the tapping conditions. The response time of BOF process control systems is commonly depending on the time needed for off‐gas sampling and analysis. A FTIR based measurement system was adapted and installed at an industrial steel converter of ArcelorMittal España S.A. in Aviles. An advanced data interpretation routine based on the quantum mechanical fundamentals of remote infrared (IR) spectroscopy was developed to enable precise determination of the {CO}‐ and {CO₂}‐concentrations, resp. their ratio, in the off‐gas. The results of the industrial measurement showed the ability of the FTIR based system for real‐time measurement of temperature, {CO}‐ and {CO₂}‐concentrations in the hot and dusty off‐gas. The influence of dust at the chosen defined optical path lengths in the IR wavelengths region can be neglected, but the collector lens clean has to be kept clean.     

大型转炉优化造渣工艺提高脱磷的效果

 针对转炉冶炼存在的转炉前期化渣速度慢,冶炼终点钢水、炉渣氧化性高,终点磷含量控制不稳定等问题,利用炉渣熔化性测定、热力学平衡计算、炉渣矿相分析的方法研究了260 t转炉造渣、供氧工艺。结果表明,转炉初期渣熔化温度为1 330 ℃,不利于转炉前期化渣;终渣熔化温度为1 200 ℃,不利于转炉后期的炉衬维护;终点钢水磷含量与渣钢间磷平衡值差距较大,说明转炉吹炼终点动力学条件不足;炉渣中游离氧化钙含量较高,有部分未熔化的石灰。通过优化转炉渣料加入顺序和数量,强化转炉终点氧枪枪位控制、底吹搅拌等技术措施,可获得较高的转炉终点脱磷率和渣-钢间磷分配比,使终点渣-钢间磷含量更接近平衡;终点炉渣发育良好,游离氧化钙含量适中。     

Control of Ejections Caused by Bubble Bursting in Steelmaking Processes

To investigate the ejection of liquid steel and slag from gas‐stirred melts in view of minimum formation of dusts and accretions, studies were performed combining laboratory experiments on single bubble/melt interactions with bench‐scale tests on 150 kg heats and with observations in metallurgical production facilities. Fine droplets are created when single bubbles burst on the melt surface or on the surface of bigger drops to form film (< 20 mm) and jet (0.1‐2 mm) droplets. At gas exit velocities of ≥ 0.1 m/s, gas flow tends to become turbulent leading to the ejection of splashes > 2 mm. In secondary metallurgy, the gas throughput is relatively small keeping the amount of small droplets (dust) low. On the other hand, the conditions for splashing are frequently met, and splashing is in fact observed in practice. An explanation model for the mechanisms of dust generation in the BOF process is derived from the lab results.     

美国的炼钢技术现状

综合介绍了美国转炉钢厂的铁水脱硫、转炉溅渣护炉的终点控制、出钢控制和钢包渣２、二镒燃烧、钢色精烧等技术,以及电弧炉钢厂的电弧炉吹氧、氧燃加热、泡沫渣操作、废钢预热、直接还原铁和电弧炉粉尘处理技术的现状和特色。     

炼钢技术的发展历程和未来展望(Ⅱ)——炼钢的未来展望

首先讨论了科技进步为推动力的铁水预处理技术、转炉冶炼技术、炉外精炼技术和连铸技术的进步。传统的KR铁水预处理技术采用了载气枪喷入脱硫剂粒子之后,增大了脱硫剂粒子进入铁液的深度并降低了粒子之间聚合的发生,既节省了脱硫剂的使用又提高了脱硫的效率;使用铬矿粉为原料通过转炉冶炼不锈钢过程中,采用副枪燃气燃烧送料技术,既实现了温度达标,也降低了铬的氧化烧损;钢液炉外精炼技术是在吹氩技术、真空技术和电磁技术等多项技术支撑下逐渐发展的;连铸技术也是在电磁技术、机械压下、数字技术的支撑下实现了无缺陷连铸坯的制造和近终形薄带连铸的产业化。然后,从钢洁净度的极限、未来的炼钢工艺展望和连续炼钢工艺3个方面讨论了炼钢技术的未来。目前钢中氧、碳、氮、磷、硫、氢6大元素总和已经能达到0.006 0%以下,特别是钢中总氧质量分数可以达到0.000 5%以下,但是关于钢中金属杂质元素包括锌、锡、铅、锑、铋、砷等去除的研究还需要加强;在信息化和自动化技术充分发展的条件下,无喷溅、无人工操作、无人工维护的“全智能转炉”是有可能实现的;连铸的大数据技术、软件技术和信息物理系统已经在一些先进钢厂得到应用;欧盟已经开始尝试铁矿...     

利用除尘灰生产海绵铁的试验研究

为了更好地实现循环经济,降本增效,合理利用太钢除尘灰资源,降低除尘灰中Zn、K、Na等元素对高炉的不利影响,采用隧道窑工艺,以转炉除灰尘、AOD除灰尘、铁鳞、高炉瓦斯灰等配料进行了试验研究。结果表明,采用该工艺处理除尘灰生产海绵铁是可行的,Fe金属化率达到80%以上,脱Zn及碱金属效果显著。     

Mathematical Modeling of Impinging Gas Jets on Liquid Surfaces

In top-blowing operations, the gas jet is a major source of momentum, so to model the momentum exchange properly with the liquid, the full-stress boundary conditions must be applied. A new mathematical method for better representation of the surface boundary condition was developed by combining the Cartesian cut cell method and volume of fluid method. The computational code was validated with the broken dam problem and reported critical phenomena in wave generation. The model was applied to impinging jets on liquid surfaces in two dimensions. The cavity depth was in good agreement with experimental measurements. The process of ligament and droplet formation was reproduced. The extent of momentum transfer to the liquid was investigated, and the trends with lance height and gas flow rate were similar to experimental evidence. The following important aspects of momentum transfer were identified: surface roughness as well as the development of local pressure gradients around wave crests. Kelvin–Helmholtz instability theory was used to interpret the results with respect to critical velocity for the onset of droplet formation. These principles were extended to conditions relevant to basic oxygen furnace (BOF) steelmaking. The critical velocities for droplets were calculated as functions of the physical properties for the gas–steel, gas–slag, slag–steel interfaces. The implications for BOF steelmaking were discussed. The mathematical model was applied to a simplified configuration of full-scale BOF steelmaking, and the local force balance was well described.     

转炉干法除尘灰气力输送方法研究

介绍了福建三钢二炼钢120t转炉原设计干法除尘烟气净化回收系统的粗、细灰收集输送工艺原理和存在缺陷,经过对粗、细灰气力输送的可行性和技术难点进行研究,提出气力输送工艺原理和实施方案。     

基于炉气分析的熔池碳含量及温度变化研究

 根据物料平衡及反应平衡原理，利用炉气分析系统在线连续检测、分析数据，建立了转炉冶炼过程中碳含量及温度变化的动态模型。该模型计算结果与检测结果吻合较好，这表明：①通过烟气流量、成分及铁水质量和初始碳含量可动态地确定熔池中的碳含量；②以动态确定的碳含量为基础，结合炉气分析数据，再经热力学平衡分析，可预测熔池温度的动态变化。     

高炉 转炉流程生产过程的硫素流分析

 针对高炉 转炉流程生产过程产生的SO2烟气造成环境污染的问题,以工业代谢理论为基础,应用物质流分析方法,建立了工序的硫素流分析模型。应用该模型,以某钢铁联合企业实际生产数据为例,分析了高炉 转炉生产流程硫的来源和去向,讨论了钢铁生产过程排放的SO2的构成,为进一步研究钢铁工业SO2的减排提供了理论依据。     

Ejection of steel and slag droplets from gas stirred steel melts

Abstract

Liquid ejections from gas stirred melts can be classified into small film and jet droplets caused by bubble bursting and larger splashes resulting from gas channels formed at higher exiting gas velocities. In view of the conditions in ladle metallurgy, experimental investigations were carried out at moderate to low gas flowrates in an arc heated, bottom stirred 150 kg steel melting furnace and an 80 L water tank. Droplets were collected at different heights above the melt level, while gas flowrates, viscosities, surface tensions, and slag layer thickness were varied. The number of steel droplets collected decreased greatly with height (in the range 30-110 mm) and with size (in the range 0·1-1·8 mm). Calculations showed that the entrainment of droplets is strongly influenced by the velocity of upward flowing gases. While at low flowrates typical for secondary metallurgy (0·1 m s ^-1), only droplets <50 μm will be entrained, BOF (basic oxygen furnace) typical flowrates (20-50 m s ^-1) will cause particles up to 500 μm to be carried into the dust removal systems. Higher surface tensions resulted in increased droplet ejection, while higher viscosities led to a decreasing quantity of ejected melt. Slag layers led to a decrease in the ejection of steel droplets and to an increase in ejected slag but they did not completely stop steel ejection, because gas bubbles appear to entrain steel drops when they rise through the slag layer. Bubble bursting in a pure slag system caused large but few slag droplets due to the high viscosity of the slag as compared to the steel melt.     

不锈钢厂电弧炉烟尘处理技术

不锈钢厂电弧炉烟尘主要由炉内高温区合金元素和组分的挥发、脱碳反应生成的CO气泡破裂所形成的金属和炉渣液滴的飞溅、被尾气直接带走的小颗粒炉料组成。与普碳钢或低合金钢厂电弧炉烟尘比较,不锈钢电弧炉烟尘含有更多的合金元素,但锌含量较低。目前不锈钢厂所采用的回收处理烟尘的工艺以熔融还原工艺为主。