Experimental Research of External Desulfurization in Situ Mechanical Stirring

This paper presents a new idea about desulfurization with in-situ mechanical stirring method on the basis of desulfurization by single blow grain magnesium and KR method, that is, the inner gases carry the magnesium vapor formed in-site in molten iron by magnesium-based desulfurization, and bubble dispersed and disintegrated under the condition of mechanical stirring, thence to improve the efficiency of desulfurization by single blow grain magnesium .It has been proved by research of cold water model experiment that the bubble dispersion and disintegration can not only improve the desulphurization efficiency but also increase the utilization rate of magnesium. Obviously, the bubble dispersion and disintegration of magnesium vapor is the key problem in improving the desulphurization efficiency and increasing the utilization rate of magnesium. Thus the research focus on exploring the performance of bubble dispersion and disintegration on the base of refining process and gas-liquid mass transfer. According to the literature and cold water model experimental result basing on principle of similitude, the influencing factors and interaction of bubble dispersion and disintegration have been studied from the perspectives of physical and numerical simulation. The study would provide the theoretical and experimental data for the new method of desulfurization with in-situ mechanical stirring.     

Study on Absorption Rate by Eccentric Mechanical Stirring in Gas Injection Refining for Iron and Steel Making

In gas injection refining processes, a great amount of gas is injected into molten metal in short time, so that very large bubbles are inevitably formed. Wide dispersion of small bubbles in the bath is indispensable for high refining efficiency. Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion. Absorption rate are used to research on the influence law of the bubble dispersion and disintegration and gas-liquid absorption by the influence of, rotation mode, rotation speed and gas flow rate. Compared to the experimental results of absorption rate under eccentric stirring and centric stirring ,provide the scientific experimental and theoretical guidance for high-temperature experiment of hot metal desulfurization .According to experimental and theoretical analysis, this paper has studied various factors effecting on gas absorption process and volumetric mass transfer coefficient using the system of CO2-NaOH-H2O.The results show that:the volumetric mass transfer coefficient and absorption efficiency of CO2 can be increased under eccentric stirring mode, Because bubble disperse quickly with eccentric mechanical stirring, which results in promoting complete reaction between CO2 and NaOH, and improving the mass transfer coefficient and absorption. Volumetric mass transfer coefficient and efficiency of CO2 increase with the increasing rotation speed under the condition of eccentric stirring .But volumetric mass transfer coefficient and efficiency of CO2 decrease with the increasing rotation speed under the condition of centric stirring.     

Development of Slag Recycling Process in Hot Metal Desulfurization with Mechanical Stirring

In order to develop an environment‐friendly steelmaking process, a slag recycling process for hot metal desulfurization by mechanical stirring was designed. The process was developed with 70 kg‐scale hot metal experiments and actual plant tests. The recycled slag has a 70% desulfurization ability compared with that of virgin flux (CaO‐5%CaF₂). The lower efficiency of the recycled slag was caused by SiO₂ contamination carried over from the previous process. There is no particular size requirement for the recycled slag, as the effect of the recycled slag size on the desulfurization ability is small. The ratio of CaO in the recycled slag to total CaO should be less than 60% in order to prevent an increase in the amount of slag. Slag recycling operation can be repeated more than twice when the optimum conditions are applied. The slag recycling process was established in an industrial operation, and consumption of desulfurization flux decreased by 40% with the process compared with that without slag recycling. Slag hot recycling was adopted at another plant where consumption of desulfurization flux decreased by 50% compared to operation without slag recycling. The positive effect of hot slag recycling is estimated to be a result of the temperature of the recycled slag.     

Improvement of Impeller Blade Structure for Gas Injection Refining under Mechanical Stirring简

Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central part of the impeller is disk- or plate-shaped, and the blades are fitted to the side of the disk or plate. In addition, a disk is put on the top side of the impeller blades. The impeller can strengthen the radial and downward flow between the blades and weaken the swirl flow in the zone above the impeller. These effects on flow phenomena are favorable for disintegration and wide dispersion of bubbles which are injected from a nozzle attached to the center of the underside of the impeller. In addition, the sloped swept-back impeller requires less power consumption. The impeller shaft should be placed away from the vessel center so as to disperse the injected bubbles widely in the bath under mechanical stirring even with unidi- rectional impeller rotation and without installing baffles. The number of gas holes in the nozzle and the direction of gas injection have a little effect on the bubble disintegration and dispersion in the bath. Highly efficient gas injection refining can be established under the conditions of proper impeller size, larger nozzle immersion depth, larger eccen- tricity and rotation speed of the impeller. The sloped swept back blade impeller can decrease the power consumption and vet improve the bubble disintegration and wide dist~ersion in the bath.     

Study on the Possibility of Using ZnO for Hot Metal Desulfurization

The possibility of using ZnO for desulfurization in hot metal was evaluated. A lab scale experimental setup was designed so that different desulfurizing agents could be added to hot metal for evaluation of their desulfurizing power. The setup had good control of both temperature and the gaseous atmosphere. It also provided stirring of the metal bath with an impeller as well as quenching facility to maintain the metal composition at high temperature. Desulfurization of hot metal using CaO powder showed evidently the applicability of the new setup. On the other hand, additions of ZnO into the hot metal under various experimental conditions showed no effect on desulfurization. The results were in contradiction to the suggestion found in literature. A thorough examination of the thermodynamic data employed by the previous work was carried out. The data used in the literature were found to be subjected to fundamental mistakes. The present experimental results convincingly rule out the possibility of using ZnO as a desulfurization agent.     

脉冲旋转搅拌喷吹铁液脱硫新工艺实验研究

采取实验室物理模拟的方法，对新型的脉冲旋转搅拌喷吹与原单向搅拌的效果进行了对比实验。脉冲式旋转搅拌方式分为搅拌器正反双向脉冲式旋转与旋转 停止 旋转脉冲式旋转。研究结果表明，与单向搅拌相比，脉冲式搅拌的熔池混匀时间明显缩短，液体表面卷入的颗粒数量明显增多，喷吹载气气泡在液体中的停留时间延长1倍。     

Study of New Hot Metal Desulfurization Process on 1t Desulfurization Experiments

For the lack of the present hot metal desulfurization processes in iron and steel industry, our group has proposed the in-situ mechanical stirring method for external desulfurization of molten iron and researched this new method. This paper investigated this new in-situ mechanical stirring hot metal desulphurization process on desulphurization experiments of one-ton scale by using the new desulfurizer. The experimental results indicated that the desulfurization efficiency of in-situ mechanical stirring desulfurization process is 90% and the lowest sulfur content in the treated hot metal is 23ppm. By comparing with the methods of direct throwing desulfurizer and in-situ injecting desulfurization, in-situ mechanical stirring desulfurization process is the suitable desulfurizaton method.     

The Recent Progress of Hot Metal Desulfurization in CSC and DSC

There are two kinds of existing processes for hot metal desulfurization in CSC. One is the injection process in torpedo car, the other is the impelling process in transfer ladle. Lime-based fluxes have been used for both processes. The former was introduced to CSC in 1982. The latter was adopted by CSC and DSC respectively in 2004 and 2010. This paper comprises a theoretical analysis on lime-based flux as desulfurizing agent and an experimental evaluation on impelling process of Kambara (or Kikai) Reactor with a water model and a hot model established in 2001. The comparison of recent mass-production performance for both processes in steelmaking shop has also been included.     

狭缝式透气砖底喷粉铁水脱硫的实验研究

 为研究狭缝式透气砖底喷粉对铁水脱硫效果的影响,以氮气为载体,通过狭缝式透气砖从底部向装有100 kg铁水的感应炉中喷吹石灰粉。实验结果表明,该工艺操作简单,稳定可靠,脱硫率高,无喷溅现象,铁损少,温降小,无污染,处理周期短,投资省,是比较理想的脱硫新工艺,具有广阔的应用前景。     

铁水纯镁脱硫工艺研究及应用

对120t铁水罐喷吹纯镁脱硫工艺进行了优化研究,结合实验室石灰石脱硫结果,确定了工业生产脱硫应采取的措施,如提高钝化镁粉纯度、控制喷枪插入深度、连续少量投放石灰石及喷枪气化室维护等。结果表明,镁利用率提高了8％,一次扒渣后硫含量范围为0．005％～O．010％。     

铁水脱硫用钙镁系粉剂的研究

论述了钙镁系粉剂在铁水脱硫过程中的反应机理及其优点,并提出了提高脱硫效率的途径。     

CO2吸收模型中容积传质系数的确定

气泡微细化是“原位机械搅拌法铁水炉外脱硫技术”的关键.气液传质系数是研究气液吸收过程的基本参数.本文根据相似性原理建立水模型实验装置,并通过测定NaOH吸收CO2的速率来研究气泡微细化过程,同时根据吸收原理定量计算出容积传质系数Ak及CO2气体利用率η.当溶液pH值从12降低到9的过程中,容积传质系数为2.938×10 4m3/s,本实验所用CO2的利用率的公式可简化为:η=18.98/Qt.本论文的研究结果可为进一步研究吸收速率提供理论依据.     

机械搅拌法与镁喷吹法铁水搅拌能和混匀时间的关系

采用永田进治公式和全浮力模型计算了机械搅拌法和喷吹法的铁水搅拌能,研究了搅拌能和混匀时间的关系,并和水模型的结果进行了比较,分析了两种搅拌能影响混匀时间的原因。结果表明,机械搅拌法的搅拌能力比喷吹法大数倍,在同一搅拌能下机械搅拌方式的混匀时间比喷吹法短。搅拌优势使得机械搅拌法比喷吹法的脱硫率比喷吹法平均高18.61%,带来的副作用是铁水温降要高于喷吹法15℃,以及对耐火材料的侵蚀速度为喷吹法的3倍。     

铁水炉外脱硫剂的研究进展及其添加剂作用的理论分析

根据目前铁水预处理技术发展与应用现状，综述几种常用炉外脱硫剂的性能与冶金效果，理论分析了复合脱硫剂中添加剂的作用。     

铁水双枪脱硫技术应用研究

铁水脱硫技术是提高钢材质量、生产高附加值产品的主要技术保证。为达到产品要求,包钢薄板厂对现有脱硫工艺进行改造,改造后采用了双抢双工位、CaO＋Mg复合喷吹脱硫模式。具有处理时间短、粉剂消耗低、处理后硫低、综合处理成本最优的特点,脱硫率和脱硫效率得到很大提高,满足了生产工艺要求。     

Effect of Gas Forming Compounds on the Vibration of a Submerged Lance in Hot Metal Desulfurization

Hot metal desulfurization is the main process step for removing sulfur in blast furnace-based steelmaking. A desulfurization reagent is pneumatically injected into the hot metal through a submerged lance causing it to vibrate. The aim of this study is to develop a mechanical vibration measurement-based method that can detect changes in the gas-forming properties of the reagent. The detection is performed using Elastic Net regression and eXtreme Gradient Boosting-based classification models the classification performance of which is compared. The lance aging causes changes in its dynamic characteristics, and the disturbing effect of this is removed from the measured data of the lance vibration prior to classification by means of a developed cleaning algorithm. The best classification performance in detecting changes in the gas-forming properties, with an area under the receiver operating characteristic curve of 0.916 and Matthews correlation coefficient of 0.699, is achieved using an Elastic Net regression-based classification model. The results of this work serve as a basis for developing industrial applications in which the effective utilization of the excitation, such as vibrations generated by the gas formation can be utilized for process monitoring and as a soft sensor for predicting the reagent-induced process variance.     

新组合式燃煤锅炉烟气脱硫装置的研究

针对目前燃煤锅炉烟气净化问题,利用湿壁塔净化洗涤的原理,研究了一种将湿式洗涤和旋风分离相结合的除尘脱硫装置,文章阐述了该装置的结构形式,基本工作原理和各工艺条件对脱硫效率的影响,工业应用表明该装置脱硫效率大于97％,设备阻力小于1200Pa。