炼钢短流程工艺国内外现状及发展趋势

全废钢连续加料电弧炉内长电弧作为炉内主要的能量来源,对废钢熔化及钢液升温至关重要。采用磁矢量势的磁流体动力学方法建立了电弧炉内电弧的数值模型,并基于该数值模型对电弧炉内电磁场、温度场和流场进行耦合求解,研究了电流大小、弧长对电弧炉内电弧的温度、速度、压力及气体剪切力特性的影响。结果表明,全废钢连续加料电弧炉内电弧等离子体呈“长钟型”分布,电弧柱较细长;随着电流增大,电弧有效作用范围增大,阳极表面电弧压力和气体剪切力增大;随着弧长增加,电弧有效作用范围减小,阳极表面的电弧压力和气体剪切力减小。短弧操作对熔池冲击剧烈,长弧操作熔池较为平稳,合理控制电流和弧长能有效提高电弧热效率。     

Analysis of electric arc furnaces efficiency via frequency spectrum-based arc coverage detection

We introduce the analysis of variables measured outside a direct current electric arc furnace that are related to the arc coverage and its electric energy efficiency. We derive an on-line reference to the arc coverage suitable for control decisions. In order to do so, we study the furnace shell vibration frequency spectrum as structure-borne sound sensed by a microphone. The data is analysed using real time software tools to obtain the sound signal spectrum associated with arc coverage likewise related to the optimal performance of the furnace. A statistical test is performed to prove the relationship between sound and electric energy efficiency.     

Acoustic characteristics of electric arc furnaces

A mathematical model is constructed to describe the appearance and development of the noise characteristics of superpower electric arc furnaces. The noise formation is shown to be related to the pulsation of the axial plasma flows in arc discharges because of the electrodynamic pressure oscillations caused by the interaction of the self-magnetic field with the current passing in an arc. The pressure in the arc axis changes at a frequency of 100 Hz at the maximum operating pressure of 66 kPa for an arc current of 80 kA. The main ac arc sound frequencies are multiples of 100 Hz, which is supported in the practice of operation of electric arc furnaces. The sound intensity in the furnace laboratory reaches 160 dB and is decreased to 115–120 dB in the working furnace area due to shielding by the furnace jacket, the molten metal, and the molten slag. The appropriateness of increasing the hermetic sealing of electric furnaces and creating furnaces operating at low currents and high transformer voltages is corroborated.     

Increase in the efficiency of electric melting of pellets in an arc furnace with allowance for the energy effect of afterburning of carbon oxide in slag using fuel–oxygen burners

The problems of increasing the efficiency of electric steelmaking using fuel–oxygen burners to supply oxygen for the afterburning of effluent gases in an arc furnace are considered. The application of a new energy-saving regime based on a proposed technology of electric melting is shown to intensify the processes of slag formation, heating, and metal decarburization.     

中国电炉炼钢降本增效关键点分析

分析了中国电炉炼钢的产量、装备、重点消耗指标现状情况,总结了中国电炉钢占比低于世界平均水平、电炉大型化取得一定成绩、电炉废钢单耗降低趋势出现扭转等特点,并从多角度提出电炉炼钢降本增效的关键环节,即电价改革、炉料结构优化、炉型选择、工艺节能、绿色化和智能化、管理创新与标准化体系建设等。同时提出电炉炼钢迎来发展机遇期,建议继续加大技术研发和应用力度,多方共同努力实现电炉炼钢可持续发展。     

锌粉矿热电炉还原反应区挂渣运行的危害

阐述了锌粉矿热电炉还原反应区挂渣运行对正常生产造成的影响,以指导矿热电炉安全操作。在实践中摸索出可行的措施,保证了设备正常运行至检修周期。     

熔分电炉冶炼金属化球团过程炉衬侵蚀分析

对熔分深还原电炉冶炼钒钛磁铁矿金属化球团过程中熔分电炉炉衬、出铁口及出渣口等部位耐火材料的侵蚀情况作了介绍,并对侵蚀原因进行了分析。电弧侵蚀、渣中氧化物的化学侵蚀、炉渣碱度不当、砖缝和裂纹等是造成熔分深还原电炉耐火材料侵蚀严重的主要原因,其中电弧侵蚀和渣中氧化物侵蚀尤为重要,占到侵蚀比例的70%以上。     

Effect of oxyfuel burner ratio changes on energy efficiency in electric arc furnace at Co-Steel Lasco

Abstract

Trials were conducted on Co-Steel Lasco's electric arc furnace (EAF) to evaluate the effect of oxyfuel burner ratio changes on furnace energy efficiency and productivity. Carefully controlled trials with the collection of numerous process and sample data over 331 heats provided statistically significant results. The oxygen available for post-combustion in the furnace was increased by 19%. As the burners were operating at their maximum oxygen constraint, this was achieved by decreasing the natural gas consumption by 43%. Results of this study indicate that decreases in terms of specific electrical energy consumption (4·0%), power on time (5·0%), and tap to tap time (4·5%) were realised. Slag chemistry, electrode consumption, and yield were not affected. Measurement data support the finding that more heat was transferred into the steel with the post-combustion burners: a flat bath was achieved earlier; high bath temperatures were reached more quickly; power on time was reduced, leading to reduced electrical energy consumption. Analysis suggests that furnace thermal energy losses were reduced by less air inleakage, less incomplete methane combustion, and earlier achievement of foamy slag conditions.     

New algorithm for controlling electric arc furnaces using their vibrational and acoustic characteristics

The processes occurring in arc discharges are analyzed as the sources of acoustic radiation in an electric arc furnace (EAF). Acoustic vibrations are shown to transform into mechanical vibrations in the furnace laboratory. The shielding of the acoustic energy fluxes onto water-cooled wall panels by a charge is experimentally studied. It is shown that the rate of charge melting and the depth of submergence of arc discharges in the slag and metal melt can be monitored by measuring the vibrational characteristics of furnaces and using them in a universal industrial process-control system, which was developed for EAFs.     

Remelting of scrap containing tungsten and nickel in the electric arc furnace

Remelting of the metallic scrap containing tungsten and nickel and thermodynamic properties of slag containing tungsten oxide are discussed. Tungsten and nickel in the metallic scrap have to be separated before the scrap may be used for melting of some steels (for example, high speed steel). To separate tungsten and nickel, such scrap (waste drills) was remelted in the 25 t electric arc furnace under oxidizing conditions. Tungsten was oxidised and transferred to the slag phase, while nickel remained in the metal. Further, the slag containing tungsten oxide was used in the melting of high speed steel. Metal containing nickel was utilized in the constructional steel production. Technology of the scrap remelting was developed on the basis of thermodynamic analysis of slag containing tungsten oxide and tungsten slag-metal partition. It was found that the coefficient of tungsten distribution between iron and basic CaO-SiO₂-Fe_tO-WO₃ slag increases with increasing slag basicity. In the industrial oxidising heats a slag of high basicity was used, it secured 94% tungsten extraction from scrap to the slag.     

电弧炉炼钢技术的发展趋势

电弧炉炼钢在环保、投资以及效率方面优势明显,为了重点推行该节能环保型炼钢工艺流程,近年来电弧炉炼钢技术得到快速发展。综述了国内外电弧炉高效化冶炼技术、绿色化生产技术和智能化控制技术的发展现状,其中绿色化和智能化是电弧炉炼钢技术的未来发展趋势。集操作、工艺、质量、成本以及环保于一体,进一步提升电弧炉炼钢技术的绿色化和全流程监测与控制的智能化,是推动整个钢铁行业向智能化和绿色化转型升级的重要举措。     

Experimental determination of the jet effect for blowing oxygen into the melting bath of electric arc furnaces

Recent practice with electric arc furnaces has been the injection of oxygen through nozzle positioned on the bottom of the furnace. This type of furnace places certain requirements on bottom injection. To enable a constant coupling of the energy over the electrodes, a calm bath surface must be guaranteed. On the other hand, a good mixing of the bath is required to avoid any thermal lamination in the bath. The latter condition in particular is prerequisite for a maximum melting capacity. When judging the effect of the jet on the bath, it must be taken into account that the oxygen disintegrates directly after entering the bath and merely transfers its impulse to the liquid melt. This jet effect is described by the calculation method introduced below which is adjusted to the actual behaviour using simulation tests. In this connection, changes in the jet consistency caused by the formation of carbon monoxide have not yet been considered. Parallel to this, the mixing of the bath was determined by conductivity measurements. In these experiments, the bath level x_f, the vessel diameter D and the blown-in water mass-flux m_w were changed. A comparison of the results for fountain height and mixing time formed the basis for the development of an optimization concept for bottom-blowing nozzles in electric arc furnaces.     

Development and application of electric arc furnace combined blowing technology

A number of electric arc furnace (EAF) plants in China use high proportions of hot metal in the charge because of availability of excess liquid iron at the steelworks and/or because of the high price of scrap relative to hot metal. Liquid steel costs are still higher than the basic oxygen furnace as the EAF is not as efficient when refining liquid iron. EAF combined blowing technology has been modelled and installed in industrial plants with the aim of increasing stirring and hence improving refining. The industrial application of the combined blowing technology in a number of steel plants indicates that the combined blowing technology of EAF can effectively improve the pool stirring strength and reaction dynamics condition of the molten pool, and optimise production.     

Heat losses and energy efficiency of arc steel-melting furnaces

The dependences of the heat loss power and the energy efficiency of arc steel-melting furnaces with a refractory lining on the arc current and length are analyzed. The influence of varying the heat loss power on the operating characteristics of an arc furnace is considered.     

直流矿热炉熔炼硅锰合金温度场-电磁场数值模拟

采用直流供电成为电弧炉熔炼硅锰合金的发展方向.由于直流供热强度增加,炉衬的温度分布及传热规律需要重新考察及设计.建立了炉衬与炉内熔池耦合的三维非稳态传热模型,研究给定不同外加电压时直流矿热炉炉内的温度场和电磁场.研究表明,外加电压由100 V增大到300 V后,电弧区的最高温度增大了 150％.底电极中心与炉壁的温差T...     

Electric arc in three-phase metallurgical furnaces

The theoretical and practical assumptions relative to the studies of electric arcs in steel-melting furnaces presented in journal Electrometallurgiya in 2011–2012 are subjected to a critical analysis. Based on classical concepts and the author experiments, the concept is presented regarding to the phases of the state and parameters of arc discharge in the ac electromagnetic field of a three-phase system. Industrial methods of eliminating the injurious effect of flash arc on furnace lining and the furnace efficiency are considered.     

On sulphur behaviour in steelmaking with sponge iron in an electric arc furnace

The sulphur behaviour in steelmaking by melting of charges containing from 38.7 to 95.4 wt.% sponge iron in the metallic input in a 70 t UHP electric arc furnace is investigated. The effect of both slag composition and temperature on the sulphide capacity of the slag and on the sulphur distribution ratio between slag and metal is studied. The kinetics of desulphurization are also treated. Regression analysis shows that the logarithm of sulphide capacity varies linearly with total lime equivalent, theoretical optical basicity and logarithm of slag basicity. Equations relating the sulphide capacity to these parameters as well as to the temperature are given. Based on these equations, functional relationships for the calculation of sulphur distribution between slag and metal are derived. Metallurgical reactions for metal desulphurization by slag and equilibrium relationships are given from which the slag-metal sulphur partition ratio can be calculated. In all cases, the results of the calculations are in line with the experimental data. The rate of desulphurization is expressed by an equation based on the boundary layer diffusion theory. Under the conditions of the present investigation, the activation energy of desulphurization is found to be 39 kJ/mol and the mass transfer coefficient of sulphur at 1600°C is equal to 0.014 cm/s.     

The use of blast furnace slag and derived materials in the vitrification of electric arc furnace dust

The electric arc furnace (EAF) dust was added to blast furnace granulated slag or a gel produced by dissolving slag in HNO₃/EtOH followed by alkaline hydrolysis and gelification, and then it was vitrified. The proportion of EAF dust used was between 5 and 30 wt pct. The physicochemical properties of the glasses produced were studied by the X-ray powder diffraction technique, differential thermal analysis, and transmission electron microscopy (TEM). Thermal properties (dilatometric softening point, glass transition temperature, and thermal expansion coefficient) were determined. Finally, analyses were performed on leachability and ecotoxicity. The results suggest that the use of either slag or slag-derived gel produces a borosilicate glass with thermal properties similar to those of conventional soda-lime-silicate glass.     

45t电炉终点碳控制技术研究与应用

对45 t电炉终点碳控制技术进行研究,优化了冶炼工艺及用氧制度,改进了泡沫渣工艺.电炉氧化末期钢水碳的合格率得到较大提高,减少了脱氧材料加入量,在一定程度上降低了LF座包钢水中的氧含量.通过优化泡沫渣工艺,电炉炉盖结冷钢现象已基本杜绝,炉子水冷件漏水现象大幅度减少,缩短了热停时间.     

Mathematical modeling of a direct current electric arc: Part I. Analysis of the characteristics of a direct current arc

A mathematical model is used to describe fluid-flow, heat-transfer, and electromagnetic phenomena in the arc region of a direct current electric arc furnace (DC EAF). Based on those model results, a detailed physical analysis of the arc was performed, where the numerical computations help to explain the arc structure, its behavior, and the highly coupled relationship among their main physical variables. This analysis leads to the conclusion that the arc behaves in such a way that all the arc characteristics are controlled by the expansion of the arc, which is the main feature used to physically describe the arc behavior. The arc expansion is evident from the arc shape, which is defined as the region where conduction of electricity takes place. The arc shape is clearly seen in several contour fields presented in this work, such as the current density, the magnetic flux density, the electric conductivity, the electric potential, and the temperature fields. The results of this article focus on process analysis, to provide insight into the inter-relationship among the arc variables, and to establish physical grounds to subsequently explore dimensionless analytical representations to describe the arc behavior.