不同开槽阳极铝电解槽的节能性研究

基于有限体积方法,建立三维传统阳极、纵向开槽和横向开槽阳极铝电解槽非稳态数学模型,采用磁动力流体模型(MHD)中电势法计算电磁场,把电磁力作为动量方程的源项,通过流体体积函数(VOF)法追踪电解质-铝液界面的波动,用离散相模型(DPM)追踪气泡的运动路径.对比分析传统阳极、纵向开槽和横向开槽阳极铝电解槽中电解质-铝液界面波动和气泡分布情况.结果表明,纵向开槽阳极下电解质-铝液界面波动幅度小于横向开槽阳极下的电解质-铝液界面波动幅度,且都小于传统阳极下电解质-铝液界面波动幅度.纵向开槽阳极底部的气体体积分数最小.     

Simulation of the Fluid Flow-Related Phenomena in the Electrolyte of an Aluminum Electrolysis Cell

A full-scale water model and mathematical simulation were used to study the fluid flow-related phenomena in a water model of an aluminum electrolysis cell. The time-dependent, multiphase fluid flow model was developed to represent the complex transient flow in the electrolysis bath. The accuracy of the mathematical model was validated by the ink dispersion and laser doppler velocimetry measurements in the water model. The shape, motion, release frequency of large-size bubbles, the fluid flow pattern, and the electrolyte–metal interface were predicted by the mathematical simulation. The design and operation of the anode were discussed, including the effect of the anode edge corner shape, the presence of a tilted bottom angle, and the magnitude of applied current density. The results indicated that coupling using a curved corner, with slot and with tilted angle at the anode, is effective for the release of bubbles and for the stability of the electrolyte–metal interface.     

330 kA铝电解槽异形阴极碳块对水平电流的影响

采用有限元仿真计算,对330 kA铝电解槽进行传统阴极碳块结构和异形阴极碳块结构的电场进行仿真模拟,主要对铝液中水平电流分布进行分析。研究发现,异形阴极碳块结构相对于传统阴极碳块结构能够在影响压降较小的前提下降低水平电流密度。模拟结果表明,在异形阴极碳块表面凸起中增加隔断并改变凸起角度,对降低铝液中水平电流效果明显,能够降低铝液中最大水平电流密度27.8%,平均水平电流密度34.3%,有效提升了铝电解槽电流效率。     

Electro-extraction of molybdenum from Mo2C-type carbide

A process for the preparation of molybdenum from molybdenum carbide was investigated. It involved fused salt electrolysis of the carbide in an inert atmosphere electrolytic cell using a KCl-K₃MoCl₆ electrolyte. The preferred conditions for electrolysis carried out in a 0.075 m (3 in.) diam cell were: voltage 0.2 to 0.5 V; cathode current density 8000 A/m2 (720 amp/f²);bath temperature 1203 K; and electrolyte composition 7.5 pct molybdenum. Under these conditions, electrolysis in a 0.15 m (6 in.) diam cell charged with 1.5 kg of the carbide yielded a total metal recovery of 71 pct at an average current efficiency of 60 pct. The metal purity was better than 99.9 pct. The electron beam melt hardness for the electro-extracted molybdenum was in the range of 150 to 160 DPH. The paper presents a part of the thesis to be submitted by A. K. SURI to the University of Bombay (India).     

槽型对5kA级惰性阳极铝电解槽流场影响仿真

提出了两种5 kA级惰性阳极铝电解槽结构,使用有限元仿真方法计算了不同槽型电解槽在仅电磁力作用、仅阳极气体作用、电磁力和阳极气体共同作用下的流场和界面波动情况。计算结果表明:铝液运动主要受电磁力控制,电解质运动主要受阳极气体控制;槽型1比槽型2整体流速更低,界面波动更小。     

稀土电解槽电极间距的模拟优化

采用多相流范畴的欧拉模型,以3 kA钕电解槽为模型,着重研究了电解槽正常工作情况下,不同电解槽电极间距时气体在熔场内的分布情况,并对得到的结果进行了分析。     

300kA新式异型阴极双钢棒铝电解槽生产实践

300kA新式异型阴极双钢棒铝电解槽可有效减缓铝液的流动、大幅降低铝液水平电流、降低铝液和电解质界面变形的波形幅度、提高电解槽的稳定性、降低电解槽的工作极距,同时使槽侧部由原来的散热型改为保温型来维持电解槽的热平衡。在保证电解槽平稳高效生产的前提下,电流效率比普通异型阴极电解槽高1个百分点以上,吨铝直流电耗降低400kWh。     

500kA预焙阳极电解槽针振和摆动现象的处理

随着铝电解槽的大型化,铝电解槽内部磁场强度显著增大,电解质与铝液熔体剧烈地波动,使大型槽针振和摆动现象愈加明显,影响了电解槽高效平稳生产,降低了电流效率。从生产实践出发,分析500kA大型槽针振和摆动产生的原因及采取的常规处理方法。     

On convection in aluminum reduction cells

The convection pattern in the bath electrolyte and the cathode metal of 150 kamp prebaked anode aluminum reduction cells has been studied by means of radioactive tracers. The initial distribution of the tracers—²⁴Na for the bath and¹⁹⁸Au for the metal phase-indicates a fast circulating movement with vortices at the ends in both phases. Circulation rates up to 100 cm per sec were observed, and an average value seemed to be 10 cm per sec. The implications of the convection on the mechanism of the secondary reactions, the dissolution of alumina in the bath electrolyte and the distribution of carbon particles in the cell are discussed.     

Mathematical modeling and computer simulation of the rotating impeller particle flotation process: Part I. Fluid flow

Removal of unwanted particles from molten metal by flotation is one of the most useful melt cleansing techniques used by the foundry industry. An effective way of flotation of particles in a melt relies on purging a gas into the molten metal through holes in a rotating impeller. Impeller rotation creates turbulence inside the melt, which helps agglomerate the impurity particles and, thereby, enhances their removal from the melt. In addition, turbulence increases the probability of particles attaching to the rising gas bubbles and, therefore, enhances the chance of their removal from the molten metal. A mathematical model has been developed to simulate the turbulent multiphase flow field inside the flotation treatment furnace. Simulations based on the model were used to demonstrate the effect of the various process parameters on the performance of a batch-type rotating impeller particle flotation process.     

168kA新型阴极高效节能铝电解槽磁流体运动的数值模拟

建立了168 kA新型阴极铝电解槽磁流体运动的数学模型,对电解质与铝液交界面的流场、电解质的流场以及阴极铝液的流场进行了模拟,并对新型阴极电解槽阳极导杆等距电压降进行了测量。研究结果表明：新型阴极铝电解槽可隔断槽内铝液流动,降低槽内阴极铝液的流速。新型阴极铝电解槽铝液与电解质交界面的速度矢量和较普通阴极铝电解槽铝液与电解质交界面的速度矢量和低2～3倍,且极值分布更为均匀。新型阴极电解槽内铝液与电解质界面处的磁流体速度最大,然后以界面为中心线逐渐减小。     

The removal of solid particles from molten aluminum in the spinning nozzle inert flotation process

The removal of solid particles from molten aluminum by flotation was investigated based on theoretical fluid dynamics. The energy spent for stirring the melt in the SNIF process accelerates the agglomeration of small particles into larger particle aggregates which can be removed from the metal by gas bubbles during the short residence time of the melt in the refining unit. Theory suggests that supplementation of thermal agglomeration of the particles with turbulent agglomeration and small gas bubbles are the major factors which can lead to high particle collection efficiencies in molten aluminum.     

Deep decarburization of iron-based melts

The decarburization of liquid iron with preliminary saturation and without saturation of the metal with hydrogen followed by vacuum and aspiration treatments has been studied. A decrease in the gas pressure above the liquid metal is experimentally shown to increase the deoxidizing capacity of carbon only to certain limits. When a steel is subjected to hydrogen treatment with preliminary saturation of the melt with hydrogen, the formation of hydrogen bubbles enhance the effect of the mixing of the metal bath and substantially increase the melt-gas interface area. As a result, the rate and degree of decarburization increase considerably. The aspiration treatment also makes it possible to decrease the carbon content in the metal due to the creation of an additional reaction surface in the volume of the melt under vacuum conditions.     

电解槽中无铝液进行电解时阴极表面炭的侵蚀与脱落

研究了铝电解槽阴极碳块表面在电解过程中被电解质侵蚀而脱落的情况,探讨了其被侵蚀脱落的机理。得出电解过程中当阴极没有铝液存在时,电解槽的阴极表面被电解质严重侵蚀并脱落掉渣。电解时测定不同极距下的槽电压,研究了不同电解质高度上的电解质熔体导电性能的变化,得出:电解开始时槽内电解质熔体的导电性能是均一的;电解一段时间后电解质熔体的电阻改变很大。这是由电解过程中有金属产物从阴极表面溶解,脱落的炭渣以及阳极气体在电解质熔体中的溶解等综合因素引起的。     

Ti2AlNb合金锭真空自耗过程宏观偏析的数值模拟

Ti₂AlNb合金锭的真空电弧重熔(VAR)是一种超高温且不透明冶金过程,很难对这一过程中的熔体流动行为和宏观偏析的形成过程进行试验研究。发展了基于欧拉多相流的电磁场、温度场、流场、溶质场的多场强耦合数学模型,研究了真空自耗过程中的多物理场相互作用机制,对Ti₂AlNb合金锭中成分偏析形成过程及分布规律进行了预测。模拟结果表明,电磁力主要分布于熔池表面,自感电磁力推动金属液由中心向下流动而加深熔池;搅拌电磁力的离心效应则大幅提升熔池的温度场均匀度,促使熔池内金属液中的溶质混合均匀。尽管铸锭外围和中心分别形成了大范围的正、负偏析区,但区域内的成分较为均匀。在搅拌和沉降的作用下,金属熔池中的等轴晶极大地缩短了铸锭中的柱状晶区。该模型的模拟结果在熔池深度与宏观偏析分布方面与试验结果吻合良好,可进一步应用于预测和研究工业级大型铸锭中的成分偏析。     

114．5kA导流槽铝液流场数值模拟研究

以商用有限元流体计算软件CFX为计算平台,对114．5kA导流型铝电解槽由电磁力引起的对铝液流动和波动的影响进行了模拟计算。结果表明,导流型电解槽铝液平均流速较传统电解槽降低了50％,在铝液填满沟槽的极限情况下,聚铝沟内铝液界面波动的最大隆起值为1．04cm,较传统槽的3．1cm有较大幅度的降低,当铝液低于沟槽2cm的一般情况下,铝液波动0．58cm,这时铝液不会溢出沟槽。     

5kA级惰性阳极铝电解槽流场仿真研究

针对铝电解槽流场计算方法的不足,率先提出一种用于铝电解槽流场仿真计算的间接耦合方法,并使用此方法对5 kA级惰性阳极铝电解槽分别在电磁力、阳极气体、电磁力和阳极气体共同作用下的电解质和铝液流场分布情况进行了仿真计算。计算表明,计算方法能够合理计算出电解质和铝液在任一体积力作用下的流场分布。5 kA级惰性阳极铝电解槽电解质流动主要受阳极气体控制,铝液流动主要受电磁力控制。电解质在仅电磁力作用、仅阳极气体作用、电磁力和阳极气体共同作用下的平均流速分别为1.784 cm/s、3.657 cm/s、3.814 cm/s,铝液平均流速分别为1.295 cm/s、3.509 cm/s、3.696 cm/s。     

降低水平电流减少铝液动态波动铝电解节能技术研究

通过计算机模拟仿真研究复合稳流综合节能技术对铝电解过程中阴极铝液内水平电流的影响。结果表明,以高导电方钢为核心的复合稳流综合节能技术可明显降低阴极铝液内水平电流大小,降低电解质-铝液界面变形,提高电解槽内磁流体的稳定性,以此来降低槽电压和提高电流效率,达到节能降耗的作用。为验证仿真模拟结果,在某企业300 kA系列电解槽进行复合稳流综合节能技术工业化试验,采用以高导电钢棒为核心的复合稳流综合节能技术,电解槽内水平电流降低明显,获得了非常小的铝液界面变形量,电解槽生产运行稳定性明显提高,吨铝直流电耗较系列传统槽、201技术槽、双钢棒技术槽都低。     

Experimental evidence for electrochemical nature of the reaction between iron oxide in calcia-silica-alumina slag and carbon in liquid iron

The electrochemical nature of the reaction between iron oxide in calcia-silica-alumina slag and carbon in liquid iron has been studied by measuring the kinetics of the slag-metal reaction. A base slag (48 pct CaO-40 pct SiO₂-12 pct Al₂O₃) containing iron oxide (≤8 wt pct FeO _t ) was reduced by an Fe-C metal bath (∼4 wt pct C) at 1400 °C. The reaction rate was calculated from measurements of the total inlet gas flow rate and the CO concentration in the outlet gas stream. The slag was “internally short circuited” by dipping an iron plate through the slag layer, and this resulted in an increase in the rate of CO evolution. An external circuit was produced by dipping a graphite rod (shielded from the slag) into the metal bath and a steel or molybdenum rod into the slag layer; the open-circuit voltage and short-circuit current were measured when iron oxide was added to the base slag layer. The reaction rate was enhanced by applying a voltage across the slag layer, and an electric arc cathode was employed in some of these “electrolysis” experiments.