利用新生CO气泡脱除铁液中的氮

大气条件下,在灰铸铁液和钢液中分别吹入O2,CO2气体并加脱氮剂以确定脱氮能力和测定表观脱氮速率常数,结果表明,在一定范围内吹气和加脱氮剂都能有效脱氮,在1400℃灰铸铁液中吹CO2,测得表观脱氮速率常数为0．095s^-1,%^-1。此外,还对脱氮限制性环节及各种影响因素进行了讨论。     

金属熔体中夹杂物的生长动力学

在单颗粒框架下,对冶金熔体中夹杂物生长的两种主要形式“扩散反应析出”和“碰撞长大”进行适当的物理简化和数学建模,推导了夹杂物的生长速率,建立了夹杂物生长的动力学理论。利用该理论,解释了早期日本学者的实验结果,并对几种生长机理进行了定量比较。结果表明：从生长过程看,夹杂物的初期生长依赖于反应长大（起主要作用）和布朗运动碰撞,后期生长依赖于湍流碰撞（占主导地位）和Stokes碰撞;从流程看,碰撞长大在粗炼环节十分显著,在连铸环节基本可以忽略,而在精炼环节则处于过渡状况。     

Fundamental of Inclusion Removal from Molten Steel by Rising Bubble

The mechanism of inclusion removal by attachment to rising bubble was analyzed, and the movement behavior of inclusion, the mechanism of bubbles/inclusion interaction, collision probability and adhesion probability were discussed. A mathematical model of inclusion removal from molten steel by attachment to fine bubble was developed. The results of theoretical analysis and mathematical model showed that the optimum bubble diameter for inclusion removal is 1 to 2mm. A new method that argon is injected into the shroud from ladle to tundish during continuous casting has been proposed to produce fine bubble. It provides theoretical guides for production of super clean steel.     

Simulation of Flow Field of Molten Salt in Neodymium Metal Electrolytic Cell Using Vortex-Flow Function Method

With the applications of Nd-Fe-B material extending in recent years, the materials of neodymium metal and other rare earth metal alloy confront the increased demand and the high quality request at the same time.These factors stimulated greatly to perfect the producing craft of RE metals and improve the equipments.The rare earth electrolysis cell is developing towards large-scale way.Notwithstanding the present electrolysis cell of Nd metal, include 6 kA and 10 kA cell, exists some insurmountable problems during operation and these problems lead to lower electric efficiency and higher operating costs.So it is significant to study the physical fields of rare earth electrolysis cell.In this paper,a numerical flow mode is established using vortex- flowing function method and the fluid flow field of 3000A Nd electrolysis cell is computed using MATLAB.The results of the study will be important reference in theory for improving and enlarging rare earth fluoride system cell.     

金属锂在LiCl-KCl熔盐体系中的溶解过程

利用等温饱和法研究了温度对金属锂在LiCl-KCl熔盐体系中溶解度的影响。采用W电极,利用电流反向计时电位法和方波电流法研究了电流密度、LiCl含量对金属锂在熔盐中溶解速率的影响,并研究了极化对金属锂溶解速率的影响。结果表明,金属锂在LiCl-KCl中的溶解度随温度的升高而增大,在熔盐中的溶解反应为吸热反应,金属锂的溶解速率不受电流密度的影响,随LiCl含量的增加先增大后减小,溶解速率受熔盐体系黏度的影响较大。极化对金属锂溶解没有影响,锂的溶解没有电化学特性。     

熔融氯化挥发工艺处理凡口窑渣综合回收有价金属的研究

采用熔融氯化挥发工艺综合回收凡口窑渣中的有价元素,考察了反应时间和氯化剂种类对有价金属挥发率的影响。结果表明:控制反应时间超过30min,以氯化钠作氯化剂,锗和铅的挥发率在90%以上,银挥发率超过80%,锌和铜的挥发率偏低(60%～70%)。该工艺具有自热、烟尘中有价元素富集比高等优点。     

Combined Low-Frequency and Electro-Impulse Treatment of Molten Metal

Metallurgist - A method is given for preparing alloy using combined low-frequency and electro-impulse action on a melt. Metallographic comparison is provided for the result of using this procedure...     

阳极气泡运动对制钠电解槽内熔盐流场的影响

模拟电解熔盐制钠过程中阳极气泡的运动,测量气泡周围流场的变化,分析阳极气泡运动对电解槽内熔盐流场的影响。利用粒子成像测速仪(PIV)测量得到平行和垂直阳极方向的流体运动,并研究液面高度及气体流量对流场的影响。     

Capacitance and Impedance of Rhenium in Molten Alkali Metal Chlorides

The electrode capacitance is determined as a function of potential by measuring the capacitance and the impedance of a rhenium electrode in NaCl, KCl, and CsCl melts at various temperatures and ac signal frequencies, and the impedance parameters are calculated. The capacitance curve is shown to have two minima in these systems and an additional third minimum in sodium and potassium chlorides. This third minimum disappears when temperature increases. The potential of the cathode minimum of capacitance measured at an ac signal frequency of about 10³ Hz coincides with the corresponding minimum of the capacitance of the double electrical layer. The potentials of the central and anode minima of capacitance measured at a frequency of about 1 Hz coincide with the potentials of the minima of adsorption capacitance.     

Wetting Transition in a Molten Metal and Solid Substrate System in High Magnetic Fields

Metallurgical and Materials Transactions A - Wetting transitions between molten metals and different solid substrates were investigated using the sessile drop method to evaluate the possibilities...     

Bubble bursting phenomenon in Gas/Metal/Slag systems

Iron droplets can be ejected into the surrounding atmosphere or entrained into the slag phase when gas bubbles pass through the metal surface or the metal/slag interface. The phenomena occurring during passage of single bubbles through the free surface and the interface were investigated by using the in-situ X-ray transmission technique. The mass of droplets ejected into the atmosphere attained a maximum value at a certain bubble size, which depended on the surface tension of the iron melt. Bubble bursting on the free surface of iron melt ejected numerous fine iron droplets called “film droplets” and a few much larger jet droplets. Two different groups of iron droplets were also observed as entrained in the slag due to bubble passage through the iron/slag interface, although the physical phenomena are to some extent different from bubble bursting to the gas phase. This article is based on a presentation given in the Mills Symposium entitled “Metals, Slags, Glasses: High Temperature Properties & Phenomena,” which took place at The Institute of Materials in London, England, on August 22–23, 2002.     

Model of Calculating Activity of Nitrogen and Vanadium in Fe-C-V-N Molten Metal

The solubility of nitrogen in the Fe-C-V-N system was measured at 1 708 K and the model of calculating activity （action concentration） of nitrogen （N） and vanadium （V） was derived according to the phase diagram and the coexistence theory of the metal melt structure. The solubility expression of nitrogen in the Fe-C-V-N system at 1 708 K was ωN =0. 058 194-0. 010 367ωc＋0. 005 543 4ωv. Comparing the computing results with the experimental resuits, a satisfactory conclusion could be obtained. The analysis of the Fe-C-V-N system using this model showed that VN was present in a high temperature metal melt, which would reduce the action concentration of nitrogen obviously. It was consequently disadvantageous to the removal of nitrogen from hot metal.     

气泡尾流去除钢液中夹杂物机理的水模型研究

采用水模型和高速摄像机研究了气泡尾流去除夹杂物的过程,分析了气泡尾流去除夹杂物的规律和气泡大小及夹杂物的尺寸和浓度对气泡尾流去夹杂的影响。结果表明,气泡尾流有利于促进夹杂物上浮;气泡尾流中存在尾流边界区和上升区;尾流去除夹杂物的过程分为3个子过程:(1)夹杂物靠近和进入气泡尾流边界区产生扰动;(2)进入气泡尾流上升区和(3)夹杂物继续上升或脱离气泡尾流上升区;气泡直径D_b和粒子浓度C_p增大有利于尾流去夹杂;粒子直径D_p越小越容易被尾流去除。     

Determination of the Lithium Content of Molten Aluminum Using a Solid Electrolyte

A lithium probe has been used for the determination of the lithium content of molten aluminum alloys. The electrolyte is a two-phase mixture of Li₃PO₄ and Li₄Si0₄ to give an overall composition of Li_3.6Si_0.6P_0.4O₄. This electrolyte was found to be slightly attacked by pure liquid lithium, but no attack was detected in the aluminum-lithium melts. However, exposure to high humidity caused the electrolyte to degrade. A satisfactory reference electrode was found to be decomposed Li₂Ti₃0₇ consisting of Li₄Ti₅O₁₂ and TiO₂. An activityvs composition plot showed that Henry’s law was obeyed, and the activity coefficient was 0.17 at 984 K and 0.26 at 1050 K. P. C. YAO, formerly Research Student in the Department of Metallurgy and Materials Science, University of Cambridge     

The Impact of a Vertically Travelling Magnetic Field on the Flow in a Cylindrical Liquid Metal Bubble Plume

This article describes laboratory experiments for the investigations of flow structures and related transport processes in liquid metal bubbly flows under the influence of a traveling magnetic field (TMF). The melt flow is driven by central gas injection into a cylindrical container filled with the low-melting-point alloy GaInSn. The velocity fields of both the liquid and the gaseous phase were measured nonintrusively using the ultrasound Doppler method. Depending on the traveling direction of the magnetic field, the TMF mainly imposes either a concurrent flow or counterflow with respect to the original bubble-driven circulation. In general, the application of a downward TMF significantly increases the liquid velocity all over the fluid volume. An upward TMF gives rise to the more complex structures of the velocity field resulting in alternately arranged upstream and downstream regions. Both the upward and downward TMF promote the occurrence of nonsteady motions with distinct velocity fluctuations leading to an intensification of related transport processes in the melt and providing the perspective of enhanced mixing efficiencies.     

超声波作用下金属液中微小夹杂物的凝聚过程

针对超声波作用下金属液中微小非金属夹杂物的凝聚过程进行了分析研究,利用数值模拟预测了微小非金属夹杂物达到平衡状态时的凝聚位置和所需要的时间,理论分析和数值模拟结果表明：利用水平超声波照射金属液时,其中的微小非金属夹杂物会凝聚于波腹,结成串或块状的大体积夹杂物,这有利于上浮分离,便于去除。     

Partitioning of Tall Buildings Using Bubble Graph Representation

In this paper it is shown that the current methods of graph representation used for finite-element mesh partitioning are inappropriate for tall buildings, where the mesh will generally consist of both one and two dimensional elements. A new graph representation, called the bubble graph, is proposed and the results of decomposing these graphs using standard graph partitioning tools are presented. The new graph representation is shown to be appropriate for the partitioning of finite-element meshes of tall buildings.     

Oscillation Characteristics of Molten Metal Free Surface Under Compound Magnetic Field

  The free surface waves of a molten low melting point Sn 32%Pb 52%Bi alloy under the imposition of an AC and a static magnetic field were visualized and recorded by use of a laser displacement sensor and a high speed video camera. The Fourier analysis method was used to analyze the oscillation characteristics. The results show that at the center of the free surface, the azimuthal and radial oscillation mode can be found simultaneously owing to AC magnetic field. With increasing coil current intensity, the amplitude and the main frequencies of the oscillations increase, and the azimuthal fluctuation at the center of the free surface is also enhanced. The fluctuation characteristics are closely related to the turbulent flow induced by the alternating electromagnetic force. A series of regular traveling waves can be observed on free surface, and the main frequencies of oscillations at three phase points decrease owing to superposing AC and static magnetic field. The static magnetic field can remarkably control the unstable swinging behavior of free surface. With increasing static magnetic flux density, the amplitude of oscillations at the center of free surface decreases firstly, and then increases, but the fluctuation amplitude at the triple phase point always reduces and keeps within 1 mm, and the azimuthal waves at the center of free surface are weakened. Especially at 144 T, the radial waves are dominant. The static magnetic flux density should be controlled in an appropriate range to obtain more stable free surface. With compound magnetic field, even if the static magnetic flux density is above 10 T, the free surface still vibrates with lower amplitude and dominant frequency.