大型预焙槽阳极极距分析

自大型预焙阳极电解槽生产技术问世以来,单组阳极的极距问题逐渐被人们重视起来,它直接挑战着大型预焙槽的设计理念、电解操作、电流效率、节能降耗和稳定生产通过对极距问题的不断研究,发现极距的均一、合理直接影响着电解生产的技术经济指标。     

铝电解槽关键极节能技术研究

在分析铝电解槽传统节能技术不足的基础上,提出了关键极节能新技术.对关键极节能技术的实施步骤及其应用情况进行了全面分析,开发了一套在低极距生产条件下新操作工艺制度.从应用情况看,得到以下结论:应用关键极节能技术实施后,可达到阳极电流分布和极距分布更加合理、铝液波动更加平稳的节能目的.     

预焙槽阳极电流分布和极距的关系

从理论分析和试验测量两方面研究了在降极距过程中预焙槽阳极电流分布的变化规律。     

铝电解槽极距的计算方法及验证

本文介绍了电解槽平均极距及极距分布的计算和测量方法,通过测试和取样化验相结合的方式分析了炭渣对极距的影响,列举了极距诊断的真实案例,并针对极距偏低和极距分布不均匀的问题提出了解决方案。经过一年的跟踪试验,试验槽取得了电流效率提高0.7个百分点、吨铝直流电耗降低145 kWh的良好效果。     

关于铝电解槽控制极距调整策略存在的问题及解决方案

论述了电解槽极距控制存在的问题,通过对当前电解槽控制极距调整策略的分析及问题确认,实施了新的控制调整策略。通过对槽控机关于极距控制基础分析、影响因素、调整方案三个方面的分析描述,提出解决办法,确保极距控制效果。     

消失模铸造阳极钢爪爪部中心距尺寸控制方法及要点

阳极钢爪是电解铝工业重要的导电部件,有三、四、六、八爪之分,其与铝导杆、阳极碳块一同组成阳极导杆组.其特殊的使用要求对钢爪爪部的中心距有严格的要求,其中六、八爪由于其中心距数量多且方向二维,中心距尺寸控制难度大.阳极钢爪往往由于中心距尺寸超标造成后续处理费用增大,严重的将报废,直接影响企业经济效益.笔者所在的公司是专业从事铝电解配套的服务企业,消失模生产阳极钢爪量每年在6 000 t左右.     

320kA铝电解槽生产的节能探索

节能对于高耗能的铝电解生产来说是企业的重要课题。国内目前平均综合电耗在14500kWh/t-Al左右,由于各个企业之间存在着不同技术思路和管理思路,使得各个企业的电耗不同,好的企业可以达到13700kWh/t-Al左右。中孚实业在320kA铝电解槽生产上经过多年探索,在管理上不断创新,使节能工作一直走在行业前列。     

温度对铂钽复合阳极电化学性能的影响

对铂钽复合阳极在200 mA/cm2的电流密度下进行了恒电流试验,通过测量动电位极化曲线以及电化学阻抗谱,研究了阳极在不同温度海水中的电化学行为,利用扫描电镜(SEM)及能谱仪(EDS)对阳极形貌及成分进行了分析。电化学试验结果表明,铂钽复合阳极能承载较大的电流密度;随温度的降低,法拉第电荷传递电阻增大,阳极电化学催化活性有所下降。SEM分析结果表明,阳极表面有微裂纹,阳极工作时表面有大量气体析出,加速了阳极的溶解。     

阳极预热技术在铝电解槽生产中的应用

换阳极是铝电解生产中很重要的一项作业,如何减少换极对电解生产的影响是铝电解工作者普遍关注的焦点。笔者结合多年铝电解生产实践得出,阳极在上槽前进行预热可以减少换极作业对生产的不利影响。本文介绍一种操作简单易于实施的阳极预热方法,并浅析阳极预热对铝电解槽生产的重要推进意义。     

谈如何提高铝电解生产的电流效率

通过对铝电解生产过程中的重要技术条件电解温度、极距、电解质水平、铝水平、电解质成分和分子比等对电流效率的影响以及应如何调整、摆布这些技术条件,提高操作管理水平两个方面入手,达到电解槽长期处在稳定的状态下工作从而达到提高电流效率的目的。     

浅析铝电解槽的电压摆

通过对铝电解槽电压波动的系统分析,认为引起电压摆的根本原因是热收入不足,次要原因是极距或铝水平偏低,操作质量是引起电压摆的外因.     

Numerical simulation of coupled thermo-electrical field for 20 kA new rare earth reduction cell

To solve the problems of high energy consumption, low efficiency and short service life of conventional rare earth reduction cells, a 20 kA new rare earth reduction cell (NRERC) was presented. The effects of the anode-cathode distance (ACD) and electrolyte height (EH) on the thermo-electrical behavior of the NRERC were studied by ANSYS. The results illustrate that the cell voltage drop (CVD) and the temperature will rise with a similar tendency when the ACD increases. Also, the temperature rises gradually with EH, but the CVD decreases. Ultimately, when the ACD is 115 mm and the EH is 380 mm, the CVD is 4.61 V and the temperature is 1109.8 °C. Under these conditions, the thermal field distribution is more reasonable and the CVD is lower, which is beneficial to the long service life and low energy consumption of the NRERC.     

基于非线性浅水模型的铝电解磁流体动力学计算

基于铝电解槽内流体体系及电磁场分布特点,建立了非线性磁流体动力学浅水模型,并应用此模型对某300 kA电解槽的熔体流场及铝液-电解质界面波动进行瞬态数值研究.在此基础上,通过动力学计算分析极距及铝液区垂直磁场对磁流体稳定性的影响.结果表明:随着极距的减小,界面波动由稳定趋向于不稳定;减小铝液区的垂直磁感应强度能大幅提高磁流体的稳定性.     

槽噪声与阳极导杆电流波动

铝电解槽生产过程中产生槽噪声的成因是各种各样的,因而噪声的性质也各不相同,根据槽噪声讯号的波形,频率分类,槽噪声大致可分为无序噪声(阳极噪声)和有序振荡(电磁力噪声)二类。用提高阳极距离的办法去抑制,对无序噪声常常有效,但对有序振荡则往往无效,有迹象表明,电磁力噪声就是由于阳极移动而激发,例如出铝(相当于移动极距)就常常引起槽不稳定。抑制噪声的正确方法应该是分清噪声的性质,迅速发现噪声源,采取有针对性的抑制措施。测量单根阳极导杆电流波动的频率和幅值是分清噪声性质,寻找噪声源的简单而有效的方法。我们近期研发的LH—70型阳极电流测量仪可作为铝电解车间操作人员用来判定噪声性质,发现噪声源的简便仪器。     

Impact of operations at low anode-cathode distance on energy consumption and greenhouse gas emissions at Aluminerie Alouette

The energy consumption for aluminum production by the Hall-Héroult process has been significantly improved during the last few decades. This has been achieved mainly as a result of improved cell design and suitable process control strategies that have allowed higher cell currents and smaller anode-cathode distance (ACD). Without taking suitable corrective actions, operations at lower ACD conditions can negatively impact aluminum re-oxidation, by-pass current, alumina dissolution and anode effect rates. Superior operational practices are therefore required to maintain acceptably low instability levels along with lower specific energy consumption. This paper discusses anode effect fundamentals and greenhouse gas emissions in relation with industrial cells operating at low ACD at the Aluminerie Alouette plant in Quebec.     

Characteristics of metal fluctuation caused by bath-metal interface oscillation in aluminum electrolysis cells

Bath-metal interface oscillation reduces the stability and efficiency of Hall-Héroult cells. However, the oscillation characteristics have not been understood in detail. A well-designed probe and an online monitor system were designed for monitoring the metal fluctuation. Experiments and analyses show the metal fluctuation can be captured, and a corresponding relationship between anode-cathode distance (ACD) and anode rod voltage drop (U_D) have been found. The stack phenomena of the fluctuation have been found as well. Analysis shows that the wave length (around 8 m in this experiment) is much bigger than the anode size; however, the wave velocity (around 0.27 m/s in this experiment) is relatively low. Because of the waves transmitting, anode current changes periodically but the cell voltage remains near constant when the metal is fluctuating.     

Pretreatment on Ti substrate for Ti/Pt anode by electrolytic plasma processing

The electrolytic plasma processing (EPP) process was employed to pretreat Ti substrates before applying Pt coating rather than using the conventional pickling route, resulting in increased efficiency and reduced environmental hazard. The successive anode-cathode EPP and single cathode EPP were used to pretreat the Ti substrate, respectively, and then the Ti/Pt anodes were prepared by the dip-coating/calcination method. The composition, morphology and electrochemical properties were investigated by X-ray diffraction, scanning electron microscopy and electrochemical workstation, respectively. The results show that the successive anode-cathode EPP-treated Ti substrate has uniform micro/nano-scale surface structure, and its corresponding Ti/Pt anode has the lowest impedance and best electrocatalytic activity among the Ti/Pt anodes prepared in this work.     

孕镶金刚石钻头中有序排列参数的确定

有序排列技术既可以降低原料成本,又可以提高工具的寿命和效率。结合金刚石钻头的碎岩机理,对金刚石有序排列的横向和纵向间距进行了分析设计和计算。分析表明:金刚石的粒径d和金刚石的横向间距l影响着破碎坑的直径D,而纵向间距s则影响着金刚石的自锐性能。间距计算结果表明,金刚石颗粒的横向间距合理值为(1～4/3)D,其中D=(2.8～3.1)d;搭接高度h=(1/3～1/2)d,纵向间距s=(1/2～2/3)d。针对具体不同的岩层,以及应用不同的工艺制作钻头时,金刚石的横向和纵向间距值应作适当的调整。在确定合理间距值的前提下,可通过模板法,电磁吸附法等,实现有序排列金刚石钻头的产业化。     

Physical modeling of gas induced bath flow in drained aluminum reduction cell

A room temperature physical model was used to study the bubble behavior and gas induced bath circulation in a drained aluminum reduction cell. By passing compressed argon through the penetrated Plexiglas box bottom plate immersed in water, gas evolution at the anode bottom surface was simulated. Bubble behavior and liquid flow field were studied and analysis was presented. Bath secondary recirculation was observed in the interpolar gap not the net rising flow as expected. Liquid driven by the bubbles forms small vortices along the interpolar gap with small mean and turbulent velocities and accordingly poor mass transfer. Secondary recirculation also exists between the slot and interpolar gap, part of the flow in the interpolar gap go to the slot with the bubbles and fluid at the bottom of the slot enters the interpolar gap directly without going to the center channel. The existence of the fluid secondary recirculation is very unfavorable to the alumina dissolution and dispersion. Increasing the anode tilt or gas flow rate, or decreasing the anode-cathode distance can make the secondary recirculation in the interpolar gap weak, however, will intensify the secondary recirculation between the slot and interpolar gap.