Study on spinel-based inert anode for aluminium electrolysis

1 IntroductionSince the Hall-Heroult process was applied in aluminium production,an inert anode was al ways thetarget that the aluminiumindustry is seeking for in the newtechnology field. The greenhouse gases CO2and the fluoride CFnemittedfromthe present carbon anodes ,give a huge pressure onthe environment .Theapplication of inert anodes will help us go through this trouble :a cell with inert anodes emits oxygen in-stead of CO2and other nocuous gases ;the newtype of cell with inert anodes …     

Density and ionic structure of NdF3-LiF melts

NdF3-LiF melts are commonly used in the electrolysis process of metallic neodymium production. Research on the density and ionic structure of the electrolyte is important for its close connection with the electrolysis mechanism and process. In this paper, the density of LiF-NdF3 melts was studied by the Archimedes method. The results showed that the density decreased with increasing temperature and LiF contents. The changing law was discussed and explained in terms of the micro ionic structure of the melts....     

铝电解质成分对钠和电解质渗透行为的影响

分别从电解质分子比、氧化铝含量和添加剂氟化镁含量的变化方面,研究电解质成分对钠和冰晶石-氧化铝熔液向阴极碳块渗透的影响.结果表明,随着电解质分子比的增加,阴极碳块中渗透的物质增多,分子比越大,渗透就越深.加大氧化铝的含量使钠向阴极碳块的渗透能力增强.添加剂氟化镁能够减小钠和电解质向阴极碳块的渗透.     

Identification of structural entities in NdF3-LiF melts with cryoscopic method

Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculations,NdF4- was identified as the most likely Nd-F entity in the melts in which the mole fraction of NdF3 was lower than 20%,considering only one single Nd species in the melt,and which was formed in accordance with Temkin model or Flood model.Then,activities of different components in the melts were researched.The results show that activity of LiF decreases,and that of NdF3 increases with increasing the mole fraction of NdF3.The value of activity coefficient of NdF3 is higher than 1,and that of LiF is lower than 1.     

Equivalent conductivity and its activation energy of NaF-AlF3 melts

Electrical conductivity of NaF-AlF3 melts was measured by continuously varying cell constant(CVCC) technique. Relationships between equivalent conductivity at 990-1 030 ℃ and temperature and composition, and relationship between equivalent conductivity activation energy and composition of the melts were then studied on the basis of two-step decomposition mechanism of AlF63-. According to the changes of molar fractions of different anions in NaF-AlF3 melts, courses of dependence of equivalent conductivity and its activation energy on composition were analyzed. The results show that the influence of temperature on equivalent conductivity of the melts is small in the researched temperature range, and equivalent conductivity increases with increasing the molar fraction of AlF3; there is a minimum point in the activation energy-composition curve when molar fraction of AlF3 is 0.29.     

金属钛制备工艺研究进展

本文介绍了热还原法制备金属钛的工艺,包括Kroll法、镁还原低价卤化物、PRP法及Hunter法及电解法,包括电解TiCl4法、FFC剑桥工艺、EMR/MSE等,分析了各种方法的机理及特点。并且认为以TiCl4为原料制备钛工艺降低成本的空间很小;如能生产出低成本的TiCl2,钛成本高的问题将很快得以解决;从熔盐中直接电解TiO2制备金属钛,是低成本金属钛制备新工艺的发展方向。     

铝电解槽中黏土质砖的抗渗性研究

通过浸泡法和坩埚法对铝电解槽用黏土质砖进行抗渗性研究,利用X射线衍射法对工业上已经使用过的黏土质砖进行分析.结果表明,黏土质耐火砖在高分子比的电解质中浸泡2h后,质量损失率是47.25%,而黏土质保温砖经90min的浸泡后完全溶解在电解质里.坩埚法试验中,耐火砖要比保温砖的抗渗性能好,但两种砖都不耐电解质渗透.工业电解槽中,渗透到黏土质砖的电解质中含有大量的NaF,黏土质砖中的莫来石变成了霞石.     

Formation of Al-Ni master alloys using nickel anode

Nickel anode was investigated as a potential anode of aluminium electrowinning for preparation of Al-Ni master alloys. The electrolysis tests were carried out in Na3AlF6-Al2O3 based melts at 940℃. The results show that the cell voltage during electrolysis has only minor instability, and there exists NiO phase in electrolyte after 0.5 h electrolysis. Ni content in A1-Ni master alloys increases with increasing the electrolysis time. Concentration limit of Ni in Al-Ni master alloys can be up to 33.8% （mass fraction）. However, substantial corrosion of the Ni-metal substrate is observed, and the oxide scale on the nickel anode after electrolysis is porous and loose that does not prevent corrosion of the substrate.     

电极材料对铝电解阴极过程研究的影响

电解铝工业中铝的析出发生在阴极上，研究铝析出反应的机理对实际工况有很好的指导意义。研究发现，炭电极上的Al、Na共沉积现象严重，致使循环伏安曲线上Al的析出峰被掩盖。因此人们试图用一些金属电极Ni、Pt、Au、Ta、Cu、W等来代替炭电极，但研究发现大部分金属电极都与Al反应生成合金，干扰了对真实电极过程的研究。只有W与Al的合金化作用较小，因此对冰晶石一氧化铝熔体的阴极电化学研究采用了W电极。而目前TiH2基可湿润阴极是极具发展前景的铝电解槽阴极材料，但这方面的研究还很不够，需做进一步的研究。     

高温合金材料在铝电解工业中的应用探讨

对高温合金在铝电解工业用作惰性金属阳极材料的选择进行阐述，并就实际应用过程中的抗氧化耐腐蚀性进行探讨；阐述适用于铝电解工业的惰性阳极合金所应具备的必要条件和必须解决的问题，并介绍目前有关的研究动态和研究方向。