Liquidus temperatures for primary crystallization of cryolite in molten salt systems of interest for aluminum electrolysis

Temperatures for primary crystallization of Na₃AlF₆ in multicomponent electrolyte systems of interest for the aluminum electrolysis process were determined by thermal analysis. The results are presented as binary and quasibinary diagrams and discussed in view of the literature data. An empirical equation describing liquidus temperatures for primary crystallization of Na₃AlF₆ was derived: $$\begin{gathered} t/(^\circ C) = 1011 + 0.50[AlF_3 ] - 0.13[AIF_3 ] - \frac{{3.45[CaF_2 ]}}{{1 + 0.0173[CaF_2 ]}} \hfill \\ + 0.124[CaF_2 ] \cdot [AlF_3 ] - 0.00542([CaF_2 ] \cdot [AlF_3 ])^{1.5} \hfill \\ - \frac{{7.93[Al_2 O_3 ]}}{{1 + 0.0936[Al_2 O_3 ] - 0.0017[Al_2 O_3 ]^2 - 0.0023[AlF_3 ] \cdot [Al_2 O_3 ]}} \hfill \\ - \frac{{8.90[LiF]}}{{1 + 0.0047[LiF] + 0.0010[AlF3]^2 }} - 3.95[MgF_2 ] - 3.95 \hfill \\ \end{gathered} $$ wheret is the temperature in degree Celsius and the square brackets denote the weight percent of components in the system Na₃AlF₆-AlF₃-CaF₂-Al₂O₃-LiF-MgF₂-KF. The composition limitations are [AlF₃] ≈ [CaF₂] ≈ [LiF] < 20 wt pct, [MgF₂] ≈ [KF] < 5 wt pct, and [A1₂O₃] up to saturation.     

物理富集—熔盐电解法从二次铝灰回收金属铝

二次铝灰是铝工业生产过程中产生的固体废弃物,含有金属铝、氧化铝和氮化铝等。通过球磨—筛分富集铝灰中的金属铝,研究球磨过程铝灰的粒度分布和金属铝的分离规律。结果表明,球磨后铝灰中的金属铝粒径变大,而其他盐类组分变细。较优条件是球磨3 h并筛分,粒度范围97～150μm的铝灰中金属铝的质量分数为24.51%,金属铝的质量占原料中金属铝总质量的41.40%。在冰晶石熔盐中电解最优条件下球磨—筛分后的铝灰,XRF分析表明：电解产物中Al和Si的质量分数分别为97.3%和1.6%,铝回收率为45.89%,电流效率为46.06%。     

The solubility of hydrogen in molten aluminum alloys

The solubility of hydrogen in molten aluminum alloys containing copper, lithium, magnesium, and silicon has been calculated from the solubility of hydrogen in pure metals and binary metal-metal interaction parameters. For the aluminum-copper binary system, where experimental data exist, the agreement between calculated and experimental values is excellent. The solubility of hydrogen in liquid silicon was calculated from the solubility data in aluminum-silicon alloys.     

流水线镁电解熔盐体系密度的研究

利用阿基米德方法研究流水线镁电解熔盐体系密度, 旨在确定适合于流水线镁电解熔盐的较优控制参数, 为生产提供指导, 为同行提供理论参考.研究结果表明:在MgCl₂-KCl-NaCl熔盐体系中, 随着氯化镁的浓度增加, 熔盐的密度增大; 随着氯化钾浓度的增加, 熔盐的密度减小; 随着氯化钠浓度的增加, 高钾含量的熔盐密度增大, 高镁含量的熔盐密度减小.当体系中出现KMgCl₃时, 熔盐的密度急剧增大; 当体系中出现K₂MgCl₄时, 熔盐的密度急剧减小.在生产中, 熔盐组分较优控制范围为: W_KCl: 50 %~70 %, W_NaCl: 18 %~23 %, W_MgCl2: 12 %~18 %; 熔盐温度较优控制范围为: 680~700 ℃.      

Electrodeposition of magnesium-yttrium alloys by molten salt electrolysis

Electrodeposition of magnesium-yttrium alloys from molten salts was studied by electrochemical techniques.LiF-YF3 was electrolyte system with magnesium oxide and Yttrium oxide as raw materials.It was proved that Mg2+ and Y3+was deposited more prior than other ions during cyclic voltammetry and potential step measurement at 1050 °C.Voltammograms showed Mg2+ could be deposited at-0.5 V,and Y3+ could be deposited at-0.7 V on tungsten electrode compared with platinum electrode.The sedimentation of Mg2+ was more positive about 230 mV than that of other ions in electrolyte.The electrolytic codeposition of yttrium and magnesium was 0.58 V on condition that the weight ratio of Y2O3/MgO was 4:1.Chronopotentiogram indicated that the process of electrodeposition of magnesium-yttrium alloys on tungsten electrode was controlled by diffusion of ions from electrolyte to electrode interface.It was feasible to prepare Magnesium-Yttrium alloys by controlling content of ions in molten salt electrolyte.     

Electrodeposition of magnesium-yttrium alloys by molten salt electrolysis

Electrodeposition of magnesium-yttrium alloys from molten salts was studied by electrochemical techniques. LiF-YF₃ was electrolyte system with magnesium oxide and Yttrium oxide as raw materials. It was proved that Mg²⁺ and Y³⁺was deposited more prior than other ions during cyclic voltammetry and potential step measurement at 1050 °C. Voltammograms showed Mg²⁺ could be deposited at ?0.5 V, and Y³⁺ could be deposited at ?0.7 V on tungsten electrode compared with platinum electrode. The sedimentation of Mg²⁺ was more positive about 230 mV than that of other ions in electrolyte. The electrolytic codeposition of yttrium and magnesium was 0.58 V on condition that the weight ratio of Y₂O₃/MgO was 4:1. Chronopotentiogram indicated that the process of electrodeposition of magnesium-yttrium alloys on tungsten electrode was controlled by diffusion of ions from electrolyte to electrode interface. It was feasible to prepare Magnesium-Yttrium alloys by controlling content of ions in molten salt electrolyte.     

熔盐电解制备Al-Cu-Y合金电解质 体系黏度的研究

采用旋转法测定了熔盐电解制备Al-Cu-Y合金的电解质体系Na₃AlF₆-AlF₃-LiF-MgF₂-Al₂O₃-CuO-Y₂O₃在温度900~1 000 ℃范围内的黏度,通过分析数据研究温度及Al₂O₃、Y₂O₃、CuO添加量对熔盐黏度的影响,确定了温度、熔盐组分和黏度之间的关系.结果表明:在温度900~1 000 ℃范围内,体系随温度升高,黏度减小;随Al₂O₃、Y₂O₃、CuO的含量增大,黏度增大;在900~1 000 ℃范围体系黏度（η）随温度（T）以及氧化物的含量W_Al2O3、W_Y2O3、W_CuO符合回归方程η=0.075-6.49×10-5T+3.7×10-4W_Al2O3+5.73×10-4W_Y2O3+6.78×10-4W_CuO.      

Na3AlF6-Al2O3熔盐中铝溶解度的测定

研究了铝在Na3AlF6-Al2O3熔盐中溶解度的测定方法。采用氟化钠与试样在高温下熔融,熔融物溶解水后加入硼酸-氢氧化钠溶液,过滤沉淀将氧化 铝除去,取其中一部分溶液在pH5.5～6.0 的条件下,加入过量的EDTA标准溶液,加热煮沸使之与铝完全络合,以二甲酚橙作指示剂,用锌标准溶液 滴定过量的EDTA ,从而得到Na3AlF6-Al2O3熔盐中铝离子的含量,再采用氟离子选择电极测定另一部分溶液中氟含量,计算得到冰晶石中铝离子含量 ,采用减氟法得到铝在Na3AlF6-Al2O33体系中溶解量。这个值是用来表征铝在电解质熔体中的溶解损失能力的大小,对生产工艺很重要。     

氟化物体系熔盐电解制备YNi合金

以Y2O3为电解原料,以金属镍棒为自耗阴极、石墨板为阳极,在常规的石墨电解槽中采用氟化物体系熔盐电解法制备了YNi合金.研究了电解时间、电解温度、电解质组成、阴极电流密度等主要技术参数对电解过程的影响,并对所制备的钇镍合金进行了表征.结果表明,熔盐电解制备钇镍合金的较优工艺条件为:电解温度1000℃,电解质YF3与Li...     

熔盐预电解脱水与电解时间对溶盐电解TiO_2脱氧行为的影响

以无水氯化钙作为熔盐,采用熔盐电解法对TiO2阴极片进行脱氧,通过X射线衍射(XRD)和扫描电镜(SEM)对TiO2电解产物的相组成、电极表面形貌与元素组成进行观察与分析,研究熔盐的预电解脱水与熔盐电解时间对TiO2电解脱氧行为的影响。结果表明,熔盐未经预电解时,TiO2阴极片不发生脱氧反应,电解产物只有CaTiO3相;熔盐经预电解脱水后,TiO2电解产物部分或全部为低价钛氧化物,预电解时间达到15h即可有效去除熔盐中的水分,从而获得较佳的熔盐电解脱氧效果,电解产物为氧含量较低的Ti2O。TiO2电解脱氧是分步进行的,随电解进行,先后出现Ti2O3、TiO、Ti2O,由于钛的化合价逐渐降低,所需分解压升高,导致脱氧效率逐渐降低。TiO2阴极的脱氧反应是由表面到心部进行,电解后的阴极片明显分层,表层为氧含量较低的Ti2O,中间层为CaTiO3和钛的低价氧化物,心部为CaTiO3。     

熔盐电解法制备铝钙合金中的反电动势

研究了在CaCl2-CaF2纯钙盐体系中下沉式铝液槽结构熔盐电解法生产Al-Ca合金新工艺,采用连续脉冲-示波器法测定电解过程的反电动势,研究了在实验室条件下电解温度、电流密度、电解时问和极距对熔盐电解法制取铝钙合金的反电动势的影响.用熔盐电解法并采用铝阴极生产Al-Ca合金比对掺法更加节省电能,降低了Al-Ca合金的生产成本,是一种有经济价值的生产方法,有很好的发展前景.     

熔盐电解制备钨铜合金粉体槽内温场条件分析

在熔盐电解法由Na2WO4和CuO制取钨铜合金粉体的研究基础上,分析电解槽内的温度场分布,特别是电极区域的温度分布情况对电解行为的影响.通过位移法测量,采取比较法分析实验误差,结果表明:电解过程中2个主要的外部条件,即电解槽内温场分布与电场分布是联动的;温度条件影响着电极电位;同时,外部槽电压通过电流扰动槽内温场,使电极区域温场分布不均.     

熔盐电解制备铜粉的实验研究

文中研究了在NaCl-KCl-CuO体系中采用熔盐电解法直接制取铜粉的方法.基本反应条件为:电解温度740~820 ℃;槽电流12~15 A;阴极电流密度110~140 mA/cm2;槽电压2.2~3.2 V;电解时间1.5~3.5 h.对阴极电解产物进行了X射线衍射（XRD）及铜粉粒度分析,同时用扫描电镜（SEM）及能谱仪（EDS）对产物的形貌及元素含量进行了分析.结果表明:在上述条件下可以得到铜粉末,产物纯度在98 %以上且平均粒度为0.91 μm.      

NaCl-KCl-Na_2WO_4-CuO体系电解制备钨铜复合粉体研究

文中研究采用熔盐电解以由Na2WO4和CuO为活性物质电解获得钨铜合金复合前驱粉体.通过循环伏安法对电解质体系及电极过程进行定性分析认为Na2WO4减缓体系活性物质扩散速度,CuO与Na2WO4的电解非同步进行.通过改变活性物质的加入方式进行对比实验,结果表明：在温度750℃;以一定比例KCl-NaCl混合熔盐为电解质,在起始槽电压1 V,先加入CuO电解2 h;后加入Na2WO4,调整槽电压至2 V电解3 h,对产物进行X射线衍射（XRD）和扫描电镜（SEM）及能谱分析（EDS）表明,可以获得纯度达到98%的W-Cu合金粉体.     

Discussion of “comments on the solubility of carbon in molten aluminum”

CHRISTIAN J. SIMENSEN:Metall. Trans. A, 1989, vol. 20A, p. 191.     

高温熔盐体系惰性阳极与月壤电解制氧技术

目前,熔盐电化学冶金普遍采用炭素阳极,阳极CO₂产物是重要的碳排放源。若在高温熔盐体系中使用惰性析氧阳极,则可实现熔盐电解过程低碳排放。因此,开发适用于熔盐电解体系的惰性阳极至关重要,也是近年来国内外研究热点。本文首先综述了各种高温熔盐体系惰性阳极的研究进展,所涉及熔盐体系包括:铝电解氟化物盐、CaCl₂熔盐、碳酸盐和熔融氧化物等。另外,近年来月球开发利用受到广泛关注,太阳能驱动的月壤原位熔盐电化学制氧,将是支撑人类未来月面生存氧气需求的重要方法之一,故惰性析氧阳极不可或缺。因此,本文也简要综述了基于惰性阳极的月壤电解制氧技术。      

熔盐电解生产Al-Sr合金的新工艺及其加料周期

研究了以SrCO3为原料熔盐电解法生产Al-Sr合金新工艺,采用连续脉冲-示波器法测定电解过程的反电动势.结果发现:(1)延长电解时间,合金中锶的质量分数逐渐增加,最高可达18.54%;(2)增加电流密度,反电动势亦随之增加,而升高温度反电动势则有所降低;(3)在电解过程中,反电动势逐渐增加,但向熔体中加入SrCO3后,反电动势明显降低.因此确定在正常电解时是SrCO3在分解.以此规律制定了正常生产的加料周期和加料量,保证了生产的稳定进行.以SrCO3为原料生产Al-Sr合金,不但减少了环境污染,也降低了Al-Sr合金的生产成本.     

Optimization of binary thermodynamic and phase diagram data

An optimization technique based upon least squares regression is presented to permit the simultaneous analysis of diverse experimental binary thermodynamic and phase diagram data. Coefficients of polynomial expansions for the enthalpy and excess entropy of binary solutions are obtained which can subsequently be used to calculate the thermodynamic properties or the phase diagram. In an interactive computer-assisted analysis employing this technique, one can critically analyze a large number of diverse data in a binary system rapidly, in a manner which is fully self-consistent thermodynamically. Examples of applications to the Bi-Zn, Cd-Pb, PbCl₂-KCl, LiCl-FeCl₂, and Au-Ni binary systems are given.