工艺条件对金属锂电解过程影响研究

在653～693K温度下电解LiCl-KCl体系制备金属锂,分别研究电解温度、电流密度、电解质比例以及阴阳极间距对金属锂电解电流效率的影响。最佳电解温度为653～673K、LiCl-KCl电解质最佳质量比为LiCl∶KCl=50%∶50%,同时较大的电流密度与极距对电流效率更有利。     

CaWO_4在NaCl-CaCl_2熔盐体系中溶解性能的研究

采用等温热饱和法研究CaWO_4在NaCl-CaCl_2熔盐体系中的饱和溶解时间,并在饱和溶解时间下,研究温度和熔盐组分摩尔比对CaWO_4溶解度的影响,采用X射线衍射方法分析熔盐极冷试样的物相组成。结果表明,在650～850℃下,两个小时内溶解基本达到饱和状态,CaWO_4的溶解度随温度的升高呈现线性增加,饱和溶解时间也逐渐缩短。在相同温度下,CaWO_4的溶解度随体系中CaCl_2含量的增加而增大。CaWO_4在体系中的溶解包括物理和化学两个过程,并且以物理溶解过程为主。     

V_2O_5在NaCl-KCl-NaF熔盐体系中溶解度及溶解机理

利用等温饱和法分别研究温度和熔盐组分对V2O5在Na Cl-KCl-Na F熔盐体系中溶解度的影响。并利用热力学软件Factsage7.0对熔盐体系各组分之间可能发生的化学反应进行计算,着重结合X射线衍射对熔盐急冷试样进行分析,确定了V2O5的溶解机理。结果表明:在该熔盐体系中V2O5优先与Na F发生反应,其溶解机理为4V2O5+6Na F=6Na VO3+2VF3+O2;V2O5的溶解度随温度的升高而增大,随组元Na F摩尔分数的增大而增大。     

Sc2O3在ScF3-LiF熔盐中的溶解特性

采用步冷曲线法测量了ScF₃-LiF熔盐的初晶温度，以等温饱和法测量了Sc₂O₃在ScF₃-LiF熔盐中的溶解度，研究了温度与ScF₃含量的影响。通过XRD探究了Sc₂O₃在ScF₃-LiF熔盐中的溶解原理。结果表明，ScF₃-LiF熔盐的初晶温度随ScF₃含量的增加而升高，添加Sc₂O₃会使初晶温度降低；Sc₂O₃在ScF₃-LiF熔盐中主要发生化学溶解，溶解平衡时间约为2 h,其溶解度随温度的升高及ScF₃含量的增大而增大。     

氧化镁在NdCl3-NaCl-KCl-MgCl2熔盐中的溶解行为

研究了氧化镁在NdCl3-NaCl-KCl-MgCl2熔盐中的溶解行为.利用正交回归实验设计研究了熔盐各组分对MgO溶解度的影响,测定了不同组分熔盐中MgO的溶解度.结果表明MgO溶解度主要决定于组分NdCl3含量.分别测定了MgO在700,780,850℃下的溶解动力学.结果表明MgO在NdCl3-NaCl-KCl-MgCl2体系中的溶解速率主要与NdCl3浓度有关,其它因素的影响不显著.得到MgO溶解反应的活化能E=33.36 kJ·mol-1.     

氧化镁在镁电解质中的溶解度

测定了MgO在电解质MgCl_2-NaCl-KCl-CaF_2(MgF_2/NaF)以及MgCl_2-NaCl-KCl-NdCl_3等体系中的溶解度,并利用正交试验设计和响应面分析研究了熔盐各组分对MgO溶解度的影响；对MgCl_2 -NaCl-KCl-CaF_2(MgF_2/NaF)体系,得到了MgO溶解度随组分MgCl_2与CaF_2含量的变化规律模型和等值面图及响应面分析图；对MgCl_2-NaCl-KCl-NdCl_3体系,研究了添加稀土氯化物对氧化镁溶解过程的影响。试验结果表明,熔盐MgCl_2-NaCl-KCl-CaF_2(MgF_2/NaF)体系中,MgCl_2与CaF_2的含量对MgO的溶解的影响显著,但体系中对氧化镁的溶解度并不大(＜0．2％)；而MgCl_2-NaCl-KCl- NdCl_3体系中,MgO有较大的溶解度,而且NdCl_3的添加量直接决定着MgO的溶解度。对MgO在不同组分熔盐中的溶解过程也作了热力学研究,结果表明：MgO在熔盐中的溶解主要是氧化镁与熔盐中组分相互作用,生成络合离子所致。     

Y_2O_3在NaF-AlF_3-LiF熔盐体系中的溶解度研究

采用等温饱和法研究了Y_2O_3在NaF-AlF_3-LiF熔盐体系中995～1 115℃范围内的溶解平衡及溶解度随温度和NaF/AlF_3摩尔比变化的规律,建立了溶解度与温度及NaF/AlF_3摩尔比之间的一次回归方程。结果表明:在995～1 115℃范围内,Y_2O_3在NaF-AlF_3-LiF熔盐体系中的溶解平衡时间不低于40 min;同时,Y_2O_3在体系中的溶解度随温度升高和NaF/AlF_3摩尔比增大均增加;995～1 115℃及NaF/AlF_3摩尔比2.3～2.9范围内Y_2O_3溶解度的回归方程拟合度超过90%。     

强制搅拌对Na3AlF6-AlF3-CaF2熔盐体系中TiO2溶解的影响

采用等温饱和法研究了静置和搅拌状态对TiO2在Na3AlF6-AlF3-CaF2熔盐体系中的溶解速率及溶解量的影响,分别对空冷和水淬处理的熔盐样品进行X射线衍射分析。结果表明：熔盐温度为960 ℃时,静置状态下,TiO2的溶解量随溶解时间的延长而增加,溶解120 min时的溶解量为2.33%;搅拌条件下,提高了溶解速率,溶解120 min时的溶解量为5.33%;XRD分析表明二氧化钛在熔盐体系中以TiO2相存在。     

铝锶合金在KCl－SrCl_2熔盐中溶解损失的研究

利用三因子一次正交回归设计导出了铝锶合金在ＫＣｌ－ＳｒＣｌ＿２熔盐体系中的溶解损失的数学表达式，发现铝锶合金中锶在ＫＣｌ－ＳｒＣｌ＿２熔盐体系中的溶解损失随温度、合金中锶含量及熔盐中ＳｒＣｌ＿２含量的升高而增大。同时探讨了合金中锶与与其熔盐体系间相互作用的机理。     

K3AlF6-Na3AlF6-AlF3体系组成对α-Al2O3溶解度和溶解速度的影响

采用EDTA络合滴定法研究了粉末状α-Al2O3在K3AlF6-Na3AlF6-AlF3体系中的溶解度和溶解速度.探讨了K3AlF6、AlF3含量和温度对氧化铝在K3AlF6-Na3AlF6-AlF3体系中溶解度和溶解速度的影响,并测定了K3AlF6-Na3AlF6-AlF3体系初晶温度30℃以上溶解度和溶解速度,比较了含钾冰晶石熔盐体系和传统钠冰晶石基熔盐体系Al2O3溶解度方面的差异.实验结果表明:K3AlF6-Na3AlF6-AlF3体系中的α-Al2O3溶解速度很快,在5～10 min内溶解已经达到饱和;850℃时,KR每增加0.2,Al2O3溶解度增加约0.5%(质量分数);随着K3AlF6含量的增加Al2O3溶解度相应的增加,相对于高钾冰晶石含量体系而言,较低K3AlF6含量时,增加K3 AlF6的量对提高氧化铝溶解度幅度更加显著;与传统钠冰晶石电解质体系相比K3AlF6-Na3AlF6-AlF3体系Al2O3的溶解度明显增大,当KR≥0.3时,差异愈加显著.     

CaCl_2-CaF_2熔盐的CaO溶解度及吸水性能研究

采用不同真空脱水工艺制备了CaCl_2-CaF_2熔盐,对CaO在熔盐中的溶解度和熔盐吸水性能进行了研究。结果表明,随着熔盐脱水温度的升高、脱水时间的增加,熔盐中H_2O、CaO的含量逐渐降低,且表现出相同的变化趋势;熔盐中CaO的溶解度随着熔盐温度、溶解时间的增加逐渐增加,CaO在不同脱水工艺制备的熔盐中的溶解度有所差异,随着熔盐中H_2O含量的增加,CaO的溶解度逐渐降低;不同脱水工艺制备的熔盐表现出不同的吸水性能,熔盐中H_2O含量越低,吸水性能越强。     

复杂铝电解质体系中锂盐和钾盐对氧化铝浓度的影响

我国铝电解企业所使用的原料氧化铝来源复杂,特别是富含锂、钾元素,造成锂盐、钾盐在铝电解质体系中大量富集,导致铝电解质成分复杂,对氧化铝的溶解过程造成极大影响。依据大量生产控制数据,解析了氟化锂、氟化钾在复杂铝电解质体系中对氧化铝的溶解性能的影响关系。结果表明,电解质体系中的锂盐、钾盐与冰晶石反应生成氟化锂、氟化钾。在低氟化锂浓度(3.00%)时,氧化铝浓度随着氟化锂浓度的增加而降低;在高氟化锂浓度(3.00%)时,氧化铝浓度随着氟化锂浓度的增加而增加。氧化铝的浓度随着氟化钾浓度的增加而增加;在复杂铝电解质体系中氟化锂的浓度控制在1.50%～2.50%可以保持铝电解过程的最优状态,铝电解质体系中尽量避免含氟化钾。     

LiCl-KCl熔盐中电解还原钛铁矿的研究

在LiCl-KCl熔盐中,采用熔盐电解法还原钛铁矿,研究了电解时间、槽电压及电解温度对还原钛铁矿的影响,探讨了在熔盐中钛铁矿电解脱氧的机理。结果表明,钛铁矿还原优先生成铁,钛氧化物由高价到低价逐步还原,而未得到金属钛及其合金,说明在LiCl-KCl熔盐中,TiO的脱氧还原是钛铁矿熔盐电解生成金属钛及其合金的反应限制性步骤。     

Preparation of Mg-Li-Sm alloys by electrocodeposition in molten salt

Electrocodeposition of Mg-Li-Sm alloys was investigated in molten KCl-LiCl-MgCl2-SmCl3-KF system.The effects of electrolytic temperature and cathodic current density on current efficiency were studied and optimal electrolysis parameters were obtained.The optimum electrolysis condition was a molten salt mixture of LiCl:KCl =50:50(wt.%),electrolytic temperature:660 oC,cathode current density:9.5 A/cm2 and electrolysis time of 40 min.The current efficiency reached 77.3%.X-ray diffraction(XRD) and scanning elec...     

Corrosion of Refractory Alloys in Molten Lithium and Lithium Chloride

Several refractory materials have been considered over the years as containment material for lithium and lithium halides. Surface modified refractory metals are being extensively investigated for containment of reactive metals, radionuclides and their compounds. An overview of experimental observations and results of liquid lithium corrosion of selected engineering refractory materials are presented. The nature of the degradation and its mechanism has been explained. The influence of temperature, microstructure, stress, impurities and service time on the corrosion behavior for various refractory alloys have been discussed. Selection rules for materials of containment for liquid lithium and lithium compounds have been suggested. Recent experimental observations on the behavior of tantalum and niobium-based refractory metal alloys in a specific molten salt environment comprising LiCl/Li₂O/Li/Li₃N at 725°C have been included in an effort to select suitable materials for molten salt equipment. It has been observed that oxygen contamination is particularly harmful for the refractory metal alloys where as nitrogen is deleterious to iron-based alloys.     

水分对金属锂电解电解效率影响及其机理探究

在LiCl-KCl体系中653~693 K电解制备金属锂,分别研究了在氩气、空气、氧气以及氮气气氛下改变水蒸气含量对金属锂电解电流效率的影响。结果表明,在氧气和水蒸气共同作用下会对金属锂电解产生不利影响。对反应过程进行了热力学计算并分析不同条件下水分对电解的影响机理。     

Corrosion of Refractory Alloys in Molten Lithium and Lithium Chloride

Abstract

Several refractory materials have been considered over the years as containment material for lithium and lithium halides. Surface modified refractory metals are being extensively investigated for containment of reactive metals, radionuclides and their compounds. An overview of experimental observations and results of liquid lithium corrosion of selected engineering refractory materials are presented. The nature of the degradation and its mechanism has been explained. The influence of temperature, microstructure, stress, impurities and service time on the corrosion behavior for various refractory alloys have been discussed. Selection rules for materials of containment for liquid lithium and lithium compounds have been suggested. Recent experimental observations on the behavior of tantalum and niobium-based refractory metal alloys in a specific molten salt environment comprising LiCl/Li₂O/Li/Li₃N at 725^°C have been included in an effort to select suitable materials for molten salt equipment. It has been observed that oxygen contamination is particularly harmful for the refractory metal alloys where as nitrogen is deleterious to iron-based alloys.     

高温共聚焦显微镜原位观察非金属夹杂物溶解行为研究进展

总结了高温共聚焦显微镜观察夹杂物在渣中溶解工作原理和非金属夹杂物溶解行为的研究现状和研究方法,探讨了未反应核模型和扩散方程2种常用于研究非金属夹杂物溶解的动力学模型,各类非金属夹杂物的溶解机制,温度、渣成分、夹杂物性质等影响非金属夹杂物溶解行为的因素,在前人研究的基础上得到不同夹杂物的溶解速率公式.指出该领域对于由钙铝...     

Recycling of magnesium alloys: Chemical equilibria between magnesium-lithium-based melts and salt melts

Magnesium-lithium alloys have been equilibrated with chloride melts at 700 °C in iron crucibles. After quenching, the compositions of the metal and salt phases were determined by chemical analyses. The obtained data were evaluated according to thermodynamic principles. The following reactions were investigated: MgCl₂+2Li=2LiCl+Mg (Reaction [1]), CaCl₂+2Li=2LiCl+Ca (Reaction [2]), and BaCl₂+2Li=2LiCl+Ba (Reaction [3]). The equilibrium of Reaction [1] is much on the right side of the reaction equation. If calcium chloride or barium chloride are added to the salt mixture (to increase the density), these chlorides are partially reduced, leading to pickup of calcium or barium, respectively, by the metal phase. Reaction [1] can be utilized in two different recycling schemes. With a magnesium chloride free lithium chloride-potassium chloride mixture, remelting of magnesium-lithium alloys is possible without loss of lithium to the slag. On the other hand, the lithium can be separated from the magnesium by conversion to lithium chloride using a magnesium chloride rich slag.     

The effect of the elemental sulfur reaction product on the leaching of galena in ferric chloride media

The dissolution of galena in 0.3 M FeCl₃-0.3 M HC1 solutions containing 0 to 6 M LiCl was studied at 80 °C, and parabolic kinetics were observed at all LiCl concentrations. The leaching rate increases gradually with increasing LiCl concentrations to ≈4 M LiCl; the presence of >4 M LiCl results in a rapid increase in the leaching rate. The solubility of PbCl₂ in 0.3 M FeCl₃-0.3 M HC1 solutions containing 0 to 6.5 M LiCl was measured over the temperature range of 50 °C to 90 °C. The solubility increases systematically with increasing temperature and LiCl concentration. The parabolic kinetics, coupled with the correlation between the leaching rate and the solubility of PbCl₂, suggest that the dissolution of galena is controlled by the outward diffusion of the PbCl₂ reaction product through the constantly thickening layer of elemental sulfur formed during leaching. This conclusion is also supported by various morphological studies which consistently indicated a thin layer of PbCl₂ between the corroding galena and the porous elemental sulfur reaction product.