LiF-DyF_3-Cu_2O-Dy_2O_3熔盐体系密度的影响因素研究

在探索出制取Dy-Cu中间合金方法的基础上,为了进一步优化电解过程的工艺参数,采用阿基米德法对LiF-DyF_3-Dy_2O_3-Cu_2O熔盐体系的密度进行了研究。考察了温度、单一氧化物(Dy_2O_3或Cu_2O)以及混合氧化物(Dy_2O_3与Cu_2O)对熔盐体系密度的影响,并通过最小二乘法对数据进行了拟合,建立了温度、 Dy_2O_3含量、 Cu_2O含量与熔盐密度之间的数学回归方程。研究结果表明,熔盐体系的密度随温度的升高而线性下降,而随单一氧化物加入量、混合氧化物加入量及混合氧化中w_(Dy_2O_3)与w_(Cu_2O)的比值增大而增大。在温度为910～1030℃,w_(Dy_2O_3)为0%～2.0%(质量分数),w_(Cu_2O)为0%～2.0%范围内,温度(t), Dy_2O_3加入量w_(Dy_2O_3), Cu_2O加入量w_(Cu_2O)与熔盐密度(ρ)的关系可以表示为:ρ=-7.01813-0.00163t+0.01832 w_(Dy_2O_3)+0.10289w_(Cu_2O)。从熔体密度角度来看,在氧化物的加入量满足2.0%≤w_(Dy_2O_3)+w_(Cu_2O)≤3.0%,w_(Dy_2O_3)∶w_(Cu_2O)3∶2,电解温度控制在960～980℃的条件下,电解LiF-DyF_3-Dy_2O_3-Cu_2O熔盐制取Dy-Cu合金较为理想。     

NaCl-KCl-NaF-(SiO2)熔盐体系密度

用阿基米德法测定了NaCl-KCl-NaF-(SiO2)熔盐体系的密度,结果表明:体系的密度与温度呈良好的线性关系,且随温度的升高而降低;当NaCl含量不变时,用KCl逐步代替NaF时体系的密度逐渐减小;当KCl含量不变时,用NaCl逐步代替NaF时,体系的密度与NaCl含量呈倒抛物线关系;体系在XNaCl∶XKCl=1∶1时,随NaF含量的增加,体系密度逐渐增大。     

Na_3AlF_6-AlF_3-LiF-MgF_2-La_2O_3-Al_2O_3熔盐体系密度的研究

采用阿基米德法研究温度、单一或混合添加La_2O_3与Al_2O_3对Na_3AlF_6-AlF_3-LiF-MgF_2熔盐体系密度的影响,并用最小二乘法建立了密度数学模型,确定了熔盐密度与温度、 La_2O_3与Al_2O_3加入量之间关系的回归方程,为了使熔盐与所制备的La-Al中间合金液的有效分离,从熔盐密度的角度分析了电解制备La-Al中间合金时的合理电解温度与氧化物加入量。研究结果表明:熔盐密度随温度的上升或Al_2O_3加入量的增加呈现线性降低的趋势,却随着La_2O_3加入量的递增而线性增加;当(质量分数)w_(La_2O_3)∶w_(Al_2O_3)=1∶9时,熔盐密度随La_2O_3-Al_2O_3混合氧化物加入量的增加而线性下降,当w_(La_2O_3)∶w_(Al_2O_3)=3∶7, 1∶1或7∶3时,密度却随La_2O_3-Al_2O_3混合氧化物加入量的增加而线性增加;在温度为905～1055℃, La_2O_3与Al_2O_3加入量分别为0%～5%, 0%～10%(质量分数)的研究范围内,熔盐密度(ρ)与温度(t), La_2O_3, Al_2O_3含量之间的关系为:ρ=3.0231-0.0011t+0.0260w_(La_2O_3)-0.0053w_(Al_2O_3),从而可以确定电解制取La-Al中间合金较为理想的Na_3AlF_6-AlF_3-LiF-MgF_2-La_2O_3-Al_2O_3熔融体系温度应控制在965～995℃之间,氧化物的加入量应满足条件w_(La_2O_3)+w_(Al_2O_3)9%,w_(La_2O_3)∶w_(Al_2O_3)1。     

NdF3-LiF-Nd2O3系熔盐密度的研究

用阿基米德法研究了ＮｄＦ３－ＬｉＦ体系熔盐的密度。采用二因子二次回归正交设计,得出密度（ρ）与ＮｄＦ３含量（ｃ）、温度（ｔ）的回归方程,讨论了ＮｄＦ３含量及温度对熔体密度的影响,并考察了加入Ｎｄ２Ｏ３对体系密度的影响。     

LiCl-Li_2O-LiF熔盐体系电导率的研究

对Li Cl-Li_2O-Li F熔盐体系的20组样品进行电导率的测定。测定结果表明:混合熔盐体系的电导率随温度升高而增大;利用最小二乘法对数据进行拟合,得到各组成的电导率与温度的一元二次方程式。最终得出结论:在一定范围内,添加Li_2O使熔盐的电导率减小,添加Li F使熔盐的电导率增大且降低该熔盐的初晶温度。     

熔盐体系表面张力的分子关联模型

将Ｒｅｉｓｓ提出的硬球表面张力模型用于计算纯熔盐和混合熔盐体系的表面张力，将硬球直径视为温度的函数，对２３个纯熔盐体系的表观张力进行了关联，得到相应的分子参数，表面张力的关联总体平均偏差为０．４８％，应用发ｖａｎｄｅｒＷａａｌｓ理论－１混合规则，将Ｒｅｉｓｓ的表面张力模型推广到混合熔盐体系，对２７个二元熔盐混合体系的张面张力进行了预测和关联，总体平均偏差分别为３．３８％和１．０４％，其结果能满足工     

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 ℃.      

冰晶石-月壤熔盐体系初晶温度的研究

冰晶石熔盐电解法可实现月壤原位利用制备金属和氧气,研究冰晶石-月壤熔盐体系的初晶温度对电解槽稳定运行具有重要意义。本文以火山渣和玄武岩复配的NEU-1月壤仿真样为原料,与冰晶石、CaF₂混合配置电解质,将其作为待测试样,利用差热分析法测量了不同月壤仿真样添加量、不同分子比的冰晶石熔盐体系的初晶温度。结果表明,当分子比为2.2时,随着月壤仿真样添加量从0%增加至24%,冰晶石熔盐体系的初晶温度从974.9℃降低至932.0℃;每添加1%的月壤仿真样,冰晶石熔盐体系的初晶温度降低约1.79℃;当月壤仿真样添加量为8%时,随着分子比从2.2升高至2.7,冰晶石熔盐体系的初晶温度从960.0℃升高至979.4℃。     

CaCl_2-CaF_2-CaO-SiO_2熔盐体系基础性质研究

分析了加入不同质量分数的CaO-SiO_2对CaCl_2-CaF_2空白熔盐的电导率、密度以及初晶温度的影响。结果表明,每添加2%的CaO-SiO_2,熔盐体系的初晶温度平均升高17.5℃、密度相应增加0.015 1g/cm~3、电导率增大0.224 13S/cm,侧面论证了CaO-SiO_2在基础体系中以硅酸盐分子形式存在。     

镁基六铝酸镧陶瓷强化烧结和熔盐腐蚀行为

采用二步固相高温烧结法制备镁基六铝酸镧(LaMgAl_(11)O_(19))陶瓷材料,并在1050℃稀土氟化物熔盐体系中进行腐蚀试验。利用X射线衍射仪、扫描电子显微镜、EDX能谱仪等表征手段测试分析烧结试样的物相组成和显微结构以及腐蚀试样的物相组成、表层形貌和元素分布。研究烧结温度对LaMgAl_(11)O_(19)陶瓷试样微观组织和耐熔盐腐蚀性能的影响,探讨LaMgAl_(11)O_(19)陶瓷材料的熔盐腐蚀行为。结果表明,随着烧结温度的提高,LaMgAl_(11)O_(19)陶瓷相对密度增加,腐蚀样中稀土氟化物特征熔盐CeF_3渗透量减少;1700℃烧结后,陶瓷体相对密度为87.6%,1050℃混合稀土氟化物熔盐电解质体系腐蚀24 h,腐蚀样中CeF_3质量分数为2.37%;熔盐腐蚀层厚度约为30μm左右。     

氟钽酸钾及其混合熔盐体系表面张力的测定

推导了柱体最大拉力法的一个经验公式用于测定熔盐体系的表面张力，并验证了该公式的正确和实用性，并用该最大拉力法测定了氟钽酸钾及其和氯化钠，氯化钾，氟化钠，氟化钾等混合熔盐体系在熔融状态下的表面张力。     

Corrosion-electrochemical behavior of zirconium in molten alkali metal carbonates

The corrosion and electrochemical characteristics of zirconium during its interaction with molten lithium, sodium, and potassium carbonates containing from 1 to 5 wt % additives to the salt phase are studied in a temperature range of 500–800°C using gravimetry, corrosion potential measurement, and anodic polarization. The substances decreasing the corrosion losses due to the strengthening and thickening of an oxide film (lithium, sodium, potassium hydroxides) are used as passivators. Sodium chloride, fluoride, and sulfate serve as corrosion stimulators (activators).     

Electrolytic Extraction of Beryllium

Beryllium possesses certain unique mechanical and physical properties which make it a special engineering material and an important alloy addition. However, its low density, high reactivity and high melting point along with its occurrence in the form of a very stable beryl ore—containing only about five percent beryllium—make its extraction difficult. The electrowinning of beryllium from molten beryllium and sodium chloride salt-mix is a low temperature commercial process. Conversion of beryl ore into beryllia precedes the fused salt electrolysis and several purification techniques are followed to produce high purity beryllium metal. This paper reviews the existing major industrial processes for beryllium production. A modified beryllium chloride-beryllium fluoride fused salt electrolysis is suggested on similar principles but with added advantage of a semi-continuous high efficiency process. The electrode reactions for this salt system have been analysed on the basis of reaction rate theory and the influence of operating parameters, such as the temperature, electrode areas, current density, etc., on the cell potential has been identified. A possible basic cell design has also been proposed.     

Corrosion-electrochemical behavior of nickel in an alkali metal carbonate melt under a chlorine-containing atmosphere

The corrosion-electrochemical behavior of a nickel electrode is studied in the melt of lithium, sodium, and potassium (40: 30: 30 mol %) carbonates in the temperature range 500–600°C under an oxidizing atmosphere CO₂ + 0.5O₂ (2: 1), which is partly replaced by gaseous chlorine (30, 50, 70%) in some experiments. In other experiments, up to 5 wt % chloride of sodium peroxide is introduced in a salt melt. A change in the gas-phase composition is shown to affect the mechanism of nickel corrosion.     

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。     

Controlled phase equilibria for the chemical utilization of sea-bitterns

The waste sea-bitterns rejected at solar salt plants are utilized, by applying successive solar evaporation, controlled phase equilibria and fractional crystallization, for the recovery of valuable mineral salts and marine chemicals such as: sodium chloride, sodium sulphate, magnesium sulphate, potassium salt of bittern, potassium chloride, magnesium chloride and bromine.     

低氧冶金级钽粉的生产工艺及产品性能

对低氧冶金级钽粉的生产工艺及产品性能进行了分析。通过钠还原氟钽酸钾的生产工艺得到的钽粉(FTa-1)是由许多原生粒子(又称一次粒子)结合组成、高比表面积空间网状结构的多孔团聚体,松装密度最小,比表面积最大,相应的氧含量也最高。经过氢化制粉得到的钽粉(FTa-2、FTa-3),经过高温烧结实现了致密化,颗粒形貌单一,是高纯的实心颗粒粉末,其松装密度大,比表面积较小,相应的氧含量也低。FTa-2、FTa-3钽粉比较适合于医用多孔钽的及3D打印的应用。     

Formation of oxide layers on aluminum, niobium, and tantalum in molten alkali metal carbonates

The electrochemical synthesis of niobium, tantalum, and aluminum oxide nanolayers is studied in the melt of lithium, sodium, and potassium carbonates with various additives to a salt phase in an oxidizing atmosphere at a temperature of 773 and 873 K. A scheme is proposed for high-temperature anion local activation of the process.     

Equilibria between ferrous and ferric chlorides in molten chloride salts

Equilibria between ferrous and ferric chlorides in molten salts have been studied for improving magnesium electrolysis and molten salt chlorination. The apparent equilibrium constants,K, of reaction FeCl_2(melt)+0.5Cl_2(gas)=FeCl_3(melt) were obtained. Measured values ofK were in good agreement with computed ones from regression equations. The composition of the melts, the partial pressure of chlorine, and the temperature were found to have important effects onK, and the effect of dissolved iron was smaller than that of other factors. At identical other conditions, the largest values ofK were observed in system 3, which suggested that the current efficiency for electrolysis of MgCl₂ should be lower when carnallite was used as electrolyte and that catalysis of iron species in molten salt chlorination would be better when molten salt systems containing high potassium chloride were used.     

磷钼蓝光度法快速测定碳素结构钢中磷的改进

试样以稀硝酸溶解后,用高锰酸钾氧化磷为磷酸,然后加入钼酸铵-酒石酸钾钠溶液与磷酸生成磷钼酸络离子,在氟化钠存在下,氯化亚锡溶液将其还原为磷钼蓝后,迅速加入氢氧化钠溶液降低酸度,以提高磷钼蓝色泽的稳定性。光度法线性好,相对标准偏差小于2.1369%,满足了炼钢生产的需要。