LaCl3-KCl熔盐体系物化性质研究

合理选择熔盐体系在电解法制备稀土金属工业生产过程中至关重要。文中采用阿基米德法、拉筒法和连续变电导池常数法（CVCC）测定了不同配比的LaCl₃-KCl熔盐在1 073~1 223 K下的密度、界面张力和电导率。结果表明，随着温度升高，相同成分的LaCl₃-KCl熔盐的密度（ρ）和界面张力（σ）均呈降低趋势，而电导率（κ）逐渐增大；在相同温度下，随着LaCl₃含量增加，LaCl₃-KCl熔盐的密度和界面张力均逐渐增大，而电导率逐渐减小。通过拟合获得密度、界面张力以及电导率的经验公式分别为ρ=a-b×T×10-3、σ=a-b×T×10-3、κ=A+B×T×10-3+C×T2×10-6，明晰了熔盐的物化性质随温度及组分的变化规律，为熔盐电解法制备镧及其镧合金提供科学依据。 

Study on the physicochemical properties of the LaCl3-KCl molten salt system

Reasonable selection of molten salt systems is crucial in the industrial production process of the rare earth metal industry prepared by electrolysis. The density, surface tension and conductivity of LaCl₃-KCl molten salt of different ratios at 1 073—1 223 K were determined by the Archimedes method, tube pulling method and continuous variable conductivity cell constant method (CVCC). The results show that as the temperature increases, the density (ρ) and interface tension (σ) of the LaCl₃-KCl molten salt of the same component decrease, while the conductivity (κ) gradually increases. At the same temperature, with increasing LaCl₃ content in the molten salt, the density and interfacial tention increase, while the conductivity gradually decreases. The empirical formulas for density, interface tension and conductivity are, ρ=a-b×T×10-3, σ=a-b×T×10-3, κ=A+B×T×10-3+C×T2×10-6, respectively. The change law of the physicochemical properties of molten salt with temperature and components is clarified, which provides a scientific basis for the preparation of lanthanum and its alloys by molten salt electrolysis.