The electrical conductivity of REF3-LiF(RE=La and Nd) molten salts(xREF3=5 mol%-40 mol%) was systematically measured over the temperature range from 1223 to 1423 K by using continuously varying cell constant(CVCC) met...The electrical conductivity of REF3-LiF(RE=La and Nd) molten salts(xREF3=5 mol%-40 mol%) was systematically measured over the temperature range from 1223 to 1423 K by using continuously varying cell constant(CVCC) method.Electrical conductivity values of LaF3-LiF and NdF3-LiF molten salts within the studied ranges are 4.11-9.39 and 3.62-9.51 S/cm,respectively.The composition and temperature dependences of electrical conductivity and the factor of RE2 O3 on electrical conductivity were investigated.The electrical conductivity nonlinearly decreases with the increasing mole percent of REF3 for the changing of structural ion in molten salts.A good linear relationship between the natural logarithm of electrical conductivity(lnκ) and the reciprocal of the absolute temperature(T-1) can be interpreted by the trend that electrical conductivity linearly increases with increasing temperature.Although it is an important factor of RE2 O3 on electrical conductivity,the influence of RE2 O3 on conductivity is small for the very limited solubility of RE2 O3 in REF3-LiF molten salts.The results of this work supplement the present electrical conductivity data of rare earth fluoride electrolyte.展开更多
The leaching kinetics of bastnaesite concentrate in HCl solution was investigated with respect to the effects of HCl concentration by changing HCl concentration,leaching temperature,liquid to solid ratio,and particle ...The leaching kinetics of bastnaesite concentrate in HCl solution was investigated with respect to the effects of HCl concentration by changing HCl concentration,leaching temperature,liquid to solid ratio,and particle size.A particle size of 25 μm was required to leach 89.6% RE2（CO3）3 and 1.5%REF3 at 90 ℃ for 90 min,when HCl concentration was 6 mol/L and liquid to solid ratio was 15：1.The leaching kinetics of bastnaesite concentrate is represented by shrinking core model with diffusion through a porous product layer.The activation energies for the dissolution reaction of RE2（CO3）3 and REF3 were calculated to be 59.39 kJ/mol and 66.13 kJ/mol respectively.展开更多
The chemical reaction and dissolution processes of RE2 O3 in REF3-LiF（RE = La and Nd） molten salts were studied by X-ray diffraction, differential thermal analysis and chemical analysis. Firstly, RE2 O3 disperses in...The chemical reaction and dissolution processes of RE2 O3 in REF3-LiF（RE = La and Nd） molten salts were studied by X-ray diffraction, differential thermal analysis and chemical analysis. Firstly, RE2 O3 disperses in molten salts and reacts with REF3 and LiF, which lead to the generation of a new phase REOF, resulting in the dissociation or formation of complex ions by part of REOF, and the sedimentation of excessive REOF at the bottom. The RE contents in molten salts were used to determine the solubility of RE2 O3. The results show that with 20 mol%-40 mol% of REF3, the solubility ranges from 1.79 to 3.05 g RE2 O3 per100 g electrolyte and the corresponding mole concentration is 0.33%-0.87%. RE2 O3 solubility increases with increasing temperature and REF3 concentration. The natural logarithm of the RE2 O3 solubility is plotted against 1/T and can be interpreted by linear relationship. The fitting parameters can be used to estimate the solubility of RE2 O3 with minimized experimental efforts and difficult experiment conditions.展开更多
基金the National High Technology Research and Development Program(2011AA03A409)Fundamental Research Funds for the Central Universities(N110202002)。
文摘The electrical conductivity of REF3-LiF(RE=La and Nd) molten salts(xREF3=5 mol%-40 mol%) was systematically measured over the temperature range from 1223 to 1423 K by using continuously varying cell constant(CVCC) method.Electrical conductivity values of LaF3-LiF and NdF3-LiF molten salts within the studied ranges are 4.11-9.39 and 3.62-9.51 S/cm,respectively.The composition and temperature dependences of electrical conductivity and the factor of RE2 O3 on electrical conductivity were investigated.The electrical conductivity nonlinearly decreases with the increasing mole percent of REF3 for the changing of structural ion in molten salts.A good linear relationship between the natural logarithm of electrical conductivity(lnκ) and the reciprocal of the absolute temperature(T-1) can be interpreted by the trend that electrical conductivity linearly increases with increasing temperature.Although it is an important factor of RE2 O3 on electrical conductivity,the influence of RE2 O3 on conductivity is small for the very limited solubility of RE2 O3 in REF3-LiF molten salts.The results of this work supplement the present electrical conductivity data of rare earth fluoride electrolyte.
基金Project(50974042)supported by the National Natural Science Foundation of ChinaProject(20090042120015)supported by Scientific Research Special Foundation of Doctor Subject of Chinese UniversitiesProject(N090302007)supported by the Fundamental Research Funds for the Central Universities,China
文摘The leaching kinetics of bastnaesite concentrate in HCl solution was investigated with respect to the effects of HCl concentration by changing HCl concentration,leaching temperature,liquid to solid ratio,and particle size.A particle size of 25 μm was required to leach 89.6% RE2（CO3）3 and 1.5%REF3 at 90 ℃ for 90 min,when HCl concentration was 6 mol/L and liquid to solid ratio was 15：1.The leaching kinetics of bastnaesite concentrate is represented by shrinking core model with diffusion through a porous product layer.The activation energies for the dissolution reaction of RE2（CO3）3 and REF3 were calculated to be 59.39 kJ/mol and 66.13 kJ/mol respectively.
基金supported by the National High Technology Research and Development Program(2011AA03A409)Fundamental Research Funds for the Central Universities(N110202002)
文摘The chemical reaction and dissolution processes of RE2 O3 in REF3-LiF（RE = La and Nd） molten salts were studied by X-ray diffraction, differential thermal analysis and chemical analysis. Firstly, RE2 O3 disperses in molten salts and reacts with REF3 and LiF, which lead to the generation of a new phase REOF, resulting in the dissociation or formation of complex ions by part of REOF, and the sedimentation of excessive REOF at the bottom. The RE contents in molten salts were used to determine the solubility of RE2 O3. The results show that with 20 mol%-40 mol% of REF3, the solubility ranges from 1.79 to 3.05 g RE2 O3 per100 g electrolyte and the corresponding mole concentration is 0.33%-0.87%. RE2 O3 solubility increases with increasing temperature and REF3 concentration. The natural logarithm of the RE2 O3 solubility is plotted against 1/T and can be interpreted by linear relationship. The fitting parameters can be used to estimate the solubility of RE2 O3 with minimized experimental efforts and difficult experiment conditions.
