The mixer-settler is a core device of solvent extraction for separating rare earth elements. There are some adverse effects like high rare earth accumulation and poor production efficiency during industrial production...The mixer-settler is a core device of solvent extraction for separating rare earth elements. There are some adverse effects like high rare earth accumulation and poor production efficiency during industrial production. Current researches usually focus on changing the structure of the mixer-settler without making a breakthrough towards gravity clarification. In this paper, in order to improve the efficiency of clarification, a mixer-settler with double stirring mode was designed and manufactured by adding a stirring device in the settler after reducing the volume of the settler. The innovation of this research involves adopting the ultraviolet-visible spectrophotometer to investigate the quantity of aqueous phase entrainment at the settler outlet in order to measure the clarification degree. Experimental results show that the clarification effect with stirring is better than that without stirring. The clarification effect is ameliorated as the stirring speed increases. Generally, the clarification effect shows a best condition when the offset distance is 12.5 cm, making the phase entrainment reduced to less than 0.1%. When the clearance over the tank bottom is 7 cm and 10 cm, respectively, the quantity of aqueous phase entrainment is better than the case with a clearance of 4 cm. The results show that the stirring paddle close to the mixed phase zone can better promote the two-phase separation.展开更多
A coaxial mixer consisting of an anchor and a Rushton turbine was selected as the research object,whose solid suspension characteristics were studied with the help of Computational Fluid Dynamics(CFD)method.Based on t...A coaxial mixer consisting of an anchor and a Rushton turbine was selected as the research object,whose solid suspension characteristics were studied with the help of Computational Fluid Dynamics(CFD)method.Based on the Eulerian–Eulerian method and modified Brucato drag model,the just-suspension speed of impeller was predicted,and the simulation results were in good agreement with the experimental data.The quality of solid suspension under different rotation modes was also compared,and the results showed the coaxial mixer operating under co-rotation mode could get the best performance,and a larger anchor speed was beneficial to solid suspension by enhancing the turbulent intensity at the bottom.Compared with the anchor,the inner Rushton turbine played a dominant role in solid suspension due to its high rotational speed,whereas an extremely high inner impeller speed would make the uniformity of solid distributions become worse.Additionally,the effects of solid phase properties were also investigated,the results revealed that the higher the overall solid volume fraction and the smaller the Shields number,the worse the performance of solid suspension,meanwhile the solid suspension was more susceptible to solid density compared with particle diameter within the same Shields number gradient.展开更多
基金supported by Hi-Tech Research and Development Program(863)of China(2010AA03A405)the National Natural Science Foundation of China(No.50974035,No.51004033)
文摘The mixer-settler is a core device of solvent extraction for separating rare earth elements. There are some adverse effects like high rare earth accumulation and poor production efficiency during industrial production. Current researches usually focus on changing the structure of the mixer-settler without making a breakthrough towards gravity clarification. In this paper, in order to improve the efficiency of clarification, a mixer-settler with double stirring mode was designed and manufactured by adding a stirring device in the settler after reducing the volume of the settler. The innovation of this research involves adopting the ultraviolet-visible spectrophotometer to investigate the quantity of aqueous phase entrainment at the settler outlet in order to measure the clarification degree. Experimental results show that the clarification effect with stirring is better than that without stirring. The clarification effect is ameliorated as the stirring speed increases. Generally, the clarification effect shows a best condition when the offset distance is 12.5 cm, making the phase entrainment reduced to less than 0.1%. When the clearance over the tank bottom is 7 cm and 10 cm, respectively, the quantity of aqueous phase entrainment is better than the case with a clearance of 4 cm. The results show that the stirring paddle close to the mixed phase zone can better promote the two-phase separation.
基金Supported by the Natural Science Foundation of China,Zhejiang Province(LY16B060003)the National Natural Science Foundation of China(21776246).
文摘A coaxial mixer consisting of an anchor and a Rushton turbine was selected as the research object,whose solid suspension characteristics were studied with the help of Computational Fluid Dynamics(CFD)method.Based on the Eulerian–Eulerian method and modified Brucato drag model,the just-suspension speed of impeller was predicted,and the simulation results were in good agreement with the experimental data.The quality of solid suspension under different rotation modes was also compared,and the results showed the coaxial mixer operating under co-rotation mode could get the best performance,and a larger anchor speed was beneficial to solid suspension by enhancing the turbulent intensity at the bottom.Compared with the anchor,the inner Rushton turbine played a dominant role in solid suspension due to its high rotational speed,whereas an extremely high inner impeller speed would make the uniformity of solid distributions become worse.Additionally,the effects of solid phase properties were also investigated,the results revealed that the higher the overall solid volume fraction and the smaller the Shields number,the worse the performance of solid suspension,meanwhile the solid suspension was more susceptible to solid density compared with particle diameter within the same Shields number gradient.
