Neodymium naphthenate-loaded organic phase stripping using sodium oxalate solution was studied to explore the feasibility of synchronous rare earth-loaded organic phase stripping,rare earth precipitation,and blank org...Neodymium naphthenate-loaded organic phase stripping using sodium oxalate solution was studied to explore the feasibility of synchronous rare earth-loaded organic phase stripping,rare earth precipitation,and blank organic phase saponification.Experimental results show that loaded organic phase stripping,rare earth precipitation,and blank organic phase saponification can be realized simultaneously.When using 20% excess of sodium oxalate over the stoichiometry with the volume ratio of organic phase to aqueous phase of 1:1 at 25℃ for 40 min,the single stage stripping rate and saponification value are about 40% and 0.29 mol/L,respectively.After 16 stages of countercurrent continuous stripping,the stripping rate of neodymium can reach 99%,the saponification value is 0.42 mol/L,the Nd^(3+) concentration in saponified organic phase is less than 0.0020 mol/L,and the main phase in precipitation isNd_(2)(C2 O_(4))3·10 H_(2) O.Afterwards,this saponified organic phase can be used in the extraction of NdCl_(3) solution,and then the loaded organic phases(neodymium naphthenate) with 0.16 mol/L Nd^(3+) can be retrieved.The morphology,particle size distribution,and composition of theNd_(2)(C2 O_(4))3·10 H_(2) O products are similar to those of the current direct precipitation products.The neodymium oxide prepared by continuous calcination of neodymium oxalate meets the national standard of China(GB/T 5240-2015).These results prove the feasibility of stripping neodymium naphthenate-loaded organic phase by using sodium oxalate solution.Sodium oxalate can serve as a stripping agent,a saponifier,and a precipitator,thereby simplifying rare earth extraction and separation.This study provides theoretical and technical support for the development of a novel method for rare earth extraction and separation.展开更多
The precipitation performance and kinetics of gibbsite from sodium aluminate solution with different sodium oxalate concentrations as well as the corresponding influence mechanism of oxalate during the seed precipitat...The precipitation performance and kinetics of gibbsite from sodium aluminate solution with different sodium oxalate concentrations as well as the corresponding influence mechanism of oxalate during the seed precipitation process were systematically investigated by physicochemical properties test,using SEM and Raman spectra.As the concentration of sodium oxalate increases,both the precipitation rate and particle size of gibbsite decrease.The presence of sodium oxalate not only increases the viscosity of sodium aluminate solution,but also promotes the transformation of Al(OH)4^? to Al2O(OH)6^2?.The overall reaction rate constant decreases and the apparent activation energy of gibbsite increases with the increasing sodium oxalate concentration,the rate controlling step of which is chemical reaction.The needle-like sodium oxalate precipitates on the gibbsite crystals and covers the active Al(OH)3 seed sites,which leads to the lower precipitation rate and the finer particle size of gibbsite during the seed precipitation process.展开更多
Purification of original crude glycerol obtained from biodiesel production was conducted in a laboratory scale equipment by means of a combined chemical and physical treatment method based upon repeated cycles of acid...Purification of original crude glycerol obtained from biodiesel production was conducted in a laboratory scale equipment by means of a combined chemical and physical treatment method based upon repeated cycles of acidification of liquid phase to the desired pH value by using 5.85% H3PO4 solution for pH value adjustment, and the mixture was kept at 70 ℃ for 60 rain to make phase separation for obtaining a glycerol-rich middle phase. The yield of crude glycerol reached 81.2%. Subsequently, upon reaction of the obtained glycerol phase with 0.03% of sodium oxalate at 80 ℃ for 30 min the impurity removal rate was equal to 19.8%. The fraction boiling between 164 ℃ and 200 ℃ was collected by vacuum distil- lation followed by decolorization with 2% of active carbon at 80 ℃ for two times to yield the product glycerol with an ac- ceptable purity of 98.10%.展开更多
基金Project supported by the Cultivation Project of the State Key Laboratory of Green Development and High-value Utilization of Ionic Rare Earth Resources in Jiangxi Province(20194AFD44003)。
文摘Neodymium naphthenate-loaded organic phase stripping using sodium oxalate solution was studied to explore the feasibility of synchronous rare earth-loaded organic phase stripping,rare earth precipitation,and blank organic phase saponification.Experimental results show that loaded organic phase stripping,rare earth precipitation,and blank organic phase saponification can be realized simultaneously.When using 20% excess of sodium oxalate over the stoichiometry with the volume ratio of organic phase to aqueous phase of 1:1 at 25℃ for 40 min,the single stage stripping rate and saponification value are about 40% and 0.29 mol/L,respectively.After 16 stages of countercurrent continuous stripping,the stripping rate of neodymium can reach 99%,the saponification value is 0.42 mol/L,the Nd^(3+) concentration in saponified organic phase is less than 0.0020 mol/L,and the main phase in precipitation isNd_(2)(C2 O_(4))3·10 H_(2) O.Afterwards,this saponified organic phase can be used in the extraction of NdCl_(3) solution,and then the loaded organic phases(neodymium naphthenate) with 0.16 mol/L Nd^(3+) can be retrieved.The morphology,particle size distribution,and composition of theNd_(2)(C2 O_(4))3·10 H_(2) O products are similar to those of the current direct precipitation products.The neodymium oxide prepared by continuous calcination of neodymium oxalate meets the national standard of China(GB/T 5240-2015).These results prove the feasibility of stripping neodymium naphthenate-loaded organic phase by using sodium oxalate solution.Sodium oxalate can serve as a stripping agent,a saponifier,and a precipitator,thereby simplifying rare earth extraction and separation.This study provides theoretical and technical support for the development of a novel method for rare earth extraction and separation.
基金Projects(51774079,51674075)supported by the National Natural Science Foundation of ChinaProject(N182508026)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The precipitation performance and kinetics of gibbsite from sodium aluminate solution with different sodium oxalate concentrations as well as the corresponding influence mechanism of oxalate during the seed precipitation process were systematically investigated by physicochemical properties test,using SEM and Raman spectra.As the concentration of sodium oxalate increases,both the precipitation rate and particle size of gibbsite decrease.The presence of sodium oxalate not only increases the viscosity of sodium aluminate solution,but also promotes the transformation of Al(OH)4^? to Al2O(OH)6^2?.The overall reaction rate constant decreases and the apparent activation energy of gibbsite increases with the increasing sodium oxalate concentration,the rate controlling step of which is chemical reaction.The needle-like sodium oxalate precipitates on the gibbsite crystals and covers the active Al(OH)3 seed sites,which leads to the lower precipitation rate and the finer particle size of gibbsite during the seed precipitation process.
基金the financial support from Scientific Research Foundation for Doctoral Program of Liaoning Province(20081104)
文摘Purification of original crude glycerol obtained from biodiesel production was conducted in a laboratory scale equipment by means of a combined chemical and physical treatment method based upon repeated cycles of acidification of liquid phase to the desired pH value by using 5.85% H3PO4 solution for pH value adjustment, and the mixture was kept at 70 ℃ for 60 rain to make phase separation for obtaining a glycerol-rich middle phase. The yield of crude glycerol reached 81.2%. Subsequently, upon reaction of the obtained glycerol phase with 0.03% of sodium oxalate at 80 ℃ for 30 min the impurity removal rate was equal to 19.8%. The fraction boiling between 164 ℃ and 200 ℃ was collected by vacuum distil- lation followed by decolorization with 2% of active carbon at 80 ℃ for two times to yield the product glycerol with an ac- ceptable purity of 98.10%.
