The recycling of rare earth elements（REE） from end-of-life REE based products is an environment friendly proposition. Waste Sm-Co based permanent magnet generated during machining is a good source for both Sm and Co...The recycling of rare earth elements（REE） from end-of-life REE based products is an environment friendly proposition. Waste Sm-Co based permanent magnet generated during machining is a good source for both Sm and Co. In the present study a simpler process of acid leaching at 80 ℃ followed by solvent extraction, oxalate precipitation and calcination is described for producing pure Sm2 O3 and Co3 O4. With either 10 vol% H2SO4 or 15 vol% HCI at 80 ℃ more than 95% Sm and Co are leached in 1 h.Extraction of Sm from sulphate leach liquor with TBP or Aliquat 336 was poor. Although extraction with TOPS-99 is quantitative but Sm from sulphate leach liquor precipitated as Sm2（SO4）3·8 H2O. The chloride leach liquor at an initial pH of 2.5 and with 1.2 mol/L TOPS-99 shows requirement of 4-stages at A：O = 3：2. Stripping with oxalic acid precipitates Sm-oxalate which is calcined at 800 ℃ to produce Sm2 O3. Co3 O4 is recovered from the raffinate through oxalate precipitation followed by calcination at450℃.展开更多
Separation of rare earth dements by solvent extraction has actually been widely used in various fields from analytical chemistry to hydrometallurgy. A representative ore sample obtained from Kadabora Batholiths-Easter...Separation of rare earth dements by solvent extraction has actually been widely used in various fields from analytical chemistry to hydrometallurgy. A representative ore sample obtained from Kadabora Batholiths-Eastern Desert of Egypt, containing the multiple oxides rare earth minerals： Samarskite, Fergusonite, Betafite, and Pyrochlore, was subjected to sulfuric acid leaching. Different sets of equilibrium loading experiments were carded out on a bench scale for the extraction of rare earths （cerium and yttrium） from the sulfate leach liquor using 8,9-dihydro[1,2,4]triazolo[1,5-a]quinazolin-6（TH）-one {TQ} dissolved in methylene chloride. Stripping was carded out by 20% sodium hydroxide. A rare earth cake was produced by oxalic acid precipitation. Its purity reached 87.3%.展开更多
Tributyl phosphate(TBP) was employed for the Bi(Ⅲ) extraction from hydrochloric acid medium.The effects of extraction time and material concentration were examined.The replacement mechanism between the anion(Cl^-) an...Tributyl phosphate(TBP) was employed for the Bi(Ⅲ) extraction from hydrochloric acid medium.The effects of extraction time and material concentration were examined.The replacement mechanism between the anion(Cl^-) and TBP was proposed for extraction.The results show the species extracted into the organic phase were found to be mainly BiCl_3·x TBP(x=2 or 3).Thermodynamic parameters of the extraction reaction were obtained from the thermodynamics analysis,which illustrates that higher temperatures show a negative effect on the extraction.Extraction isotherm was obtained with 2.16 mol/L TBP for a typical solution containing 0.1 mol/L of bismuth and 1.0 mol/L of hydrochloric acid.About 98.5 % of bismuth has been extracted from the leaching solution under the optimum condition.Moreover,oxalate was explored as a precipitation stripping agent for BiCl_3·x TBP(x=2 or 3) complexes,by which Bi(Ⅲ) was stripped in the form of Bi_2(C_2O_4)_3·7H_2O.A stripping efficiency of 99.3% was obtained in only one stage at the phase ratio of 1 and TBP also could be recycled.Therefore,the method is an efficient,effective and highly selective approach to extract Bi(Ⅲ) and to recover metal bismuth.展开更多
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 facile chemical synthesis of silver sulphide nanocrystals from metal-loaded organic media, containing a silver-selective organophosphorous ligand as extractant, is reported. The method involves the phase-transfer ...The facile chemical synthesis of silver sulphide nanocrystals from metal-loaded organic media, containing a silver-selective organophosphorous ligand as extractant, is reported. The method involves the phase-transfer of silver species from aqueous nitrate media to organic solution using the commercial extractant Cyanex? 471x (tri-isobutylphosphine sulphide, Cytec Co.) as extractant, followed by precipitation stripping using ammonium sulphide as strip reagent. The nanoparticles were structurally characterized, and some aspects of the synthetical process, are briefly discussed. Under the conditions studied, the extractant Cyanex? 471x was able to act as stabilizer adsorbing on the particles surface, maintaining the size of the particles nanometrical.展开更多
Ultra-fine zinc oxalate powders were prepared through a precipitation stripping method with bis(2-ethylhexyl)phosphate(HDEHP)diluted by tetrachloride carbon as the extractant,and oxalic acid ethanol aqueous solution a...Ultra-fine zinc oxalate powders were prepared through a precipitation stripping method with bis(2-ethylhexyl)phosphate(HDEHP)diluted by tetrachloride carbon as the extractant,and oxalic acid ethanol aqueous solution as the re-extractant and precipitator.Zinc oxide powders were obtained by decomposing zinc oxalate powders at 450℃.The prepared zinc oxide powders were characterized by transmission electron microscope(TEM),Scanning electron microscope(SEM),Thermogravimetric analysis(TG),X-ray diffraction(XRD)and Fourier transmission infrared(FT-IR)spectrum.The photocatalytic performance of methylene blue by zinc oxide was studied based on the Langmuir model and Photo-Layer model.The results show that some zinc oxide powders were micro-multipore materials with hexagonal crystal.The particle size was around 32 nm.The photocatalytic process was the control step in the chemical reaction.The photo catalytic process followed pseudo-first order kinetics and NOH concentration inside the photo-layer in different reaction condition were calculated according to the Photo-Layer model.展开更多
基金supported by Sustainable Technologies for the Utilisation of Rare Earths(SURE),CSC-0132 supported by CSIR,India
文摘The recycling of rare earth elements（REE） from end-of-life REE based products is an environment friendly proposition. Waste Sm-Co based permanent magnet generated during machining is a good source for both Sm and Co. In the present study a simpler process of acid leaching at 80 ℃ followed by solvent extraction, oxalate precipitation and calcination is described for producing pure Sm2 O3 and Co3 O4. With either 10 vol% H2SO4 or 15 vol% HCI at 80 ℃ more than 95% Sm and Co are leached in 1 h.Extraction of Sm from sulphate leach liquor with TBP or Aliquat 336 was poor. Although extraction with TOPS-99 is quantitative but Sm from sulphate leach liquor precipitated as Sm2（SO4）3·8 H2O. The chloride leach liquor at an initial pH of 2.5 and with 1.2 mol/L TOPS-99 shows requirement of 4-stages at A：O = 3：2. Stripping with oxalic acid precipitates Sm-oxalate which is calcined at 800 ℃ to produce Sm2 O3. Co3 O4 is recovered from the raffinate through oxalate precipitation followed by calcination at450℃.
文摘Separation of rare earth dements by solvent extraction has actually been widely used in various fields from analytical chemistry to hydrometallurgy. A representative ore sample obtained from Kadabora Batholiths-Eastern Desert of Egypt, containing the multiple oxides rare earth minerals： Samarskite, Fergusonite, Betafite, and Pyrochlore, was subjected to sulfuric acid leaching. Different sets of equilibrium loading experiments were carded out on a bench scale for the extraction of rare earths （cerium and yttrium） from the sulfate leach liquor using 8,9-dihydro[1,2,4]triazolo[1,5-a]quinazolin-6（TH）-one {TQ} dissolved in methylene chloride. Stripping was carded out by 20% sodium hydroxide. A rare earth cake was produced by oxalic acid precipitation. Its purity reached 87.3%.
基金Project(2011AA061002)supported by the High-Tech Research and Development Program of ChinaProject(2010SK2010)supported by the Key Program of Science and Technology of Hunan Province,ChinaProject supported by the Hunan Nonferrous Metals Fund,China
文摘Tributyl phosphate(TBP) was employed for the Bi(Ⅲ) extraction from hydrochloric acid medium.The effects of extraction time and material concentration were examined.The replacement mechanism between the anion(Cl^-) and TBP was proposed for extraction.The results show the species extracted into the organic phase were found to be mainly BiCl_3·x TBP(x=2 or 3).Thermodynamic parameters of the extraction reaction were obtained from the thermodynamics analysis,which illustrates that higher temperatures show a negative effect on the extraction.Extraction isotherm was obtained with 2.16 mol/L TBP for a typical solution containing 0.1 mol/L of bismuth and 1.0 mol/L of hydrochloric acid.About 98.5 % of bismuth has been extracted from the leaching solution under the optimum condition.Moreover,oxalate was explored as a precipitation stripping agent for BiCl_3·x TBP(x=2 or 3) complexes,by which Bi(Ⅲ) was stripped in the form of Bi_2(C_2O_4)_3·7H_2O.A stripping efficiency of 99.3% was obtained in only one stage at the phase ratio of 1 and TBP also could be recycled.Therefore,the method is an efficient,effective and highly selective approach to extract Bi(Ⅲ) and to recover metal bismuth.
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This work was supported by grants from the Fondo de Apoyo a la Investigación(UASLP)and Fondos Mixtos Consejo Nacional de Ciencia y Tecnología-Gobierno de San Luis Potosí(Project FMSLP 2002-5630).
文摘The facile chemical synthesis of silver sulphide nanocrystals from metal-loaded organic media, containing a silver-selective organophosphorous ligand as extractant, is reported. The method involves the phase-transfer of silver species from aqueous nitrate media to organic solution using the commercial extractant Cyanex? 471x (tri-isobutylphosphine sulphide, Cytec Co.) as extractant, followed by precipitation stripping using ammonium sulphide as strip reagent. The nanoparticles were structurally characterized, and some aspects of the synthetical process, are briefly discussed. Under the conditions studied, the extractant Cyanex? 471x was able to act as stabilizer adsorbing on the particles surface, maintaining the size of the particles nanometrical.
基金supported by the National Natural Science Foundation of China(Grant No.20476010).
文摘Ultra-fine zinc oxalate powders were prepared through a precipitation stripping method with bis(2-ethylhexyl)phosphate(HDEHP)diluted by tetrachloride carbon as the extractant,and oxalic acid ethanol aqueous solution as the re-extractant and precipitator.Zinc oxide powders were obtained by decomposing zinc oxalate powders at 450℃.The prepared zinc oxide powders were characterized by transmission electron microscope(TEM),Scanning electron microscope(SEM),Thermogravimetric analysis(TG),X-ray diffraction(XRD)and Fourier transmission infrared(FT-IR)spectrum.The photocatalytic performance of methylene blue by zinc oxide was studied based on the Langmuir model and Photo-Layer model.The results show that some zinc oxide powders were micro-multipore materials with hexagonal crystal.The particle size was around 32 nm.The photocatalytic process was the control step in the chemical reaction.The photo catalytic process followed pseudo-first order kinetics and NOH concentration inside the photo-layer in different reaction condition were calculated according to the Photo-Layer model.
