Ytterbium purification by an electrolysis reduction in sulfuric acid medium was investigated without nitrogen or argon protection, in which Ru-Ir-Ti alloy nets and mercury were used as anode and cathode, respectively....Ytterbium purification by an electrolysis reduction in sulfuric acid medium was investigated without nitrogen or argon protection, in which Ru-Ir-Ti alloy nets and mercury were used as anode and cathode, respectively. How the conditions such as the acidities of cathode and anode solutions, and the concentration of Yb（ Ⅲ ） to affect the circuit and ratio of Yb（ Ⅱ ）/Yb （ Ⅲ ） in electrolysis reduction were studied.展开更多
The reaction of the mixed rare earth concentrate including monazite ( REPO4 ) and bastnaesite ( REFCO3 )decomposed by CaO and NaCl additives at the temperature range from 100 to 1000 ℃ was studied by means of XRD and...The reaction of the mixed rare earth concentrate including monazite ( REPO4 ) and bastnaesite ( REFCO3 )decomposed by CaO and NaCl additives at the temperature range from 100 to 1000 ℃ was studied by means of XRD and TG-DTA.The results show that when CaO and NaCl are not added, only REFCO3 can be decomposed at the temperature of 377 ～ 450 ℃.The decomposition products include REOF, RE2O3 and CeO2.However, REFCO3 can not be decomposed.When CaO is added, the decomposition reactions occur at the temperature range from 660 to 750 ℃.CaO has three decomposition functions: ( 1 ) REPO4 can be decomposed by CaO and the decomposition products include RE2O3 and Ca3 (PO4)2; (2) CaO can decompose REOF, and the decomposition products are RE2O3 and CaF2; (3)CaO can decompose REPO4 with CaF2, and the decomposition products are RE2 O3, Ca5 F( PO4 )3.The decomposition ratio of the mixed rare earth concentrate increased obviously, when CaO and NaC1 were added.NaC1 can supply the liquid for the reaction, improve the mass transfer process and accelerate the reaction.At the same time, NaC1 participated in the reaction that REPO4 was decomposed by CaO.展开更多
The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface are...The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface area and XRD analysis. The studies indicate that the separation of the microemulsion phase during the preparation procedure can decrease the specific surface area of sample, adding hydrogen peroxide in the matrix solution can increase the specific surface area and stability of sample. The surface area of sample calcined at 550 ℃ for 5 h is 149 m^2·g^(-1), and that calcined at 900 ℃ for 6 h is 88 m^2·g^(-1). The sample with tetragonal symmetry Ce_(0.5)Zr_(0.5)O_2 phase has a higher stability.展开更多
Ce_（1–x）La_xO_y solid solution was simply prepared using mixed rare earth chloride（RECl_3·x H_2O, RE=Ce, La99%, containing unseparated Ce and La from rare earth metallurgical industry） as precursor by ultras...Ce_（1–x）La_xO_y solid solution was simply prepared using mixed rare earth chloride（RECl_3·x H_2O, RE=Ce, La99%, containing unseparated Ce and La from rare earth metallurgical industry） as precursor by ultrasonic-assisted co-precipitation method with different ultrasonic frequencies（CLf, f=200, 400, 600, 800, 1000 Hz）. A compared Ce_（1–x）La_xO_y solid solution（CL＊） was also prepared by the same mothod with 10% less precipitant. X-ray diffraction results confirmed the formation of Ce1–xLaxOy solid solution, and the crystal structures of these catalysts were not very sensitive to ultrasonic frequency and precipitant amount. However, both of the factors had obvious effect on morphology and surface area of CL, and precipitant amount seem to play a more crucial role than ultrasonic frequency for Ce_（1–x）La_xO_y solid solution preparation. When soot and catalyst were tight contacted, the peak temperature（Tpeak） of soot oxidation and oxygen reducing temperature for CLf catalysts decreased linearly with increasing surface area. Under loose contact condition, the Tpeak had obvious negative correlation with H_2 consumption. It was inferred that good reducibility of the Ce_（1–x）La_xO_y solid solution favored the soot oxidation reaction. The Ce_（1–x）La_xO_y solid solution prepared from unseparated rare earth chloride showed a good soot oxidaiton activity. Controlling the preparation conditions to prepare a CL catalyst would high surface area will enhance its reducibility and activity.展开更多
Based on the carbothermal reduction technology applied in industry,the dephosphorization behavior of Baotou mixed rare earth concentrate(Baotite) with carbon at high temperature was investigated.The experimental resul...Based on the carbothermal reduction technology applied in industry,the dephosphorization behavior of Baotou mixed rare earth concentrate(Baotite) with carbon at high temperature was investigated.The experimental results showed that both the charred coal and the coking coal were effective carbonaceous reductants for the dephosphorization of the Baotite.Among them,the charred coal was more suitable for the dephosphorus due to its high carbon content and lower volatile and ash.When the rare earth pellets,made by pressing the mixture of the Baotite,charred coal and water in mould,were roasted at 1500 oC for 2 h,its dephosphorus rate was as high as 98%.Roasting temperature was a main factor for the dephosphorus rate,and roast time was the second one.The size of both charred coal and coking coal also had influence on the dephosphorus,and was better less than 150 μm.展开更多
Two phosphorylcarboxylic acids,3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid(PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid(PPPA),were synthesized for separating yttrium from other rare eart...Two phosphorylcarboxylic acids,3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid(PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid(PPPA),were synthesized for separating yttrium from other rare earths in the chloride feed of ion-adsorption type rare earth concentrate.The effect of the factors such as pH_(1/2),temperature,saponification degree and phase modifiers was investigated.The separation efficiencies of PPA and PPPA are obviously better than the typical extractants such as sec-octylphenoxy acetic acid(CA-12) and naphthenic acid(NA).The extraction process of rare earths by PPA and PPPA is a cation exchanging reaction,which is similar to those of CA-12 and NA.The loaded rare earths in both PPA and PPPA systems can be effectively back-extracted by 0.5 mol/L HCl or higher concentration.A cascade extraction process for separating yttrium from other rare earths was developed using PPPA as the extractant.The yttrium product with the purity of 97.20 wt% was obtained by 35 stages of extraction and 12 stages of scrubbing.展开更多
Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. I...Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. In this work, a novel high-entropy(HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized. This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3, without reaction with Al2O3 as high as 1600℃ in air. Moreover, the thermal expansion coefficient(TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4(8.9 × 10^-6/℃ at 300–1000℃) is close to that of Al2O3. The thermal conductivity of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 at room temperature is as low as 2.08 W·m^-1·K^-1, which is about 42% lower than that of La PO4. Good chemical compatibility, close TEC to that of Al2O3, and low thermal conductivity indicate that HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3 f/Al2O3 composites.展开更多
Ⅰ. INTRODUCTION In recent years several double rare-earth oxide solid solutions have been synthesized and their physical properties have been determined. These studies are important for developing the rare-earth soli...Ⅰ. INTRODUCTION In recent years several double rare-earth oxide solid solutions have been synthesized and their physical properties have been determined. These studies are important for developing the rare-earth solid state physics science.展开更多
文摘Ytterbium purification by an electrolysis reduction in sulfuric acid medium was investigated without nitrogen or argon protection, in which Ru-Ir-Ti alloy nets and mercury were used as anode and cathode, respectively. How the conditions such as the acidities of cathode and anode solutions, and the concentration of Yb（ Ⅲ ） to affect the circuit and ratio of Yb（ Ⅱ ）/Yb （ Ⅲ ） in electrolysis reduction were studied.
文摘The reaction of the mixed rare earth concentrate including monazite ( REPO4 ) and bastnaesite ( REFCO3 )decomposed by CaO and NaCl additives at the temperature range from 100 to 1000 ℃ was studied by means of XRD and TG-DTA.The results show that when CaO and NaCl are not added, only REFCO3 can be decomposed at the temperature of 377 ～ 450 ℃.The decomposition products include REOF, RE2O3 and CeO2.However, REFCO3 can not be decomposed.When CaO is added, the decomposition reactions occur at the temperature range from 660 to 750 ℃.CaO has three decomposition functions: ( 1 ) REPO4 can be decomposed by CaO and the decomposition products include RE2O3 and Ca3 (PO4)2; (2) CaO can decompose REOF, and the decomposition products are RE2O3 and CaF2; (3)CaO can decompose REPO4 with CaF2, and the decomposition products are RE2 O3, Ca5 F( PO4 )3.The decomposition ratio of the mixed rare earth concentrate increased obviously, when CaO and NaC1 were added.NaC1 can supply the liquid for the reaction, improve the mass transfer process and accelerate the reaction.At the same time, NaC1 participated in the reaction that REPO4 was decomposed by CaO.
文摘The CeO_2-ZrO_2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface area and XRD analysis. The studies indicate that the separation of the microemulsion phase during the preparation procedure can decrease the specific surface area of sample, adding hydrogen peroxide in the matrix solution can increase the specific surface area and stability of sample. The surface area of sample calcined at 550 ℃ for 5 h is 149 m^2·g^(-1), and that calcined at 900 ℃ for 6 h is 88 m^2·g^(-1). The sample with tetragonal symmetry Ce_(0.5)Zr_(0.5)O_2 phase has a higher stability.
基金Project supported by National Natural Science Foundation of China(21403015)the Program of the General Research Institute for Nonferrous Metals(53515)
文摘Ce_（1–x）La_xO_y solid solution was simply prepared using mixed rare earth chloride（RECl_3·x H_2O, RE=Ce, La99%, containing unseparated Ce and La from rare earth metallurgical industry） as precursor by ultrasonic-assisted co-precipitation method with different ultrasonic frequencies（CLf, f=200, 400, 600, 800, 1000 Hz）. A compared Ce_（1–x）La_xO_y solid solution（CL＊） was also prepared by the same mothod with 10% less precipitant. X-ray diffraction results confirmed the formation of Ce1–xLaxOy solid solution, and the crystal structures of these catalysts were not very sensitive to ultrasonic frequency and precipitant amount. However, both of the factors had obvious effect on morphology and surface area of CL, and precipitant amount seem to play a more crucial role than ultrasonic frequency for Ce_（1–x）La_xO_y solid solution preparation. When soot and catalyst were tight contacted, the peak temperature（Tpeak） of soot oxidation and oxygen reducing temperature for CLf catalysts decreased linearly with increasing surface area. Under loose contact condition, the Tpeak had obvious negative correlation with H_2 consumption. It was inferred that good reducibility of the Ce_（1–x）La_xO_y solid solution favored the soot oxidation reaction. The Ce_（1–x）La_xO_y solid solution prepared from unseparated rare earth chloride showed a good soot oxidaiton activity. Controlling the preparation conditions to prepare a CL catalyst would high surface area will enhance its reducibility and activity.
基金Project supported by the National Natural Science Foundation of China (59804003)
文摘Based on the carbothermal reduction technology applied in industry,the dephosphorization behavior of Baotou mixed rare earth concentrate(Baotite) with carbon at high temperature was investigated.The experimental results showed that both the charred coal and the coking coal were effective carbonaceous reductants for the dephosphorization of the Baotite.Among them,the charred coal was more suitable for the dephosphorus due to its high carbon content and lower volatile and ash.When the rare earth pellets,made by pressing the mixture of the Baotite,charred coal and water in mould,were roasted at 1500 oC for 2 h,its dephosphorus rate was as high as 98%.Roasting temperature was a main factor for the dephosphorus rate,and roast time was the second one.The size of both charred coal and coking coal also had influence on the dephosphorus,and was better less than 150 μm.
基金Project supported by the National Key Research and Development Project of China(2019YFC0605003)the Strategic Priority Research Program of CAS(XDA02030100)。
文摘Two phosphorylcarboxylic acids,3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid(PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid(PPPA),were synthesized for separating yttrium from other rare earths in the chloride feed of ion-adsorption type rare earth concentrate.The effect of the factors such as pH_(1/2),temperature,saponification degree and phase modifiers was investigated.The separation efficiencies of PPA and PPPA are obviously better than the typical extractants such as sec-octylphenoxy acetic acid(CA-12) and naphthenic acid(NA).The extraction process of rare earths by PPA and PPPA is a cation exchanging reaction,which is similar to those of CA-12 and NA.The loaded rare earths in both PPA and PPPA systems can be effectively back-extracted by 0.5 mol/L HCl or higher concentration.A cascade extraction process for separating yttrium from other rare earths was developed using PPPA as the extractant.The yttrium product with the purity of 97.20 wt% was obtained by 35 stages of extraction and 12 stages of scrubbing.
基金financially supported by the National Natural Science Foundation of China (Nos. 51672064 and U1435206)
文摘Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. In this work, a novel high-entropy(HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized. This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3, without reaction with Al2O3 as high as 1600℃ in air. Moreover, the thermal expansion coefficient(TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4(8.9 × 10^-6/℃ at 300–1000℃) is close to that of Al2O3. The thermal conductivity of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 at room temperature is as low as 2.08 W·m^-1·K^-1, which is about 42% lower than that of La PO4. Good chemical compatibility, close TEC to that of Al2O3, and low thermal conductivity indicate that HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3 f/Al2O3 composites.
基金Project supported by the National Natural Science Foundation of China
文摘Ⅰ. INTRODUCTION In recent years several double rare-earth oxide solid solutions have been synthesized and their physical properties have been determined. These studies are important for developing the rare-earth solid state physics science.
