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Efficient Flotation Tests on Luanchuan Molybdenum Ore

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 1-4
Flotation tests on Luanchuan molybdenum ore were carried out by one-stage rougher-two-stage scavenger-one-stage cleaner flotation in closed circuit with soluble glass as inhibiting agent and MBF-103 as collector. The molybdenum grade and recovery of the resultant concentrate is 5. 304 0 % and 92.24% respectively. Compared with conventional process with kerosene as collector, the above process has higher flotation efficiency.
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Study on Non-uniformity Law in Tungsten Smelting Solution System

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 5-9
The non-uniformity law was studied in tungsten smelting solution systems such as sodium tung- state solution, ammonium tungstate solution and strippant solution. The results show that WO4^2- has a greater non-uniformity degree than Cl^- ,and non-uniformity rate first increases and then decreases for all the three solution systems. The non-uniformity phenomenon is not obvious for OH^- of a smaller molar mass. For WO4^2- ,Cl^- and OH^- ,the greater the ratio of molar mass to ionic radius,the greater the non-uniformity degree of the solution. And the non-uniformity rate is much slower for the solution of large viscosity.
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Experimental Study of Molybdate Reduction with Copper

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 10-13
On the basis of electrochemical properties difference, Mo reduction experiment was carried out with Cu as the reductant and EDTA as the complexing agent or without complexing agent. The effects of EDTA dosage,acidity,reducing time and temperature on Mo reduction rate were studied. The results show that EDTA addition results in Mo reduction rate decreased. Cu direct reduction reaction can be adopted. And Mo reduction rate is improved at pill. 0-1.5,60℃ reaction temperature and with longer reduction time.
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Vanadium Extraction from Vanadium-containing Carbonaceous Shale by Acid Leaching-Extraction-Ammonia Precipitation

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 14-17
V2O5 was extracted from vanadium-containing; carbonaceous shale in Jiangxi using the process of carbon removal by oxidation roasting-oxidation leaching in sulfuric acid-solvent extraction in P204 + TBP system-vanadium precipitation with ammonia. The effects of H2SO4 dosage,extraction and stripping stages and stripping solution pH on the process were studied. The results show that the leaching rate of vanadium can exceed 96% by vanadium ore crushing and then oxidation leaching using sodium chlorate in sulfuric acid solution. The product containing more than 98.0% V2O5 is obtained by P204+TBP solvent extraction -dilute sulfuric acid solution stripping-vanadium precipitation with ammonia. And the total recovery of V205 is 86.14~93.09% from ore to product. The process has high vanadium recovery,simple operation, low production costs and less environmental pollution.
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Adsorption Behavior of Chelate Resin for Vanadium(Ⅳ) Ion

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 18-20
The adsorption behavior of chelate resin A for vanadium (Ⅳ) ion was studied,and the effects of acidity, resin dosage, reaction time and temperature and concentration of the standard vanadium solution on static adsorption were investigated. The results show that chelate resin A can adsorb 184.2 mg/g vanadium (Ⅳ) under the conditions of pH4,1.0 g resin, 60 ℃× 4 h reaction. In addition, desorption behavior of the chelate resin and effect of coexisting cations were analyzed.
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Effects of Plasma Mo Penetration on the Wear Resistance and Tensile Property of the Alloy TC4

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 21-25
The wear resistance and tensile property of TC4 was studied after its surface was treated with plasma Mo penetration. SEM, EDS and SMM were used to analyze the microstructure, composition and fracture morphology of the layer modified by Mo penetration, and then its wear mechanism and tensile property were discussed. The results show that when treated with plasma Mo penetration,the TC4 surface has better wear resistance with higher hardness, and its tensile strength is only slightly lower than the original substrate. Therefore, the wear resistance of the alloy can be improved through plasma Mo penetration without change of mechanical property of the substrate.
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Analysis of the Temperature Stability Defect of Sintered Nd-Fe-B Magnet

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 26-29
The cause of abnormally high open-circuit flux irreversible loss (hirr) in the sintered Nd-Fe-B magnet was investigated by the means of SEM,EDAX and powder particle size analysis. The results show that non-uniform crystal grain size distribution and coarse grains in the magnet microstructure are the main factors leading to the temperature stability defects of the magnet,i, e. a small amount of the finished magnet showing abnormally high hirr The basic measure for preparing the sintered Nd-Fe-B magnet with excel- lent temperature stability is to improve the techniques of ingot casting and powder preparation, avoiding coarse powder particles,reducing very fine powder particles and ensuring uniform fine magnet microstruc- ture.
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Preparation of BaMgAl10O17∶Eu2+ Blue Phosphor with Microwave Heating

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 30-33
The blue phosphor BaMgAl10O17 : Eu^2+ (BAM : Eu^2+) was prepared with microwave heating. The effects of synthesis temperature, heat preservation time and heating rate on the luminescent properties of BAM : Eu^2+ were studied by orthogonal tests. XRD results show that the blue phosphor BAM : Eu^2+prepared with microwave heating is hexagonal with the space group P63/mmc. The results from spectral analysis show that the peak wavelength of the sample is 450 nm,corresponding to Eu2+ broadband transition 4f^65d→4f^7(^8S7/2). And the chromaticity coordinates x and y are equal to 0. 146 3 and 0. 069 3 respectively. The relative brightness is 106.8%. The results from particle size analysis show that the center size Ds0 is 7.00 μm and particle size distribution is concentrated.
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The Latest and Future Development of Nitride Phosphor Used in White LED

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 34-37
:The latest development of nitride phosphor used in white LED is reviewed, and the problems and trends are analyzed. The nitride phosphor M2Si5 N8 : Eu(M= Ca, Sr,Ba) is emphatically introduced. Appli- cation prospect of new nitride phosphor is pointed out. Preparation of high purity metal materials such as Eu,Ca,Sr and synthesis of nitride powders are critical for the development of new nitride phosphor.
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The Effects of ZrO_2 Addition on the Mechanical Property of Si_3N_4 Composite Ceramic Material

Rare Metals and Cemented Carbides | Vol., Issue 1, 2012 | pp. 38-40
ZrO2-Si3N4 composite ceramic material was prepared by non-pressurized sintering and characterized by drainage method,SEM and DDL100 universal tensile machine. The effects of ZrO2 content were investigated on the density, microstructure and mechanical properties of Si3N4 ceramics. The results show that the density of Si3N4 ceramics increases with increased ZrO2 content,while bending strength and fracture toughness first increase and then decrease. When ZrO2 content is up to 10% ,the bending strength and fracture toughness of Si3N4 are the maximum, i. e. 362 MPa and 7.0 MPa · m^1/2, respectively. The mechanism of ZrO2 toughening to Si3N4 ceramics is based on stress-induced phase transition.
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