Nd2O3 was recovered from the sintered Nd-Fe-B waste with the sulphate double salt precipitation method,the secondary oxalate precipitation method and the phosphate precipitation method.The industrially produced Nd-Fe-B waste was pretreated with sulfuric acid or oxalic acid.After alkalization and acid dissolution,neodymium ions were separated from iron by precipitation with oxalic acid or ammonium carbonate,and finally the crude Nd2O3 product was obtained by calcination.The morphology of Nd2O3 powder was observed by scanning electron microscope,and the purity of Nd2O3 product was determined by EDTA titration and the recovery rate was calculated.The purity and recovery rate of crude Nd2O3 products prepared with different methods are quite different.The purity of Nd2O3 is 74%~92%,the total recovery rate is 24%~29%,and the particle size is 3~200μm.These Nd2O3 products are of irregular shape and relatively high dispersity,and they are multihole and mostly fluffy.Considering the complexity of the process and the purity and recovery rate of Nd2O3,the sulfate double salt precipitation method has advantages in the practical application of Nd2O3 recovery from sintered Nd-Fe-B waste.

Vanadium was separated and recovered from titanium dioxide wastewater by solvent extraction using P507 as the extractor.The effects of extractor type and concentration,O/A phase ratio,solution pH,extraction temperature and time on the extraction rate of vanadium in titanium dioxide wastewater were investigated.The results show that the extraction rate of vanadium is more than 98% under the following conditions:organic phase of 15%P507+5%2-octyl alcohol+80% sulfonated kerosene,solution pH value of 2.0,O/A phase ratio of 1.25∶1,extraction temperature and time of 50℃ and 6min.The V2O5 product with a purity greater than 99% is obtained by sulfuric acid reverse extraction of the saturated organic phase,NaClO3 oxidation,ammonium salt precipitation and roasting at 540℃.

Using the leaching residue from acid treatment of spent automobile exhaust gas purifier catalysts as the adsorbent,the heavy metals Cu^2+and Cd^2+in the wastewater simulation solution were separated,and the effects of temperature,pH,adsorbent amount and adsorption time on the adsorption rates of Cu^2+and Cd^2+were investigated.The optimal adsorption conditions were obtained:temperature of 50℃,pH of 5.5,adsorbent amount of 0.5g and adsorption time of 1h.Under the optimal conditions,the adsorption rates of Cu^2+and Cd^2+in 20mg/L solution are 99.95%and 99.22%,and the saturated adsorption capacities of Cu^2+and Cd^2+in 1g/L solution are 99.61mg/g and 42.17mg/g,respectively.The adsorption of Cu^2+and Cd^2+by the leaching residue conforms to the second-order kinetic model,and chemical adsorption is the dominant adsorption mode.

In order to explore the effect of the combined action of Ce and La in natural bastnaesite on denitration performance,the CexLa1-x active component was prepared by microwave heating and loaded onγ-Al2O3 for activity test.Ce0.8La0.2 catalyst has the best denitration effect and 78%NO conversion at 350℃.The results of BET,NH3-TPD,XRD,Raman and XPS show that the active component of Ce0.8La0.2 catalyst is a solid solution containing Ce and La,which has better adsorption capacity of NH3 and higher specific surface area,and the surface adsorption of oxygen on Ce0.8La0.2 catalyst is one of the reasons for improving the catalytic performance of NH3-SCR.

La-Fe-B alloys prepared by arc melting were analyzed by X-ray powder diffractometer,scanning electron microscope,energy spectrometer and differential thermal analyzer,to obtain their phase composition,microstructure and phase transition process.The experimental results show that the solidification microstructure of the alloys is composed ofα-Fe andα-La phases.With the increase of rare earth La content,the content ofα-Fe phase obviously decreases,and the formation temperature of La2Fe14B phase decreases.The solidification phase transition process of the alloys was simulated by using phase diagram calculation technique and Scheil model.The simulated results are in good agreement with experimental results.

The principle,research progress,advantages and disadvantages are briefly introduced of several titanium powder preparation technologies such as atomization method,hydrogenation dehydrogenation method,thermal reduction method,and radio frequency plasma spheroidization method.According to the deficiencies of each technology,the future development trend of titanium powder preparation is pointed out.

Perovskite oxide La0.6Ca0.4Co0.9Mn0.1O3 was prepared by sol-gel method under different conditions,and its electrocatalytic properties in bifunctional oxygen electrode was investigated,then the best synthesis conditions were determined.The TG-DSC curves show that the lowest synthesis temperature of La0.6Ca0.4Co0.9Mn0.1O3 is above 600℃.On this basis,the effects of the initial pH value of the solution,the amount of citric acid and the calcination temperature have been studied on the catalytic performance of perovskite oxide bifunctional oxygen electrode.The results of physicochemical characterization and electrochemical performance test of perovskite oxides show that the catalytic activity of perovskite oxides is better when the initial pH of the solution is 5,the molar ratio of metal ions to citric acid is 2∶3,and the calcination temperature is 750℃.

The annealing treatment of ATI425 titanium alloy bars in the range of 650~800℃was carried out at different temperatures.The microstructure,tensile properties at room temperature and Vickers hardness of the annealed ATI425 alloy bars were tested by metallographic microscope,universal testing machine and microhardness tester.The experimental results show that the yield strength and tensile strength of the ATI425 alloy annealed at 650℃decrease by about 30MPa,the elongation increases by 2%,and the Vickers hardness decreases by about 20 HV1 compared with those of the hot-working titanium alloy ATI425.When the heat treatment temperature is raised from 650℃to 800℃,the secondaryαphase in the alloy is equiaxly spheroidized,the primaryαphase grows up and the number of β phase decreases.Also the strength and Vickers hardness and microstructure is well at the annealing temperature controlled between 700℃and 750℃,which provides a reference for further production and application.

Vanadium carbide(VC)nanowhiskers were synthesized by high temperature carbothermal reduction using precursors as raw materials.The effects of synthesis temperature and time on phase composition and microstructure of the reactive products were investigated using XRD,SEM,FESEM and TEM.The results show that VC nanowhiskers with a diameter of about 80nm,good linearity and smooth surface are prepared at 1000℃for 2h.The synthesis temperature and time have important influences on the growth of VC whiskers.Both too low synthesis temperature and too short reaction time are not conducive to the reduction of V2O3 to VC.If the synthesis temperature is too high and the reaction time is too long,VC particles are easily obtained,which is not conducive to the preparation of whiskers.

Nano-MoS2 modified lithium-rich manganese-based cathode material Li1.2Mn0.54Ni0.13Co0.13O2 was prepared by simple liquid-phase grinding method.The constant current charge and discharge test results show that the nano-MoS2 modified material exhibits excellent electrochemical cycle stability.3%MoS2 modified material has a discharge specific capacity of up to 235mA·h/g after 120cycles at 0.5C,and the capacity retention ratio reaches 88.4%,which is significantly higher than 70.1%capacity retention ratio and 153.8mA·h/g discharge specific capacity of the blank.In addition,the voltage decay of 3%MoS2 modified material is only 0.44 Vafter 120 cycles compared with the blank of 0.70 V.It can be seen that the voltage decay of the material during cycle is also significantly improved.