Alkaline extraction method with quaternary ammonium salt was proposed for deep removal of va- nadium from vanadium-containing ammonium tungstate solution and experimental research was carried out. The effects of organic phase composition and equilibrium aqueous pH on extraction were investigated as well as the effect of O/A ratio on stripping. Isotherms of extraction and stripping were plotted and the simulated multi-stage countercurrent extraction and stripping experiments were conducted. The results show that the concentration of vanadium in the aqueous phase drops below 10 mg/L and tungsten loss is below 5% after six-stage countercurrent extraction under the following conditions： organic phase composi- tion （volume fraction） of 1% N263, 5% 2-octanol and sulfonated kerosene,feed pH of 8.7 （by evaporation deamination pretreatment） ,phase ratio （O/A） of 1.25 ： 1 and 25 ℃. Vanadium in the loaded organic phase can be completely stripped with 2 mol/L NaOH solution,and the stripped organic phase can be returned to the extraction process for recycle.

Molybdenite microwave roasting process was studied. The main influencing factors and levels were determined by single factor experiments, and then the influences of roasting time, material weight and roasting temperature on roasting effect were studied by response surface methodology. The multiple re- gression equations were established for predicting MoO3 ratio and sulfur content and the technical parame- ters were optimized. The results show that roasting temperature, roasting time and material weight have obvious effect on roasting, and the level of influence is as follows：roasting temperature〉roasting time〉 material weight. Under the optimal conditions of 56.95 min roasting duration,8.33 g material and 649.55 ℃ roasting temperature,MoO3 ratio and sulfur content are 94.3% and 0. 054% respectively by microwave roasting, while MoO3 ratio and sulfur content are 85.5 % and 0. 471% respectively by traditional resistance furnace heating roasting. Microwave roasting greatly improves the molybdenite oxidation effect.

With 15 kA rare earth electrolytic cell as the research object,its temperature field was simulated by using the electro-thermal coupling module of COMSOL software,and the law was analyzed of tempera- ture distribution in the rare earth electrolytic cell. The results show that the transverse temperature distri- bution in the rare earth electrolysis cell is as follows：the region between the arc-shaped anode and its adja- cent cathode has the highest temperature,and the region between the cathode and the cathode has slightly lower temperature. The temperature rises at first and then declines from top to bottom along the vertical direction of the electrolytic cell.

To overcome the problem of inadequate utilization of Li resource in lithium-containing residue, Li2CO3 was prepared from lithium-containing residue by H2SO4 leaching, NaOH purification and EDTA deeply purification, and lithium precipitation with Na2 CO3. The results show that the optimal technological parameters are as follows： in the process of H2SO4 leaching, H2SO4 concentration of 5% （volume frac- tion） ,leaching temperature of 70 ℃ ,and leaching time of 60 min. In the process of NaOH purification and EDTA deeply purification,end pH of NaOH addition of 12 ,EDTA addition of 2.0 g/L;in the process of Li precipitation with Na2CO3 ,Li＋ concentration of 23 g/L in solution,Na2CO3 concentration of 300 g/L,and Na2CO3 dosage of 1. 10 times of the theoretical quantity, bath temperature of 95 ℃,reaction time of 40 min. With the optimal technological parameters, the indexes of Li2 CO3 products basically meet the require- ments of Li2CO3-0 level,and the comprehensive recovery rate of Li is over 95%.

Induction plasma spheroidization process was applied to deal with irregularly shaped W and Cr powders,and the effect of powder-feed rate on powder spheroidization was investigated. The morphology, phase composition, particle size distribution and apparent density of the powders before and after sphe- roidization were characterized by scanning electron microscopy （SEM）,X-ray diffraction （XRD）,laser par- ticle size analyzer and Hall flow meter. The results show that the spherical W and Cr powders with single phase can be prepared by induction plasma spheroidization, and their apparent density and powder flow-ability are greatly improved. The spheroidization ratio of W and Cr powders increases with the decrease of powder-feed rate,and the maximum spheroidization ratio is higher than 98%. The particle size and particle size distribution of the sphericized powders are affected by the dispersion of the raw powders.

W-Cu blanks with complex shape were prepared by non-aqueous gel-casting. The effect of disper- sant content and solid content on slurry viscosity was investigated. The blank drying curve was drawn and the drying system was established. Microstructure and bending strength of the blank were characterized. The results show that when the dosage of dispersant is 0.15%（ mass fraction and based on the quality of the metal powder）,slurry viscosity reaches the minimum and the slurry can obtain 45% （volume fraction） solid to meet the requirement of gel-casting. The blank is dried firstly at room temperature for 10 h and then placed in a constant temperature drying oven at 100℃ for 8 h to obtain W-Cu blank without deforma- tion and cracking on its surface. With the increase of solid content, both the density and uniformity of the blank increase. The blank has good surface quality and its bending strength can be up to 26.9 MPa.

Based on the Hall-Petch formula,the quantitative model of grain size and yield strength of niobium sheet was developed by quantitative metallography and mechanical property tests. By experimental ver- ification, the relative error between the calculated value and the experimental value is less than 8 %, indica- ting that the model has a high prediction accuracy.

The evaporation behavior of metal cerium was analyzed and proper evaporation temperature was determined. And then design of the electromagnetic induction evaporation device and research of evapora- tion technology were carried out. Evaporation rate of metal cerium was measured, vapor density distribu- tion was analyzed with film thickness method, and vapor density was measured with weighing method. The results show that evaporation rate of metal cerium at 2 000 ℃ is about 99-135 g/h,and the measured val- ue is slightly lower than the theoretical value. The density distribution of cerium vapor approximately fol- lows the relationship of high order power of cosine function,and atomic vapor density magnitude is about 1011 atom/cm3. The application of electromagnetic induction heating evaporation for cerium film deposition is feasible.

. LiFe1-xCex PO4/C （x= 0,0. 01,0. 03,0. 05） cathode material doped with rare earth Ce was syn- thesized with hydrothermal method. The electrochemical properties of the prepared material were studied by a series of systematic tests. XRD results show that the olivine crystal structure of LiFePO4 stays the same after doping 1 %- 5 % Ce, but cell volume is extended, which is favorable for the Li＋ extraction-inser- tion. The SEM images further demonstrate that doping rare earth Ce can refine the grain size,and then ef- fectively reduce Li＋ diffusion and migration pathway. In the potential range of 2. 044.0 V,the initial dis- charge specific capacity of LiFe1-xCexPO4/C at the discharge rate of 0.1C firstly increases and then decrea- ses with Ce dosage increasing,and it reaches the maximum value of 144.1 mA /g at x= 0. 03 , increased by 17.4% compared with the undoped LiFePO4/C. And its capacity retention ratio is 95.0% after 50 cy- cles. CV and EIS measurements show that LiFe1-xCexPO4/C （x=0.03） has the lowest charge transfer re- sistance,and the redox peak of the sample remains visible after 50 cycles at the charge and discharge rate of 0.1C,demonstrating that the sample has stable structure and good reversible reaction performance.

The semi-solid A356-0.5Ce （mass fraction） alloy ingots with ideal tensile properties and solidifi- cation microstructure were prepared by the combined process of intermittent reversible electromagnetic stirring and low superheat casting. The effects of melt stirring methods （without stirring, 30 Hz single-way continuous electromagnetic stirring, 30 Hz intermittent reversible electromagnetic stirring） on grain size and morphology of primary a phase were investigated by OM. The results show that with 30 Hz intermit- tent reversible electromagnetic stirring, the primary grains are well refined and spheroidized with average equal-area circle diameter of 35.9 ~m and shape factor of 0.79. In addition,the tensile properties and frac- ture morphology of the alloy ingots with three stirring methods were studied by SEM. The experimental results show that compared with the conventional casting, the tensile strength of the alloys obtained by 30 Hz single-way continuous electromagnetic stirring and 30 Hz intermittent reversible electromagnetic stir- ring increases from 125 MPa to 143 MPa and 176 MPa,the elongation increases from 4.2% to 5.4% and 7.8% ,and the fracture mechanism is changed from brittle cleavage fracture to ductile fracture.