Research progress is reviewed on saponification process of rare earth extraction separation in re- cent years, focusing on the principles and characteristics of ammonia saponification technology, sodium sa- ponification technology, calcium saponification technology, magnesium saponification technology and so on. And future development direction of the saponification process is proposed.

Research progress is reviewed on hydrometallurgical and pyrometallurgical separation technolo- gies of zirconium and hafnium,and each technology is introduced in detail, especially including Xiao tech- nology,that is a novel pyrometallurgical process. Hf removal rate of 99% and high separation factor of 640 can be obtained with Xiao technology of compact process and wide application prospects.

Primary amine extractant HBDW-201 was used to selectively extract tungsten from high concen- tration sodium molybdate solution. The effects were investigated of extractant composition, reaction tem- perature,contact time,feed pH value,and phase ratio on extraction separation of tungsten and molybde- num. The conditions of Mo elution and W stripping from loaded organic phase were also studied. The re- sults show that tungsten extraction rate can be close to 100% and the molybdenum extraction rate reaches 13.31% after the four-stage countercurrent extraction under the conditions of extractant composition of 20% HBDW-201 and sulfonated kerosene,feed solution containing about 30 g/L WO3,100 g/L Mo,feed pH= 7.55,and phase ratio O/A= 1.5 ： 1,temperature of 25 ℃ and contact time of 10 min,and the finally obtained sodium molybdate solution contains more than 80 g/L Mo and less than 5 × 10^- 6 g/L WO3. Thus, deep removal of tungsten from high concentration sodium molybdate solution can be achieved with this method. Using 0.6 mol/L NaOH as the eluent,Mo elution rate is 61.86%,W elution rate is 11.38% andthe mass ratio of Mo and W is 2.30 in washing water by washing the organic phase under the conditions of phase ratio O/A= 5 ： 1 and 30 ℃ Using 2 mol/L NaOH as stripping agent under the conditions of O/A= 5： 1,30 ℃ temperature and 10 rain contact time,W single-stage stripping rate reaches over 99% ,Mo strip- ping rate reaches 97.39% ,and the stripping solution with 79.67 g/L WO3 and 16.30 g/L Mo is obtained, which could be further treated by the existing tungsten and molybdenum separation process.

Vanadium was selectively separated by solvent extraction from vanadium-containing sodium tung- state solution. The effects were investigated of extraction system composition,initial feed pH,phase ratio, oscillation time and temperature on vanadium extraction, extraction stages and stripping system were de- termined,and the effect of recycling extractant was also investigated. The experimental results show that employing the organic solution containing 20% N263, 40% 2-octanol and 40% sulfonated kerosene to sep- arate vanadium from the solution with initial pH of 8.70,66.21 g/L WO3 and 11.46 g/L V2O3 ,V2O5 ex- traction rate is more than 99.95% ,WO3 co-extraction rate is only about 8.00%, and the concentration of V2O5 in raffinate can be below 10 mg/L after 6-stage countercurrent extraction with O/A ratio of 1/2.5 at room temperature. The loaded organic phase can be stripped by using 1.5 mol/L NaCl and 2 mol/L NaOH solution,and the single-stage stripping rate of V2O5 reaches 95.24% while that of WO3 reaches 100% with O/A ratio of 3/1 at room temperature. The extractant basically has the same extraction effect for vanadium and tungsten during recycling.

P507/HZ818 impregnated resin was prepared with styrene-divinylbenzene copolymer （HZ818） as the carrier and 2-ethylhexyl phosphonic acid mono （2-ethylhexyl） ester （P507） as the extractant, which was characterized by scanning electron microscope （SEM） and infrared spectra （IR）. The selective adsorp- tion performance of In （Ⅲ） with the impregnated resin in sulfuric acid system was studied. Static adsorp- tion experimental results show that P507/HZ818 impregnated resin has high selectivity to In （ Ⅲ ） in indi- um and gallium binary system and In/Ga separation coefficient reaches the maximum value when solution pH is 1.2. In multicomponent system of indium, gallium, zinc, iron and copper, the impregnated resin has the best adsorption selectivity to In （Ⅲ ） when solution pH is 0.9. Dynamic adsorption experimental results show that the resin column provides little adsorption capacity for Ga （Ⅲ ） and high selectivity for In （ Ⅲ ） in indium and gallium binary system of pH= 1.2,achieving indium separation from gallium. Indium can be well enriched in indium,gallium,zinc,iron and copper system by controlling solution pH at 0.9.

The viscosity of molten lithium varies with temperature. Calcium and silicon were precipitated and separated from molten lithium by using the differences in density and melting point between lithium and impurities of calcium and silicon. The change principles of the content of calcium and silicon in molten lithium versus temperature were analyzed in an argon atmosphere under the conditions of 220 - 320 ℃ temperature, 10 rain stirring time and 2 h insulation time. The experimental results show that the settle- ment performance of calcium and silicon impurities in molten lithium becomes better at higher tempera- ture. When the temperature increases up to 280 ℃ ,the content of calcium and silicon in molten lithium de- creases to 82 mg/L and 63 mg/L,respectively.

Cu/W-Cu/Cu heat sink composite material was prepared by diffusion welding process. The effects were investigated of welding temperature, heat preservation time, and welding pressure on welding inter- face bonding strength and interracial diffusion. When welding temperature is 980 ℃ ,heat preservation time is 4 h and welding pressure is 55 MPa,Cu/W-Cu/Cu interface bonding strength is the maximum,indicating the best effect of diffusion welding and the highest quality of welded joints.

Using ultra-fine WC-12Co composite powder prepared by spray conversion as raw material,WC- 12Co coating was prepared on 45# steel substrate by high velocity oxygen-fuel （HVOF） spray. The micro- hardness,fracture toughness and abrasive wear resistance of the coating were investigated. The phases of composite powder and coating were analyzed by XRD, and the microstructure of composite powder and coating cross-section was analyzed by SEM. The results indicate that WC particles of porous spherical shell composite powder are obviously decarburized during spraying. The coating contains W2 C, Co2 W4 C, W and amorphous phase, and shows typical lamellar microstructure. WC grains grow up and turn round. The aver- age HV0.3/10 microhardness and fracture toughness coating are 1 084 and 5.24 MPa · m1/2 ,respectively. The wear resistance of coating surface increases with roughness decreasing and microhardness increasing, and the average wear mass loss is 0. 783 mg/min.

The microstructure and mechanical properties of Ti-Al based alloy with nominal composition of Ti-22Al-15Nb were investigated,and the deformation behavior under quasi-static and dynamic loading con- ditions was also discussed. The results show that as-cast Ti-22Al-15Nb alloy has equiaxed microstructure mainly composed of α2-Ti3 Al phase and B2-Ti2 AlNb phase, and lamellar α2 phase with random orientation is distributed uniformly in B2 matrix. Investigation on mechanical properties shows that the alloy exhibits higher yield strength of 1 100 MPa and higher compressive strength of 1 750 MPa,and better ductility dur- ing dynamic compression rather than quasi-static compression. Failure mechanism analysis shows that shear failure occurs in the alloy during quasi-static compression,and micro-cracks initiate in α2 phase or the boundary between az phase and B2 matrix and extend along the direction of the maximum shear stress to form main cracks, finally leading to alloy failure. Failure mode of the alloy during dynamic compression is adiabatic shear failure,adiabatic shear bands form at an angle of about 45° with the loading direction,and cracks initiate in the shear band and propagate with the increased strain, finally leading to alloy failure.

Lanthanum carbonate was prepared by merging precipitation with ammonium bicarbonate and ammonia as the mixed precipitant and lanthanum chloride solution as the material. The effects were inves- tigated of rare earth concentration in base solution,reaction time and reuse of precipitation wastewater on product quality. Phase structure and morphology of the product were analyzed, and technical indexes were compared between the above process and the existing process with ammonium bicarbonate as the precipita- tion agent. The results show that the main component of lanthanum carbonate product is La2 （CO3）3 · 8H2O with〉0.07% Cl- and ≥45% REO under the conditions as follows ： rare earth concentration in base solution of 30 g/L,reaction time of 7 h and reusing precipitation wastewater. At the same time,5.9 m3 pre- cipitation wastewater is generated for 1 t REO with ammonium chloride content of 169 g/L. Compared with the existing process with ammonium bicarbonate as the precipitation agent,the use of mixed precipi- tants significantly reduces the output of wastewater and its treatment cost,and effective use of carbon re- duces the emission of CO2 and dosage of NH4 HCO3 ,with good economic and environmental benefits.