Based on the analysis and investigation of SnO2 and Cu2FeSnS4＇s thermodynamic difference in caustic soda leaching,the influence of roasting pretreatment on the leaching ratio of tin was studied.Results show that in caustic soda leaching process,SnO2 is very hard to leach with leaching rate close to zero,while the leaching rate of Cu2FeSnS4 is much higher,which can reach 40%~50% under normal leaching conditions.Upon oxidization and roasting of the tungsten concentrate,the leaching ratio of stannum can be greatly reduced.At roasting temperature 700～800 ℃,roasting duration 2 h,the tin sulfides in Cu2FeSnS4 can be fully all converted into SnO2,and the leaching ratio of tin is reduced from 5.96% down to about 1%.

Based on the single-factor condition test,the optimal technological parameters are determined for vanadium extraction by the＂roasting without additives-alkaline leaching＂and the oxidizer-oxidizing-acid leaching processes.The test results show that with mineral particle size 0.074 mm,oxygen partial pressure 10～100 Pa,roasting duration 3 h,leaching temperature 90 ℃,3 h leaching duration,caustic soda concentration 40 g/L,liquid-solid ratio 1.5∶1.0,the leaching rate of vanadium pentoxide by roasting without additives-alkaline leaching＂ can reach 83.8%,20% higher than that bytraditional sodium roasting-acid or alkaline leaching,with mineral particle size 0.074 mm,MnO2 oxidizer consumption at 5%,sulfuric acid concentration at 40%,leaching temperature 90 ℃,9 h leaching duration,liquid-solid ratio 2.5∶1.0,the leaching rate of vanadium pentoxide by oxidizer-oxidizing-acid leaching can reach 72.4%,10% higher than that by the traditional sodium roasting.

At pH1,La concentration is determined by EDTA volumetric titration in the two phases of P204-HCl-HAc extraction system,and study is made on the effect of solution acidity and extractant concentration on La distribution ratio.Based on the infrared spectrum testing and analysis of La loaded organic phase in the P204-HCl-HAc system,investigation is made on the extraction mechanism of La in P204-HCl-HAc system and the extraction equilibrium constant is determined.The results show that at pH1,the extraction is actually a displacement reaction between La and group P-OH based on the cation exchange mechanism and complexing and coordination action between La and group P=O with extraction equilibrium constant KLa is 10-0.02.

Study is made of the effect and refinement mechanism of rare earth element on Al-Ti-B-RE refiners prepared by casting of pure Ti particle.The results show that the addition of rare-earth element can improve the wetting quality of the molten Al to TiB2 and TiAl3 phase,and heterogeneous nucleation ability and delay decay time.The refinement result of different refiners mainly depends on the characteristic of TiB2 and TiAl3 grains,especially the morphologysize and quantity of TiAl3 phase.The refiners containing massive,small and dispersible lumpy TiAl3 phase work well,and TiB2 phase is the main factor affecting the effective nucleation quantity of α-Al.The Al-Ti-B-RE refiners are superior to Al-Ti-B refiners made both at home and abroad in respect of the refinement result and anti-recession ability.

AlTiC master alloys were prepared by aluminum-thermal reduction.Analysis is made of the composition,microstructure and morphology of the AlTiC master alloys through X-ray diffraction（XRD） and scanning electron microscopy（SEM）.Study is made of the refinement of the commercial pure Al by the self-developed AlTiC grain master alloy and the refining results are analyzed and compared through optical microscope and refining mechanism is preliminarily discussed.The test results show that the refining effect of AlTiC master alloy is better than that of the domestic AlTiB master alloy.

Surface Nb impregnation on TC11-based alloy is done by DGPSAT process.Microstructure,composition,phases and elastic modulus of the Nb-impregnated TC11 alloy layer were analyzed through scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,X-ray diffraction（XRD） and nanoindenter tester respectively.The result indicated that the Nb element is distributed in graded pattern throughout the impregnation layer layer,which are mainly composed of Nb substituted solid solution formed in β-Ti（Nb） and AlNb2 phase effective thickness of the impreganation layer was up to 14 μm.After Nb impregnation,the nano-hardness of TC11 was 1.9 times higher,while the elastic modulus was slightly lower than that of the substrate.

La2O3-doped Mo-12Si-8.5B alloys with different mass fraction of lanthanum oxide were prepared by liquid-liquid doping and plasma activated sintering technology.The phase analysis and observation of microstructures of Mo-Si-B alloys are conducted through XRD and optical microscope.And the mechanical property of alloy is tested.Results show that the Mo-Si-B alloys mainly consist of α-Mo,Mo3Si and Mo5SiB2 three phases,and the microstructure of the doped Mo-Si-B alloy was refined and the compressive strength was improved with the increasing of La oxide doped.

Six（6） groups of WC-Co carbides with different Mo content were manufactured by powder metallurgy.The mechanical properties were measured at room temperature,and the phase structure and microstructure were studied through XRD,SEM and EDS.The result shows that the small addition of Mo can refine WC grain improve the relative density and hardness;but flexural strength is reduced.When the Mo addition reaches 2.4%,the material has the best microstructure and mechanical property.