The process is applied of the calcium salt precipitation-Cr removal by washing in dilute hydrochloric acid and W and Mo separation with concentrated hydrochloric acid to recover the tungsten and molybdenum from high-Mo tungsten solution resulted from the waste superalloy treatment.The effects were investigated of pH value of calcium salt precipitation,hydrochloric acid concentration,reaction temperature,reaction time and liquid to solid ratio on separation of tungsten and molybdenum.The experimental results show that during calcium precipitation,tungsten and molybdenum precipitation rate is more than 99% with pH value of 9.5,CaCl_2 excess coefficient of 1.2,and temperature of 80~90 ℃.Chromium can be removed from solid precipitation by washing with dilute hydrochloric acid,and chromium removal rate get close to 100% with 3% hydrochloric acid concentration.In addition,tungsten in the insoluble solid was separated from molybdenum with concentrated hydrochloric acid.Under the conditions of hydrochloric acid concentration of 250g/L,reaction temperature of 65℃,reaction time of 30 min,and liquid to solid ratio of 3∶1,more than 98% molybdenum dissolves in solution,while tungsten exists in solid form of tungsten acid.Thus,the separation of tungsten,molybdenum and chromium is realized.

The solubility of ammonium paratungstate in（NH4）2HPO4-NH3·H2O-H2O system was studied with dissolution equilibrium method.As the ammonia concentration increases,the solubility of APT drops slightly at first and then rapidly rises,and tungstophosphoric acid concentration is significantly reduced in the solution,while the concentration of isopolytungstate and normal tungstate ions significantly increases.With the same concentration of diammonium phosphate,the solubility of APT in（NH4）2HPO4-NH3·H2O-H2O system is much higher than that in（NH4）2HPO4-H2O system.

Rare earth associated phosphate rock was dissolved with 55% nitric acid to obtain the digested solution,where rare earth elements were extracted with ion exchange method.Effects were studied of ion exchange time,eluent pH,EDTA concentration and calcium ion in the digested solution on rare earth extraction.The results show that the optimum technological conditions are as follows：ion exchange time of 50 min,eluent pH of 9.0,EDTA concentration of 0.020 mol/L and elution time of 50 min.Under the above conditions,rare earth adsorption rate of the resin can be up to 50%from the digested solution by one step ion exchange,and rare earth elution rate is beyond 94% by one step elution.Rare earth adsorption rate significantly increases after calcium is removed from the digested solution by concentrating and freezing.

Investigation was made on the kinetics of titanium slag roasting with ammonium sulfate to extract TiO_2.The effects were studied of roasting temperature,titanium slag particle size and mass ratio of ammonium sulfate to titanium slag on TiO_2 extraction rate.The results show that the reaction rate of titanium slag roasting with ammonium sulfate is controlled by chemical reaction,the activation energy of the roasting reaction is 66.59kJ/mol,and the kinetic equation is 1-（1-x）1/3=0.246 2×10^3exp[-66 587/（RT）]×t.

An alkaline reduction smelting method has been proposed to efficiently extract the valuable metals such as vanadium,lead and zinc from the descloizite ore.Through alkaline reduction smelting process,PbO is reduced to crude lead and deposited at the bottom.ZnO is reduced to zinc and evaporated into flue gas at high temperature,and then collected as ZnO powder from dust collecting system.Vanadium is transformed into soluble vanadate in the smelting slag,and then dissolved into aqueous solution through subsequent leaching process.The main factors affecting smelting and leaching process were investigated.Adding 10% carbon powder and 35% Na_2CO_3 based on descloizite mass and smelting at 1 250 ℃ for 30 min,the crude lead with higher purity than 97% is obtained with 98.6% lead recovery ratio,and the evaporation ratio of zinc reaches 78.9%.After V-containing smelting slag is leached at 95 ℃ for 90 min with 2∶1 solidliquid ratio,vanadium leaching ratio reaches 97.8%.

Using hydrochloric acid as leaching agent,the influences were investigated of leaching temperature,leaching time,ratio of hydrochloric acid volume to red mud mass,and HCl concentration on gallium leaching rate during gallium recovery from red mud by traditional or microwave-assisted hydrochloric acid leaching.The primary and secondary sequence of the factors affecting gallium leaching rate was determined through the orthogonal tests as well as the optimum leaching conditions.The results show that the optimum leaching conditions of traditional hydrochloric acid leaching according to the primary and secondary sequence are as follows：leaching temperature of 100℃,time of 4h,HCl concentration of 8mol/L,and the ratio of hydrochloric acid volume to red mud mass of 7mL∶1g.And those of microwave-assisted hydrochloric acid leaching are as follows：leaching temperature of 80 ℃,leaching time of 25 min,the ratio of hydrochloric acid volume to red mud mass of 7mL∶1g,and HCl concentration of 7mol/L.Compared with traditional hydrochloric acid leaching process,microwave-assisted hydrochloric acid leaching process has higher gallium leaching rate,lower leaching temperature,shorter leaching time and lower hydrochloric acid concentration.

10% WO_3-ZSM-5/SBA-15 catalyst was synthesized by modifying ZSM-5/SBA-15 microporous and mesoporous composite molecular sieve with tungstate acid as tungsten source.And the catalyst was characterized by XRD and SEM.The results show that tungstate acid is distributed uniformly on the catalyst surface.Taking FCC gasoline as the research object,the effects were investigated of reaction temperature,reaction time,H_2O_2 dosage,and WO_3-ZSM-5/SBA-15 amount on catalytic oxidation desulfurization rate.The results show that the desulfurization rate reaches 71.89% under the following conditions：FCC gasoline of 20 mL,reaction temperature of 70 ℃,reaction time of 100 min,mass ratio of catalyst to FCC gasoline of 1∶50,volume ratio of H_2O_2 to FCC gasoline of 2%.The desulfurization sequence of different sulfides is DBT〉4,6-DMDBT〉BT.

Pure tungsten powder was successfully directly consolidated into the dense material by high-pressure torsion at 440 ℃.The effects of HPT on dense consolidation,grain refinement and room-temperature brittleness of pure tungsten powder were investigated by metallographical microscope,micro Vickers hardness tester,scanning electronic telescope and X-ray diffractometer.The experimental results indicate that the pores among tungsten particles are effectively closed by high pressure torsion,particles are well combined and the interface has no obvious gaps.The microhardness of tungsten billet prepared by HPT is HV854～1 194,its grain size is 141～394nm,and its room-temperature microhardness indentation is neat with clear boundary and without crack defect in four corners.Compared with powder pressing and sintering process,high-pressure torsion process can more effectively eliminate particle agglomeration,reduce pore number,refine grain size and improve microstructure uniformity and room-temperature brittleness.

Study was made of Nb-Al master alloy preparation by thermit reduction of Nb_2O_5 outside the furnace,and Al metal particle size was determined.It is concluded that Nb-Al master alloy preparation by thermit reduction of Nb_2O_5 is feasible.Meanwhile,analysis was made of Al loss during preparation,and phase composition,metallographical microstructure and Nb segregation of the reaction product.The results show that prepared with 3mm particle size of Al metal as the thermite,the Nb-Al master alloy has higher purity and more uniform Nb distribution.

Pure Al coating was deposited on NdFeB magnet by direct current（DC）magnetron sputtering.The influences of sputtering power and substrate temperature on microstructure and corrosion resistance of Al coating were investigated.The surface morphology of Al coating was characterized by scanning electron microscopy（SEM）.The adhesion strength between Al coating and NdFeB substrate was characterized by vertical tensile test.The corrosion resistance was investigated by potentiodynamic polarization curves and neutral salt spray（NSS）test.The results indicate that the lower the sputtering power,the higher the substrate temperature,and the better the properties of Al coating.Al coating deposited at 2.0 kW sputtering power and 300 ℃ substrate temperature has smooth surface and fine and compact grains,and its adhesion strength to the substrate reaches 25.13 MPa.Furthermore,the above coating has the optimal corrosion resistance,and it is still intact with a little pitting on surface after 6 d NSS test.