Scheelite is the main industrial raw material for tungsten smelting in China.Most of scheelite concentrates are obtained by flotation, and therefore a large number of organic flotation reagents remain in the concentrates, which can easily lead to overswelling phenomenon during subsequent hydrometallurgical smelting and bring adverse effects on production.At the same time, the traditional alkali pressure boiling process of scheelite is of low production efficiency, and there are certain safety risks.To solve the above problems, a new smelting process for decomposing scheelite through sodium phosphate roasting-water lea-ching-sodium phosphate crystallization cycle was proposed.The research results show that under the conditions of mass ratio of sodium phosphate to scheelite of 2∶1,roasting temperature of 700 ℃,roasting time of 2 h, water leaching temperature of 80 ℃,water leaching time of 2.5 h and water leaching liquid to solid ratio of 2.5∶1,the leaching rate of tungsten reaches 99.81%.The excess sodium phosphate in sodium tungstate solution can be crystallized by adding sodium hydroxide, the recovery rate of sodium phosphate can reach more than 97%,and the sodium phosphate can be recycled for the decomposition of scheelite concentrate.This process can effectively overcome the adverse effects of flotation reagents on traditional hydrometallurgical tungsten smelting, and efficiently improve the utilization rate of scheelite decomposition reagents.

The process of preparing APT by evaporation and crystallization method is simple, but the particle size of the prepared APT is relatively large, which seriously reduces the quality of subsequent products.The influences of stirring speed, ammonium tungstate concentration, and reaction temperature on the D;and Span of APT were studied by response surface method, and then the evaporation and crystallization process of APT was optimized.The results show that among the three factors, the order of influence on D;is reaction temperature>ammonium tungstate concentration>stirring speed, and the order of influence on Span is ammonium tungstate concentration>stirring speed>reaction temperature.The optimal process conditions are stirring speed of 271 r/min, ammonium tungstate concentration of 178.9 g/L,and reaction temperature of 81.6 ℃.Under the optimal process conditions, the D;and Span of the APT prepared in the experiment are 20.31 μm and 1.323,respectively, which are greatly reduced compared with other samples.The reason for the reduction is that low stirring speed and low reaction temperature inhibit crystal growth, and high ammonium tungstate concentration promotes crystal nucleation.

The electrolytic manganese anode slime was subjected to harmless resource treatment by reduction roasting-acid leaching technology to reduce tetravalent manganese to divalent manganese.The reduction product was used as raw material for electrolytic manganese production,and the valuable metal Pb in the slag was also recovered.The experimental results show that when the reduction roasting temperature is 850~900℃,the roasting time is 40~60 min,and the reducing agent dosage is 10%~15%,the manganese leaching rate in sulfuric acid system is more than 99%,the lead content in the slag is more than 50%,and the best effect is achieved of reduction roasting-acid leaching treatment of electrolytic manganese anode slime.

Tungsten powders were prepared by hydrogen reduction with chromium-doped tungsten oxide, purple tungsten oxide and yellow tungsten oxide as raw materials at different reaction temperatures.The phase and microstructure of tungsten powders prepared by reduction of different tungsten oxides were analyzed by XRD and SEM,and the influence of chromium doping on the reduction process of tungsten oxide was explored.The results show that under the same reduction conditions, purple tungsten oxide is the easiest to reduce due to its loose and breathable fine needle-like structure, and the prepared W powder has good dispersibility, fine particle size and uniform distribution.Chromium-doped tungsten oxide is the most difficult to reduce due to the inhibitory effect of Cr₂O₃,and the prepared W powder has a large number of fine-grained aggregates, with poor powder particle size uniformity and small average particle size.The reduction difficulty of yellow tungsten oxide is between purple tungsten oxide and chromium-doped tungsten oxide due to its dense and airtight cubic structure, and the prepared W powder has coarse particle size and serious agglomeration.

Using tungsten trioxide, magnesium powder and diluents as raw materials, tungsten powder was prepared by self-propagating high temperature synthesis method.The influence of diluent types on the properties of tungsten powder in different raw material states was studied, and the determination of the best reaction diluent and process improvement for the preparation of tungsten powder by self-propagating high temperature synthesis were further explored.The experimental results show that elemental tungsten powder can be obtained regardless of whether the reactants are in powder state or pressed state, and the particle size of tungsten powder prepared in powder state is smaller.Different types of diluents have a significant effect on the morphology of the product tungsten powder.Using MgO as the diluent, the particles of the product tungsten powder is relatively larger and the distribution is relatively uneven.Using K₂CO₃,Na₂CO₃and Li₂CO₃as the diluent, the particle size of the obtained tungsten powder is un-even and increases in turn.NaCl is the best diluent for the preparation of tungsten powder by self-propagating high temperature synthesis method, the morphology of the obtained tungsten powder is the best, and the overall particle size of tungsten powder is less than 200 nm.

The NiMoO₄@NiMn₂O₄ composite electrode material based on nickel foam was successfully prepared by two-step hydrothermal method.The phase composition and microstructure of the electrode material were studied by X-ray diffractometer(XRD)and scanning electron microscope(SEM).The electrochemical performance of the electrode material was tested by cyclic voltammetry(CV),galvanostatic charge-discharge(GCD)and electrochemical impedance spectroscopy(EIS).The results show that the velvet-like NiMn₂O₄is attached to the nanowire-like NiMoO₄,which increases the specific surface area and the specific capacitance of the electrode material.At the current density of 1 mA/cm²,the specific capacitances of NiMoO₄ and NiMoO₄@NiMn₂O₄ are 240 mF/cm²and 2120 mF/cm²,respectively.Compared with the single NiMoO;electrode material,the NiMoO₄@NiMn₂O₄composite electrode material exhibits more excellent electrochemical performance due to the dual optimization of composition and structure.

Bayan Obo bastnaesite was selected as the research object,and according to its Ce/La mass ratio,(Ce,La)CO₃F crystal grains were synthesized by hydrothermal method to study their NH₃-SCR denitration performance.The results show that(Ce,La)CO₃F synthesized by adding excess NaHCO₃has better catalytic effect.After roasted at 500℃,the(Ce,La)CO₃F grains have the best denitration effect,and the NO_x conversion rate is 34%at the catalytic reaction temperature of 200℃.The combined action of Mn-Fe loading and sulfuric acid acidification can excite the active components of(Ce,La)CO₃F catalyst.After the catalyst with the combined action is roasted at 400℃,the NO_x conversion rate of 93%is obtained at the catalytic reaction temperature of 250℃.The reaction mechanism of(Ce,La)CO₃F catalyst was explored by in-situ infrared technology.The results show that the surface reaction of Mn-Fe loaded and sulfuric acid acidified(Ce,La)CO₃F catalyst mainly follows the E-R mechanism.The reactive species are NH⁺₄/NH₃(a)generated by NH₃(g)adsorption on the catalyst surface and NO,which undergo a series of intermediate reactions to produce N₂ and H₂O.This study can provide theoretical guidance for the use of rare earth concentrates as denitration catalysts.

The chemical reforming hydrogen production method has the advantages of easy availability of raw materials,low energy consumption,and high cost-effectiveness.However,its stable and efficient catalytic system is not yet perfect,and using rare earths to modify reforming hydrogen production catalysts has a good effect.From the perspectives of chemistry and energy,the research progress of reforming hydrogen production catalytic systems modified by rare earths at home and abroad is reviewed and commented.The effects of modification of reforming hydrogen production catalysts and their carriers respectively by La,Ce and Pr three commonly used rare earths on improvement of hydrogen production performance are emphatically expounded,and the mechanism of rare earth modification is analyzed.Combined with the current research trend that catalyst modification focuses on composite carrier modification,promoter modification and synthesis process optimization,the in-depth research direction of rare earth modified reforming hydrogen production catalysts in the future is proposed.

Ta-2.5 W alloy was subjected to room temperature compression and annealing, and the influence of deformation degree and annealing process on the microstructure and mechanical properties of the alloy was investigated by scanning electron microscope and microhardness tester.The experimental results show that when the annealing process is the same(1 350 ℃× 60 min),with alloy deformation degree increa-sing, the recrystallization degree increases, and the grains gradually become more uniform and finer.When the cold deformation degree of Ta-2.5 W alloy is 70%,in the temperature range of 1 200~1 350 ℃ for the holding time of 5~60 min, both increasing the temperature and prolonging the holding time are beneficial to obtain fine grains, and the average grain size of Ta-2.5 W alloy can be finally refined from the original 90 μm to 32 μm.

Zr-1 Nb-0.1 Fe-0.1 Cu plate samples with a thickness of 1.4 mm were prepared with sponge zirconium by electrode pressing,vacuum consumable arc melting,forging,homogenization treatment,quenching,hot rolling,multi-pass cold rolling and annealing.The metallographic microstructure of Zr-1 Nb-0.1 Fe-0.1 Cu alloy and the composition,size,structure and distribution of the second phase were analyzed by OM,SEM and TEM.The test results show that the metallographic microstructure of Zr-1 Nb-0.1 Fe-0.1 Cu alloy annealed at 580℃for 2 h is basically recrystallized equiaxed crystal,the grain size grade is 13,and the average grain size is less than 6μm.Elliptical second-phase particles are precipitated and dispersed in the grains and grain boundary of the alloy.More than 95%of the second-phase particles have smaller size than 200 nm.There are three kinds of second-phase particles in Zr-1 Nb-0.1 Fe-0.1 Cu alloy,includingβ-Nb precipitate with a large content,a grain size of less than 100 nm,and bcc structure,(Zr,Nb)₂Fe precipitate with a less content,a grain size of less than 200 nm,and hcp structure,and Zr;Cu precipitate with the least content,a greater grain size than 200 nm,and tetragonal structure.