Tungsten smelting slag produced by smelting with NaOH and phosphoric acid of wolframite and scheelite mixed ore was treated with hydrochloric acid as a decomposition reagent,to achieve the goal of impurity removal and tungsten maximum enrichment.The results show that WO3 content in the slag increases from the initial 2.56% to 9.35%,which is nearly 3 times higher under the optimal conditions of liquid-solid(hydrochloric acid solution-tungsten smelting slag) ratio 10∶1,reaction time 3 h,temperature 60 ℃ and hydrochloric acid concentration 2 mol/L.In the acid reaction process,there is no significant tungsten loss,and 91.02% tungsten remains in the slag.The mass of the slag obtained from acid reaction is reduced to one quarter of the original tungsten slag,and it can be mixed with tungsten concentrate for secondary smelting,which effectively realizes emission reduction and resource recycling of tungsten slag and resolves the problem of tungsten smelting slag accumulation.

Using fly ash with germanium as the raw material,the enrichment of Ge from the fly ash was carried out by second enrichment process at high temperature.The effects of C content and sintering temperature on the volatilization rate of Ge were mainly studied,and the reasons were analyzed.The results show that appropriate C content and sintering temperature can promote the reduction and volatilization of Ge in fly ash.Excessive C will reduce part of iron oxides to Fe.And then Fe combines with Ge to form germanate,which is difficult to volatilize,affecting the enrichment and volatilization of Ge.Too high sintering temperature makes C not fully combusted to form CO,and part of Ge combines with CaO and MgO to form composite oxide,which reduces the volatilization rate of Ge.Under the optimum conditions of sintering temperature 1 700 ℃,C content 1%,basicity 1.0 and duration time 1 h,the Ge content of the pretreated fly ash is the lowest and the Ge volatilization rate reaches 96.2%.

In alkaline system,the method of ultrasonic-microwave synergistic oxidation leaching with the oxidant of NaClO3 was used to extract tellurium from copper-separated residue of copper anode slime.Based on the model optimal design principle of response surface method,the multiple quadratic regression equation of the influence of ultrasonic power,microwave power,reaction time and their interaction on the tellurium leaching rate was established,and the optimal leaching process was obtained.The results show that the optimal conditions of ultrasonic leaching are ultrasonic power 150 W,ultrasonic time 30 min,leaching temperature 90 ℃,NaClO3 addition amount 1.5 times copper-separated residue amount,liquid-solid ratio 9∶1 and NaOH concentration 1.2 mol/L,and the leaching rate of tellurium reaches 93.15%.The optimal conditions of microwave leaching are microwave power 700 W,microwave time 4 min,liquid-solid ratio 10∶1,temperature 85 ℃ and NaClO3 addition amount 1.2 times copper-separated residue amount,and the leaching rate of tellurium reaches 91.08%.The optimal conditions of ultrasonic-microwave leaching are ultrasonic power 414 W,microwave power 287 W and reaction time 14 min,and the predicted leaching rate of tellurium is 96.73%.The model is a second-order polynomial model.Compared with the average leaching rate of 93.40%±0.95% obtained in the validation experiment,the predicted value has little deviation,which is consistent with the model.

The effects of adding the refiner Na2SO4 in the stirring sodium reduction process during capacitor tantalum powder preparation on the particle size of the intermediate product washed powder and the particle size and electrical properties of the final product FTB-48 tantalum powder were studied.The experimental results indicate that the particle sizes of the washed powder and FTB-48 tantalum powder prepared by adding the refiner Na2SO4 were reduced,and the sintering shrinkage and weight specific capacitance of FTB-48 tantalum powder were improved to some extent.The intermediate product washed powder will agglomerate and sinter during the high-temperature heat treatment,which causes the particle size of FTB-48 tantalum powder product to increase.

X-ray fluorescence spectrometer(XRF),X-ray diffractometer(XRD) and scanning electron microscopy(SEM) were used to characterize the rare earth tailings.It is found that there are many elements in the tailings,and the relationship among minerals is complex.According to the characteristics of rare earth tailings,the catalytic denitrification performance of rare earth tailings was tested in a vertical tube furnace.The results show that NO conversion rate increases with the increase of reaction temperature and gas residence time,and NO conversion rate in fixed bed reactor is higher than that in bubbling bed reactor.When the reaction temperature is 800 ℃,NO conversion rate reaches 98.7%.The denitration catalyst was prepared by grinding and roasting with pseudo-boehmite and rare earth tailings as raw materials.When the total amount of rare earth tailings remains unchanged,the NO conversion rate increases with the increase of pseudo-boehmite mass.When the reaction temperature is 600 ℃,the NO conversion rate of the catalyst with the mass ratio of pseudo-boehmite to rare earth tailings of 1∶2 is 15% higher than that of the pure rare earth tailings.The thermodynamic calculation proves that the rare earth tailings with high iron content is feasible for CO reduction denitrification.

In order to study the effect of annealing time on structure and gaseous hydrogen absorption and desorption properties of LaMgNi3.9Mn0.2 alloy,the phase and microstructure of the alloy were tested by XRD and SEM,and the hydrogen absorption and desorption kinetics plot was tested by semi-automatic Siever′s method.The experimental results show that with the increase of annealing time,the content of main phase LaMg(NiMn)4 decreases,while the content of(La,Mg)(NiMn)5 increases.The surface of as-cast and annealed alloys is mainly composed of columnar crystals with different sizes,which has obvious structural heredity.With the increase of annealing time,the content differences of La,Mg and Ni in the columnar crystal region of the alloy decrease,which makes the element distribution more uniform.Mn element disappears in the columnar crystal intergranular region of the alloy annealed for 15 h and 20 h.After the first hydrogen absorption of as-cast and annealed alloys,the corresponding maximum hydrogen absorption is reached.Therefore,the annealing time has no effect on the activation performance of the alloy,but has a significant effect on the maximum hydrogen absorption and the saturated hydrogen absorption and desorption of the alloy.With the increase of annealing time,the maximum hydrogen absorption and saturated hydrogen absorption and desorption of the alloy decrease,but the hydrogen absorption and desorption saturation increases firstly and then decreases,and that of the alloy annealed for 15 h is relatively high.

Sm-Fe alloy was prepared by induction smelting.The effects of smelting pressure and times on Sm volatilization during smelting and the Sm content,phase composition and microstructure evolution of Sm-Fe alloy at smelting end were studied by XRD,SEM and XRF.The optimum raw material state and Sm compensation amount were determined.The results show that the phase distribution of Sm-Fe alloy is more uniform and stable after multiple smelting.However,Sm-Fe alloy should not be smelted for too many times to avoid excessive volatilization of Sm,and three smelting times are enough.The higher the smelting pressure,the lower the Sm volatilization.Higher melting pressure can also inhibit the growth of the internal structure of the alloy.Using uniform and stable Sm-Fe alloy as the raw material of smelting is more conducive to suppressing the evaporation of Sm in the smelting process.Excessive Sm compensation cannot stabilize the Sm content of Sm-Fe alloy at smelting end.Generally,4% pure samarium compensation amount can be selected for induction smelting.

Lattice structure and intrinsic magnetic property principle of Sm2Fe17N3 interstitial compound are briefly analyzed.The current preparation methods of Sm2Fe17N3 permanent magnetic material and the influence of element addition on its magnetic properties are mainly introduced.Besides,the preparation status of Sm2Fe17N3/α-Fe dual-phase nanocomposites is reviewed.Finally,the existing problems in preparation process and development tendency of Sm2Fe17N3 permanent magnetic material are summarized and prospected.

TiO2 flexible electrode materials were prepared by hydrothermal adjustment of NaOH concentration,hydrothermal reaction time and reaction temperature.The optimal conditions of hydrothermal synthesis are NaOH solution concentration of 0.5 mol/L,reaction temperature of 200 ℃,and reaction time of 16 h.TiO2 prepared under the conditions has a porous network structure,which can enhance the electrolyte infiltration,shorten the Li+ diffusion path,and accelerate the transport of lithium ions and electrons.Constant current charging performance test results show that TiO2 with porous network structure has good cycle stability.The reversible capacity is 112 mA·h/g and the capacity retention rate is 67.8% after 50 cycles at the current density of 800 mA/g.The TiO2 also has an excellent rate performance.When the current density is as high as 1 600 mA/g,the reversible capacity can still be maintained at 103.4 mA·h/g.

Ti(C5N5),Mo2C,Ru and Ni powders were mixed,and then Ti(C,N)-based cermets were prepared by powder metallurgy.The effects of Ru on microstructure and properties of Ti(C,N)-based cermets were studied as well as the mechanism.The results show that the Ti(C,N)-based cermets doped with Ru exhibit a core-ring structure.With the increase of Ru content,the main grains are refined,and the binder phase tends to be uniform.The change in Ru content has an effect on the concentration gradient of the binder phase in Ti(C,N)-based cermets.The thickness of the gradient layer increases at first and then decreases as the Ru content increases.Ti(C,N)-based cermet with 1.5% Ru has fracture toughness of 9.9 MPa·m1/2 and Vickers hardness of 1 500 HV10.Ru doping greatly improves the comprehensive mechanical properties of Ti(C,N)-based cermets,due to strengthening of the binder phase.