There are a lot of metal elements in fly ash,which has a certain extraction value.In this paper,the existing state of lithium in fly ash and the economical efficiency of lithium extraction are analyzed.Also,the research progress of lithium leaching technology from fly ash and the separation extraction technology of lithium from the leaching solution is reviewed.The key nodes of lithium extraction from fly ash are briefly discussed,giving reasonable suggestions and research directions.

Aiming at the recycling with high value of the lithium-extracted tailings from lithium iron phosphate battery waste,dissolution process conditions of the lithium-extracted tailings with hydrochloric acid were optimized and leaching kinetics was studied.The effects of hydrochloric acid concentration,solid-toliquid ratio and leaching time on the dissolution efficiency of the lithium-extracted tailings were mainly studied,and the leaching kinetics of the main component iron phosphate in hydrochloric acid solution was investigated.The results show that under the conditions of hydrochloric acid concentration 3 mol/L,liquidsolid volume-to-mass ratio 15 mL/g,reaction time 4 h and leaching temperature 30℃,the dissolution rate of lithium-extracted tailings reaches 92.4%.The leaching process of iron phosphate in hydrochloric acid conforms to the shrinking core model without a solid product layer,with an apparent activation energy of 25.45 kJ/mol,representing that the leaching process is controlled by internal diffusion.The iron phosphate powder was prepared by precipitation of the leaching solution.The XRD pattern of the product matches well with the standard pattern of iron phosphate,and its EDS pattern shows that P,Fe and O are evenly distributed.Therefore,the prepared powder is judged to be iron phosphate,its iron-phosphorus molar ratio is 0.97 and the content of other elements is scarce,which meets the industry standard of battery-grade iron phosphate and can be used in battery production.

Coal gangue is a kind of solid waste containing gallium,which has an important recycling value.The experimental study was carried out on the extraction of gallium from coal gangue by enhanced leaching,and the influences of such leaching parameters as sulfuric acid concentration and calcium fluoride dosage on leaching efficiency of gallium were investigated.The results show that the addition of calcium fluoride could accelerate the dissolution of gallium,significantly improve the leaching efficiency of gallium,and reduce the consumption of sulfuric acid.The leaching efficiency of gallium in coal gangue reaches 95%under the conditions of coal gangue particle size of less than 0.045 mm,sulfuric acid concentration of 20%,calcium fluoride dosage of 5%,leaching temperature of 80 C,liquid to solid ratio of 7.5 mL/g,stirring speed of 400 r/min and reaction time of 120 min.This study may provide a new idea for the efficient recovery of gallium from coal gangue.

Gallium and iron from sulfuric acid leaching solution of coal gangue were separated by extraction with 2-ethylhexyl phosphate mono-2-ethylhexyl ester(P507).The effects of solution pH value,P507 concentration,oscillation time,oscillation intensity and extraction temperature on the extraction efficiency of gallium and iron were investigated.The results show that the single-stage extraction rate of Ga³⁺reaches 82%while that of Fe²⁺is lower than 18%,under the conditions of A/O ratio of 1:1,P507 concentration of 20%,solution pH value of 1.5,oscillation time of 15 min,oscillation intensity of 200 r/min and extraction temperature of 35℃.The extraction experiments were performed by changing the A/O ratio,and then the equilibrium isotherm of gallium extraction was determined.Under the condition of 4:1 A/O ratio,the theoretical extraction stage of gallium is four,and the extraction rate of gallium is 98.4%while the extraction rate of iron is 17.4%,and the extraction rate of other metal ions is less than 10%.Therefore,the selective extraction of gallium from sulfuric acid leaching solution of coal gangue could be realized.

The research status and development trend of bismuth pyrometallurgical and hydrometallurgical processes are reviewed.The characteristics,application scope and existing problems of bismuth metallurgical process in the research stage and industrial production practice are clarified.A method for extracting bismuth from bismuth sulfide concentrates by oxygen pressure leaching with methanesulfonic acid as the leaching agent is proposed.This method has the advantages of high bismuth leaching rate,ittle corrosiveness to the reactor,and no SO emission in the process,and has a good development prospect.

The effects of carbon ion irradiation at 7oo C on the surface morphology,microstructure and surface hardness of pure tungsten were studied by scanning electron microscopy,transmission electron microscopy and nanoindenter.The results show that carbon ion irradiation can lead to irradiated pits on the surface of the samples,and the size of the pits increases with the increase of irradiation dose.Carbon ion irradiation produces a large number of dislocation loops inside the sample,and the size and number density of the loops increase with the increase of radiation dose.Also,carbon ion irradiation causes a severe irradiation hardening effect on the tungsten surface,and the surface hardness of the samples increases significantly with the increases of irradiation dose.The average hardness of the tungsten surface reaches 15.85 GPa when the irradiation dose reaches 8.0 dpa.The dislocation loops generated by irradiation are the main cause of the irradiation hardening.

Tungsten(W)and oCr13Al steel were jointed in vacuum under the conditions of 5 MPa pressure and heat preservation at 1120 ℃ for 60 min with 90W-8.5Fe-1.5Cr(w/%)mixed powder as the interlayer and pure copper foil as the brazing filler metal.The particle size distribution and morphology of the WFe-Cr mixed powder were studied by laser particle size analyzer and SEM,and the microstructure,composition,mechanical properties and fracture characteristics of the joints were studied by SEM,EDS and electronic universal tester.The results show that the joint is composed of tungsten base metal/W-Fe-Cr heavy alloy layer/steel base metal,in which the W-Fe-Cr heavy alloy layer is formed through solid-phase sintering of W-Fe-Cr mixed powder.Also,the W-Fe-Cr heavy alloy layer/tungsten base metal interface is brazed through an extremely thin brazing seam,while the W-Fe-Cr heavy alloy layer/steel base metal interface is joined by brazing at first and then solid-phase diffusion welding.High-energy ball miling of W-Fe-Cr mixed powder plays a key role in densification and homogenization of W-Fe-Cr heavy alloy layer under relatively low jointing pressure.The shear strength of the tungsten/steel joints is 41 MPa and all joints were fractured near the interface of tungsten base metal and W-Fe-Cr heavy alloy layer with brittle fracture characteristics.This study provides a new idea for the design of tungsten/steel joint interlayer with adjustable linear expansion coefficient and without active element Ni,which is useful for further improving the applicability of tungsten/steel joint structure in nuclear fusion reactors.

LaB₆ nanopowders were successfully prepared by calciothermic reduction method for the first time.The effects of reduction temperature on the phase composition,morphology and particle size of powder products were studied by X-ray diffractometer(XRD)and field emission scanning electron microscope(FE-SEM),and the optical absorption properties of nanopowders were characterized by UV/VIS/NIR spectrophotometer.The results show that the prepared LaB₆ nanopowders have a simple cubic single-phase crystal structure,good crystallinity and nearly spherical particle morphology with an average grain size of(35±6)nm.With the increase of reaction temperature,the particle size of the powders increases and the particle morphology shifts to cubic shape.The absorption spectrum shows that the LaB₆ nanopowder prepared at 800℃has strong absorption properties in the ultraviolet and near-infrared regions,and its maximum transmission light wavelength is 595 nm,which is essentially in agreement with the first-principles calculation results of LaBe₆.

The ratio of cerium to lanthanum is one of the key factors affecting the physical and chemical properties and performance of the cerium-based polishing powder.In this study,the polishing powders with different ratios of cerium to lanthanum were prepared with the precipitation method.The study results show that the cerium and lanthanum components form stable composite carbonate precursors,and form composite oxides with a single crystal phase after calcination.When the proportion of cerium in cerium and lanthanum is 95%,the primary particle size of the polishing powder is less than 100 nm,and the agglomeration effect is weak.The polishing powders with medium and low cerium proportion(≤85%)have obvious agglomeration effect and large average particle size,but they have stronger cutting force on K9 optical glass in a short time.The polishing powders with high cerium proportion(85%,95%)have more durable cutting force.Doping with a small amount of lanthanum is beneficial to improve the strength and durability of the cutting force of cerium-based polishing powder on K9 optical glass.

The effects of adding rare earth to steel,heat treatment process and their combined action on MnS-dominated inclusions in steel were studied by using as-cast U75V as the experimental steel grade.The results show that there are three main types of inclusions in the original as-cast U75V steelpure MnS inclusions,Al₂O₃-SiO₂-MnO composite inclusions and MnS semi-encapsulated Al₂O₃-SiO₂composite inclusions.The average size of the inclusions is 4.75μm and the average aspect ratio is 1.27.When the original U75V ingot is heated to 1300 ℃ for 1 h and then air-cooled,there is no significant change in the type and composition of the inclusions in the steel,but their average size is reduced to 3.8μm,a reduction of about 20%,and the average aspect ratio is reduced by nearly 4.7%.The addition of 0.0013%rare earth Ce to steel complicates the composition of inclusions,and in addition to pure MnS,three other different forms of inclusions containing Ce are found.Also,the addition of rare earth Ce significantly reduces the average size of inclusions by 1.91μm(about 40%)compared with the original U75V steel,but the aspect ratio of inclusions increases slightly by about 1.6%.The addition of rare earth Ce to the steel followed by heat treatment at 130o C for 1 h and then air-cooling results in a reduction of the average size of inclusions of about 34%compared with the original U75V steel,while the aspect ratio of inclusions is slightly reduced by 2.4%.In comparison,the addition of 0.0013%rare earth Ce to U75V steel and subjecting it to heat treatment at 1300℃for 1 h and then air-cooling result in a significant reduction in the size and aspect ratio of MnS and otherrelated inclusions in the steel.