Extraction method was employed to recover molybdenum from the high-sulphate ammonium molybdate solution obtained by the pressurized oxidized ammonia leaching-purification process of molybdenum concentrate.The effects of 2-octanol concentration, acid dosage, O/A phase ratio and oscillation time on Mo extraction were investigated.The results show that the optimal extraction conditions are 2-octanol volume fraction of 15%,1∶1 sulfuric acid dosage of 10% feed liquid volume, O/A phase ratio of 1.2/1 and oscillation time of 5 min.Through single-stage extraction, washing and single-stage stripping, the average Mo extraction rate reaches 99.61%,the Mo stripping rate is close to 100%,and the average Mo and SO₄^2-contents are 161.99 g/L and 18 g/L,respectively, realizing the efficient recovery of molybdenum.

Taking 6 kA rare earth electrolyzer as the research object, rare earth metals were prepared by electrolysis using fluorine salt system, and the effects of electrolysis temperature, oxide addition rate and metal extraction mode on the content of oxygen and titanium in rare earth metals were studied in combination with field production conditions and GDMS detection results.The results show that the oxygen and titanium content in rare earth metals can be stably controlled when rare earth metals are siphoned out of the oven, electrolytic temperature is controlled at 1 040~1 060 ℃,and oxide addition rate is 7~8 kg/h.The oxygen content in rare earth metals is less than 0.010% and the titanium content is less than 0.012%.

Taking Pr-NdCl3 feed solution prepared from mixed rare earth ore as the research object, the extraction of non-RE impurity of aluminum from high concentration Pr-NdCl3 feed solution was carried out with naphthenic acid-isooctanol-sulfonated kerosene as the extraction organic system.The effects of naphthenic acid concentration, organic saponification degree, phase ratio and extraction temperature on aluminum removal rate, rare earth loss rate and separation coefficient βAl/RE were investigated.The results show that when the concentration of naphthenic acid is 0.53 mol/L and the degree of organic saponification is 50%,more than 99% of Al in Pr-NdCl3 feed solution can be extracted and separated under the conditions of room temperature and 0.5∶1 phase ratio of organic phase and Pr-NdCl3 feed solution with Al content less than 0.35 g/L,and the rare earth loss rate is about 3%,which meets the requirement of Pr-NdCl3 feed solution for aluminum content.Under the optimum conditions, the extraction has fast phase disengagement, no third phase and no emulsification, which provides basic data for the production process of continuous extraction and separation of aluminum from Pr-NdCl3 feed solution.

Carbothermal reduction process was used to roast rare polymetallic mixed concentrate, and XRD,SEM and EDS were used to study the changes in the morphology and phase of the mineral during roasting.The results show that during roasting at low and medium temperatures, the main changes in minerals are as follows: Fe metallization rate gradually rises, Fe in iron ore is reduced, Fe encapsulated in silicate mine-rals precipitates and forms elementary substance, and Nb, Mn and Ti associated with iron minerals form oxides, which are not reduced by carbon, while rare earth minerals are stable and non-reactive, except for the partial decomposition of bastnaesite.As the roasting temperature increases, elemental Fe and SiO2 react to form FeSi by carbothermal reduction, bastnaesite is gradually decomposed, ZrSiO₄ begins to be pyrolyzed to form small particles of ZrO₂,and other metal compounds are stable.

Three rounds of technological improvement were carried out on the reverberatory furnace smelting process for the recovery of tin, antimony and bismuth.The main measures were employed of adding water-cooled flue, replacing solid fuels with gas fuels and increasing oxygen enriched smelting.The technological improvement has a significant effect and promotes the development of reverberatory furnace smelting technology in the direction of environmental protection and energy saving, making a demonstration for the industry to promote the upgrading of reverberatory furnace smelting technology.

The 92 W alloy with 0.15% La₂O₃ was prepared by conventional powder metallurgy method, the effects were investigated of coarse and fine tungsten powder with two different particle sizes sintered at 1 490~1 520 ℃ on mechanical properties and microstructure of the prepared high density 92 W alloy.The results show that with the increase of sintering temperature, the tensile strength of the alloy prepared with fine tungsten powder decreases, elongation increases, and impact toughness increases at first and then decreases, while the tensile strength of the alloy prepared with coarse tungsten powder increases at first and then decreases, and the elongation and impact toughness increase.Thus, different sintering temperatures should be adopted for the best comprehensive mechanical properties of tungsten alloy with La₂O₃ prepared with tungsten powder of different particle sizes.The aggregation and segregation of La₂O₃ particles in the alloy become more and more obvious with the continuous increase of sintering temperature.The grain size of tungsten alloy prepared with fine tungsten powder is coarser than that of the alloy prepared with coarse tungsten powder at lower sintering temperature, but the result is opposite when sintering is carried out at higher temperature.

Under the synergistic action of microwave-ultrasonic, Dy₂O₃ precursor(Dy(OH)CO₃·H₂O) was prepared by the reaction of a certain concentration of DyCl₃ solution with urea as precipitant, and then the nano spherical Dy2O3 was obtained by calcination.The effects of Dy³⁺ concentration, urea concentration and ultrasonic power on the morphology of Dy₂O₃ precursor were explored.The morphology and microstructure of Dy₂O₃ precursor before and after calcination were characterized, and the calcination decomposition mechanism was analyzed by scanning electron microscope, synchronous thermal analyzer, X-ray diffractometer, and Fourier infrared spectrometer.The results show that Dy(OH)CO₃·H₂O with uniform particle size, smooth surface, good dispersion and particle size of about 220 nm can be obtained under the conditions of Dy³⁺ concentration of 0.045 mol/L,urea concentration of 2.5 mol/L,microwave power of 500 W,ultrasonic power of 800 W,ultrasonic mode of 1∶2,reaction time of 1 h and reaction temperature of 90 ℃.The precursor can be completely decomposed at the calcination temperature of 800 ℃,and nano spherical Dy₂O₃ with particle size of about 200 nm can be obtained.

High-quality lanthanum acetate was prepared by concentration crystallization of recycled mother liquor, and the recycled lanthanum acetate mother liquor for some times was separated for extraction reaction with P507 and then transformation into lanthanum chloride solution with hydrochloric acid.The effects of phase ratio, reaction temperature and time on the extraction efficiency were studied.The results show that the quality of lanthanum acetate is not affected by crystal precipitation from the recycled mother li-quor.Under the conditions of O/A phase ratio 4∶1,extraction temperature 35 ℃,and reaction time 6 min, the rare earth extraction efficiency from the mother liquor is optimal, which can smoothly realize the maximum resource utilization of mother liquor.

The reduction reaction of FeNb₂O₆ in microwave field was investigated by combining microwave heating with the carbon thermal reduction characteristics of FeNb2O6.The effects of temperature, particle size and carbon content on the reaction rate of microwave carbothermal reduction of FeNb₂O₆ were studied by microwave thermogravimetry, and the kinetics of the carbothermal reduction of FeNb₂O₆ in microwave field was also analyzed.The results show that FeNb₂O₆ has a good heating characteristics during microwave heating.Compared with conventional heating, FeNb₂O₆ can react at a lower temperature in microwave field under the same holding time and temperature.The weight loss rate of FeNb₂O₆ in microwave field increases with the increase of temperature, while the weight loss rate of microwave carbothermal reduction can be increased by increasing the particle size and carbon content at the same temperature.According to the kinetic analysis, the apparent activation energy of carbothermal reduction of FeNb₂O₆ in microwave field is 127.3 kJ/mol, which is lower than that of conventional heating, indicating that microwave heating can reduce the activation energy of the reaction.

A new scheme of reduction leaching with malic acid and sodium bisulfite followed by carbonate precipitation to regenerate cathode materials in spent lithium-ion batteries was proposed.The effects were investigated of stirring speed, organic acid concentration, sodium bisulfite dosage, leaching temperature and leaching time on the leaching rates of Li, Co, Ni and Mn.The results show that the optimum leaching conditions are as follows: stirring speed of 400 r/min, malic acid concentration of 2.5 mol/L,sodium bisulfite dosage of 1.25 mol/L,leaching temperature of 90 ℃ and leaching time of 120 min.Under the above conditions, the leaching rates of Li, Co, Ni and Mn reach 99.91%,98.14%,99.27% and 98.43%,respectively.The performance of the regenerated cathode material was analyzed by XRD,SEM and electrochemical test.The results show that the first cycle discharge specific capacity of the regenerated LiNi_0.5Co_0.2Mn_0.3O₂ cathode material is 175.5 mA·h/g, and its capacity retention rate is up to 71.96% after 200 cycles.The performance of the regenerated cathode material is relatively excellent.