Effects of isooctanol,2-octanol,TBP and alcohol as the modifiers were studied on molybdenum extraction from acid leaching solution of Ni-Mo ore with N235.The optimal extraction temperature and time,stripping reagent concentration and stripping time were determined.The results show that TBP has the best effect of eliminating the third phase and it is the most suitable modifier.The optimal extraction system composition（volume fraction）is 20% N235＋20% TBP＋kerosene.The above extraction system has the best molybdenum extraction results at 20 ℃ and the extraction equilibrium time of 60 s.After 3-stage countercurrent extraction,molybdenum extraction rate is 98.84%.The optimal concentration of ammonia as the stripping reagent is 8mol/L,and stripping equilibrium takes 5min.After 2-stage countercurrent stripping,molybdenum stripping rate is greater than 99% by ammonia.

Vanadium-containing carbonaceous shale concentrate was obtained by pre-flotation of Hubei high calcium and magnesium mica carbonaceous shale containing vanadium,and then the concentrate was used as raw material for leaching experiments.The results indicate that high vanadium leaching rate of 86.18%can be obtained under the following conditions：H2SO4concentration of 30%,liquid to solid ratio of 4∶1,leaching temperature of 90 ℃,sodium fluorosilicate dosage of 16% and leaching time of 12 h.

The process was studied of Nb and Ti separation and extraction from Nb and Ti rich sulfuric acid solution with 7.84g/L Nb2O5 and 47.40g/L TiO2.Titanium was precipitated from the Nb and Ti rich sulfuric acid solution by ammonium sulfate precipitation.When the enrichment ratio is 2.5,ammonium sulfate dosage is 450g/L,precipitation time is 90 min,calcination temperature is 900℃and time is 90 min,industrial titanium dioxide with more than 93.4% TiO2 is obtained,and Ti total recovery rate is more than 95.19%.Niobium was precipitated from the titanium-precipitated solution by calcium carbonate neutralization-ammonia precipitation.When the neutralized solution pH value is about 1.0,the niobium-precipitated solution pH value is about 5.0,calcination temperature is 800℃and time is 60 min,niobium oxide concentrate with an average Nb2O5 content of 30.51%is obtained,and Nb total recovery rate is over 98.9%.

Thermodynamics of monazite decomposition with sodium hydroxide was studied by taking LaPO4 as a representative.According to the known thermodynamic data,lgc-pH diagrams of La-P-H2O system were established at 25 ℃.The technical conditions of monazite decomposition with sodium hydroxide were analyzed based on these diagrams.According to the calculation results,at the range of 2.77〈pH〈13.73,the concentrations of total lanthanum and total phosphorus are extremely low and even lower than the theoretical limit concentration of LaPO4 in aqueous solution,so the pH range can be considered as the stable region for LaPO4 precipitates.At the range of pH〈2.77,the concentration of La^3＋ increases rapidly with decreasing pH value,which is the process of acid decomposition of LaPO4 precipitates.When the pH value is higher than 14.1,LaPO4 precipitates can be resolved into La（OH）3（aq）,La（OH）^4-,La（OH）3（s）and PO4^3-,and it is the process of the alkaline decomposition of LaPO4 precipitates.According to the solution equilibrium characteristics of each component in the solution,industrial practice and the experimental results,it can be concluded that monazite can theoretically be completely decomposed as long as the concentration of sodium hydroxide is high enough.

With a simplified model of the settler in industrial rare earth extraction tank as the research object,the flow field of the settler with baffles was numerically simulated by using a fluid simulation software of Fluent.The effects of baffle installation height on settling velocity of the settler were analyzed based on the thickness of dispersion band.The results show that either too high or too low baffle installation height is not conducive to the separation of two phases,and the best baffle installation height is 310 mm for 50 L extraction tank.The formation of dispersion band is microscopically analyzed by velocity vector diagrams,and the role that baffles play in the settler is explained from the aspect of liquid flow patterns to further verify the best baffle installation height.

Tellurium was recovered from lead anode slime after pre-oxidation treatment,leaching and reduction precipitation.The results show that optimized recovery processes of tellurium are as follows：natural stacking oxidation treatment-leaching in the system of sulfuric acid,sodium chloride and sodium chloratepotential controlled precipitation of tellurium with sodium sulfite.Leaching rate of tellurium is 92.15% after the lead anode slime is treated by natural stacking oxidation for 4d,and then leached in the solution system of 3 mol/L sulfuric acid,3 mol/L sodium chloride and 20% sodium chlorate under the following conditions：liquid to solid ratio of 5∶1,reaction temperature of 80℃,reaction time of 4hand stirring leaching.More than 90%copper and other valuable metals are leached,while silver and lead remain in the residue.The process of potential controlled precipitation of tellurium with sodium sulfite was conducted in leaching solution,and the reduction rate of tellurium reaches 92.57% by controlling the potential at 0.342～0.568 Vand adding 2times theoretical amount of sodium sulfite as the reducer.Copper and other valuable metals remain in the solution to be recovered in the next step.Tellurium comprehensive recovery rate can be up to 85% by using the above optimized process to recover tellurium from lead anode slime to coarse tellurium slag.

According to the characteristics of high density and insolubility of superalloy,fine particles with high activity were prepared from waste superalloy by vacuum atomization.Rhenium in waste superalloy powder was dissolved into solution in the form of ReO4^- after oxidation acid leaching.And Re leaching rate reaches 99.02%.Subsequently,the pH value of the acid leaching solution was adjusted to 1.5with saturated NaOH solution,and then rhenium was adsorbed onto D296 anion exchange resin.And Re adsorption rate reaches 98.76%.During the process of desorption,Mo loaded in the D296 resin was preferentially desorbed with the mixed solution of ammonia and ammonium chloride,with Re loss rate of 4.97%.Rheniumwas desorbed with ammonium thiocyanate solution,with Re desorption rate of 94.98%.The Re-containing products were prepared from the desorbed solution containing rhenium by adding KCl or NH4Cl and evaporation cooling crystallization.Re crystallization rate is higher than 90% by controlling the rhenium concentration over 22.38g/L in concentrated solution.The results of X-ray fluorescence analysis show that the purity of potassium rhenate and ammonium rhenate reaches 99.21% and 99.58%,respectively.

The behavior of various impurities in silver electrolyzation process is analyzed,purification methods of silver electrolytic waste liquid at present are introduced,and the advantages and disadvantages of these methods are compared.The development direction of comprehensive recovery and treatment technology of silver electrolytic waste liquid is pointed out.

Nickel-based tungsten carbide（Ni60-WC）was coated on 40 Cr substrate by oxygen-acetylene flame spraying,and then the coating was subjected to electrical contact strengthening.Microstructure of coating section was observed by metallographic microscope before and after electrical contact strengthening,microhardness distribution of coating section was analyzed by microhardness tester,and tungsten element distribution of coating and substrate was analyzed by SEM surface scan.The results indicate that electrical contact strengthening can significantly improve the coating quality and hardness,and result in metallurgical bonding between coating and substrate.

TiO2and CdS-TiO2 photocatalysts were prepared with sol-gel method,and they were characterized by X-ray diffraction（XRD）,scanning electron microscope（SEM）and UV-Vis absorption spectroscopy.The results indicate that TiO2 is anatase and CdS is hexagonal after 500℃ vacuum treatment.CdS-TiO2 has the smallest particles with CdS doping amount of 5% molar fraction.Cd and S atomic ratio approaches1∶1.And CdS doping results in red shift of the absorption edge of TiO2.With the increase of doping amount of CdS,photocurrent of CdS-TiO2 is enhanced firstly and then weakened,and 5% CdS-TiO2 has the highest photocurrent of 1.2mA/cm^2.The results of degradation experiments of methylene blue in visible light show that with the increase of CdS doping amount,the degradation rate of methylene blue increases gradually by CdS-TiO2.The highest degradation rate of methylene blue is 57%,which is attributed to5% CdS-TiO2.