Dissolution properties of ammonium paratungstate（APT）in （NH4）2HPO4-H2O system were studied with dissolution equilibrium method.The results show that the solubility of APT decreases with the increase of（NH4）2HPO4 concentration at the temperature of70℃,but increases with the increase of（NH4）2HPO4 concentration at the temperature of70℃.The formation of tungstophosphate acid at high temperature is the main reason for a substantial increase of APT solubility and dissolution rate.

To solve the problem of high-zinc concentration in the ammonium molybdate solution obtained by roasting and ammonium leaching of a complex low grade molybdenum concentrate,a new two-stage purification process with ammonium carbonate-ammonia and ammonium sulfide was applied for the treatment of ammonium molybdate solution pretreated with ammonium sulfide.The effects were emphatically investigated of reagent dosage,pH value,reaction temperature and reaction time on zinc removal rate.The optimal conditions of purification process are obtained as follows：in the primary purification,ammonium carbonate dosage is 1.2 times of the theoretical amount with reaction temperature of 45℃,reaction time of 0.5 hand pH value of 9,and zinc removal rate over 95%.In the secondary purification,ammonia and ammonium sulfide addition is 1.1 times of the theoretical amount with reaction temperature of 45 ℃ and reaction time of0.5h,pH value of 8.5,zinc removal rate above 96%.The comprehensive removal rate of zinc is beyond 99.5%,and molybdenum loss rate is less than 1%.The purified solution can be directly treated through acid precipitation and crystallization to obtain ammonium molybdate product of the first grade.

Extraction method was employed for ammonia recovery to prepare ammonium chloride instead of the traditional neutralization evaporation crystallization process.Through the selection and application of the organic phase,diluted ammonia from APT evaporation and crystallization stage was extracted and recovered,and then ammonium chloride was prepared by stripping with concentrated hydrochloric acid going back to the circuit as desorption agent.The whole process is in a relatively closed system to reduce the leakage of ammonia and improve the working environment.

Molybdenum and vanadium were recovered from spent HDS catalysts by two-stage hydrometallurgical extraction including NaOH leaching and H2O2 oxidation leaching without roasting pretreatment at atmospheric pressure.The effects were studied of the dosage of NaOH and H2O2,leaching temperature,leaching time and solid-liquid ratio on molybdenum and vanadium leaching.The results show that the leaching rate of molybdenum and vanadium is greatly influenced by NaOH and H2O2 dosage,increasing along with the increase of the dosage under certain conditions.However,leaching temperature and time have less effects.In addition,the leaching rate of molybdenum decreases with the increase of liquid-solid ratio.After a simple pretreatment of raw material,the leaching rate of molybdenum and vanadium can be above 90%under the optimal experimental conditions as follows：mass ratio of NaOH to Mo and V of 2.5∶1,ratio of H2O2 total volume to spent catalyst mass of 0.8∶1,liquid-solid ratio of 2∶1,NaOH leaching time of 1h,H2O2 batch-feeding leaching time of 2h,and temperature of 35 ℃.

Based on the characteristics of vanadium-bearing chromium residue from vanadium extraction,the process of NaOH alkaline leaching-H2O2 oxidation leaching was applied to extract vanadium and chromium from vanadium-bearing chromium residue.The effects were studied of material particle size,H2O2 dosage,NaOH concentration,leaching temperature and time on the leaching rate of vanadium and chromium,and the optimal leaching conditions were determined.The results show that vanadium and chromium can be effectively extracted and their leaching rates are 95.68% and 92.9%,respectively,under the conditions in the primary leaching as follows：raw material mass of 5g,particle size less than 74 mm,NaOH concentration of 100g/L,liquid-solid ratio of 10∶1,leaching temperature of 70℃and leaching time of 20 min,and the conditions in the secondary leaching as follows：H2O2 dosage of 3mL,agitating oxidation time of 30 min,leaching temperature of 95 ℃ and leaching time of 1h.

A new process was applied of copper extraction with Mextral 984 Hat first and then cobalt extraction with a new extractant of HBL110,to recover cobalt from the heap leaching solution of copper-cobalt ore containing such impurities as iron.The effects were investigated of extractant concentration and saponification rate,equilibrium pH value,temperature and phase ratio on cobalt extraction.The experimental results show that cobalt extraction rate is over 95% after four-stage countercurrent extraction under the conditions as follows：extractant concentration of 50.5%,saponification rate of 50%,equilibrium pH value of 2.4~2.6,phase ratio of 1∶1,temperature of 30 ℃ and time of 5 min.The loaded organic phase was washed by pure water and then cobalt was stripped.The stripping rate of cobalt is more than 94% after four-stage countercurrent stripping with 0.7mol/L H2SO4 solution under the conditions as follows：phase ratio of 8∶1,temperature of 40℃and time of 5min.Cobalt is enriched and separated from such impurities as iron,manganese and magnesium,and its concentration is 20g/L in the stripped solution.

Low-sulfur gold and silver-associated limonite was pretreated by calcination-sulfuric acid leaching to remove most of the impurities and improve silver leaching rate during subsequent cyanidation leaching.The optimal pretreatment conditions are 650 ℃ calcination temperature,2hcalcination time,1.5 mol/L sulfuric acid concentration,4∶1liquid-solid ratio,room temperature,300r/min stirring speed and 4h leaching time.The experimental results show that when the ore of particle size less than 0.074 mm is pretreated by calcination-sulfuric acid leaching,silver leaching rate is 27.89%,about 14% higher than pretreated by calcination-ammonia leaching and 20% higher than without pretreatment.When the ore has lower particle size of 0.025 mm,silver leaching rate increases to 42.61%.However,copper content is still 0.26%in the pretreated limonite by calcination-sulfuric acid leaching.Thus,further study is needed for impurity separation and silver extraction to realize high-efficiency utilization of resources.

（Ti,50W）C solid-solution powders were prepared with precursor method plus vacuum carbothermal reduction.The effects of synthesis temperature and heat preservation time on the microstructure and phase composition of the samples were investigated by XRD,SEM and FESEM.The results show that（Ti,50W）C solid-solution powders with particle size less than 100 nm can be obtained by 2hheat preservation at 1 100 ℃.Compared with the traditional industrial preparation method,precursor method requires lower synthesis temperature and raw material costs to prepare（Ti,50W）C solid-solution powders.

Super-speed friction and wear experiments were carried out with a reconstructive Hopkinson bar as the device and the effects were studied of different projectile impact velocity on friction and wear properties of W-20%Cu/7075 Al and W-20%Cu/45 steel.And the wear mechanism was also discussed.The results show that adhesive wear,abrasive wear and oxidative wear happen between W-20%Cu and 7075 Al under the super-speed condition,while adhesive wear and abrasive wear happen between W-20%Cu and 45 steel.W-20%Cu/7075 Al and W-20%Cu/45 steel have the similar friction coefficient of 0.03~0.20,decreasing with the faster sliding speed.With friction frequency increasing at the same sliding speed,the friction coefficient decreases at first,then increases and keep stable at last for W-20%Cu/7075 Al but increases at first,then decreases to keep stable for W-20%Cu/45 steel.Both W-20%Cu/7075 Al and W-20%Cu/45 steel show negative wear rate,and the absolute value of their wear rate has a decreasing trend with sliding speed increasing.

Ti（C,N）-Co-Mo-WC samples were sintered in vacuum under different conditions of heating temperature and rate.The sample size was measured before and after sintering to calculate the shrinkage.Microstructure of the sample was observed with scanning electron microscopy and its density was determined with Archimedes method.Microstructure evolution rule was investigated of Ti（C,N）-based cermets during sintering.The results show that the green body expands firstly and then shrinks with the increase of sintering temperature from 1 000℃to 1 200℃,and sharply shrinks at 1 300℃.There are mainly diffusion reaction and solid solution reaction at the stage of solid phase sintering to form W and Mo-rich inner ring phase of（Ti,W,Mo）（C,N）.Liquid phase sintering at 1 300~1 500 ℃ can promote rapid densification of the cermets and form Ti-rich outer ring phase of（Mo,W,Ti）（C,N）.