Tungsten powders coated by nickel were prepared with proper nickel compound as the raw material and corresponding addition method.Trace nickel can be coated evenly on the surface of tungsten powders.The above tungsten powders were used to produce compact tungsten rods by activated sintering.The tungsten rods were applied in rare earth electrolysis as the cathode of better corrosion resistance than traditional molybdenum cathode.The compact tungsten electrode of a relative density over 90% can be prepared by activated sintering at a temperature below 1 500 ℃ and using the tungsten powders coated with 0.4% nickel.The above tungsten electrode preparation process has the advantages of short flow,low production cost,and stable product quality.

The process of high concentration ammonia and nitrogen wastewater treatment with organic compound denitrification agent was studied.By this process,the ammonia and nitrogen concentration in the wastewater is reduce from as high as 104 mg/L and even more than 105mg/L to meet the national emission standards for NH3-N level（GB 18918-2002）,and the denitrification rate is above 99.9%.The results of practical application shows that the process can save energy,its engineering investment is half less than other denitrification processes,and the economic benefit of NH3-N recovery is obvious.

The processes of atmospheric absorption and pressure swing adsorption（PSA） are now commonly used to recover and purify the hydrogen in tungsten and molybdenum reduction system.They are analyzed and compared in detail in respect of process flowsheet,technical and economic inde,and application effect.The existing problems of PSA process for tungsten and molybdenum reduction system are clearly pointed out and some improvement measures are proposed.

The molybdenum metal samples were dissolved with hydrogen peroxide and then their trace arsenic contents were determined by hydride generation flame atomic absorption spectrometry.The results show that the above method is of good accuracy and precision with 91.8%～102.0% standardized recovery,9.96% RSD,0.28 μg/L arsenic detection limit.

The microstructure and electrochemical property of multiphase La-Mg-Ni hydrogen storage alloy are influenced by its preparation techniques.The latest development in this area is reviewed.The microstructure of the La-Mg-Ni alloy plays a decisive role on its electrochemical parameters.Based on this view,the advantages and disadvantages of different preparation techniques are compared to provide ideas and basis for preparing hydrogen storage alloy of excellent electrode performance.

The latest development at home and abroad of anode slime pyrometallurgical treatment process is briefly reviewed from its technology and equipment in the three process steps of reducing smelting,oxidation refining,and comprehensive recovery of valuable metals.The gap between domestic and foreign anode slime pyrometallurgical processes is analyzed and studied.Oxygen-enriched air smelting and process subdivision comprehensive recovery based on automatic control are the development direction of the anode slime pyrometallurgy.

In view of some problems in temperature control in sodium reduction operation during tantalum smelting,based on the computer technology,MCGS configuration software is applied during sodium reduction for the real-time monitoring,data recording and curve drawing of real-time temperature,sodium injection temperature and dosage,mixing motor and fan running state and so on.Sodium reduction process can be perfected and improved,and the productivity is also improved by analyzing these recorded data.

Based on the analysis and investigation of SnO2 and Cu2FeSnS4＇s thermodynamic difference in caustic soda leaching,the influence of roasting pretreatment on the leaching ratio of tin was studied.Results show that in caustic soda leaching process,SnO2 is very hard to leach with leaching rate close to zero,while the leaching rate of Cu2FeSnS4 is much higher,which can reach 40%~50% under normal leaching conditions.Upon oxidization and roasting of the tungsten concentrate,the leaching ratio of stannum can be greatly reduced.At roasting temperature 700～800 ℃,roasting duration 2 h,the tin sulfides in Cu2FeSnS4 can be fully all converted into SnO2,and the leaching ratio of tin is reduced from 5.96% down to about 1%.

Based on the single-factor condition test,the optimal technological parameters are determined for vanadium extraction by the＂roasting without additives-alkaline leaching＂and the oxidizer-oxidizing-acid leaching processes.The test results show that with mineral particle size 0.074 mm,oxygen partial pressure 10～100 Pa,roasting duration 3 h,leaching temperature 90 ℃,3 h leaching duration,caustic soda concentration 40 g/L,liquid-solid ratio 1.5∶1.0,the leaching rate of vanadium pentoxide by roasting without additives-alkaline leaching＂ can reach 83.8%,20% higher than that bytraditional sodium roasting-acid or alkaline leaching,with mineral particle size 0.074 mm,MnO2 oxidizer consumption at 5%,sulfuric acid concentration at 40%,leaching temperature 90 ℃,9 h leaching duration,liquid-solid ratio 2.5∶1.0,the leaching rate of vanadium pentoxide by oxidizer-oxidizing-acid leaching can reach 72.4%,10% higher than that by the traditional sodium roasting.

At pH1,La concentration is determined by EDTA volumetric titration in the two phases of P204-HCl-HAc extraction system,and study is made on the effect of solution acidity and extractant concentration on La distribution ratio.Based on the infrared spectrum testing and analysis of La loaded organic phase in the P204-HCl-HAc system,investigation is made on the extraction mechanism of La in P204-HCl-HAc system and the extraction equilibrium constant is determined.The results show that at pH1,the extraction is actually a displacement reaction between La and group P-OH based on the cation exchange mechanism and complexing and coordination action between La and group P=O with extraction equilibrium constant KLa is 10-0.02.