Taking ultra-coarse tungsten powder as raw material,and liquid paraffin as wetting agent,the double cone mixing method was used to evenly distribute paraffin on the surface of tungsten powder,and then powdered carbon black was added to the mixture for ball milling.Through analysis of different paraffin additions and carbon distribution uniformity,the influence of paraffin addition on carbon blending effect and total carbon content was discussed.The samples were carbonized under the same process conditions,the quality of the final product tungsten carbide was compared and analyzed,and then the influence of adding trace liquid paraffin on the carbonization effect of ultra-coarse tungsten powder was discussed.The results show that the addition of trace liquid paraffin can make the carbon black distribution more uniform after the tungsten powder is mixed with carbon,and it can also avoid tungsten-carbon separation during boat loading before carbonization.Meanwhile,compression forming is easier,and the tungsten-carbon combination is tighter,which improves the carbonization efficiency and quality,and can produce pure tungsten carbide with coarse grains.Liquid paraffin will decompose at high temperature to produce activated carbon,which combines with tungsten to increase the total carbon content and needs to be balanced during determining carbon amount.Excessive addition of liquid paraffin will result in carbon black aggregation and decreasd particle size of tungsten carbide.Comprehensively considering,when the paraffin content is 0.5‰~3‰,the effect is the best.

Study on optimization of chemical composition of the adhesive phase in cemented carbide roll ring was emphatically carried out.The results of the first-principle calculation show that increasing the nickel content in the adhesive phase can stabilize the face-centered cubic structure of the adhesive phase,weaken the bondability and reduce the magnetic properties,thereby significantly improving the fracture toughness and ductility of the cemented carbide.The experimental results show that the fracture toughness of the cemented carbide is increased by 29%after all the cobalt in the adhesive phase is replaced with nickel.The new series of high-nickel cemented carbide roll ring products,which is developed according this achievement,has significantly reduced cracking phenomenon during low-temperature rolling of rebar steel.

Dry milling tests were conducted for 1 Cr18 Ni9 Ti stainless steel by using cemented carbide tools with different matrix materials.The tools with different milling time were observed before and after corrosion by SEM and EDS,and the tool life and failure mechanism were compared and analyzed to obtain the basis for tool matrix material selection in dry milling of 1 Cr18 Ni9 Ti stainless steel.The experimental results show that adhesive wear,oxidation wear,thermal fatigue and boundary wear are the main failure mechanisms of the tools.The cutting condition of intermittent cutting and grinding chips in stainless steel milling is the basic reason for thermal fatigue of the tool.The cemented carbide tools with the three kinds of matrix show the same characteristics of thermal fatigue.There is a good corresponding relationship between the boundary wear of the tool and the toughness of the matrix.The worse the toughness,the more serious the boundary wear.When choosing the tools for dry milling of stainless steel,the single index of toughness or hardness can not be used as the basis for selecting tool matrix,while the matrix material with appropriate comprehensive mechanical properties can be selected.

水是生命之源,是人类赖以生存和发展的物质基础,是国民经济和社会发展的命脉,即农业的命脉、工业的血液、生命的源泉。离开水,所有的生灵意味着死亡与毁灭。水与人类息息相关,而我们日常生活中,却有意无意地挥霍、破坏着宝贵的水资源。人们误认为水是"取之不尽,用之不竭"的可再生资源。殊不知,有些水资源一旦被污染、破坏,就很难再生。即便再生,也需要几十年、几百年甚至上千年。

The extraction of vanadium and scandium from red mud were carried out by leaching with tita-nium dioxide wastewater.The effects of liquid to solid ratio, leaching temperature, leaching time and stirring rate on the leaching rate of vanadium and scandium were investigated.The phase composition of lea-ching residue and the chemical composition of leaching solution were analyzed by XRD and ICP-AES.The results show that under the conditions of liquid to solid ratio of 6 mL/g, stirring rate of 400 r/min, leaching temperature of 75 ℃ and leaching time of 1 h, the leaching rates of V and Sc are 75% and 80%,respectively.Compared with the titanium dioxide wastewater, the leaching solution contains significantly decreased H+ concentration, vanadium and scandium are enriched and the concentration of iron and aluminum is also increased.Compared with the red mud, anhydrite minerals appears in the leaching residue, while calcite is completely dissolved, cancrinite, brookite and hematite are partially dissolved.

The electrochemical reduction process of Y(Ⅲ) and the cathode behavior of Y₂O₃ in YF₃-LiF molten salt system were studied by cyclic voltammetry.The results indicate that the reduction potential of Y(Ⅲ) on molybdenum electrode is-0.95 V(vs.Pt) in YF3-LiF molten salt system, and the reaction is a quasi reversible reaction that transfers three electrons in one step.The redox peak does not change with the scanning speed, which indicates that the reaction is a quasi reversible reaction with great reversibility.The peak current Ip is linearly related to v^1/2,so the reaction is controlled by diffusion with diffusion coefficient of 3.626 4×10^-8 cm²/s.The addition of Y₂O₃ into molten salt contributes to reducing reduction potential of Y(Ⅲ) and has a certain depolarization effect.There are three different reduction current peaks in the reduction process of Y(Ⅲ) on the iron electrode.Yttrium-iron alloy phase is formed by underpotential deposition and yttrium metal is formed by electroreduction.

The solubility of yttrium oxalate in oxalic acid solution with different concentration(0.6~1.0 mol/L) was determined by FBRM combined with dynamic method at atmospheric pressure and 318.15~343.15 K.The experimental results show that the solubility of yttrium oxalate in oxalic acid solution with different concentration decreases with the increase of temperature and increases with the increase of oxalic acid concentration.Apelblat equation and polynomial empirical equation are used to fit and correlate the experimental data, and the correlation results are good.When the concentration of oxalic acid is low, the effects of the two models are similar.When the concentration of oxalic acid is high, Apelblat equation is slightly better than polynomial empirical equation.The solution enthalpy and entropy of yttrium oxalate in different oxalic acid solution calculated by Van′t Hoff equation are negative, the dissolution process is a non-spontaneous exothermic process, and the main driving force of this process is entropy driving.

Ferrosilicon alloy containing titanium was prepared by carbothermal reduction and induction melting with a polymetallic ore from Xinjiang as raw material.The effects of carbothermal reduction temperature, carbon content and holding time on metal recovery, alloy composition and slag phase were studied by single factor experiment.The experimental results show that under the optimum single factor conditions of 2 073 K carbothermal temperature, 0.8 times of theoretical carbon content and 0.5 h holding time, the highest metal recovery is 52%.The contents(mass fraction) of Al, Si, Fe, Ti and C in alloy are 0.338%,39.74%,45.54%,6.84% and 0.058%,respectively, and the main phase of reduced slag is MgAl₂O₄.

Zirconium is an indispensable material in nuclear industry due to its excellent nuclear properties.Hafnium co-exists with zirconium in nature, their physicochemical properties are extremely similar, but their nuclear properties are quite opposite.Therefore, the separation of zirconium and hafnium for nuclear grade zirconium production has been an important research topic in nuclear industry for a long time.At present, a variety of zirconium and hafnium separation technologies have been developed, which can be roughly divided into pyro-and hydro-metallurgical processes according to their characteristics.In this paper, the research progress on the main zirconium and hafnium separation technologies is reviewed, and the research and development of new nuclear grade zirconium production technologies are prospected.