Preparation of sodium molybdate from molybdenum concentrate by microwave roasting and alkali leaching

The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient development of molybdenum concentrate resources,this paper proposes a new process for efficient recovery of molybdenum from molybdenum concentrate and preparation of sodium molybdate by microwave-enhanced roasting and alkali leaching.Thermodynamic analysis indicated the feasibility of oxidation roasting of molybdenum concentrate.The effects of roasting temperature,holding time,and power-to-mass ratio on the oxidation product and leaching product sodium molybdate (Na_(2)MoO_(4)·2H_(2)O) were investigated.Under the optimal process conditions:roasting temperature of 700℃,holding time of 110 min,and power-to-mass ratio of 110 W/g,the molybdenum state of existence was converted from MoS_(2) to Mo O3.The process of preparing sodium molybdate by alkali leaching of molybdenum calcine was investigated,the optimal leaching conditions include a solution concentration of 2.5 mol/L,a liquid-to-solid ratio of 2 mL/g,a leaching temperature of 60℃,and leaching solution termination at pH 8.The optimum conditions result in a leaching rate of sodium molybdate of 96.24%.Meanwhile,the content of sodium molybdate reaches 94.08wt%after leaching and removing impurities.Iron and aluminum impurities can be effectively separated by adjusting the pH of the leaching solution with sodium carbonate solution.This research avoids the shortcomings of the traditional process and utilizes the advantages of microwave metallurgy to prepare high-quality sodium molybdate,which provides a new idea for the highvalue utilization of molybdenum concentrate.

Financial Support for Rural Cooperative Economy in China Based on Grey Correlation Analysis

This paper firstly analyzed current situations of financial support for rural cooperative economy in China and tested the correlation between rural finance and rural cooperative economy using the grey correlation analysis method. Results indicate that there is a close relationship between amount,structure and efficiency of rural finance and development of rural cooperative economy. The amount of rural finance has the largest promotion function to development of rural cooperative economy,the next is rural finance structure,and the least is efficiency of rural finance. Based on research conclusions,it came up with pertinent policy recommendations.

Self-Healing Hydrophilic Porous Photothermal Membranes for Durable and Highly Efficient Solar-Driven Interfacial Water Evaporation

It is highly desirable to develop a solar-driven interfacial water evaporatorwith a self-healing ability and high-efficiency water evaporation performance for water distillation and desalination;however,this process is considerably challenging.Herein,by exploiting the advantages of a self-healing hydrophilic polymer,a self-healing hydrophilic porous photothermal(SHPP)membrane was fabricated by curing a mixture of the polymer,carbon black,and NaCl,followed by removal of the NaCl from water.Since the SHPP membrane could serve as a photothermal layer and water transportation channel simultaneously,a solar-driven interfacial evaporator could be fabricated readily by assembling the SHPP membrane with polyethylene foam.We have shown that the SHPP membrane-based evaporator exhibited a water evaporation rate of 1.68 kg m^(−2) h^(−1) and an energy efficiency of 97.3%.These values are superior to those obtained using solar-driven interfacial evaporators with self-healing capability.Notably,by hydrogen bonds reformation between the fracture surfaces,the SHPP membrane could regain its structural integrity after breaking,making the SHPPmembrane-based evaporator the first to heal entirely and repeatedly from physical damage to sustain itswater evaporation capacity.Therefore,the potential of using SHPP membranes to develop stable,long-last ing,andhigh-efficiency solar-driven interfacial water evaporators is highlighted.