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.

Effect of fluoride ions on coordination structure of titanium in molten NaCl–KCl

The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spectral techniques.The α was taken as a factor to indicate the molar concentration ratio of F^(-) and Ti^(n+).Cyclic voltammetry(CV),square wave voltammetry(SWV),and open circuit potential method(OCP)were used to study the electrochemical behavior of titanium ions under conditions of various α,and in-situ sampler was used to prepare molten salt samples when α equal to 0.0,1.0,2.0,3.0,4.0,5.0,6.0,and 8.0.And then,samples were analyzed by X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy.The results showed that F^(-) in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable.Ti^(2+) cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state.Investigation revealed that the mechanism behind those phenomenon is the coordination compounds(TiCl_(j) F_(i)^(m-)) forming.

Fuzzy Reliability Analysis of One Paralleling System

In this paper,we analyze the fuzzy reliability of paralleling system,focusing on the situation of the early failure mode.The early failure mode of fuzzy reliability mainly obeys the Weibull distribution.Based on this,we obtain the distribution function,density function,failure function,reliability function and the formula of the mean time to failure.For the paralleling system composed of multiple components,C1,C2,???,Cn,especially whenη=1,we also obtain the corresponding formulas.Finally,we cite an example to verify the formula and deepen the understanding.

Surface chemical characterization of deactivated low-level mercury catalysts for acetylene hydrochlorination

Mercury-containing catalysts are widely used for acetylene hydrochlorination in China. Surface chemical characteristics of the fresh low-level mercury catalysts and spent low-level mercury catalysts were compared using multiple characterization methods. Pore blockage and active site coverage caused by chlorine-containing organics are responsible for catalyst deactivation. The reactions of chloroethylene and acetylene with chlorine free radical can generate chlorine-containing organic species. SiO_2 and functional groups on activated carbon contribute to the generation of carbon deposition. No significant reduction in the total content of mercury was observed after catalyst deactivation, while there was mercury loss locally. The irreversible loss of HgCl_2 caused by volatilization, reduction and poisoning of elements S and P also can lead to catalyst deactivation. Si, Al, Ca and Fe oxides are scattered on the activated carbon. Active components are still uniformly absorbed on activated carbon after catalyst deactivation.

An Improved Measurement Uncertainty Calculation Method of Profile Error for Sculptured Surfaces

The current researches mainly adopt "Guide to the expression of uncertainty in measurement(GUM)" to calculate the profile error. However, GUM can only be applied in the linear models. The standard GUM is not appropriate to calculate the uncertainty of profile error because the mathematical model of profile error is strongly non-linear. An improved second-order GUM method(GUMM) is proposed to calculate the uncertainty. At the same time, the uncertainties in different coordinate axes directions are calculated as the measuring points uncertainties. In addition, the correlations between variables could not be ignored while calculating the uncertainty. A k-factor conversion method is proposed to calculate the converge factor due to the unknown and asymmetrical distribution of the output quantity. Subsequently, the adaptive Monte Carlo method(AMCM) is used to evaluate whether the second-order GUMM is better. Two practical examples are listed and the conclusion is drawn by comparing and discussing the second-order GUMM and AMCM. The results show that the difference between the improved second-order GUM and the AMCM is smaller than the difference between the standard GUM and the AMCM. The improved second-order GUMM is more precise in consideration of the nonlinear mathematical model of profile error.

Fuzzy Reliability Analysis of One Parallelingseries System

In this paper,we analyze the fuzzy reliability of paralleling-series system,focusing on the situation of the early failure mode.The early failure mode of fuzzy reliability mainly obeys the Weibull distribution.Based on this,we obtain the distribution function,density function,failure function,reliability function and the formula of the mean time to failure.For the paralleling-series system composed of multiple components,C1j,C2j,Cn j…,C nj(j=1,2,…,K),especially whenη=1,mij=m,i=1,…n,j=1,2,…,k,we also obtain the corresponding formulas.Finally,we cite an example to verify the formula and deepen the understanding.

Analyzing the characterization of pore structures and permeability of diesel contaminated clays under different aging conditions

In this study,mercury intrusion porosimetry(MIP)and X-ray micro-computed tomography(XRµCT)were used to characterize the pore structures and investigate the permeability characteristics of clay after aging and contamination with diesel.The results of the MIP tests showed that aging leads to reductions in porosity and average diameter,as well as an increase in tortuosity.The XRµCT analysis yielded consistent results;it showed that aging renders pores more spherical and isotropic and pore surfaces smoother.This weakens the pore connectivity.Micromorphological analysis revealed that aging led to the rearrangement of soil particles,tighter interparticle overlapping,and a reduction in pore space.The combination of MIP and XRµCT provided a comprehensive and reliable characterization of the soil pore structure.An increased diesel content increased the porosity and average diameter and reduced the tortuosity of the pores.Mechanistic analysis showed that aging weakens interparticle cohesion;this causes large agglomerates to break down into smaller agglomerates,resulting in a tighter arrangement and a subsequent reduction in porosity.An increase in diesel content increases the number of large agglomerates and pore spaces between agglomerates,resulting in increased porosity.Both aging and diesel content can weaken the permeation characteristics of soil.

Ecological control strategy for cooperative autonomous vehicle in mixed traffic considering linear stability

Purpose–This paper aims to present a cooperative adaptive cruise control,called stable smart driving model(SSDM),for connected and autonomous vehicles(CAVs)in mixed traffic streams with human-driven vehicles.Design/methodology/approach–Considering the linear stability,SSDM is able to provide smooth deceleration and acceleration in the vehicle platoons with or without cut-in.Besides,the calibrated Virginia tech microscopic energy and emission model is applied in this study to investigate the impact of CAVs on the fuel consumption of the vehicle platoon and trafficflows.Under the cut-in condition,the SSDM outperforms ecological SDM and SDM in terms of stability considering different desired time headways.Moreover,single-lane vehicle dynamics are simulated for human-driven vehicles and CAVs.Findings–The result shows that CAVs can reduce platoon-level fuel consumption.SSDM can save the platoon-level fuel consumption up to 15%,outperforming other existing control strategies.Considering the single-lane highway with merging,the higher market penetration of SSDM-equipped CAVs leads to less fuel consumption.Originality/value–The proposed rule-based control method considered linear stability to generate smoother deceleration and acceleration curves.The research results can help to develop environmental-friendly control strategies and lay the foundation for the new methods.