MIVM在真空蒸馏分离锡锌合金中的应用及实验研究

基于分子相互作用体积模型,首先使用牛顿迭代法结合Sn、Zn的无限稀活度系数γS∞n、γ∞Zn计算得出对势能相互作用参数Bij和Bji,并利用Bij和Bji计算Sn-Zn二元系的活度aSn、aZn,并将理论计算值与实验值进行对比分析,最后计算得到Sn-Zn合金真空蒸馏过程中的气液相平衡组成。结果表明:活度计算值和实验值吻合较好;蒸馏温度为1073 K,液相中含锡量为90%时,气相中含锡仅为0.00001%,Sn-Zn合金能够通过真空蒸馏实现良好分离。进一步实验验证结果表明,蒸馏温度1073K、恒温时间100 min,15 Pa条件下,液相中含锡为90%时,气相中含锡为0.002%,实验结果与预测结果吻合较好。此研究为真空蒸馏分离Sn-Zn合金提供了可靠的理论依据及预测模型。

Selective recovery of zinc from zinc oxide dust using choline chloride based deep eutectic solvents

Deep eutectic solvents(DESs) are a kind of potential lixiviant for selective metal processing due to their versatile complexation properties. In this study, we investigated the recovery of zinc from zinc oxide dust using choline chloride-ureaethylene glycol(ChCl-urea-EG) DESs. The zinc extraction efficiency can be up to 85.2% when the slurry concentration is 50 g/L, leaching temperature is 80 °C and stirring speed is 600 r/min. The leaching process is controlled by the diffusion and the corresponding activation energy is 32.1 k J/mol. The resultant solution was directly used for the electrodeposition of zinc. The pure zinc deposit is obtained with a current efficiency of 82.6%. Furthermore, the ChCl-urea-EG DESs can be recycled. This approach is shown to be promising for the recycling of zinc from the zinc-containing dust.

Effect of cooling ways on properties of Al/Pb-0.2%Ag rolled alloy for zinc electrowinning

In order to study the new anode materials for zinc electrowinning,Al/Pb?0.2%Ag rolled alloy was produced by composite casting and hot rolling.Then the effect of cooling ways on properties of Al/Pb?0.2%Ag rolled alloy was investigated.As the results of metallographic test indicated,with the increasing of cooling intensity,both Vickers hardness and yield strength of Al/Pb?0.2%Ag rolled alloy increase.Furthermore,the Al/Pb?0.2%Ag rolled alloy,cooled by ice salt,presents the finest grain size and shows the lowest oxygen evolution potential(1.5902V),while that of alloy cooled by water and air are1.6143V and1.6288V,respectively.However,the corrosion current density and corrosion rate of the Al/Pb?0.2%Ag rolled alloy,cooled by ice salt,are the highest.This can be attributed to its largest specific surface area,which promotes the contact between the anode and electrolyte.

φ-pH diagram of As-N-Na-H_2O system for arsenic removal during alkaline pressure oxidation leaching of lead anode slime

In order to illustrate the thermodynamic characteristics of arsenic during alkaline pressure oxidation leaching process oflead anode slime(NaNO3as oxidant;NaOH as alkaline reagent),theφ-pH diagrams of As-Na-H2O,N-H2O,As-N-Na-H2Osystems at ionic mass concentration of0.1mol/kg and temperatures of298,373,423and473K were established according tothermodynamic calculation.The results show that the existence forms of arsenic are associated with pH value,which mainly exists inthe forms of H3AsO4,24H AsO-,24HAsO-,H2AsO2-and As2O3in lower pH region,while it mainly exists in the form of3AsO4-when pH>11.14.High alkali concentration and high temperature are advantageous to the arsenic leaching.The alkaline pressureoxidation leaching experiments display that the tendency of arsenic leaching rate confirms the thermodynamic analysis resultsobtained from theφ-pH diagrams of As-N-Na-H2O system,and the highest leaching rate of arsenic reaches95.85%at453K.

Transformation behavior of ferrous sulfate during hematite precipitation for iron removal

The transformation behavior of ferrous sulfate was examined during hematite precipitation for iron removal in hydrometallurgical zinc.Specifically,the effects of the method used for oxygen supply(pre-crystallization or pre-oxidation of ferrous sulfate)and temperature(170–190℃)on the redissolution and oxidation–hydrolysis of ferrous sulfate were studied.The precipitation characteristics and phase characterization of the hematite product were investigated.The results showed that the solubility of ferrous sulfate was considerably lower at elevated temperatures.The dissolution behavior of ferrous sulfate crystals was influenced by both the concentrations of free acid and zinc sulfate and the oxydrolysis of ferrous ions.Rapid oxydrolysis of ferrous ions may serve as the dissolution driving force.Hematite precipitation proceeded via the following sequential steps:crystallization,redissolution,oxidation,and precipitation of ferrous sulfate.The dissolution of ferrous sulfate was slow,which helped to maintain a low supersaturation environment,thereby affording the production of high-grade hematite.

Theoretical research on vacuum separation of Au-Ag alloy

To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.

Mechanism of coconut husk activated carbon modified by Mn(NO3)2

To study the mechanism by which activated carbon is modified by HNO3 and Mn(NO3)2,the pore texture and surface chemical characteristics of carbon materials in coconut husk activated carbon(AC)were examined via scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),and X-ray photoelectron spectroscopy(XPS).After being modified by HNO3,the millipore character of AC became deformed,and the character of the adjacent pores remained consolidated.The surface manganites of Mn/AC-1 presented as block and reticular fiber structures,Mn/AC-2's surface manganites presented as petty mammock crystals,and Mn/AC-3's surface manganites were observed as gauze nanosheets that interlace to fill in the pore canal.Nitric acid modification was shown to enlarge surface pores but decrease the specific surface area of AC.Mn loading can be used to construct a new pore structure that,in turn,increased the total specific surface area as well as the specific surface area and the volume of the millipores.Mn/AC-2's pore structure was optimized at a calcination temperature of 500℃and a loading quantity of 5%.The ash content of AC was considerably reduced after modified by HNO3.The active materials for Mn/AC-1 mainly consisted of Mn3O4,with a few Mn2O3 crystals,whereas Mn/AC-2's materials were mainly Mn3O4 and some MnO crystals.Mn/AC-3 was exclusively composed of Mn3O4.HNO3 activation and Mn loading modification did not considerably affect the functional group species present on the catalyst.Modification conditions using the same loading quantities and higher calcination temperatures decreased the number of O—H and N—H bonds while conversely increasing the number of CC and C—O bonds.On the contrary,the use of a higher loading quantity while maintaining the same calcination temperature increased the number of O—H and N—H bonds.A higher loading quantity is beneficial for increasing Mn^4+species.A higher calcination temperature is beneficial for increasing Mn^3+species.The results can optimize the conditions under which Mn/AC catalyst modification occurs,thus improving the physical and chemical properties of carbon-based sorbents.

Theoretical analysis and experimental verification of thermal decomposition mechanism of CuSe

Experiments on the thermal decomposition of CuSe were carried out by using a thermogravimetric analyzer(TGA)at different heating rates.The kinetic parameters and mechanisms were discussed based on model-free and model-based analyses.The decomposition rate and decomposition behavior of CuSe were investigated by using a vacuum thermogravimetric furnace.The results showed that the R3 model was identified as the most probable mechanism function under the present experimental conditions.The average values of activation energy and the pre-exponential factor were 12.344 J/mol and 0.152 s^(−1),respectively.The actual decomposition rate of CuSe was found to be 0.0030 g/(cm^(2)·min).

Optimization of microwave heating thickness for spent automobile catalyst

A new method was developed to optimize the microwave heating thickness of the spent automobile catalyst in order to improve the uniform distribution of the temperature field. The average penetration depth and the microwave heating thickness of the spent automobile catalyst were calculated by Gauss model and numerical calculation based on dielectric loss tangent and reflection loss. The results showed that the spent automobile catalyst was a medium loss material. The average penetration depth was 1.11 m from room temperature to 800 ℃. The optimum microwave heating thickness of the spent automobile catalyst was about 0.83 m or 0.75 times of the average penetration depth. Industrial application analysis indicated that the optimization of heating thickness could improve the uniform distribution of the temperature field and reduce energy consumption.

密度泛函理论在化学链燃烧的应用

化学链燃烧利用载氧体晶格氧化燃料,降低NO排放,是一种高效清洁的燃烧方式。一直以来对载氧体的性能进行不断的实验探索,但是对载氧体与燃料反应,不同活性组分与担体复合形成复合载氧体改变原有性能的机理认识不够充分。基于国内外密度泛函理论研究化学链燃烧,着重对Fe基、Cu基、Ni基、Ca基四种载氧体与担体复合,活性组分掺杂,还原气体,无机物的微观反应进行分析,揭示载氧体改性、还原的机理,为寻找最优载氧体提供理论支撑。

钠基固体电解质及其在能源上的应用

由于以钠基固体电解质为核心的新型钠电池体系具有低成本和高安全性,在能源领域应用潜力巨大。高离子电导率和稳定性是钠基固体电解质应用于新型钠电池体系的前提。近年来,人们通过对制备方法改进和掺杂改性等方面的研究显著提高了钠基固体电解质的离子电导率和稳定性。此外,新型钠电池体系亟需解决固体电解质与电极间的界面接触性差和界面稳定性差等问题。本文首先总结了β″-Al_2O_3、NASICON型、硫化物类和聚合物类钠基固体电解质的研究进展,然后介绍了钠基固体电解质在以钠-硫电池,有机/水混合系钠-空气电池和全固态钠离子电池为代表的新型钠电池体系中的应用情况,并对界面问题和采取的解决策略进行系统论述。基于固体电解质的新型钠电池体系在能源上的大规模应用还需要电池材料、界面和电池设计等多方面的研究同时突破。