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Lead acid batteries are often used, and they produce an abundant amount of lead acid battery waste, which is a source of lead carbonate. Lead oxide was manufactured via thermal decomposition in a vacuum from recycled lead carbonate that was extracted from lead acid battery waste. The decomposed products were characterized by X-ray diffraction and decomposition rate. The impact of the decomposition conditions, including temperature, preservation time, particle size and system pressure, on the lead carbonate decomposition rate were evaluated. The results show that the newly developed lead carbonate vacuum decomposition technique does a good job, and that the decomposition conditions strongly affect the lead carbonate decomposition rate and phase compositions. For instance, at a temperature range of 310–580 °C, a pressure ranging from 10 to 60 Pa, and a preservation time of 30 min, decomposition rates reached as high as 95.77%. At the temperature of 310 °C, when the preservation time increased from 30 min to 180 min, the decomposition rate increased from 29.62% to 78.40%. In terms of the effect of particle size, the mixed particles (≤20 mesh and ≤400mesh) worked best. Furthermore, the lower pressure can explain the lower temperature obtained, and the vacuum system is suited for decomposition, coinciding with a higher decomposition rate.

Stibnite is the main raw material employed to produce antimony. With the excessive exploitation of high-grade stibnite, low-grade stibnite become more and more important. This study aimed to introduce a vacuum process for recovering and enriching antimony from low-grade stibnite. At the pressure of 10 Pa, by controlling heating temperature, Sb2S3 and Sb2O3 from stibnite (12.8 wt% Sb) was evaporated and enriched. We investigated the influence of vacuum distillation temperature and time on the recovery of low-grade Sb2S3. The result indicated antimony recovery could reach about 97% for suitable vacuum distillation conditions, and the purity of Sb2S3 was about 95 wt%. As for high-grade stibnite, through two-step vacuum distillation, Sb could not only be recovered in the form of Sb2S3, but also purified to commercial Sb2S3 with a purity about 99.5 wt%. The results demonstrated that vacuum distillation is a possible way to recover antimony from low-grade stibnite and purify Sb2S3 from high grade stibnite.

A new process to fabricate porous titanium by calcium vapor in-situ reduction of titanium sespuioxide was presented in this paper. The mixture of Ti2O3 and CaCl2 powders was preformed and reduced by calcium vapor. The porous titanium structure was obtained after leaching reduction products with hydrochloric acid and deionized water. The pore structure, morphology, composition of reduction products were investigated by SEM-EDS and XRD. The influence of different contents of anhydrous calcium chloride on porosity was discussed. The results show metallic titanium products with two types of pore structures and vacuum sintering treatment strengthened effectively connection between titanium particles. The porosity of porous titanium samples was 62%–82% and more than 90% of pores are open-pores.

The volatilization and condensation behaviours of magnesium during the sublimation and desublimation processes were investigated at 10 Pa, respectively. The average volatilization rate increases with increasing temperature, but decreases with increasing specific surface area. The condensation position at which the magnesium vapor becomes solid is further away from the heating source with the temperature of the heating source increasing, but the value of the condensation temperature is maintained in an interval (603–733 K). It can be beneficial to the condensation and crystallization of magnesium vapor with increasing the temperature and temperature gradient of the condensing zone appropriately.

Lead sulfide is the main raw material employed to produce lead. And it is believed to be a very stable substance. The dissociation pathway of lead sulfide is believed to be 2PbS = 2Pb(l)+S2, and its initial dissociation temperature at 10 Pa is believed about 1273 K, and there is no report that it could directed dissociate into lead and sulfur. In this work, we theoretically calculated the stability of lead sulfide at the pressure of 10 Pa, and experimentally investigated the dissociation product of lead sulfide. The first part of this article investigated the dissociation pathways of lead sulfide based on thermodynamic calculation. The second part studies the dissociation as well as volatilization product using X-ray diffraction, ICP-AES and SED. The result indicated we could obtain lead from the direct dissociation of lead sulfide, and the dissociation pathway is 2PbS (g) = 2Pb(l)+S 2 . At 1153 K, the decomposition rate is 39.23%, and the purity of lead is 99.9%.

This paper introduces a new process to process noble lead by vacuum distillation, which is produced from the fire reduction smelting of lead anode slime with a large number of valuable and precious metals. Lead anode slime is important as a raw material for the extraction of precious metals. However, some of the shortcomings of the traditional process, such as serious pollution, complex processes, large resource consumption, and low metal recovery rate, must be overcome. Based on a study of the saturated vapor pressure in the metal and vapor–liquid equilibrium diagram of a binary system, we carried out a large-scale recovery experiment for bismuth and lead with the enrichment of silver and copper. The experimental results show that the copper and silver contents in the residue are higher than 80%. Secondary continuous vacuum distillation resulted in a residue with a Ag content of less than 20 g/t. At the same time, the direct yield of silver from the whole process is higher than 99%, and the evaporation contents of Pb and Bi are above 90%. Achieved a comprehensive recovery of valuable metals recycling.

This paper introduces a new process for refining crude lead by vacuum distillation. The saturated vapor pressures of lead and impurity elements were calculated, and the removal effect of impurity elements was quantitatively predicted using the vapor-liquid equilibrium diagram. In addition, the low temperature followed by high temperature vacuum distillation method and the high temperature followed by low temperature method were adopted to adjust the order of impurity removal. The refining effect was experimentally studied using these two methods, and the best parameters were determined. The predictions are in close agreement with the experimental results. Based on theoretical and experimental analyses, a new, clean and efficient process for refining crude lead was developed. First, the crude lead was distilled by vacuum distillation at 10 Pa and 1673 K for 30 min, and then, the volatiles and residues were collected. Second, the volatiles were vacuum distilled at 10 Pa and 1273 K for 30 min. The removal rates of Cu, Sn, Ag, Zn, Sb and Bi were 99.73%, 99.72%, 96.23%, 90.78%, 74.80% and 8.82% respectively, and the purity of Pb reached 99.03%.

Vacuum distillation of a zinc-silver (Zn–Ag) alloy under a system pressure of 5–10 Pa was conducted in the temperature range of 1173–1373 K. The Zn content in the Zn–Ag alloy was reduced from 70.80 wt% to 0.0026 wt% via a single-stage distillation process at a temperature >1373 K. The molecular interaction volume model (MIVM) was reasonably simplified. The activities of the Zn–Ag alloy components were calculated using the simplified molecular interaction volume model (SMIVM). The calculated average standard deviation for Zn and Ag were ±0.0078 and ±0.0082, and the average relative deviations were ±4.6758% and ±4.7564%, respectively. Simplicity and reliability are significant advantages of the SMIVM. The vapor-liquid equilibrium (VLE) phase diagram (T-x diagram) of the Zn–Ag alloy during vacuum distillation was calculated using the SMIVM and VLE theory. The results agree with the VLE data determined from experiments, which indicate that the resulting VLE phase diagram is reliable. The VLE phase diagram of alloys provides an intuitive and effective method for process optimization, development, and prediction of the dependence of product composition on system pressure and temperature during vacuum distillation.

In this work, the kinetics of Pb evaporating from Pb-Sn alloy has been investigated. The experiments were performed in the temperature range 1200 K–1400 K and the pressure of 10 Pa. The results indicated that the evaporation of Pb follow first order kinetics. The overall mass transfer coefficients of lead evaporation from Pb-Sn alloy are 2.68 × 10−6 m s−1, 5.01 × 10−6 m s−1 and 1.92 × 10−5 m s−1 at 1200 K, 1300 K and 1400 K, respectively. Additionally, the apparent activation energy of lead evaporation from molten Pb-Sn alloy was calculated. It revealed that the mass transfer of lead in the vapor phase is not rate limiting in the vacuum distillation. The Pb evaporation from Pb-Sn alloy was mix-controlled by vaporization and liquid mass transfer. The mass transfer in the liquid phase is a major rate-limiting step under the present experimental conditions.

In this paper, thermal decomposition process of molybdenum concentrate in vacuum was thermodynamically analyzed, and decomposition mechanism of Mo S system in molybdenum was mainly studied. To further investigate and analyze the electronic properties in different temperature, the simulation calculations of MoS 2 (0 0 1) surface and Mo 2 S 3 (0 0 1) surface density of states, electron density difference, electronic orbital and Mulliken overlap population were carried out by density functional theory(DFT) formalism. The dynamics simulations results of MoS 2 (0 0 1) surface and Mo 2 S 3 (0 0 1) surface were obtained the temperature range of phase transforming are 1573 K–1673 K and from 1473 K to 1573 K at 20Pa, respectively. The interaction of MoS 2 and Mo 2 S 3 shows that thermal-decomposition of MoS 2 and Mo 2 S 3 does react, when new S S bonds and Mo Mo bond are formed instead of Mo S bond fracture. The experimental results of the thermal decomposition of MoS 2 and Mo 2 S 3 were in accordance with the thermodynamics theoretical calculation results and ab-initio molecular dynamics simulation results.

The vapor-liquid equilibria (VLE) for Sn Bi binary alloy at 5 Pa were carried out at distillation temperatures in the range of 1150 K–1550 K under vacuum condition. The experimental results indicate that Bi can be satisfactorily removed from crude Sn, the content of tin in liquid phase reaching more than 99.99 wt% at a temperature higher than 1300 K. The thermodynamic consistency of the experimental data was checked by Van Ness method. The Wilson equation is used to predicate VLE data. The results show good agreement with the experimental data, indicating that VLE phase diagram is feasible and practical for the process of vacuum distillation of alloys.

Jamesonite is an important complex antimony mineral which treated by conventional methods have shortcomings, such as sulfur dioxide emission and low antimony and lead recovery. This study applied vacuum metallurgy technology to treat jamesonite. The vacuum decomposition behavior of jamesonite (Pb4FeSb6S14) was investigated, and a two-step vacuum distillation process of separation of antimony trisulfide (Sb2S3) and lead sulfide (PbS) from jamesonite was developed. First of all, the decomposition behavior of Pb4FeSb6S14 under vacuum condition was comprehensively studied. The results indicate it decompose into Sb2S3, PbS and FeS at 823 K under vacuum condition, then, Sb2S3 and PbS volatilize at different temperatures. Based on above results, we investigated the effects of vacuum distillation temperature and time on the recovery of Sb2S3 and PbS as well as the effects of temperature on the purity of them. The results indicate that the optimal temperature for separating Sb2S3 and PbS are 923 K and 1173 K, respectively. Under optimal conditions, up to 98% of Sb2S3 with a purity of 99.17% and up to 99.5% of PbS with a purity of 98.7% could be recovered.

Ab-initio molecular dynamics simulations are performed to study the structural and electronic properties of liquid Pb–Sb alloys at eight concentrations. This alloy is known as azeotropic compounds within a certain ingredients at different temperature. The separation of Pb–Sb alloys is experimental carried out by vacuum distillation at 1173 K. Our predictions are coincident with the available experimental data. The experiment results indicate that there exists common volatilization for Pb–Sb alloys when Sb content is 15–20 wt.%. In addition, the calculation results show that when the content of Sb is around 15 wt.%, there is an intense interaction between Pb and Sb, which supports the experimental results. And this point (Pb-15 wt.%Sb) is azeotropic point.

Vacuum decomposition process of molybdenite concentrate was investigated under pressure of 5–35 Pa for 15–120 min at the temperature range 1473 K–1973 K. The theoretical and experimental results showed that Gibbs free energy of vacuum decomposition reactions and evaporation rate of pure sulfur provided the theoretical calculation basis for temperature and heat preservation time selection in vacuum decomposition experiments of molybdenite concentrate. Melting points and saturated vapor pressures of pure substances and compounds predicted the evaporation behavior of impurity elements and its compounds during the experimental process. Both Cu and Fe could partly evaporate into condensate and Cu had better evaporation ability than Fe. MoO3 could easily and Al2O3, SiO2 could partly evaporate into the condensate. Kilo-scale experiment was performed based on the small experiments and its results showed that the Mo content of molybdenum metal product was 92.38% and the S content of sulfur product was 96.28%, and the molybdenum recovery rate reached to 95.94%. Both the theoretical and experimental results proved that it was feasible to produce crude molybdenum and sulfur from molybdenite concentrate through vacuum decomposition.

AlN chlorination route, in the present work, was proposed to extract Aluminum from aluminum nitride under vacuum. Density functional theory (DFT) were implemented to study the interaction of AlCl 3 molecule and AlN ( 10 1 ¯ 0 ) surface. The results of DFT indicate that chemisorbed AlCl 3 adsorption configuration was observed on the clean AlN ( 10 1 ¯ 0 ) surface after structure optimization, and adsorbed AlCl molecules were generated after 1 ps dynamic simulation time. The phase and composition of condensate were examined by means of XRD and EDS. It was found that 97.76 wt% of Al metal was obtained in the experiment B (in the presence of AlCl 3 ), however, no condensate was collected in the experiment A (without AlCl 3 ) at 1760 K under pressure of average 60 Pa. The results show that AlN chlorination route is an alternative Al production method from aluminum nitride.

A procedure has been proposed to calculate the vapor–liquid equilibrium (VLE) phase diagrams of Pb–Sn and Pb–Ag alloys in vacuum distillation based on VLE calculations and molecular interaction volume model (MIVM). The results show good agreement with experimental data which indicate that VLE phase diagram under vacuum obtained by this method is available and reliable. The VLE phase diagram provides an intuitive and convenient way to analyze the product component dependence of temperature or pressure during the process of vacuum distillation. It has a significant advantage to guide for the experiment and industrial production in vacuum metallurgy.

Pre-oxidation vacuum decarburization process was employed to decarburize high carbon ferromanganese. In pre-oxidation stage, the degree of oxidation was controlled by changing roasting time and 13.17% carbon was removed. In the vacuum decarburization stage, C in ferromanganese and O captured in pre-oxidation stage further reacted to decarburize ferromanganese by increasing reaction temperature and prolonging time. The ferromanganese with 0.47% carbon was obtained after the ferromanganese with 6% carbon was roasted for 3 h at 600 °C and decarburized at 1100 °C, 25 Pa for 4 h. At the same time, 19.28% manganese volatilized and was collected as condensate that would compensate the loss of Mn in the low carbon ferromanganese product. Preparing ferromanganese products with different carbon content will be realized by adjusting the technical parameters, such as holding time and temperature, in pre-oxidation and vacuum decarburization procedures respectively.

Based on the molecular interaction volume model (MIVM), the vapor–liquid phase equilibrium of Sn–Sb alloy was calculated, which was used to predict the element distribution of Sn–Sb alloy between vapor and liquid phase during vacuum distillation. A central composite design (CCD) was used to optimize the process parameters influencing the content of Sn in liquid phase and the direct yield of Sn. The studied parameters were distillation temperature, feeding materials and soaking time. Two quadratic mathematical model equations were derived for predicting the content of Sn in liquid phase and the direct yield of Sn. The analysis of variance (ANOVA) shown that distillation temperature was the most significant factor affecting the separation of Sn–Sb alloy. In the process optimization, while the direct yield of Sn equal to 92%, the maximum content of Sn in liquid phase should be 99.66 wt.% under the conditions of 1531 K, 137 g and 46 min. The confirmation test values of 91.22% and 99.43 wt.% were fair agreement with the predicted data, which demonstrated that these models were very good and can be used for parameter optimization in vacuum distillation.

A novel technology was developed to remove impurities from crude lead with high impurities by vacuum distillation. Refined lead (purity over 99%) was achieved through vacuum distillation using crude lead (92.88%) with high impurities as input material under a dynamic vacuum of 5–15 Pa. The results show that vacuum distillation should be taken to obtain lead from crude lead matrix, in which low-volatile impurities namely Cu, Sn, Ag and partial Sb are concentrated in residue at the first fraction stage of 1373 K. Volatilized lead containing high-volatile impurities such as Zn and As is distilled to remove these impurities at the second fraction stage of 973 K. But the property of impurity Bi is similar to lead that can not be separated from crude lead. The separation coefficient ( β i ) and the activity coefficient ( γ i ) of impurity elements are calculated according to the experiments to fill the inadequate data of the thermodynamics.

In this paper, the molecular interaction volume model (MIVM) has been used for a calculation of the activities of components of Pb–Sn–Sb ternary alloy system. The separation coefficients of the related binary alloys Sn–Pb and Sn–Sb and the vapor–liquid phase equilibrium of the Pb–Sn–Sb alloy system were also calculated by using the MIVM. Experiments for the separation of the Pb–Sn–Sb ternary alloy were carried out for the proper interpretation of the results of the model. The predicted data are in good agreement with the experimental results, which indicates that MIVM is reliable and convenient since it has certain physical meaning from the viewpoint of statistical thermodynamics and requires only two infinite dilute activity coefficients for each sub-binary system.

Characteristics and synthesis mechanism of Gd 2 O 2 S:Tb phosphors prepared by vacuum firing were investigated by photoluminescence (PL) spectra, X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). The mixtures of raw materials were tested by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The firing temperature was reduced to about 725 °C by the vacuum firing method. The particle size decreased. Meanwhile the particle size distribution and morphology were improved and the luminescence of Gd 2 O 2 S:Tb phosphors was also enhanced as the degree of vacuum decreases. With the decrease of the degree of vacuum, the intensity of the excitation spectrum was strengthened and the band was widened being the particle size of the host lattice decreased to nano scales. The peak with high intensity around 272 nm in the excitation spectra ( λ Em = 545 nm) of Gd 2 O 2 S:Tb nanophosphor may be attributed to the 4d–5f transitions of Gd atoms, which may play a significant role in the energy transfer between Tb 3+ and Gd 3+ ions. 5 D 4 – 7 F J transitions of Tb 3+ ion were mainly concentrated in the narrow green emission spectrum (535–555 nm) with its sharp peak at 545 nm. The synthesis mechanism of Gd 2 O 2 S:Tb phosphors prepared by vacuum firing was also studied.

A method is presented for calculating the separation coefficients of Pb–Au and Pb–Sn alloys in vacuum distillation based on molecular interaction volume model (MIVM). A significant advantage of the model lies in its ability to predict the thermodynamic properties of liquid alloys using only binary infinite activity coefficients. The calculated results of Pb–Ag, Pb–Au, Pb–Sb, Pb–Sn and Sb–Sn show good agreement with experimental data in literature. It shows that the prediction effect of the proposed method is of better stability and reliability because the MIVM has a good physical basis.

The quantity of silicon lost during evaporation is greater than theoretical expectation during the purification of metallurgical grade silicon by vacuum evaporation. In this paper, silicon volatilization rates were measured for evaporation times of 30, 45 and 60 min at 1723, 1773 and 1823 K, respectively. Results indicate that volatilization rates determined in our experiments are one or two orders of magnitude greater than those from theoretical calculation. The equation for theoretical calculation was revised (ω = (2.23–6.30)× 10−1 ppa(M/T)1/2) using silicon evaporation coefficient of 8.5–24. The details of the experimental set-up were found to be important and the mass of silicon evaporated in particular was found to be related to the water-cooling system. The carbon/graphite inserts also and the presence of trace amounts of oxygen in the vacuum furnace could reduce the content of silicon in gaseous phase and support the evaporation of silicon. It was found under certain conditions that there are two principal stages involved: 1) Formation of vapor–liquid equilibrium, 2) Maintenance of the established vapor–liquid equilibrium during the silicon evaporation process. It was found that silicon process losses can be reduced by shortening the time of the first stage.