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•No any chemical additives are added in whole recycling process.•High value-added Li2CO3 and Mn3O4 are in situ recovered without any additive.•Mechanical treatment is used in the ...recovery process to improve the handling capacity.
The large-batch application of lithium ion batteries leads to the mass production of spent batteries. So the enhancement of disposal ability of spent lithium ion batteries is becoming very urgent. This study proposes an integrated process to handle bulk spent lithium manganese (LiMn2O4) batteries to in situ recycle high value-added products without any additives. By mechanical separation, the mixed electrode materials mainly including binder, graphite and LiMn2O4 are firstly obtained from spent batteries. Then, the reaction characteristics for the oxygen-free roasting of mixed electrode materials are analyzed. And the results show that mixed electrode materials can be in situ converted into manganese oxide (MnO) and lithium carbonate (Li2CO3) at 1073K for 45min. In this process, the binder is evaporated and decomposed into gaseous products which can be collected to avoid disposal cost. Finally, 91.30% of Li resource as Li2CO3 is leached from roasted powders by water and then high value-added Li2CO3 crystals are further gained by evaporating the filter liquid. The filter residues are burned in air to remove the graphite and the final residues as manganous-manganic oxide (Mn3O4) is obtained.
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•A new technical process was proposed to recover valuable components from GRR.•Zn, Pb and Ga were selectively separated from Ga-rich residues with complex compositions.•High purity Zn ...and Pb products were obtained by low-temperature vacuum carbothermal reduction.•Clarified the mechanism of metal separation and finally obtained a condensate containing 1.49 % Ga.
In this study, the gallium-rich residue (GRR) obtained from phosphorus flue dust (PFD) after phosphorus removal was taken as the research object, and a novel technology for efficient recovery of valuable metals from GRR was proposed. This technology mainly adopted a two-stage vacuum carbothermal reduction process to selectively recover Zn and Pb and concentrate Ga. The feasibility of separating these three metals from GRR was investigated by thermodynamic analysis, and the effects of temperature, reducing agent dosage and holding time on metals recovery were explored. A promising recovery rate of up to 96.84%, 97.98% and 86.32% was achieved for Zn, Pb and Ga, respectively, under the optimal conditions. The purity of Zn and Pb in the condensate reached 98.57% and 80.56%, respectively, which can be used as raw materials for downstream enterprises and have high economic value. Additionally, the resulting Ga-rich condensate contained 1.49 % Ga, which is much higher than other traditional Ga-containing secondary resources, and can be further purified by hydrometallurgical process or other technologies. The whole process has almost no secondary pollution, with remarkable efficiency, providing a new approach for the comprehensive utilization of PFD.
Silver and tellurium are crucial valuable metallic elements in anode slimes. During pyrometallurgical processing, tellurium exists in the alloy as the stable compound Ag2Te. The current process of ...separating tellurium from silver-tellurium compounds in crude silver by oxidizing tellurium into slag leads to undesirable loss of silver, low recovery rates of tellurium, and considerable slag. An environmentally friendly and efficient vacuum thermal decomposition process of Ag2Te was proposed, and the effects of temperature, pressure, and holding time on the decomposition of Ag2Te were investigated. The Experimental temperature was thermodynamically calculated to be in the range of 1473–1673 K and pressure in the range of 1–100 Pa. As the temperature increases, especially above 1573 K, the silver volatiles increase significantly, and silver and tellurium vapors react strongly to form stable silver-tellurium compounds. Investigating the volatilization and condensation mechanisms of silver and tellurium highlights the importance of inhibiting silver volatilization to achieve efficient separation of silver and tellurium. Volatiles containing 98.85% tellurium mainly as tellurium monomer, and a remained melt consisting of 95.56% silver primarily as silver monomer were produced at 1523 K, 50 Pa, and an 8-h holding time.
•This study provides theoretical guidance and experimental basis for removing tellurium from silver-tellurium alloys.•The migration, distribution, and condensation law of Ag and Te during the vacuum decomposition of Ag2Te were investigated.•Volatiles mainly as tellurium monomer and the remained melt primarily as silver monomer was produced.
Yellow phosphorous flue dust (YPFD) is a solid waste produced by the yellow phosphorus industry that contains heavy metals such as zinc (Zn) and lead (Pb), causing environmental damage. In this work, ...a vacuum metallurgy method is proposed to separate and recover Zn and Pb from solid waste YPFD. Under optimized conditions of 1173 K, 30 wt% reductant dosage, 60 min, and 5–10 Pa, the pre-separation of Zn and Pb was realized and the recovery rates of Zn and Pb reached 92.47% and 99.78%, respectively. In addition, gallium (Ga) remained in the residue with little loss, and then recovered by raising the reaction temperature to 1323 K. The recovery rates of Ga reached 87.57%. The principle of metal volatilization under vacuum at different temperatures was also clarified. The thermodynamic calculations of the carbothermal reduction reaction of metal oxides under vacuum were carried out. The analysis of the product obtained at 1173 K showed that Zn and Pb mainly existed in the form of elemental or simple compounds. At 1323 K, Ga in the residue was highly enriched in the condensation zone, which is conducive for the subsequent purification. The whole process is short, there is no waste water, low levels of pollution of emitted, and the technology provides a clean and sustainable way to reuse YPFD.
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•A new method for separation and recovery of Zn, Pb, and Ga from YPFD was proposed.•92.47% Zn, 99.78% Pb, and 87.57% Ga in YPFD were recovered by vacuum metallurgy.•The content of Ga in the condensate was 1.37%, which was enriched about 30 times.•Clarified the separation principle and reaction mechanism of this technology.
Arsenic–containing copper dust is a typical solid hazardous waste generated from the copper smelting pyrometallurgical process. It has become one of the key factors restricting to hinder the ...sustainable development of copper pyrometallurgical enterprises owing to its potential environment threat, although containing considerable value metals besides arsenic. In this study, we propose a novel process of vacuum carbothermal reduction–vulcanization roasting to remove arsenic. In the stage of vacuum carbothermal reduction, the arsenic in arsenate was reduced and volatilized, and partial arsenic was reduced to form intermetallic compounds with other metals, which inhibited the further removal of arsenic, resulting in 70% arsenic removal in the reduction stage. The arsenic in reduction slag was removed by following sulfur roasting and the roast slag with below 1% arsenic was recycled. The overall arsenic removal rate is 95% higher, and major metals such as lead, bismuth, copper, and tin in the sample were deposited in the slag. Most of the arsenate and metal arsenide in the dust, such as Cu3As and FeAs, were eventually transformed into volatile arsenic and arsenic trioxide. The proposed novel process has a remarkable effect on the separation of arsenic in arsenic–containing copper dust with complicated composition and has certain application prospects.
•A vacuum carbothermal reduction–vulcanization roasting process to remove arsenic from copper smelting dust was proposed.•Low‒toxicity disposal of high arsenic copper dust can be realized by two‒step roasting.•The evolution behavior of various substances in the roasting process was investigated.•The volatilization and condensation behavior of arsenic and arsenic trioxide were presented.
Silver in Kaldo smelting slag of copper anode slime is diffuse and hard to be enriched. In this study, a novel process consisting of reduction smelting and vacuum metallurgy was developed to enrich ...Ag in Kaldo smelting slag of copper anode slime through laboratory and scale-up experiments. Pb, Bi and Ag in the slag were first enriched in Pb–Bi–Ag alloy by reduction smelting. Results show that when the reduction smelting was conducted for 40min under 1350 °C with the addition of reductant, limestone and iron powder accounting respectively for 10%, 20% and 26% of the raw feed, the recovery of Pb, Bi and Ag was 95.12%, 98.13% and 99.11%, respectively. After the reduction smelting, Ag was separated from Pb and Bi by vacuum distillation based on their difference in vapor pressure. Results show that Pb and Bi in Pb–Bi–Ag alloy were removed under the pressure of 3Pa, distillation temperature of 1000 °C and distillation duration of 2 h. After the vaccum metallurgy process, Ag enrichment ratio is above 9. The scale-up experiment shows that Ag recovery is higher than 98%, and more than 97% of Pb and Bi form Pb–Bi alloy product, which further proves that this novel process is simple but efficient for silver enrichment and separation from Pb and Bi in Kaldo smelting slag of copper anode slime.
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•Ag in Kaldo slag of copper anode slime is enriched by reduction smelting and vacuum metallurgy.•Over 99% Pb and Bi are removed by vacuum metallurgy from reduction smelted product Pb–Bi–Ag alloy.•Ag enrichment ratio is over 9 times and its recovery is high up to over 98%.
•The 3D periodic and coupled numerical model was developed for cold crucible simulations.•The simulations were validated against the experimental data from the industrial unit.•The meniscus shape was ...successfully predicted both in the top and crucible contact region.•The charge amount directly affects the meniscus shape and the resulting purification performance.•The skull size is the key parameter for the multiphase flow in the cold crucible furnace.
A numerical and experimental study of free surface motion and heat transfer within an induction skull melting furnace is discussed in this paper. The developed computational domain was three-dimensional with defined periodic boundary conditions, which correspond to the segmented geometry of an actual cold crucible. An electromagnetically driven flow and temperature field within the numerical domain was simulated on the basis of two-way coupling of electromagnetic and fluid dynamic fields. To predict the electromagnetic field, a set of Maxwell’s equations was solved. Then, the information regarding the Lorentz force and Joule heat distributions was transferred to a fluid dynamics submodel. These fields appeared as source terms in the momentum conservation and energy equations, respectively. The multiphase flow was considered turbulent with a free surface. It was simulated using a realizable k-ε model and a volume of fluid approach. Moreover, to consider the radiation heat transfer, the discrete ordinates method was applied. The proposed coupled mathematical model was compared with experimental results obtained from an industry induction skull melting furnace. The model validation clearly showed high accuracy in the discussed numerical model despite the applied simplifications. The shape of the free surface obtained from the computational model was within the standard deviation of the measurements, with a relative error under 4%. The charge temperature, after achieving steady state, was predicted with very high accuracy; however, the heating process was slightly underestimated. Finally, a qualitative comparison for the lower part of the meniscus was also performed. In that region, characteristic tooth-shaped peaks in the connection between the charge and crucible walls were identified for both experimental and numerical analyses.
One of the greatest challenges for long-term human activities on the Moon is the development of in-situ resource utilization (ISRU) technologies, including in-situ oxygen extraction. In this study, a ...novel method called laser thermal vacuum metallurgy (LTVM) was proposed for oxygen extraction from lunar regolith, specifically using TiO2 as raw material. Firstly, the theoretical feasibility of oxygen production from TiO2 was elucidated through thermodynamic calculations. Subsequently, the impact of laser power density on the decomposition behavior of TiO2 was investigated. The results demonstrate that through the augmentation of laser power density to elevate temperatures, there is a substantial enhancement observed in both the pyrolysis and vaporization processes of TiO2. Under the conditions of a laser power density of 2.48 kW/cm2, the surface temperature of TiO2 can be maintained at approximately 2175 °C. The resulting pyrolysis products consist of Ti6O11 (8.2 ± 0.5 wt %), Ti5O9 (23.7 ± 0.6 wt %), Ti4O7 (10.9 ± 0.4 wt %), and Ti3O5 (57.2 ± 0.8 wt %). Further combining with the result of gas collection, the estimated oxygen extraction rate is approximately 43.3 L per kilogram of TiO2. Therefore, LTVM holds the potential to provide a new approach for in-situ oxygen extraction from titanium-containing lunar regolith on the Moon.
•A novel method for in-situ oxygen extraction from TiO2 on the moon using laser thermal vacuum metallurgy was proposed.•The feasibility of oxygen production via vacuum pyrolysis of TiO2 was elucidated through thermodynamic calculations.•The vacuum pyrolysis behavior of TiO2 and its corresponding oxygen extraction were investigated and discussed.•Laser thermal vacuum metallurgy has the potential to extract ∼43.3 L of O2 per kg of TiO2.
As–Pb alloys exist in the smelting process of non-ferrous metals. Both arsenic and lead are toxic and need to be recycled. Vacuum distillation can be used to recover these metals, but the distilled ...materials still need to be processed by multiple distillation, which may waste of manpower and material resources. In this work, a new method of vacuum separation of alloys has been discovered which can be used to recover those metals with high efficiency at one time. The purity of condensate arsenic and lead were over 99.98% and 99.96% respectively by using this method. Furthermore, the condensation ranges of lead concentrates between 480 and 700 °C, and the arsenic concentrates between 200 and 310 °C when the pressure is 5–20 Pa. At the same time, this method also provided the theoretical basis and solutions for non-ferrous metal refining and alloys recovery.
•A new method of vacuum separation of alloys has been discovered.•The purity of condensate arsenic and lead were over 99.98% and 99.96% respectively by using this method.•The condensation area of arsenic and lead at 5-20 Pa was defined.
In this work, vapor–liquid equilibria (VLE) of the Ag–Cu–Pb system were experimentally investigated in vacuum distillation. The experimental results show that the content of Pb in liquid phase is ...0.005 (mole fraction) under the experimental condition of 1173 K, 90 min and 10 Pa. The amount of Pb in volatiles increased to 0.9911 (mole fraction). It indicates that Pb can be satisfactorily removed from Ag–Cu alloy. With the Wilson equation, the partial Gibbs free energies of Pb in liquid Ag–Cu–Pb alloys were calculated, and the predicted values agree well with the experimental data, which shown that the interaction parameters are reliable. Using binary data only, the VLE for the Ag–Pb and Ag–Cu–Pb systems under vacuum condition were obtained. The calculation results demonstrate that this approach can lead to accurate VLE data predictions for the binary and ternary systems based on the Wilson equation.
•VLE (vapor–liquid equilibria) measurements under vacuum condition are reported for the Ag–Cu–Pb system.•The experimental results of VLE for the Ag–Cu–Pb system were correlated using Wilson equation.•Calculated partial Gibbs free energies were compared with the experimental values.
