ACS Sustainable Chemistry & Engineering
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2023
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IF 8.4
Handong Jiao,Mengjun Liu,Zhe Wang,Manpeng Lin,Zhaoliang Qu,Jianxun Song,Shuqiang Jiao
Molten salt electrorefining is expected to be a powerful technology for upcycling titanium scrap because of its robust ability of removing impurities. However, realizing the stable operation of electrorefining, for example, the current efficiency of the anode and the cathode is still a key challenge from the viewpoint of industrial applications. Here, we study titanium’s anodic dissolution and cathodic deposition processes via a direct three-dimensional visualization method based on a computed tomography technology under high-temperature operational conditions. Real-time quantitative results show that the current efficiency is obviously affected by the concentration of titanium ions in the melt. Visual analysis of the local dissolution rate and the curvature of the titanium anode at different electrolysis stages reveals the kinetic origin of the concentration-induced current efficiency changes, which arise from the priority of the side reactions being dependent on the concentration of titanium ions. Finally, we show that employing the high concentration and single existence forms of titanium ions is an effective strategy to prevent the side reactions and improve the current efficiency. This work provides a fresh and fundamental understanding of the side reactions occurring at the interface of electrodes and is significant for facilitating the stability of electrorefining engineering of titanium.
研究领域:
材料科学
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冶金工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2022
·
IF 9.224
Changliu Xiang,Sijun Zhu,Jinbo Song,Yougang Li,Tao Luo,Cong Chang,Junjie Qu,Shenghai Yang,Changhong Wang,Yongming Chen
The conventional electrorefining process of crude lead (Pb)─employing a bone glue (BG)- and calcium lignosulfonate (CL)-synergistically assisted fluosilicic acid (H2SiF6) system─suffers the undesired environment burden caused by the high saturated vapor pressure and low stability of H2SiF6. Herein, we propose an additive-assisted methanesulfonic acid (MSA) system for green and efficient electrorefining of crude Pb based on the low volatility and high stability of MSA. Combinations of MSA with additives are evaluated and screened using photographic images, SEM observations, XRD, white light interference, etc. The electrochemical analysis of cyclic voltammetry and chronoamperometry elucidates the Pb deposition behavior in the Lugalvan BNO12-assisted MSA system, in which a three-dimensional nucleation model is applicable. Using MSA as the solvent and β-naphthol ethoxylate (Lugalvan BNO12) as the assisted additive, the bench-scale operation of crude Pb electrorefining experimentally achieves an electric energy requirement (W) of 87 kWhe/t Pb and a cathodic current efficiency (η) of 99.6%. This is very competitive with the W of 120 kWhe/t Pb and η of 95.0% for the BG-CL-assisted H2SiF6 system. Also, the bench-scale operation obtains a plat and dense deposit sample with a Pb purity of >99.99%. The distribution behavior of elements shows that most of the Pb element is recovered in the form of the cathodic Pb, elements Sn, Zn, and Fe mainly accumulate in the electrolyte, and elements As, Sb, Bi, Ag, and Cu remain in the anode slime. This work opens new directions for more technically and economically feasible Pb electrorefining.
研究领域:
冶金工程
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环境科学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2019
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IF 5.107
Yusheng Yang,Chaoqun Lan,Lingyun Guo,Zhuoqing An,Zengwu Zhao,Baowei Li
Tens of thousands of tons of rare-earth permanent magnet (REPM) wastes are produced worldwide every year. The recovery of rare-earth elements from the wastes can effectively reduce the exploitation of rare-earth minerals. The recovery of neodymium and praseodymium from a REPM waste is investigated by electrolysis in molten LiF-CaF 2 where no anode gas releases, making the process environmentally attractive. Neodymium and praseodymium are selectively oxidized from the REPM waste and transformed into rare-earth ions. To facilitate the oxidation of rare-earth elements inside the REPM waste, we intended to make REPM electrode form channels by oxidation of Nd-Pr and Nd 2 Fe 14 B alloys. By analyzing the microstructure of REPM electrode after forming channels, it can be found that the channels provide continuous transport access of the electrolyte to the inside of the REPM electrode. The separation rates of Nd and Pr increase with increasing current, while the rate of oxidation reaction is proportional to current. In addition, the oxidation of Fe initially occurs at the inside of the REPM electrode where rare-earth elements have been first depleted. The separated rare-earth ions are directly prepared as rare-earth metals at the cathode by electrolysis, leaving the porous Fe 2 B alloy and metallic Fe.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Central South University
·
2024
·Vol. 31
·期 9
·3079-3089
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IF 3.7
Jiang Yan-ying,Liu Ai-min,Tang Zi-rui,Lu Xiao-qing,Liu Feng-guo,Hu Xian-wei,Shi Zhong-ning
The electrochemical behavior of Al(III) in urea-1-butyl-3-methylimidazolium chloride-aluminum chloride (urea-BMIC-AlCl 3 ) ionic liquids, and the effect of potential and temperature on the characterization of cathode products, current efficiency and energy consumption of aluminum electrorefining have been investigated. Cyclic voltammetry showed that the electrochemical reduction of Al(III) was a one-step three-electron-transfer irreversible reaction, and the electrochemical reaction was controlled by diffusion. The diffusion coefficient of Al(III) in urea-BMIC-AlCl 3 ionic liquids at 313 K was 1.94×10 −7 cm 2 /s. The 7075 aluminum alloy was used as an anode for electrorefining, and the cathode products were analyzed by XRD, SEM and EDS. The results from XRD analysis indicated that the main phase of the cathode products was aluminum. The results from SEM and EDS characterization revealed that the cathode product obtained by electrorefining −1.2 V (vs. Al) was dense and uniform, and the mass fraction of aluminum decreased from 99.61% to 99.10% as the experimental temperature increased from 313 K to 333 K. In this work, the optimum experimental conditions were −1.2 V (vs. Al) and 313 K. At this time, the cathode current efficiency was 97.80%, while the energy consumption was 3.72 kW·h/kg.
研究领域:
材料科学
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电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF NUCLEAR MATERIALS
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2024
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IF 2.8
Tan Tan,Kui Liu,Weiqun Shi
A 2D axial electrokinetic mean-field model was developed using the level set method, which well predicts the structural characteristics of the dendritic uranium deposit in molten salt. This model reproduces the average dimensions of the deposit and is validated by comparison with experimental observations. The simulation results emphasize two important controlling parameters, the bulk concentration of uranium in molten salt and the initial current density. High bulk concentration conditions (> 4.78 wt%) tend to reduce the volume of the deposit and improves its compactness. In addition, large initial current density will promote the growth of dendrite due to the diffusion limit effect. An umbrella-like structure can be observed on the surface of the molten salt, which gets larger and thinner with the rising of current density. However, this model fails to capture the anomalous dendrites, which cannot be assumed as a dense region in simulation and appeared in the experiment at high bulk concentration (> 10 wt%) and a range of current density between -200 and -800 mA/cm 2 . Finally, an electrochemical map of dendritic deposits pattern as a function of initial current density and bulk concentration was constructed based on simulation and experimental results.
研究领域:
材料科学
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电化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF NUCLEAR MATERIALS
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2021
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IF 2.936
Kui Liu,Tan tan,Xuanpu Zhou,Nantao Zheng,Yue Ma,Mingliang Kang,Biao Wang,Zhifang Chai,Weiqun Shi
In the widely researched and demonstrated molten salt-based electrorefining process, it is extremely important to control the morphology and growth of uranium dendritic in order to guide the design, operation, safeguard and even upgrade of industrial equipment. Herein this work focuses on the influences of various electrochemical techniques and cathode materials on the dendrite growth and deposition performance for uranium electrorefining. The corresponding current efficiency, deposition rate , deposit compactness, dendrite size distribution and growth rate were studied and compared. It was found that the electrode material has limited effects on the current efficiency, whilst the deposition rate of uranium and growth rate of dendrites on inert cathodes (W and Mo) are relatively higher than that on active cathodes such as stainless steel, Ni and graphite. For controlled current techniques, both the uranium deposition rate and dendrite growth rate are linearly related to the current density. For the controlled potential techniques, only the uranium deposition rate has a linear relationship with the overpotential, whilst the dendrite growth rate has a power exponential relationship with the overpotential. Regardless of the electrolysis technique, controlling the growth of uranium dendrites will sacrifice the deposition rate. In addition, the pulse potential technique can exponentially reduce the growth rate of uranium dendrite at the expense of 30–40% deposition rate.
研究领域:
冶金学
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电化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2024
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IF 13.3
Leyang Li,Ruiyang Sun,Rui Yuan,Manpeng Lin,Linlin Wang,Qi Wang,Jiguo Tu,Handong Jiao,Shuqiang Jiao
Molten-salt electrorefining (MSE) is currently the primary method for purifying many elements, offering promise for the sustainable upcycling of spent metals in the future. However, the conventional constant-current electrolysis protocol inevitably leads to deterioration of the microenvironment near the electrode, leading to reaction runaway and process inefficiency. In this work, we comprehensively studied for the first time the effect of constant- and pulse-electrolysis protocols on environmental evolution in electrode–electrolyte interfaces during the MSE of Ti, using a computer model. The results showed that compared to constant electrolysis, pulse-electrolysis protocols could effectively regulate the interfacial microenvironment and improve the electrorefining efficiency. Furthermore, a correlation between interfacial reconstruction and pulse parameters was established, indicating that the duty ratio was the key factor in inhibiting the deterioration of the interfacial microenvironment. To further verify the simulation results, the real-time morphological evolution of the electrodes during electrolysis was monitored by a novel in situ X-ray computed tomography (CT) technology under pulse-electrolysis protocols. The experimental results indicated that the pulse-electrolysis protocols enhanced the interfacial microenvironment and promoted electrolysis efficiency. Collectively, this work demonstrated that MSE could be effectively advanced by rationally designing the pulse-electrolysis protocols, facilitating its large-scale application in industry.
研究领域:
材料科学
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冶金工程
✓ 已验证
产品关联
DOI
高影响因子
TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
·
2023
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IF 4.5
You-gang LI,Shan-shan LIU,Chang-hong WANG,Jun-jie QU,Chang-liu XIANG,Tao LUO,Shuai LI,Cong CHANG,Sheng-hai YANG,Heng-hui WANG,Xiao-bo MIN,Yong-ming CHEN
A promising methanesulfonic acid (MSA) system, in lieu of conventional fluosilicic acid system, for green and efficient electro-refining of Pb, was proposed, due to its low volatility, low corrosivity, desired thermal stability and high conductivity. The electro-deposition behavior of the MSA-based Pb electro-refining (MPR) was explored, including its operation mechanism, reaction reversibility, nucleation, and growth mode. Based on cyclic voltammetry (CV) and chronoamperometry (CA), the diffusion-controlled and irreversible lead deposition process of MPR was revealed, and the theoretical model of MPR lead deposition nucleation and growth with transient nucleation was established. The bench-scale proof-of-concept operation of MPR achieved energy consumption of 104.22 kW·h/t Pb and current efficiency of 99.24%, which was competitive with the energy consumption of 120 kW·h/t Pb and current efficiency of 95% for H 2 SiF 6 system. The bench-scale operation of MPR obtained a smooth and compact deposit sample with Pb purity of 99.9925%, which satisfied the standard of Pb ingot (GB/T 469—2013) of 99.97%.
研究领域:
冶金工程
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电化学
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2022
·Vol. 15
·期 8
·2789
·
IF 3.748
Chang Liu,Guangqiang Li,Lifeng Zhang,Qiang Wang,Qiang Wang
A transient three-dimensional comprehensive numerical model was established to study ion transport caused by diffusion, convection, and electro-migration in the electro-refining process for scrap-metal recycling. The Poisson–Nernst–Planck equations were used to define ion transport within the electrolyte, while the Naiver–Stokes equations and the energy equation were employed to describe fluid flow and heat transfer. In addition, the Butler-Volmer formulation was used to represent the kinetics of the electrochemical reaction. The comparison between the measured and simulated data indicates the reliability of the model. Under the action of diffusion and electro-migration, the positive copper ion moves from the anode to the cathode, while the negative sulfate ion migrates in the opposite direction. The distribution of the ion concentration, however, greatly changes if the fluid flow is taken into account. The ion concentration around the anode and the rate of the electrochemical reaction that occurs at the anode surface are reduced by the fluid flow. The proposed computational framework offers a valuable basis for future research and development in the field of scrap-metal recycling technology.Keywords:metal recycling;electro-refining process;ion transport;convection;electro-migration;computational fluid dynamics
研究领域:
冶金工程
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环境科学
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2020
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IF 3.807
Kewei Jiang,Yawei Shao,Valeri Smolenski,Alena Novoselova,Qi Liu,Minghui Xu,Yongde Yan,Jing Yu,Milin Zhang,Jun Wang
The electrode reactions of the Ce 3+ /Ce couple in molten LiCl–KCl eutectic in the temperature range 723–823 K on solid Mo electrodes were investigated by electrochemical techniques . The mechanism of deposition of metallic cerium has been established. It was found that the cathode reaction is irreversible and proceeds in one stage. The apparent standard Gibbs energy of CeCl 3 formation from the elements was calculated. The values of enthalpy and entropy were equal: ΔH* = − 1000.2 kJ/mol, ΔS* = 166.0 J/mol·K. The conditions of high-purity cerium production have been studied. The chemical structure of cathode deposits as well as the surfaces of the crucible were investigated by XRD , ICP and SEM-EDS methods. It was established that the best results for purification of the cathode product from impurities were achieved in the range 40–60 mA/cm 2 using a two-stage electrolysis. The amounts of the main impurities in the final product were 0.005 wt% Al, 0.0021 wt% Fe, and 0.003 wt% Si. The total purity of metallic cerium after cleaning was increased up to 99.971 wt% if a vitreous carbon crucible was used.
研究领域:
冶金学
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电化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）