Materials Today Communications
·
2023
·
IF 3.8
Jiaming Li,Youjian Yang,Wenju Tao,Zhaowen Wang,Jiangyu Yu,Jiaxin Yang,Zhibo Liu
As China's aluminum electrolysis industry expanded its production capacity, it produced a large amount of bath materials– cryolite based molten salt, which is not utilized fast enough and piled up in aluminum factories. It is of great significance to find a proper way to process the accumulated bath materials. Through the method introduced in this paper, aluminum fluoride can be produced from cryolite-based electrolyte and fed back into the aluminum electrolysis cell as a necessary additive. This method includes four steps: Calcination of crystalline aluminum nitrate with cryolite. Cryolite and crystalline aluminum nitrate are mixed and preheated. The main chemical reaction that occurs in this step will produce sodium nitrate (NaNO 3 ), β-aluminum fluoride (β-AlF 3 ), chiolite (Na 5 Al 3 F 14 ) and the aluminum hydroxyfluoride hydrate (AHF). After calcination, the products are washed with water to separate soluble NaNO 3 from the other products. The insoluble products obtained after washing are calcined with ammonium bifluoride to convert AHF into AlF 3 . The mixture obtained after preheating is then washed with an aqueous solution of aluminum salt (such as Al(NO 3 ) 3 ) to remove Na 5 Al 3 F 14 . Aluminum fluoride of high purity is obtained in the end. Calcination step is the most important among the four steps. The effects of calcination temperature (85 – 135 ℃) and molar ratio of crystalline aluminum nitrate to cryolite (0.5 – 2) on the conversion rate of cryolite were studied. The experimental results show that the highest conversion rate of cryolite can reach 97.03%. Through SEM, EDS , ICP and other analysis methods, it was found the final products contained more than 98.8 wt% aluminum fluoride and less than 0.4 wt% sodium, and the average particle size of aluminum fluoride is approximately 15 – 20 µm.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Yichong Li,Huizhong Zhao,Han Zhang,Jun Yu,Wei Wang,Jiulin Xu
Ferrotitanium slag (FTS) is the waste product that has gained attention as a potential calcium hexaaluminate (CA 6 ) resource in recent years. In this study, the phase distribution of FTS and CA 6 aggregate was compared, and its effect on the cryolite resistance of castables was further studied. Scanning electron microscopy and least-squares refinement program were used to characterize the phase distribution and crystallographic parameters of ferrotitanium slag. Computational and experimental results demonstrate that ferrotitanium slag contains denser and larger hibonite crystals compared to synthetic calcium hexaaluminate. Ti element exists in the hibonite crystal in the form of coupled substitution or direct substitution of Al 3+ . Performance evaluation in refractory castables also confirms the resulting improvement in corrosion resistance.
研究领域:
材料科学
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冶金工程
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DOI
高影响因子
ENERGY
·
2021
·
IF 7.147
Wei Shi,Yunlan Sun,Baozhong Zhu,Jianzhong Liu
To improve the ignition and combustion performance of micron-sized aluminum powder (m-Al) in CO 2 , a self-made pipe furnace experimental platform was established to study the effects of sodium fluoroaluminate (Na 3 AlF 6 ) on the ignition delay times, combustion processes , combustion efficiencies , and combustion products of 1–2, 5, and 30 μm aluminum (m-Al 1 , m-Al 5 , and m-Al 30 ) powders in CO 2 at 1000 °C. The combustion phenomenon was recorded by a high speed camera. The ignition delay time was obtained by post-processing the sequential images. m-Al containing Na 3 AlF 6 has a lower initial reaction temperature and a shorter ignition delay time than those of m-Al without Na 3 AlF 6 addition. The effect of Na 3 AlF 6 content on the ignition delay time is different for m-Al with different sizes. The ignition delay times for m-Al 1 and m-Al 5 increase with increasing the Na 3 AlF 6 content, while the corresponding values of m-Al 30 first increase and then decrease. The combustion products were subjected to the analyses of morphology, composition, and combustion efficiency. The oxidation shell of Al is fluorinated by Na 3 AlF 6 , thereby promoting its ignition and burning. The combustion efficiency of m-Al is significantly enhanced, especially for m-Al 30 . The effect mechanism of Na 3 AlF 6 on the ignition and combustion of m-Al in CO 2 was discussed.
研究领域:
材料科学
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燃烧学
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DOI
高影响因子
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
·
2018
·Vol. 49
·期 4
·2071-2076
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IF 1.834
Yan Hengwei,Yang Jianhong,Liu Zhanwei,Wang Chengzhi,Ma Wenhui
The cryolite ratio (CR) is an important parameter for the electrolyte in aluminum reduction cells. The measurement method for the CR of the KF-NaF-AlF 3 system acid (CR < 3) electrolyte by means of electrical conductivity was initially developed, and the formula for calculating the CR was deduced. This method has the advantages of simple operation and high precision. In addition, the relative standard deviations (RSD) of the measurement are < 1.2 pct, and the analysis error of the NaF or KF content has little effect on the determination of the CR.
研究领域:
冶金学
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材料科学
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DOI
高影响因子
JOURNAL OF ENVIRONMENTAL MANAGEMENT
·
2024
·
IF 8
Guangping Wang,Yang Zhenhua,Jianhua Liu,Xing Daqing,Jie Li
The industrial wastewater of aluminum electrolysis contains a large amount of fluorine and valuable metals, and the pH value is high. Direct discharge will cause water pollution. Therefore, this paper studies a process of synthesizing cryolite from aluminum electrolysis industrial wastewater by supplementing aluminum source and adjusting pH value by adding acid, which is used as electrolyte for electrolytic aluminum. Fluoride ion electrode, XRD, Fourier transform infrared spectroscopy, laser particle size analyzer, XPS and SEM-EDS were used to characterize the fluoride ion concentration, phase composition, structure characterization, particle size distribution, chemical bond and morphology-element composition. The results showed that when the synthesis temperature was 30 °C, the pH value was 7 and the ratio of aluminum to fluorine was 1:6, the fluorine recovery rate was the highest, reaching 98.7 %. The synthesized product is cryolite (molecular ratio is 2.815) with an average particle size of about 20 μm. When used as electrolyte, the liquidus temperature is 950 °C, the solubility of Al 2 O 3 is 6.94 %. This process solves the environmental pollution of wastewater from the aluminum electrolysis industry. It provides an efficient, economical and green way for the recycling of aluminum electrolysis industrial wastewater.
研究领域:
环境科学
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材料科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LUMINESCENCE
·
2024
·Vol. 39
·期 11
·e70013
·
IF 3.2
Qi Tan,Bingliang Gao,Pengde Gao,Chao Fan,Haijun Li
The future production of electrolytic aluminum will be characterized by low temperature, low carbon emissions, and environmental friendliness, which will result in a more complex electrolyte system. Real-time analysis of electrolytes can significantly enhance the efficiency of the electrolytic process. However, accurately analyzing the composition of complex aluminum electrolytes online has been a technical challenge. This research primarily focuses on determining the ingredient contents of complex aluminum electrolytes based on elemental concentrations measured using X-ray fluorescence (XRF) according to an applicable standard. Calibration curves were established based on 53 standard samples of complex aluminum electrolytes to establish relationships between XRF fluorescence intensity and real concentrations. Analysis conducted on industrial complex electrolytes confirms that these newly constructed curves effectively reduce relative errors to less than 3%. Additionally, a feasible solution is proposed for determining the cryolite ratio (CR) in aluminum electrolytes using XRF. Results demonstrate an average deviation as low as approximately 0.02, fully meeting industrial production requirements. This technique offers numerous benefits including rapid analysis, ease of use, and cost savings.
研究领域:
冶金学
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材料科学
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产品关联
DOI
PubMed
高影响因子
JOM
·
2019
·Vol. 72
·期 1
·247-252
·
IF 2.305
Yan Hengwei,Liu Zhanwei,Ma Wenhui,Huang Liqiang,Wang Chengzhi,Liu Yingxin
The development of low-temperature aluminum electrolysis makes it possible to reduce energy consumption and greenhouse gas emissions. The KF-NaF-AlF 3 -based electrolyte is a promising low-temperature electrolyte for aluminum reduction. The liquidus temperatures of KF-NaF-AlF 3 electrolytes with a total cryolite ratio (CR t ) fixed at 1.3–2.0, and with different concentrations of NaF (with a step change of 5 mol.%), were investigated by the cooling curve method. The results showed that the liquidus temperature of KF-NaF-AlF 3 mixtures increases with the increase of the CR t , which has a bigger influence on the liquidus temperature than the traditional NaF-AlF 3 electrolyte currently used in aluminum smelters. When the content of NaF is 10–20 mol.%, the curves of the liquidus temperature vs. NaF content reach a peak. When the NaF content ranges from 30 to 40 mol.%, the liquidus temperature is relatively low (695–900°C). The precipitated order of the compounds in molten KF-NaF-AlF 3 electrolytes with a CR t of 1.3 is as follows: K 2 NaAlF 6 (or K 3 AlF 6 ) → Na 3 Al 5 F 14 → K 2 NaAl 3 F 12 → KAlF 4 .
研究领域:
材料科学
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冶金学
·
电化学
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产品关联
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2021
·
IF 3.599
Pengfei Shuai,Libing Liao,Qingfeng Guo,Dan Yang,Ruiqi Shi,Lefu Mei
Cryolite was considered to be an ideal up-conversion host material due to its low phonon energy, which can effectively suppress the radiation-free transition process of excited state energy levels. In the present paper, a novel up-conversion material K 3 YF 6 :Ho 3+ , Yb 3+ with cryolite structure was prepared successfully using a high-temperature solid state method. The up-conversion luminescence properties of K 3 YF 6 doped with different Ho 3+ /Yb 3+ doping ratio were investigated and the optimal doping ratio were confirmed in this system. Under 980 nm excitation, Ho 3+ /Yb 3+ co-doped K 3 YF 6 revealed a strong green emission at the 541 nm, 549 nm and a weak red emission peaking at 666 nm, corresponding to the 5 F 4 , 5 S 2 → 5 I 8 and 5 F 5 → 5 I 8 transitions of Ho 3+ , respectively. All the red and green up-conversion emission of K 3 YF 6 :Ho 3+ , Yb 3+ belong to two-photon process and energy transfer from Yb 3+ to Ho 3+ simultaneously. Additionally, to understand the energy transfer and electronic transition process of the red and green light emitted, the possible luminescence mechanism were also analyzed in this paper. All the results indicate that Ho 3+ /Yb 3+ co-doped K 3 YF 6 have potential application value in green up-conversion luminescent materials.
研究领域:
材料科学
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光学
·
发光材料
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DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Zhipeng Jing,Aimin Liu,Yongjun Wang,Yuankun Zhang,Fengguo Liu,Chengdan He,Xianwei Hu,Jin Wang,Zhenkun He,Zhongning Shi
The combined process of aluminothermic reduction, electrodeposition alloying, and molten salt electrolysis using inert anode provides a viable pathway for producing Al and O 2 from lunar soil simulant. Utilizing the electrolyte derived from aluminothermic reduction of lunar soil simulant in cryolite molten salt as raw material, electrodeposition alloying was employed to reduce the concentrations of impurity elements Si, Fe, and Ti in the electrolyte. The influence of cell voltage and electrodeposition time on the impurity removal rates were investigated. The results indicate that increasing the cell voltage from 1 V to 4 V reduced the mass fraction of SiO 2 in the upper molten salt from 2.09 wt% to 1.06 wt%, and extending electrodeposition time from 1 h to 4 h decreased SiO 2 mass fraction from 1.64 wt% to 0.96 wt%. Under the optimal electrodeposition conditions (3.5 V, 3 h), the removal rates of Si, Fe, and Ti elements in the electrolyte were 68.53 %, 89.53 %, and 85.00 %, respectively. The cathode products obtained by electrodeposition contained Si, MoSi 2 , Mo 5 Si 3 , and FeSi 2 alloys. Subsequently, electrolysis was performed using purified alumina-rich cryolite molten salt with a 57 wt% Fe-43 wt% Ni inert anode. The cathode product was a 91.49 wt %Al-4.44 wt% Fe-3.86 wt% Si alloy, achieving a cathode current efficiency of 40.79 %. When the inert anode electrolysis process stabilized, the volume fraction of O 2 in the anode gas was kept above 90 %, and the anode current efficiency tended to be above 50 %.
研究领域:
无机化学
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材料科学
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冶金工程
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空间资源利用
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电化学
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产品关联
DOI
高影响因子
Science Advances
·
2022
·Vol. 8
·期 50
·
IF 14.957
Qingxun Guo,Liang Wang,Longbo Yang,Jiashun Duan,Hainan Du,Guoqi Ji,Nian Liu,Xue Zhao,Chao Chen,Ling Xu,Liang Gao,Jiajun Luo,Jiang Tang
Next-generation wide color gamut displays require the development of efficient and toxic-free light-emitting materials meeting the crucial Rec. 2020 standard. With the rapid progress of green and red perovskite light-emitting diodes (PeLEDs), blue PeLEDs remain a central challenge because of the undesirable color coordinates and poor spectra stability. Here, we report Cs 3 CeBr x I 6− x ( x = 0 to 6) with the cryolite-like structure and stable and tunable color coordinates from (0.17, 0.02) to (0.15, 0.04). Further encouraged by the short exciton lifetime (26.1 ns) and high photoluminescence quantum yield (~76%), we construct Cs 3 CeBr x I 6− x -based rare-earth LEDs via thermal evaporation. A seed layer strategy is conducted to improve the device’s performance. The optimal Cs 3 CeI 6 device achieves a maximum external quantum efficiency of 3.5% and a luminance of 470 cd m −2 with stable deep-blue color coordinates of (0.15, 0.04). Our work opens another avenue to achieving efficient and spectrally stable deep-blue LEDs.
研究领域:
材料科学
·
光电子学
·
固态照明
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无机化学
·
显示技术
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）