Bismuth has a wide range of applications such as in metallurgy, chemical engineering, electronic industry, medical service, aeronautics, astronautics, and nuclear industry, etc., owing to its excellent properties including large density, low melting point, nontoxicity as well as the abnormal nature of expansion in cooling down and contraction in heating up. As one of the nonrenewable and scarce metal resources, the extraction and recycling of bismuth has received increasing attention in recent years. Molten salt electrolysis is one of the most widely used methods for metal extraction. Therefore, extraction of bismuth from BiCl3 directly by molten salt electrolysis was evaluated in the present work in order to develop an environmentally friendly technology for bismuth recovery. Firstly, the electrochemical behavior of Bi(III) ions in molten NaCl?KCl at 700℃ was investigated by cyclic voltammetry, square wavevoltammetry, and chronopotentiometry on a glassy carbon working electrode. The results indicated that the reduction of Bi(III) in the NaCl?KCl molten salt was a one-step process with three electrons exchanged Bi3++3e?=Bi, and the initial reduction potential of Bi(III) ions was detected at 0.05 V (vs. Ag/AgCl), approximately. Meanwhile, the reduction of Bi(III) ions in the melts was a quasi-reversible diffusion-controlled process, and the diffusion coefficient of Bi(III) in molten salt at 700℃ were determined to be 0.83×10–5 and 1.0×10–5 cm2/s, respectively, based on the results of cyclic voltammetry and chronopotentiometry using the Berzins-Delahay equation and the Sand equation. Then, potentiostatic electrolysis at –0.3 V (vs. Ag/AgCl) was carried out in molten NaCl?KCl?BiCl3 under 700℃ and spherical metal granules were obtained around cathode. The cathodic products were compact in microstructure and confirmed to be pure bismuth with no other impurities detected by XRD and SEM?EDS analyses. The present results confirmed that it was an effective method for extraction of bismuth by direct electrolysis of bismuth chloride in molten NaCl?KCl, which could be subsequently used to recycling of bismuth from bismuth-bearing materials.
Huan LIU Jiwen HE Zhongsheng HUA Liang XU Saijun XIAO Zhuo ZHAO
. Electrochemical behavior of Bi(III) in molten NaCl-KCl[J]. The Chinese Journal of Process Engineering, 2019
, 19(2)
: 317
-322
.
DOI: 10.12034/j.issn.1009-606X.218155
[1] 彭支乾. 铋的性能、用途及市场简述[J]. 中国钨业, 1993(1):13-16.
PENG Zhiqian. A brief description of the properties, application and market of bismuth[J]. China Tungsten Industry, 1993(1): 13-16.
[2] Bagwasi S, Tian B, Zhang J, et al. Synthesis, characterization and application of bismuth and boron Co-doped TiO2: a visible light active photocatalyst[J]. Chemical Engineering Journal, 2013, 217: 108-118.
[3] Fernandes K G, de Moraes M, Neto J A G, et al. Evaluation and application of bismuth as an internal standard for the determination of lead in wines by simultaneous electrothermal atomic absorption spectrometry[J]. Analyst, 2002, 127(1): 157-162.
[4] CHAUS A S. Application of bismuth for solidification structure refinement and properties enhancement in as-cast high-speed steels[J]. ISIJ international, 2005, 45(9): 1297-1306.
[5] Cesarino I, Gouveia‐Caridade C, Pauliukait? R, et al. Characterization and Application of Bismuth‐Film Modified Graphite‐Polyurethane Composite Electrodes[J]. Electroanalysis, 2010, 22(13): 1437-1445.
[6] 汪立果. 铋冶金[M] . 北京: 冶金工业出版社, 1986.
WANG Liguo. Bismuth Metallurgy[M] . Beijing: Metallurgical Industry Press,1986.
[7] Chen Y, Liao T, Li G, et al. Recovery of bismuth and arsenic from copper smelter flue dusts after copper and zinc extraction[J]. Minerals Engineering, 2012, 39: 23-28.
[8] Kim D, Wang S. Bismuth recovery from hydrochloric acid solution[J]. Canadian Metallurgical Quarterly, 2008, 47(3): 317-326.
[9] Ficeriová J, Balá? P, Villachica C L. Thiosulfate leaching of silver, gold and bismuth from a complex sulfide concentrates[J]. Hydrometallurgy, 2005, 77(1-2): 35-39.
[10] Castrillejo Y, Haarberg G M, Palmero S, et al. Chemical and electrochemical behaviour of BiCl3 in a PbCl2+ KCl equimolar mixture at 475° C[J]. Journal of Electroanalytical Chemistry, 1994, 373(1-2): 149-155.
[11] Yang J G, He D W, Tang C B, et al. Thermodynamics calculation and experimental study on separation of bismuth from a bismuth glance concentrate through a low-temperature molten salt smelting process[J]. Metallurgical and materials Transactions B, 2011, 42(4): 730-737.
[12] Ebe H, Ueda M, Ohtsuka T. Electrodeposition of Sb, Bi, Te, and their alloys in AlCl3–NaCl–KCl molten salt[J]. Electrochimica Acta, 2007, 53(1): 100-105.
[13] Ueda M, Tsuchiya S, Ohtsuka T. Electrodeposition of Bi-Sb-Te Alloys by Pulse Electrolysis in AlCl3-NaCl-KCl Molten Salt[J]. Electrochemistry, 2009, 77(8): 659-662.
[14] Hua Z, Wang J, Wang L, et al. Selective extraction of rare earth elements from NdFeB scrap by molten chlorides[J]. ACS Sustainable Chemistry & Engineering, 2014, 2(11): 2536-2543.
[15] Hua Z S, Wang L, Wang J, et al. Extraction of rare earth elements from NdFeB scrap by AlF3–NaF melts[J]. Materials Science and Technology, 2015, 31(8): 1007-1010.
[16] Hua Z, Liu H, Wang J, et al. Electrochemical Behavior of Neodymium and Formation of Mg–Nd Alloys in Molten Chlorides[J]. ACS Sustainable Chemistry & Engineering, 2017, 5(9): 8089-8096.
[17] Hur J M, Jeong S M, Lee H. Underpotential deposition of Li in a molten LiCl–Li2O electrolyte for the electrochemical reduction of U from uranium oxides[J]. Electrochemistry Communications, 2010, 12(5): 706-709.
[18] Bard A J, Faulkner L R. Electrochemical Methods: Fundamentals and Applications [M]. Beijing: Chemical Industry Press, 2005, 225-227.
[19] Ramaley L, Krause M S. Theory of Square Wave Voltammetry [J]. Anal. Chem., 1969, 41(11): 1362-1365.
[20] HAN W, JI N, LI M, et al. Electrochemical Formation of Al-Tb Alloys from Tb4O7 Fluorinated by AlF3 in NaCl-KCl Melts[J]. Acta Physico-Chimica Sinica, 2016, 32(10): 2538-2544.
[21] Bard A J, Faulkner L R. Electrochemical Methods: Fundamentals and Applications [M]. Beijing: Chemical Industry Press, 2005, 65-175.
[22] 陈丽军, 张密林, 韩伟,等. Mn(Ⅱ)在LiCl-KCl-MgCl2-MnCl2熔盐体系中的电化学行为[J]. 高等学校化学学报, 2012, 33(2):327-330.
CHEN Lijun, ZHANG Milin, HAN Wei, et al. Electrochemical Behavior of Mn(Ⅱ) in the Melt LiCl-KCl-MgCl2-MnCl2[J] . Chemical Journal of Chinese Universities, 2012, 33(2):327-330.
