摘要
电解槽内气泡一方面使得有效电导率下降、槽电压升高、能耗加大,另一方面又是加速电解质对流、强化传质的有效手段,目前关于熔盐电解阳极气泡行为的研究主要集中在铝电解过程,对于氯化物熔盐电解鲜有文献报道。本文采用邱式透明电解槽研究了碱/碱土金属氯化物熔盐电解过程中石墨阳极上气泡的析出行为,采用摄像机从阳极侧部方向记录了不同氯化物熔盐体系中气泡的生长与释放过程,并通过图像分析获得了气泡的厚度及直径等参数。结果表明:NaCl、55wt.%LiCl-45wt.%KCl和5wt.%MgCl_(2)-53wt.%NaCl-42wt.%KCl熔盐电解过程中气泡析出行为相似,均以扁平状大气泡的形式周期性从阳极表面脱离,气泡直径为50 mm,气泡层厚度在3.7~4 mm;KCl熔盐电解过程中气泡行为与其他氯化物熔盐存在显著差异,气泡以较快速度脱离阳极表面,气泡直径约8 mm,气泡层厚度为2 mm,并不形成覆盖阳极表面的大气泡;当电流密度大于0.7 A·cm^(-2)时,NaCl电解体系会发生阳极效应;在NaCl、5wt.%MgCl_(2)-53wt.%NaCl-42wt.%KCl、KCl电解体系中,电解一段时间后熔液会呈现红棕色,这是由于电解生成的Cl_(2)分散在电解质熔液中导致。
Gas bubbles in electrolytic cells present a dual effect:they diminish the effective electrical conductivity,thereby increasing cell voltage and energy consumption,while concurrently enhancing mass transfer through the promotion of electrolyte convection.Current research on anode bubble behavior in molten salt electrolysis predominantly focuses on aluminum production,with limited investigation into chloride-based molten salts.This study utilized a Qiu-style transparent electrolytic cell to investigate the evolution of bubbles at a graphite anode during the electrolysis of alkali/alkaline earth metal chloride molten salts.Bubble growth and detachment processes in various chloride salt systems were recorded from side-view using a video camera,with image analysis providing parameters such as bubble diameter and bubbles layer thickness.It was found that bubble behavior during the electrolysis of NaCl,55wt.%LiCl-45wt.%KCl,and 5 wt.%MgCl-53wt.%NaCl-42wt.%KCl molten salts was similar.In these systems,large bubbles periodically detached from the anode surface,exhibiting diameters of approximately 50 mm and bubble layer thicknesses ranging from 3.7 to 4 mm.Conversely,the bubble behavior in the KCl molten salt system exhibited marked differences.Bubbles detached at a significantly faster rate,with diameters around 8 mm and a layer thickness of 2 mm,and failed to coalesce into large bubbles covering the anode surface.Additionally,an anode effect was observed in NaCl molten salts when the current density exceeded 0.7 A·cm^(-2).Following prolonged electrolysis,the NaCl,5wt.%MgCl_(2)-53wt.%NaCl-42wt.%KCl,and KCl systems developed a reddish-brown coloration.This phenomenon is attributed to the dissolution or dispersion of electrolytically generated chlorine gas(Cl_(2))in the molten electrolyte.
作者
黄义鹏
杨酉坚
王兆文
HUANG Yipeng;YANG Youjian;WANG Zhaowen(School of Metallurgical Engineering,Jiangxi University of Science and Technology,Ganzhou 341000 China;School of Metallurgy,Northeastern University,Shenyang 110819,China)
出处
《中国有色冶金》
北大核心
2025年第4期147-155,共9页
China Nonferrous Metallurgy
基金
国家自然科学基金项目(NO.51434005)。
关键词
碱/碱土金属
氯化物熔盐电解
透明电解槽
石墨阳极
气泡析出行为
气泡直径
气泡层厚度
阳极效应
alkali and alkaline earth metals
chloride molten salts electrolysis
transparent electrolysis cells
graphite anode
bubble behavior
bubble diameter
bubble layer thickness
anode effect
