Na₃AlF₆-Al₂O₃熔盐中铝溶解度的测定

来源期刊：冶金分析2011年第5期

论文作者：张跃宏 翟秀静 李斌川 周杨 杨超 冯乃祥

文章页码：7 - 11

关键词：EDTA； 氟离子选择电极； Na₃AlF₆-Al₂O₃熔盐； 铝溶解度

Key words：EDTA； fluoride ion selective electrode； Na₃AlF₆-Al₂O₃molten salt； aluminum solubility

摘    要：研究了铝在Na₃AlF₆-Al₂O₃熔盐中溶解度的测定方法。采用氟化钠与试样在高温下熔融,熔融物溶解水后加入硼酸-氢氧化钠溶液,过滤沉淀将氧化铝除去,取其中一部分溶液在pH5.5～6.0的条件下,加入过量的EDTA标准溶液,加热煮沸使之与铝完全络合,以二甲酚橙作指示剂,用锌标准溶液滴定过量的EDTA,从而得到Na₃AlF₆-Al₂O₃熔盐中铝离子的含量,再采用氟离子选择电极测定另一部分溶液中氟含量,计算得到冰晶石中铝离子含量,采用减氟法得到铝在Na₃AlF₆-Al₂O₃体系中溶解量。这个值是用来表征铝在电解质熔体中的溶解损失能力的大小,对生产工艺很重要。

Abstract: A method for the determination of solubility of aluminum in Na₃AlF₆-Al₂O₃ molten salt was studied.The sodium fluoride and sample were melted at high temperature.The fusant was dissolved in water followed by adding H₃BO₃-NaOH solution.The Al₂O₃ was removed by filtration and precipitation.At pH 5.5-6.0,the excessive EDTA standard solution was added into partial prepared solution.The aluminum could be fully complexed with EDTA through boiling.The excessive EDTA was titrated with Zn²⁺ standard solution using xylenol orange as indicator.Consequently,the content of Al³⁺ in Na₃AlF₆-Al₂O₃ molten salt could be obtained.Then,the content of fluorine in another part of solution was measured by fluorine ion selective electrode to calculate the content of aluminum ion in cryolite.Therefore,the dissolution amount of aluminum in Na₃AlF₆-Al₂O₃ system could be obtained by subtraction.The value was important to production process and it could characterize the size of aluminum loss due to solution in electrolyte molten salt.