氟硅酸钾沉淀-酸碱滴定法测定硅质耐火材料中二氧化硅

来源期刊：冶金分析2011年第2期

论文作者：李环亭 董艳艳 刘晓毅 孙晓红 赵维平

文章页码：67 - 70

关键词：氟硅酸钾； 滴定法； 硅质耐火材料； 二氧化硅

Key words：potassium fluosilicate； titration method； siliceous refractory material； silicon dioxide

摘    要：提出一种不用铂金坩埚和不需要用氢氟酸挥硅的氟硅酸钾沉淀-酸碱滴定法测定硅质耐火材料中SiO₂含量方法,考察了检测的准确度和精确度,探讨了影响检测的干扰因素和可能的干扰机理。试样在银或者镍坩埚中,用氢氧化钠熔融,二氧化硅转化为硅酸钠,在有过量氯化钾存在的强酸性溶液中加入氟化钾溶液,生成氟硅酸钾沉淀,经过滤、洗涤后溶于沸水中,以酚酞为指示剂,NaOH标准溶液滴定水解后生成的氢氟酸。试样中SiO₂的质量分数与Al₂O₃的质量分数比值大于或等于3.5时Al₂O₃对测定没有影响。应用本法检测硅质砂岩、硅砖等硅质耐火材料样品中的SiO₂含量,测定值与认定值相符,且重复性较好。

Abstract: A determination method of silicon dioxide in siliceous refractory materials by potassium fluosilicate precipitation-acid-base titration method was established.Neither a platinum crucible nor the volatilization of silicon by hydrofluoric acid was needed.The determination accuracy and precision were investigated.The interference factors and possible interference mechanism were discussed.The samples were melted in a silver or nickel crucible with sodium hydroxide,during which the silicon dioxide in sample was converted into sodium silicate.Then,potassium fluoride solution was added into strong acid solution containing excessive potassium chloride to form potassium fluosilicate precipitation.After filtration and washing,the precipitates were dissolved in boiling water.The generated hydrofluoric acid through hydrolysis was titrated with standard sodium hydroxide solution using phenolphthalein as indicator.It was generally considered that,when the ratio between mass fraction of silicon dioxide and aluminum oxide in sample was higher or equal to 3.5,the aluminum oxide had no influence on the determination.This method has been applied to the determination of silicon dioxide in siliceous refractory materials such as siliceous sandstone and silica brick.The measurement results were consistent with the certified values.Moreover,the repeatability was very good.