Determination of silicon dioxide in rare earth fluoride by silicomolybdic blue spectrophotometry
GAO Li-hong1,2, ZHOU Kai-hong1,2, WANG Yan-xia3, XING Rong-rong1,2
1. Rui Ke National Engineering Research Centre of Rare Earth Metallurge and Function Materials Co.,Ltd.,Baotou 014030,China; 2. Baotou Research Institute of Rare Earths,Baotou 014035,China
Abstract：The rare earth fluoride was a kind of widely used materials. The content of silicon dioxide in rare earth fluoride was a key index to measure the quality of product, which directly influenced on the alloy production process and product quality. The sample was fused with sodium carbonate-boric acid mixed flux with mass ratio of 4:1. After acidification by hydrochloric acid, the pH of sample solution was controlled at about 1 by adding 0.4 mL of sulfuric acid (1+5). The orthosilicic acid reacted with ammonium molybdate in boiling water bath for 3-5 s to form silicon-molybdenum heteropoly acid. The interference elements such as phosphorus and arsenic were destroyed by adding oxalic acid-sulfuric acid mixture. The silicon-molybdenum heteropoly acid was reduced to silicomolybdic blue by ascorbic acid. The determination method of silicon dioxide in rare earth fluorides by spectrophotometry was established. The results showed that Beer’s law was obeyed for the mass concentration of silicon dioxide in range of 0.04-2.0 μg/mL. The detection limit and low limit of determination for silicon dioxide was 0.002 8% and 0.010% (mass fraction), respectively. The proposed method was applied to the determination of silicon dioxide in three actual samples of rare earth fluoride. The relative standard deviations (RSD, n=10) were between 2.3% and 5.2%. The results were consistent with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES).
王亚军,王红宇,索全伶,等.氟化稀土的制备及组成研究[J].内蒙古大学学报:自然科学版,1998,29(5):667-671.WANG Ya-jun,WANG Hong-yu,SUO Quan-ling,et al.A study on the preparation and component of rare earth fluoride[J].Journal of Inner Mongolia University:Natural Science Edition,1998,29(5):667-671.
[2]
涂华民,张秀凤,张迈生.轻稀土氟化物的微波固相快速合成法[J].稀有金属,2004,28(5):875-879.TU Hua-min,ZHANG Xiu-feng,ZHANG Mai-sheng.Rapid synthesis of light rare earth fluorides in a microwave field[J].Chinese Journal of Rare Metals,2004,28(5):875-879.
[3]
潘建忠,朱岚.稀土氟化物中氟的测定方法研究[J].江西有色金属,2004,18(4): 36-38.PAN Jian-zhong,ZHU Lan.Study on the determination of content of fluorine in rare earth fluoride[J].Jiangxi Nonferrous Metals,2004,18(4):36-38.
[4]
郑艳玲,钟亮.低C、O含量氟化稀土的制备工艺研究[J].上海有色金属,2012,33(3):131-134.ZHENG Yan-ling,ZHONG Liang.Study on the prepartion technology of rare earth fluoride with low carbon and oxygen production[J].Shanghai Nonferrous Metals,2012,33(3):131-134.
高华,谢晓东.钼蓝光度法测定硅铁中硅[J].冶金分析,2005,25(2):91-92.GAO Hua,XIE Xiao-dong.Determination of silicon in ferrosilicon by molybdenum blue photometric method[J].Metallurgical Analysis,2005,25(2):91-92.
[7]
周礼仙,郑小敏.钼蓝光度法测定钒铝合金中硅[J].冶金分析,2015,35(11):74-78.ZHOU Li-xian,ZHENG Xiao-min.Determination of silicon in vanadium-aluminum alloy by molybdenum blue photometric method[J].Metallurgical Analysis,2015,35(11):74-78.
[8]
季娟娟.氟化锂中二氧化硅的测定[J].新疆有色金属,2007(2):33-34.JI Juan-juan.Determination of silicon in lithium fluoride[J].Xinjiang Nonferrous Metals,2007(2):33-34.
