微波辅助酸消解-ICP-OES直接同时测定钨精矿中主要共存元素含量

Simultaneous Determination of Major Coexisting Elements in Tungsten Concentrates by Microwave-Assisted Acid Digestion and ICP-OES

研究建立了微波辅助酸消解一电感耦合等离子体原子发射光谱法（ICP-OES）同时测定钨精矿样品中砷、铜、锰、钼、磷、硅、钡等7种主要共存元素的新方法。试验优化了微波辅助酸消解样品的程序，研究选择了ICP-OES的最优测试条件和各被测元素的最佳分析谱线。结果表明：采用盐酸＋硝酸＋氢氟酸（5＋3＋2）混酸作为微波消解酸，微波消解升温到160℃后保持10min，可将样品完全溶解，溶液清亮，可用于直接测定，无需分离钨基体；仪器最优测试条件为射频功率1200W，雾化气流量0．75L·min^-1，辅助气流量1．5L·min^-1，冷却气流量15L·min^-1，观察高度10mm，泵流量2．0L·min^-1；综合信噪比，谱线干扰等因素，选择的最佳分析线分别为As（193．696nm），cu（324．754nm），Mn（257．610nm），Mo（202．032nm），P（178．222nm），Si（250．690nm），Ba（455．403nm）。本法的检出限为6×10^-4～7×10^-2μg·ml^-1，加标回收率在95．7％-110％之间，相对标准偏差为1％～7％。用本法分析了美国国家标准与技术研究院（NIST）的黑钨精矿标样（SRM277）和白钨精矿标样（SRM2430），测定结果在标准值±扩展不确定度内。本法流程短、操作简单，精密度和准确度均能满足钨精矿常规、贸易等分析要求。

A new method of simultaneous determination of major coexisting elements such as As, Cu, Mn, Mo, P, Si, Ba in tung- sten concentrates using microwave-assisted acid digestion and inductively coupled plasma optical emission spectrometry （ICP-OES） was established. Microwave-assisted acid digestion procedure was optimized, and optimum analysis line and optimum instrument test condi- tions was selected. The results showed that with mixed HCI-HNO3-HF（5 ＋ 3 ＋ 2） as digestion solution, microwave digestion heated to 160 ℃ and holding for 10 min, the solution was clear and suitable for immediate determination, none separation of tungsten matrix was needed; the optimum conditions of the instrument were RF power 1200 W, nebulization gas flow 0.75 L·min^-1, auxiliary gas flow 1.5 L·min^-1 , cooler gas flow 15 L·min^-1 , view distance 10 mm and pump flow 2.0 L·min^-1; considering integrated signal to noise ratio, spectral line interference and other factors, the optimum analysis lines were chosen as： As （193. 696 nm） , Cu （324. 754 nm）, Mn （257. 610 nm）, Mo （202.032 nm）, P （178. 222 nm）, Si （250.690 nm）, Ba （455. 403 nm）. The detection limit of this method was 6 × 10^-4 -7 × 10^-2μg·ml^-1. The recovery for standard addition was 95.7%~ 110% , and the relative standard deviation was 1%-7%. This method was used to analyze NIST SRM 277 （tungsten concentrate） and SRM 2430 （scheelite ore）. Test results was in the expanded uncertainty of SRMs＇s certified or reference value. The method had the advantages of short process, simple operation, high precision and high accuracy, which was suitable for routine and commerce analysis of coexisting elements content in tungsten concentrate.