微波消解-电感耦合等离子体质谱法测定铁矿石中15个稀土元素

分析地质样品中稀土元素的含量,现有的方法都受到基体干扰和共存元素干扰,电感耦合等离子体质谱(ICP-MS)已在痕量元素分析中得到广泛应用,通过条件优化可准确测定稀土元素。本文建立了ICP-MS同时测定铁矿石中钇镧铈镨钕钐铕钆铽镝钬铒铥镱镥15个稀土元素的方法,样品用盐酸、硝酸和氢氟酸高温密闭消解,消解完全后转移定容,在线加入¹⁰³Rh、¹¹⁵In、¹⁸⁵Re内标液进行测定,方法回收率为95%~104%,精密度(RSD)≤3.5%。对12个国家24个代表性主产区进口的铁矿石样品进行检测,分析其稀土元素的配分模式特征为右倾型轻稀土富集,现阶段的进口铁矿粉多为多产区复合配矿。本方法较其他传统方法大幅降低能耗,提高了分析效率,初步探讨的稀土元素丰度特征可为研究主产区铁矿石的矿床成因、提高我国烧结球团矿的加工工艺提供依据。

Determination of Fifteen Rare-earth Elements in Iron Ores Using Inductively Coupled Plasma Mass Spectrometry with Microwave Digestion

Matrix interference and co-existent elemental interference are the two key factors necessary to obtain accurate analysis results for Rare earth elements (REEs) in geological samples using the traditional methods. Since Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is widely conducted in the field of trace element analysis, accurate results of REEs are obtained under optimized conditions. This method was established using ICP-MS to determine 15 REEs and is detailed in this paper. The samples were digested in sealed containers with HCl, HNO₃ and HF at high temperature. The solutions were set into a constant volume. Internal standard solutions of ¹⁰³Rh, ¹¹⁵In and ¹⁸⁵Re were on-line loaded into the sample solution during the measurement. The recovery rates are 95%-104% and the RSDs are less than 3.5%. REEs in 24 representative ore samples from 12 countries were analyzed and are reported in this paper. The results show that importing iron ores are LREEs enrichment type. Currently, imported fine ores are mostly combined with different iron ores from multi productive areas. This provides a technical reference for the comprehensive utilization of rare earth elements in iron ore and pollution control and also provides valuable information on the origin of the iron ore.