摘要:
黑钨矿单矿物通常混入铬、钙、镁、钴、钪和稀土等元素,属于富含稀土型矿物,准确测定黑钨矿中的稀土元素对判定黑钨矿矿床的成因相当重要。黑钨矿单矿物样品经硝酸-氢氟酸高压密闭溶解,蒸干除去氢氟酸,以硝酸提取使稀土元素进入溶液,钨则以钨酸的形式从溶液中沉淀而分离,采用电感耦合等离子体质谱法测定稀土元素的含量。用Rh、Re双内标校正,有效地降低了分析信号漂移对分析结果的影响;Ba对153Eu干扰、Pr、Ce对157Gd干扰,采用分析软件在线扣除。该方法消除了钨基体元素的干扰,复溶沉淀实验表明残留稀土相对量小于10%,稀土元素的测定值与过氧化钠碱熔法的结果相符。方法加标回收率为94.2%~104.0%,相对标准偏差小于10%,检出限小于0.026 μg/g。方法简便,准确度高,检出限低,适用于黑钨矿单矿物的分析。
Abstract:
Wolframite is the rare earth elements (REEs) bearing mineral and was mixed with Cr, Ca, Mg, Co, Sc and REEs. The accurate measurement of REEs in wolframite is very important to study ore forming in wolframite deposits. A method has been developed for the determination of REEs in wolframite by Inductively Coupled Plasma-Mass Spectrometry. Samples were dissolved by nitric acid-hydrofluoric acid in a sealed bomb under high pressure. The hydrofluoric acid was then evaporated. REEs were dissolved using nitric acid. Tungsten was precipitated from the solution in the form of tungstic acid and the matrix interference of the tungsten substrate was eliminated. By dissolving precipitation it was shown that the relative residual rare earth amount was less than 10%. The results of this method were consistent with the results by sodium peroxide melting. The double internal standards of Rh and Re were applied to reduce the effect by the drift of analytical signals. 153Eu and 157Gd had interferences from Eu, and the polyatomic ion interferences from Gd were calibrated using Ba, Pr and Ce oxides and hydroxides. The interferences from Eu and Gd were calibrated by using pure standard solutions of Ba, Pr and Ce with on-line analysis software. Recoveries ranged from 94.2%-104.0%, detection limits were less than 0.026 μg/g, and the relative standard deviations were better than 10% (n=10). The established method was simple and had a low detection limit with high accuracy.
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