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电感耦合等离子体发射光谱法测定包头稀土矿中的稀土总量

Determination of Total Rare Earth Contents of Baotou Rare Earth Concentrates by ICP-AES

  • 摘要: 包头矿中的稀土总量根据提取稀土的工艺流程,含量范围为0.0x%~0.x%。对于高含量稀土总量(20%~80%)的测定,国家标准采用草酸盐重量法,但该方法分离干扰元素的步骤多,流程长。应用电感耦合等离子体发射光谱法不需复杂的分离步骤即可测定稀土元素,但由于受到精密度的限制,测定高含量稀土总量的波动范围较大,不易得到准确结果。本文针对包头稀土矿组成复杂、酸溶难于分解的情况,建立了应用碱熔处理样品,电感耦合等离子体发射光谱(ICP-AES)测定稀土总量的方法。用氢氧化钠、过氧化钠溶解样品,水提取熔融物,各种元素以离子或氢氧化物形式进入溶液,过滤除去铝、硅、磷等杂质元素及大量的钠盐,减小了基体元素及共存元素的干扰;以钪为内标校正仪器波动及基体效应的影响,无需基体匹配即可测定稀土总量。对于稀土总量在30%~50%的样品,相对标准偏差小于0.7%,对于稀土总量在2%的样品,相对标准偏差小于1.2%;各稀土元素回收率为98.0%~103.3%。本方法比国家标准方法简便,与文献中应用ICP-AES测定高含量稀土总量的方法相比精密度有很大改善,可快速准确地测定包头稀土矿中2%~50%的稀土总量。

     

    Abstract: According to the technological process of extracting rare earth in Bao Tou Mine, the content of total rare earth ranges from x%-xx%. The national standard of the oxalate gravimetric method is applied to detecting high content of rare earth, which yields between 20% and 80%, but the operation of the method separating interference elements is complex. In fact, Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) could quickly determine each rare earth element content, and avoid complicated separating steps. However, it was difficult to obtain accurate results by ICP-AES, as a consequence of unfavourable precision for high contents rare earth. The method of alkali fusion combined with ICP-AES was applied to overcome problems of complex components and difficult decomposition in acid for rare earth ores from Bao Tou Mine and is reported herein. The sample was melted by sodium hydroxide and sodium peroxide, and leached with deionized water, in order to transfer all kinds of elements into solution as forms of ions or hydroxide. The interference of elements in the solution was reduced by filtering aluminum, silicon, phosphorus, and a mass of sodium ion. During determination of rare earth contents with ICP-AES, the instrument stability and matrix effect were adjusted by adding an internal standard with scandium. When rare earth content in the sample was 2%, RSD was less than 1.2%. When rare earth content in the sample was between 30% and 50%, the method was successfully used with RSD < 0.7%. The recoveries were in the range of 98.0%-103.3%. The method is simpler than the national standard. Compared with ICP-AES reported in the literatur, the precision of the method was significantly improved. Rare earth content in Bao Tou Mine between 2%-50% was quickly and accurately measured using this method.

     

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