电感耦合等离子体发射光谱法测定稀土矿石中的三氧化二铝

铝是稀土矿石常检的杂质元素,目前采用电感耦合等离子体发射光谱法(ICP-AES)基体匹配校正模式测定矿石中的铝量,对基体中铝的空白及基体量有一定的要求;且稀土矿石的品种很多,铝在其中的存在形式也较复杂,简单的酸溶很难彻底地将铝转入溶液中进行准确测定.本文采用碱熔法处理样品,滤液酸化后用ICP-AES测定稀土矿石中的Al2O3.通过共存元素干扰实验发现样品中的稀土元素及钍对铝的测定产生严重的光谱干扰,提出预先以碱分离除去消除干扰,有效地降低了检测下限:采用基体校正模式,消除了盐分对测定的影响.方法检出限为0.021～0.035 mg/g,测定范围为0.50％ ～ 8.00％,精密度(RSD)＜7.1％.对不同含量的样品进行分析,测定值与化学容量法测定结果基本相符.该方法具有测定含量范围宽、分析速度快、结果准确等优点.

Determination of Aluminum Oxide in Rare Earth Ore by Inductively Coupled Plasma-Atomic Emission Spectrometry

The element Al is determined frequently in rare earth ore since Al is a common impurity element in this ore. At present, the Inductively Coupled Plasma-Atomic Emission Spectrometric (ICP-AES) method, which has certain requirements of the Al blank and the matrix concentration, is used to determine the content of Al in ore with a matrix matching calibration. Because Al has complicated patterns in many kinds of rare earth ores, it is difficult to dissolve Al completely into solution for determination by a routine acid-leaching method. In this paper, a new method is described, whereby the sample is digested by alkali fusion and the filtrate acidulated before the content Al in rare earth ore is determined by ICP-AES. The effect of spectrum interferences of REEs and Th on the Al was studied. The detection limit was reduced effectively by eliminating the interferences of coexisting elements. The matrix correction mode was undertaken to eliminate the salt influence. The determination limit of the method was from 0.021 mg/g to 0.035 mg/g and the determination content range was from 0.50 % to 8.00%. The RSD was less than 7.1%. The result of the samples with the presented method is consistent with the volumetric method. The method is fast with a wide measuring range and extremely high precision.