微波消解电感耦合等离子发射光谱法测定三水铝土矿中的有效铝、活性铝和活性硅

摘要

Available alumina and active silicon in gibbsite bauxite are important indicators for the quality of bauxite.These two components are commonly determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES).In this method,available alumina in solution after digestion is determined first and active silicon is then determined after acid dissolution of the residue.However,because the solution is not easy to determine,and the residue cannot be digested completely,the results have poor reproducibility.By heating and acidifying the solution and taking Co as the internal standard,the conventional method can be improved upon.Active alumina and active silicon were simultaneously determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS),and available alumina was quantified indirectly by calculation.The method precision (RSD) is greater than 3％ (n =13) and the recoveries range from 97.0％ to 102.6％.The results of international standard materials are consistent with the certified values.The proposed method solves the issues of the conventional method and improves the influence of the matrix effect and equipment drift on analytical results.This method can determine simultaneously active alumina and active silicon.The concept of active alumina can be used to comprehensively evaluate gibbsite bauxite and the adjustment of the production method of aluminum oxide.%有效铝、活性硅是判定三水铝土矿质量的重要指标,这两项指标的测定通常采用微波消解电感耦合等离子体发射光谱法(ICP-OES).该方法首先测定出消解试液中的铝(即有效铝),再将剩余的残渣酸化溶解,进而测定出硅(即活性硅).然而,由于消解试液不易澄清和残渣酸溶不完全,往往导致结果的重现性较差.本文对此方法作一改进,将消解的试液酸化加热,以钴为内标,采用ICP-OES同时测定出溶液中的活性铝和活性硅,然后间接计算出溶液中的有效铝.方法精密度(RSD,n=13)小于3％,回收率为97.0％～102.6％,用国际标准物质验证的测定结果与标准值吻合.本方法解决了消解后的溶液不易澄清和剩余残渣酸溶不完全的问题,克服了基体效应和仪器波动对测定结果的影响,能同时测定出活性铝和活性硅,并且提出的活性铝的概念可应用于三水铝土矿的综合评价和氧化铝生产工艺的调整.