乙醇浸泡-活性炭富集火焰原子吸收光谱法测定烧结机头电除尘灰中金

Determination of gold in electrostatic precipitator dust of sinter machine head by flame atomic absorption spectrometry after ethanol immersion-activated carbon enrichment

烧结机头电除尘灰中含量较高的碳硫物质极易吸附烧结机头电除尘灰样品溶解液中Au(Ⅲ),对Au的测定影响严重,若采用焙烧的方法直接去除碳硫,因样品中碱金属含量高,极易烧结成块,不仅不能完全去除碳硫物质,反而给溶样造成困难。针对这一问题,实验提出了采用无水乙醇对样品进行浸泡后再焙烧的方法去除碳硫物质,然后再采用NaCl-NaFKMnO_4-王水(1+1)体系处理样品,以活性炭富集Au,建立了火焰原子吸收光谱法(FAAS)测定烧结机头电除尘灰中Au的方法。实验表明,在30g样品中加入30 mL无水乙醇进行浸泡,低温加热10min,经抽滤烘干后,置于马弗炉于700℃焙烧1h,冷却,加入10g NaCl、0.5g NaF、1g KMnO_4、80mL王水(1+1),加热微沸30min可将样品溶解完全。Au质量浓度在0.5~4.0μg/mL范围与其吸光度呈良好的线性关系,线性相关系数为0.999 2,方法检出限为0.12μg/mL。干扰试验表明,经活性炭富集分离后,共存元素对Au测定的干扰可忽略。采用实验方法对烧结机头电除尘灰实际样品中金进行测定,结果与火试金-重量法一致,相对标准偏差(RSD,n=6)小于5.0%。

For electrostatic precipitator dust sample of sinter machine head,Au（Ⅲ） in the sample solution could be very easily adsorbed by high content carbon and sulfur substances,thus greatly influencing the determination of Au.If the carbon and sulfur was directly removed by roasting method,the sample was easily agglomerated due to the exist of high content of alkali metals.As a result,the carbon and sulfur substances could not only be fully removed,but also the sample dissolution became a problem.The sample was immersed in anhydrous ethanol followed by roasting to remove carbon and sulfur substances.Then the sample was treated with NaCl-NaF-KMnO_4-aqua regia（1＋1）system,and Au was enriched with activated carbon.Consequelty,a determination method of Au in electrostatic precipitator dust of sinter machine head by flame atomic absorption spectrometry（FAAS）was established.The results showed that the sample could be fully dissolved under the following conditions：30g of sample was immersed in 30 mL of anhydrous ethanol;after heating at low temperature for 10 min,the suspension was filtrated and the sample was dried;then the sample was roasted in muffle furnace at 700℃ for 1h;after cooling,10 g of NaCl,0.5g of NaF,1g of KMnO_4 and 80mL of aqua regia（1＋1）were added;the solution was heated and slightly boiled for 30 min.The mass concentration of Au in range of 0.5-4.0μg/mL had good linearity to its corresponding absorbance with correlation coefficient of 0.999 2.The detection limit of method was 0.12μg/mL.The interference tests indicated that the interference of coexisting elements with the determination of Au could be ignored after enrichment and separation by activated carbon.The experimental method was applied to the determination of gold in electrostatic precipitator dust actual sample of sinter machine head.The results were consistent with those obtained by fire assaying-gravimetric method.The relative standard deviation（RSD,n=6）was less than 5.0%.