重量法和滴定法在测定钢砂铝中铝和铁的应用

自行设计一整套试验装置,应用重量法和滴定法测定了钢砂铝中铝和铁。将钢砂铝试样置于不锈钢漏盆中,然后放在不锈钢托盘上。将整个装置置于马弗炉中800 ℃加热15~30 min以使金属铝大部分被熔化,此时铝液从漏盆底部圆孔流到托盘中。对凝固的金属铝进行称量,并将带有固体残留物的不锈钢漏盆浸入盛有饱和氢氧化钠溶液的聚乙烯塑料盆中进行反应。反应结束后,将漏盆中钢砂干燥后称重,所得结果即为试样中金属铁的质量。浸取液则经稀释定容后用慢速滤纸过滤,再准确移取一定量的滤液,加入过量的EDTA标准溶液,调节pH值至5~6,于乙酸-乙酸铵缓冲溶液中,以1-(2-吡啶偶氮)-2-萘酚(PAN)为指示剂,采用硝酸铜标准溶液对滤液中铝进行滴定。将试样熔融时凝固的铝质量和滤液中的铝质量相加可求得试样中铝的总质量。采用实验方法对钢砂铝样品进行多次平行测定,铝和铁的相对标准偏差(RSD,n=5)分别为4.1%和10.9%;自制钢砂铝样品中铝和铁的回收率在99.5 %~100.0 %之间。选取3个钢砂铝样品按实验方法进行测定,并与参考值进行比较,测定结果基本一致。

Application of gravimetry and titration in determination of aluminum and iron in steel grit aluminum

An experimental setup was self-designed, anda determination method of aluminum and iron in steel grit aluminum was established with the application of gravimetry and titration.The steel grit aluminum sample was placed in stainless steel leaking basin, which was then put on the stainless steel tray. The whole setup was placed in muffle furnace to melt most of metallic aluminum by heating at 800 ℃ for 15-30 min. The aluminum liquid flew through the circular holes on bottom of basin into the tray. The mass of solidified aluminum was weighed. The stainless steel leaking basin with residual mixture was leached in polyethylene plastic pot with the saturated sodium hydroxide solution for reaction. After reaction, the mass of steel grit in leaking basin was dried and weighed, which was the mass of metallic iron in samples. The leaching solution was diluted into constant volume, and filtrated with slow speed filter paper. Certain volume of filtrate was accurately sampled. After adding excessive EDTA standard solution, the pH of solution was adjusted to 5-6. The content of aluminum in filtrate was titrated with copper nitrate standard solution in acetic acid-ammonium acetate buffer solution with PAN as indicator. The total mass of aluminum in sample was obtained by adding the mass of solidified aluminum in sample fusion process to the mass of aluminum in the filtrate. The parallel determinations of steel grit aluminum samples by the experimental method were conducted. The relative standard deviation (RSD, n=5) of aluminum and iron was 4.1% and 10.9%, respectively. The recoveries for aluminum and iron in self-made steel grit aluminum samples were between 99.5% and 100.0%. The proposed method was applied to the determination of three steel grit aluminum samples, and the results were consistent with the reference values.