重铬酸钾氧化-硫酸亚铁铵返滴定法测定铜闪速冶炼烟尘中砷  

Determination of arsenic in copper flash smelting dust by potassium dichromate oxidation-ferrous ammonium sulfate back titration

作　　者：万双 刘天一 WAN Shuang;LIU Tianyi(Yanggu Xiangguang Copper Co.,Ltd.,Liaocheng 252327,China)

机构地区：[1]阳谷祥光铜业有限公司,山东聊城252327

出　　处：《冶金分析》2022年第10期70-76,共7页Metallurgical Analysis

摘　　要：准确测定铜闪速冶炼烟尘中的砷对于炉前配料的计算和生产控制具有重要的作用。采用硝酸-氯酸钾饱和溶液、氟化铵溶液、高氯酸溶解样品,再用硫酸(1+1)驱除硝酸后,在盐酸介质中以硫酸铜为催化剂,用次亚磷酸钠把溶液中的砷离子还原为单质砷,过滤分离其他杂质。以过量的重铬酸钾标准滴定溶液溶解单质砷,以N-苯代邻氨基苯甲酸溶液为指示剂,用硫酸亚铁铵标准滴定溶液滴定过量的重铬酸钾标准滴定溶液,建立了硫酸亚铁铵返滴定法测定铜闪速冶炼烟尘中砷的方法。采用次亚磷酸钠将溶液中的砷还原为单质砷沉淀时,可能会有部分砷因未被还原而被过滤到溶液中,试验考察了滤液中残存的砷量对砷测定结果的影响。研究表明,滤液中砷的质量分数小于0.01%,相对于样品中的砷可以忽略不计。共存元素的干扰试验表明,样品中共存的铜、铅、铁、锌等元素对砷测定的影响可忽略不计。将实验方法应用于测定3个铜闪速冶炼烟尘样品中的砷,并进行加标回收试验,测定结果的相对标准偏差(RSD,n=11)在0.35%~2.6%之间,加标回收率在99%~101%之间。采用实验方法测定2个铜闪速冶炼烟尘样品中的砷,测定结果与微波消解-电感耦合等离子体原子发射光谱法(ICP-AES)相符。Accurate determination of arsenic in copper flash smelting dust is of great significance for the calculation of matter burdening and production control. The sample was dissolved with nitric acid-potassium chlorate saturated solution, ammonium fluoride solution and perchloric acid. After removing nitric acid with sulfuric acid(1+1), the arsenic ions in the solution were reduced to elemental arsenic with sodium hypophosphite in hydrochloric acid medium using copper sulfate as the catalyst. Other impurities were separated by filtration. The elemental arsenic was dissolved with excessive potassium dichromate standard titration solution. The excessive potassium dichromate standard titration solution was titrated with ferrous ammonium sulfate standard titration solution using N-phenylanthranilic acid as the indicator. The method for determination of arsenic in copper flash smelting dust by ferrous ammonium sulfate back titration was established. During the reduction of arsenic ions into elemental arsenic with sodium hypophosphite, some arsenic ions were possibly not reduced and then filtrated into the solution. The influence of residual arsenic in filtrate on the determination results was investigated. The results showed that the influence of arsenic in sample could be ignored because the mass fraction of arsenic in filtrate was less than 0.01%. The interference tests of coexisting elements showed that the influence of coexisting copper, lead, iron and zinc in sample on determination of arsenic could be ignored. The proposed method was applied for the determination of arsenic in three copper flash smelting dust samples. Meanwhile, the recovery tests of standard addition were conducted. The relative standard deviation(RSD, n=11) of determination results were between 0.35% and 2.6%. The recoveries were between 99% and 101%. The contents of arsenic in two copper flash smelting dust samples were determined according to the experimental method. The found results were consistent with those obtained by microwave digestion-ind

关 键 词：重铬酸钾 硫酸亚铁铵返滴定法 铜闪速冶炼烟尘 砷 

分 类 号：O655.2[理学—分析化学] TF811[理学—化学]