次亚磷酸钠分离-重铬酸钾滴定法测定钨尾矿中砷含量  

Determination of Arsenic Content in Tungsten Tailings by Potassium Dichromate Titration Method with Sodium Hypophosphite Separation

作　　者：吕长宽 骆捡花 唐莉福 唐碧玉 曾志平 LYU Changkuan;LUO Jianhua;TANG Lifu;TANG Biyu;ZENG Zhiping(China Nonferrous Metal(Guilin)Geology and Mining Co.,Ltd.,Guilin,Guangxi 541004,China;Heng Sheng Water Environmental Management Co.,Ltd.,Guilin,Guangxi 541100,China)

机构地区：[1]中国有色桂林矿产地质研究院有限公司,广西桂林541004 [2]恒晟水环境治理股份有限公司,广西桂林541100

出　　处：《中国无机分析化学》2024年第7期881-888,共8页Chinese Journal of Inorganic Analytical Chemistry

基　　金：广西科学研究与技术开发计划项目(桂科AD20325011)。

摘　　要：选矿中产生的钨尾矿长期堆放,经过雨水冲刷,钨尾矿中的砷会进入到水土中,造成环境污染,准确测定钨尾矿中砷含量,有利于监测钨尾矿中砷对环境的污染程度。采用硝酸-氯酸钾饱和溶液和氟化铵溶液分解样品,再用硫酸溶液冒烟赶尽硝酸,在盐酸介质中,以硫酸铜为催化剂,用次亚磷酸钠将砷离子还原成元素态,析出的砷过滤分离,除去其他杂质。在硫酸溶液中,用过量的重铬酸钾标准溶液滴定溶解单质砷,过量的重铬酸钾以二苯胺磺酸钠为指示剂,用硫酸亚铁标准溶液返滴定。通过优化样品溶解条件和砷沉淀还原条件,建立了次亚磷酸钠分离-重铬酸钾容量法测定钨尾矿中砷含量的分析方法。通过测定滤液中的砷含量,考察了滤液中砷含量对砷测定结果的影响,可忽略不计,表明实验中砷沉淀完全。通过沉淀单质砷,过滤使砷与杂质元素分离,消除了杂质元素对砷测定的影响。运用重铬酸钾容量法测定3个钨尾矿样品中的砷,并进行加标回收实验,测定结果的相对标准偏差(RSD,n=11)在0.14%~2.1%,加标回收率在97.0%~101%。方法操作简单、精密度高,适合钨尾矿中高含量砷的测定,测定结果与碱融分离-碘量法结果基本一致。Tungsten tailings produced in mineral processing are piled up for a long time,and after being washed by rain,the arsenic in tungsten tailings will enter the water and soil,causing environmental pollution.Accurate determination of the arsenic content in tungsten tailings is conductive to monitoring the degree of environmental pollution caused by arsenic in tungsten tailings.The sample was decomposed with nitrate and potassium chlorate saturated solution and ammonium fluoride solution,and then smoked with sulfuric acid solution to drive out nitric acid.In hydrochloric acid medium,with copper sulfate as catalyst,sodium hypophosphite was used to reduce arsenic ions to elemental state,and the precipitated arsenic was filtered and separated to remove other impurities.In sulfuric acid solution,the dissolved elemental arsenic was titrated with excess potassium dichromate standard solution,and the excess potassium dichromate was reversed titrated with ferrous sulfate standard solution using sodium diphenylamine sulfonate as an indicator.A method for the determination of arsenic content in tungsten tailings by sodium hypophosphite separation-potassium dichromate volumetric method was established by optimizing the conditions of sample dissolution and arsenic precipitation reduction.The effect of arsenic content in filtrate on the results of arsenic determination was investigated,and arsenic content in the filtrate could be ignored.The results showed that arsenic precipitated completely in the experiment.Arsenic was separated from impurity by precipitation and filtration,and the influence of impurity on arsenic determination was eliminated.The potassium dichromate volumetric method was used to determine arsenic in three tungsten tailings samples,and the standard recovery test was carried out.The relative standard deviation(RSD,n=11)of determination results were between 0.14%and 2.1%.The spiked recoveries were between 97.0%and 101%.The method was simple,accurate and suitable for the determination of high arsenic content in tu

关 键 词：固体废物 次亚磷酸钠 重铬酸钾 钨尾矿 砷 

分 类 号：O652[理学—分析化学]