电感耦合等离子体原子发射光谱法测定铌钽精矿中铌和钽

准确分析铌钽精矿中铌、钽含量,对选冶及新材料的研发具有重要意义。实验以氢氧化钠作为熔剂,使用银坩埚,通过碱熔方式消解样品(熔融温度为720℃,熔融时间为20min),再酸溶后使用电感耦合等离子体原子发射光谱法(ICP-AES)测定铌钽精矿中铌、钽。对样品常见的消解方式、内标元素和分析线对的选择、共存元素的影响等因素进行了试验研究。结果表明:确定钴作为铌的内标元素,铬作为钽的内标元素,分析谱线及内标线为Nb 309.4nm-Co345.3nm、Ta 240.0nm-Cr 284.3nm。铝、硅、钾、钠、钙、镁、铜、铅、锌、硫酸根、锰、磷、铬、钡、钴、砷、镍、锶、铍、钪、锡等不会对铌、钽的测定产生干扰。方法中铌和钽的检出限分别为0.007%和0.011%。按照实验方法测定4个铌钽精矿实际样品中铌和钽,并以多家实验室的测定平均值作为推荐值进行比对,结果表明,铌和钽测定结果的相对标准偏差(RSD,n=10)均小于0.6%,相对误差处于±5%之间。

Determination of niobium and tantalum in niobium-tantalum concentrate by inductively coupled plasma atomic emission spectrometry

The accurate analysis of niobium and tantalum contents in niobium-tantalum concentrate is of great significance for the dressing and smelting as well as the development of new materials. The sample was digested by alkali fusion (fusion at 720℃ for 20min) in silver crucible using sodium hydroxide as the flux. After acid dissolution, the contents of niobium and tantalum in niobium-tantalum concentrate were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The digestion methods of sample, the selection of internal standard elements and analytical line pairs, and the influence of coexisting elements were investigated. The results showed that cobalt and chromium was selected as the internal standard element for niobium and tantalum, respectively. The analytical line and internal standard line was Nb 309.4nm-Co 345.3nm and Ta 240.0nm-Cr 284.3nm, respectively. The coexisting elements such as aluminum, silicon, potassium, sodium, calcium, magnesium, copper, lead, zinc, sulfate, manganese, phosphorus, chromium, barium, cobalt, arsenic, nickel, strontium, beryllium, scandium and tin had no interference with the determination of niobium and tantalum. The limit of detection of niobium and tantalum was 0.007% and 0.011%, respectively. The contents of niobium and tantalum in four actual niobium-tantalum concentrate samples were determined according to the experimental method. Meanwhile, the average values of determination results in several laboratories were used as the recommended values for comparison. It indicated that the relative standard deviations (RSD, n=10) of determination results for niobium and tantalum were all less than 0.6%. The relative error was within ±5%.