碘化氨除锡后封闭酸溶-电感耦合等离子体质谱测定锡矿石中的共生和伴生元素  

Determination of Symbiotic and Associated Elements in Tin Ore by ICP-MS Combined with Pressurized Acid Digestion and Detinning Process

作　　者：马生凤[1] 赵文博[1] 朱云[1] 孙红宾[1] 王蕾[1] 温宏利[1] MA Sheng-feng;ZHAO Wen-bo;ZHU Yun;SUN Hong-bin;WANG Lei;WEN Hong-li(National Research Center for Geoanalysis,Beijing 100037,China)

机构地区：[1]国家地质实验测试中心,北京100037

出　　处：《岩矿测试》2018年第6期650-656,共7页Rock and Mineral Analysis

基　　金：国家重点研发计划"国家质量基础的共性技术研究与应用"重点专项课题(2016YFF0201604-3)

摘　　要：锡矿石是难分解的矿物,主要存在形式是锡石(SnO_2),且共生和伴生元素多,常用的酸溶方法几乎不能溶解SnO_2,从而给锡矿石中的共生与伴生元素的准确测定带来困难。本文基于碘化氨在较低温度下熔融可产生无水状态的碘化氢,利用碘化氢的酸性和氨的还原性分解SnO_2,使Sn呈SnI_4升华分离的原理处理锡矿石。实验中以高纯铂丝作催化剂,加入碘化铵在450℃的马弗炉中分解锡矿石30 min,使得Sn以SnI_4形式挥发,除锡率达到98%以上,再用2 mL氢氟酸和1 mL硝酸封闭溶解残渣,电感耦合等离子体质谱测定钴镍铜铌钽钍铀等24个共生和伴生元素。元素检出限在0. 001～2. 9μg/g之间,90%以上元素的相对标准偏差(RSD)小于5%,相对误差小于10%。本方法解决了锡矿石难分解的问题,可测定共存金属元素,也适合测定Sn含量在1. 27%～62. 49%之间的锡矿石中的微量和痕量元素及锡精矿中的微量元素。BACKGROUND:Tin ore is a hard-to-decompose mineral.The main form is cassiterite(SnO2),and there are many symbiotic and associated elements.The commonly used acid-digestion method can barely dissolve SnO 2,making it difficult for accurate measurement of symbiotic and associated elements in tin ore.OBJECTIVES:To decompose the tin ore completely,and accurately determine the symbiotic and associated trace elements in ore.METHODS:Hydrogen iodide can be produced in a non-aqueous state during the melting of ammonium iodide at a lower temperature,and the acidity of hydrogen iodide and the reductive decomposition of SnO 2 by ammonia,and Sn separation by the sublimation of SnI 4 which is the basis of the study.Under the catalysis of a high purity platinum,ammonium iodide was used to decompose cassiterite for 30 minutes in a Maffer furnace at 450℃.Tin was removed in the form of SnI 4 with a removal rate of 98%.The residue was dissolved by 2 mL HF and 1 mL HNO 3 using pressurized acid digestion.Inductively Coupled Plasma-Mass Spectrometry(ICP-MS)was used to accurately determine 24 elements in tin ore.RESULTS:The element detection limits are from 0.001 to 2.9μg/g,and more than 90%of the elements have a relative standard deviation(RSD)of less than 5%.The relative error is less than 10%.CONCLUSIONS:The method solves the problem of tin ore being difficult to decompose,can measure the coexisting metal elements,and is also suitable for determining trace and ultra-trace elements in tin ore with Sn contents between 1.27%and 62.49%and trace elements in tin concentrate.

关 键 词：锡石 金属元素 除锡率 碘化铵 电感耦合等离子体质谱法 

分 类 号：O657.63[理学—分析化学]