微波消解-电感耦合等离子体质谱法同时测定金属硫化矿中的稀散元素

铜精矿、镍精矿和锌精矿是金属硫化矿物,且为大宗进口商品,准确分析其中的稀散元素有利于矿物的综合利用。这类矿物中的稀散元素含量极低,各元素性质各异,尤其Ge和Se在湿法消解中由于挥发损失而无法准确定值,很难进行多种元素的同时测定,传统的方法需要通过预先分离富集,采用不同的仪器进行测定。本文以铜精矿、锌精矿和镍精矿为代表性硫化矿,采用微波消解对样品进行密闭前处理,电感耦合等离子体质谱法(ICP-MS)测定稀散元素含量,实现了多种元素的同时测定。条件实验表明在同时检测镓、锗、硒、镉、铟、碲、镧、铊的过程中,总固溶量、内标、质谱干扰消除的条件对三种金属硫化矿均一致,只是前处理过程中用酸的选择有些差异。硝酸-盐酸-氢氟酸-过氧化氢体系适合于测定镍精矿和锌精矿中的Ga、Ge、Se、Cd、In、Te、La、Tl和铜精矿中的Ga、Ge、Se、Cd、In、La、Tl,各元素的回收率在85.5%～116.6%之间;王水溶样法更适合测定铜精矿中的Te。

Determination of Dispersed Elements in Metal Sulfide Ores by Inductively Coupled Plasma-Mass Spectrometry Using Microwave Digestion

BACKGROUND: Copper nickel and zinc concentrates all belong to metal sulfide minerals and are import commodities. The rapid and accurate analysis of dispersed elements in these samples is beneficial to the comprehensive utilization of mineral. However, the content of rare elements in such minerals is extremely low, and the properties of each element are different. In particular, Ge and Se cannot be precisely determined due to volatilization loss in wet digestion, and it is difficult to simultaneously measure various elements.
OBJECTIVES: To simultaneously determine the various elements in the sample.
METHODS: Copper, zinc and nickel concentrates were used as representative sulfide minerals. The sample was pre-sealed by microwave digestion, and the content of rare elements was determined by inductively coupled plasma-mass spectrometry (ICP-MS). Simultaneous determination of various elements was realized. The experimental conditions of total solid solution, internal standard, mass spectrum interference elimination and pretreatment acid selection were compared.
RESULTS: During determination of Ga, Ge, Se, Cd, In, Te, La and Tl by microwave digestion in ICP-MS analysis, total amount of solid solution, internal standard, and mass spectrum interference elimination conditions was consistent in three types of metal sulfide ores. Unfortunately, the acid types were not the same. HNO₃-HCl-HF-H₂O₂ system was more suitable for measuring Ga, Ge, Se, Cd, In, Te, La and Tl in nickel and zinc concentrates, and Ga, Ge, Se, Cd, In, La and Tl in copper concentrate. The recoveries of these elements ranged from 85.5% to 116.6%. The HCl-HNO₃ (3:1) system was more suitable for detecting Te in copper concentrate.
CONCLUSIONS: The method is simple, and the simultaneous determination of multiple elements is realized. Other factors of the method are the same, the acid digestion system is the key to selection.