Determination of Seven Rare Metal Elements in Copper Concentrates by Inductively Coupled Plasma-Mass Spectrometry Combined with Microwave Digestion

Accurate and rapid determination of the distribution of seven rare metal elements (germanium, indium, gallium, selenium, tellurium, thallium and lanthanum) in copper concentrates plays an important role in the comprehensive utilization and reduction of technical barriers in transaction. However, the low content of target elements, for example, the content of germanium and thallium is as low as 10^-7, requires a highly sensitive analytical method. Microwave digestion together with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) was adopted to achieve rapid and accurate determination of seven rare elements. Hydrochloric acid-nitric acid mixture (volume ratio was 3 to 2) was used as the microwave digestion reagent of copper concentrates. By selecting appropriate analytical quality, tuning the instrument and utilizing mathematical calibration equations, it was possible to eliminate spectral interferences. Under optimal conditions, the target element recoveries ranged from 80.2% to 123.3% and relative standard deviation was less than 13.4%. The detection limits of target elements were below 0.08 mg/kg while that of selenium was 1.3 mg/kg. To avoid spectral interferences, the low natural abundance ⁸²Se was selected as the analytical mass of selenium. The detection limits of target elements of the proposed method were much lower than those using Inductively Coupled Plasma-Atomic Emission Spectroscopy or Atomic Absorption Spectrometry. Simultaneous determination of the target element in bulk copper concentrates was achieved by the proposed method by reducing the reagent blank, simplifying operational processes, and improving analytical sensitivity.