Determination of tungsten,molybdenum,copper,lead,zinc and chromium in tungsten ore and molybdenum ore by inductively coupled plasma atomic emission spectrometry with high-pressure digestion in closed system

Tungsten ore and molybdenum ore with multiple paragenetic and associated elements are important metal mineral resources. The accurate determination of contents of tungsten, molybdenum and associated elements is of great significance for the development of tungsten molybdenum mineral resources and the comprehensive evaluation of deposits in China. The current national standard methods generally adopt alkali fusion or open acid dissolution. However, a large amount of salt will be introduced in alkali fusion method, leading to matrix effect, which influences the determination accuracy. For the open acid dissolution method, the samples with high content of tungsten and molybdenum are hardly completely dissolved, leading to lower determination results. In this study, the sample was digested in high-pressure closed system at 180 ℃ using hydrofluoric acid and nitric acid as the digestion reagent. The redissolution with tartaric acid-aqua regia system could effectively solve the issues of hydrolysis and difficult dissolution for tungsten and molybdenum. By optimizing the digestion conditions and instrumental parameters, an analytical method for the simultaneous determination of tungsten, molybdenum, copper, lead, zinc and chromium in tungsten ore and molybdenum ore by inductively coupled plasma atomic emission spectrometry (ICP-AES) was established. The results showed that the linear relationship of each element in determination range was good, and the correlation coefficients were not less than 0.999 8. The limits of detection of this method ranged from 0.50 μg/g to 2.01 μg/g. The relative errors (RE) of determination results of certified reference materials (CRMs) were between -3.21% and 3.33%, and the relative standard deviations (RSD, n=6) ranged from 0.83% and 3.8%. The spiked recoveries were between 95.8% and 104%. The analysis results of actual samples were basically consistent with those obtained by traditional methods. The proposed method had the advantages of fast analysis speed, wide linear range, green and environmental protection, which was suitable for the rapid detection of batch samples.