Efficiency of acid digestion procedures for geochemical analysis of tungsten mining wastes

Abstract

Tungsten is a critical element used in the industry with increasing global demand. There are millions of tons of current and legacy mineral processing tungsten tailings worldwide that can potentially contaminate the environment and pose human health risks. These tailings could also potentially turn into valuable resources if we thoroughly characterise their geochemical composition. In this study, an innovative method was developed to achieve the complete digestion of tungsten tailings. We tested three different digestion methods (hotplate digestion, bomb digestion, and ColdBlockTM digestion) and compared the results. Additionally, an alkali fusion for major element analysis was also applied and tested. The results showed that alkali fusion is the best method for major elements analysis, while bomb digestion is the best method for tungsten and trace element analysis, but volatile chlorite loss was also observed. The hot plate digestion method for tungsten mine tailings was not recommended, because of poor recoveries of trace elements compared to the bomb digestion method. The quick and safer ColdBlockTM digestion method could be used for Bismuth (Bi), Molybdenum (Mo), and several rare earth element analyses indicated by their recoveries being close to the bomb digestion method.