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

Abstract

There is an increasing global demand for tungsten, which is a critical element used in various industries. 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 become valuable resources if we thoroughly characterize 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 applied and tested. The results showed that alkali fusion is the best method for major element analysis, while bomb digestion is best for tungsten and trace element analysis, although volatile chlorite loss was also observed. The hot plate digestion method was not recommended, owing to poor recovery of trace elements compared to the bomb digestion method. The quicker and safer ColdBlockTM digestion method can be used for bismuth, molybdenum, and several rare-earth element analyses, as indicated by their recovery being close to that from the bomb digestion method.