Increasing value and decreasing environmental risk by reprocessing and stabilizing tungsten tailings at Cantung Mine, NT, Canada

Reprocessing mine waste to extract additional value is a potentially sustainable alternative to exploration and development of new mines. Combining the extraction of additional value and the reduction of deleterious elements, the environmental impact of stored mine tailings can be minimized, one of the goals of sustainable mining. At Cantung mine in northern Canada, tailings contain ore grade values of tungsten and minor additional value of copper and gold. The tailings are currently in steep-sided impoundments with little oxidation but some have spilled into the river and exhibit extensive oxidation and acidic drainage. Our long-term objective is to transform the Cantung mine from an inactive and environmentally problematic site in a vulnerable Northern setting to one where additional value can be extracted from tailings with a comprehensive remediation design that reduces environmental risk. Here we report on the first stages of the project: characterization of the tailings in terms of modal mineralogy, scheelite grain size and liberation, and acid-base accounting. The mobility of tungsten under the wide range of pH, Eh and variable mineralogy has also been studied.