Tungsten tailings issues and reprocessing solutions

This paper aims to provide an overview of tungsten (W) tailings properties, detrimental impacts of these tailings, approaches to mitigate these impacts, and a presentation of methods to reprocess them to capture their economic value. Since W is widely used in a variety of industries, it has been extensively mined since the 19th century, and the mining continues to generate significant volumes of tailings. Recent data show that global W production stands at 84 kt per year, and more than 100 Mt of W tailings exist containing over 100 kt of WO3. The tailings contain variable amounts of valuable products and deleterious environmental substances. Some of the contained metals are in great demand for the energy transition. However, these tailings usually contain FeS2/Pyrrhotite and FeAsS minerals, which, when exposed to air and water, can produce acid mine drainage. As such, W tailings may pose environmental and human health risks. Globally, the reprocessing of W tailings presents a potential resource that can be regarded as a paradigm of sustainability and circular economy. Flotation, enhanced gravity separation, and wet high-intensity magnetic separation have been reported to be the common approaches to reprocessing W tailings. However, W processing presents particular difficulties owing to complex material properties, such as fine particle size, surface weathering, similarity in surface properties exhibited by gangue materials (fluorite, apatite, calcite), low concentrations of the elements of interest, and poor mineral liberation.