Tailings disposal facilities project for a Brazilian niobium mine: innovation and sustainability in tailings management

Companhia Brasileira de Metalurgia e Mineração (CBMM) is implementing a new tailings disposal facility. The Tailings Storage Facilities 9 (TSF9) project incorporates innovative technologies and engineering practices to optimise safety and efficiency in the management of tailings generated by niobium production. TSF9 includes three main facilities: main dam, with a capacity of 92.8 million cubic metres, and two dry stacking piles with capacities of 16.8 million and 43.5 million cubic metres. The project utilises specific dewatering methods, minimising operational and environmental risks. The tailings were categorised into magnetite, coarse flotation, fine flotation and ultrafine flotation, allowing for more efficient disposal. The physical, chemical and mineralogical characterisation of the tailings was conducted to ensure the best dewatering and disposal solutions for each type of tailings. The magnetic tailings exhibit large, compact grains that drain more easily. In contrast, the flotation tailings, due to their fine granulometry, present challenges in achieving optimal moisture content for compaction, while the coarse fraction of these tailings showed good filtration results. Complementary geotechnical studies, such as compaction and permeability analyses, reinforced the safest techniques for each type of tailings. The solution for the magnetite tailings involves dewatering with hydrocyclones and placement in a specific compacted pile, increasing the potential for re-use as iron ore. Coarse flotation tailings are filtered and placed in compacted piles, while the finer flotation tailings undergo thickening before being disposed of as high-density slurry in the main dam reservoir. The facilities were designed with efficient drainage systems and geomembrane liners to ensure long-term safety. The project also promotes sustainability by re-using materials as byproducts, such as the production of iron ore concentrate.