Recycling Lepidolite from Tantalum–Niobium Mine Tailings by a Combined Magnetic–Flotation Process Using a Novel Gemini Surfactant: From Tailings Dams to the “Bling” Raw Material of Lithium

On January 25, 2019, the tailings dam at Vale's Córrego do Feijao mine (Brumadinho, Minas Gerais, Brazil) ruptured, releasing about 12 million cubic meters of tailings, killing over 240 people and posing a considerable and ongoing environmental hazard. Thus, the recovery of valuable minerals from tailings can contribute to a sustainable disposal of this hazardous residue, saving human lives and protecting the environment. The tailings of a tantalum–niobium mine usually contain a considerable amount of lepidolite resource. Nonetheless, the method of sustainably acquiring the lepidolite resource from tailings of a tantalum–niobium mine at low-temperature environments has always been needed. In this study, we synthesize a new amine-based gemini surfactant, butanediyl-α,ω-bis(dimethyldodecylammonium bromide) (BDB). It is introduced as a collector in the flotation of lepidolite from the tantalum–niobium mine tailings for the first time at low temperatures. We compare its capability to collect lepidolite with the monomeric surfactant 1-dodecylamine (DA). In bench-scale flotation experiments, the Li2O recovery of lepidolite concentrate with 80 g/t BDB was 10.96% and 31.85% higher than that with 160 g/t DA at 298 and 275 K, respectively, which indicated that BDB is a better collector for lepidolite than DA. BDB is a novel and superior collector for disposing of lepidolite tailings ponds.