Recovery of Ti and Li from spent lithium titanate cathodes by a hydrometallurgical process

Despite the potential application of lithium titanate (Li4Ti5O12) battery, recovering Ti and Li from the spent batteries remains a largely unexplored but important topic. In this contribution, a process including leaching, extraction for the separation of titanium from leaching liquor and synthesizing TiO2 nano-particles by a homogeneous precipitation method is presented as a successful strategy. Various operating parameters were optimized, affording more than 97% leaching efficiency of both Ti and Li at a sulfuric acid solution of 4 M, H2O2 of 20 vol.%, solid-to-liquid ratio of 0.025 g mL− 1, leaching temperature of 80 °C and leaching time of 4 h. In the case of the extraction, the solvent extraction efficiency of titanium about 99% can be achieved with 30 vol.% primary amine N1923 as an extractant and kerosene as a diluent at highly acidic condition, organic phase/aqueous phase (O/A) ratio 2:1 within 10 min of contact time in ambient temperature, while the solvent extraction efficiency of lithium is only 1.4%. The raffinate was concentrated from 0.74 g L− 1 to 1.11 g L− 1 by evaporation, then lithium carbonate was precipitated by adding saturated solution of sodium carbonate affording 85% recovery. Finally, the stripping was fast with equilibrium time of 10 min with 2 M H2SO4 and titanium stripping of 98%. The results of XRD and SEM show that the size of as-prepared TiO2 powders is 100–200 nm from the stripped solution by the homogeneous precipitation method.