An Antisolvent Extraction Strategy for Extrusion Granulation Enhancement of Aluminum-Based Lithium Adsorbent Used in Ultrahigh Mg2+/Li+ Salt Lake Brines

Granulation is an essential process for the industrial application of adsorbents packed in adsorption towers, given the high bed pressure drop and powder loss. In this study, a novel extrusion granulation method together with an antisolvent strategy was developed for the aluminum-based lithium adsorbent powder, which has been successfully applied in the lithium extraction industry. Compared with the traditional adsorbent granules, the compressive and flexural strengths of the improved granules were increased from 0.618 to 1.431 MPa and from 0.363 to 1.184 MPa, respectively. Meanwhile, the adsorption rate was significantly sped up without any powder leakage attributed to the flatter and denser film formed on the surface, which firmly encapsulated the powders and formed more pores, improving the mass transfer efficiency in the adsorption process. Moreover, the enhanced aluminum-based lithium adsorbent granules demonstrated a great adsorption performance in the Qarham old brine with a Mg2+/Li+ mass ratio of 294.24, whose Li+ adsorption capacity was stable at 4.45–4.86 mg/g in 24 cycles without structural transformation. Besides, the working adsorption capacity in the fixed bed remained within the range of 3.89–4.44 mg/g; meanwhile, the Mg2+/Li+ mass ratio in desorption solutions could descend to 0.26 from 294.24.