Investigation on desorption process in fixed bed for lithium recovery

Abstract

• Desorption process of Li + in the fixed bed is studied with lithium-aluminum hydroxides adsorbent. • Basic mass transfer equations for Li + desorption process are established and solved. • The observed Li + elution curves in fixed bed columns were well described by the mathematical model. With the development of lithium-ion batteries, the demand for lithium increase rapidly. Adsorption method is one of the most promising method to extract lithium from salt lake brine. In this work, desorption process for lithium recovery from simulated salt lake brine was systematically investigated under various operational conditions in fixed bed columns packed with lithium-aluminum hydroxides adsorbent, including the effects of washing volume, temperature and flowrate on the washing performance, as well as the effects of elution flowrate and volume on elution rate of Li + . The optional washing temperature is 283 K, and washing flowrate is 45 mL/min. The desorption rate of lithium is only affected by elution volume, and flow rate may not affect the Li desorption significantly under the temperature of 333 K. The reason might be that the diffusion rate is fast enough and the process is dominated by adsorption equilibrium. Thus, temperature may be a key factor to the performance of fixed bed desorption process. The concentration-dependent Homogeneous Surface Diffusion Model (HSDM) was developed to fit and simulate the dynamic elution performance of lithium in fixed bed column. The overall pattern of the elution process can be represented by the HSDM. These results provided significant data for the design, optimization and scale-up of the column desorption process for brine lithium recovery.