Modelling of column lithium desorption from Li+-loaded adsorbent obtained by adsorption from salt brine

Abstract Desorption technology is important to fabricate the economical process for Li + recovery from brine by adsorption method, but there have been no systematic studies on the column Li + desorption. The purpose of this paper is to find the elution conditions to have the eluate with high Li + concentration in a short time, from which Li 2 CO 3 can be precipitated without pre-concentration. The promising conditions of column Li + desorption could be proposed on the bases of column desorption experiments and model calculations. The natural salt brine (pH 6.8) containing 0.21 M (1 M = 1 mol dm − 3 ) Li + , 2.7 M Na + , 0.51 M K + , 1.3 M Mg 2 + , 5.4 M Cl − , and 0.25 M SO 4 2 − was used for the Li + adsorption. The granulated adsorbent sieved to 0.42–0.71 or 0.71–1.0 mm was prepared with colloidal silica as a binder. The Li + -loaded adsorbents were prepared by treating the granulated adsorbent with the NaHCO 3 added brine by a batch method. The column elution experiments were carried out by passing HCl or H 2 SO 4 solutions with different concentrations through the Li + -loaded adsorbents at different flow rates. A model consisting of Li + migration in the solid phase and of surface H + /Li + exchange was proposed for the analysis of desorption behavior. The calculated elution curves well approximated the experimental ones when the effective acid concentration and the elution delay were considered. These approximations may be caused by the influence of the other metal ions co-adsorbed from brine. The calculation showed that the elution by passing a 2 M acid solution at a space velocity of 10/h up to 2 bed volume produces the eluate of high Li + concentration (1.15 M) with high Li + recovery (87%). This process has the advantages of eliminating the step of pre-concentration of eluate for precipitation and reducing the acid consumption.