Study On Extracting Lithium From Li_1.6Mn_1.6O₄ And Adsorption Properties Of Lithium Ion-sieve

As recycled lithium battery technology development contemporarily, the demand of lithium resources also grows sharply. Development of mineral resources of lithium can not meet the demand of lithium resource market in the long term, and liquid lithium resources （including brine and seawater） become the focus of research and development. Presently, due to the simple process, low cost, high selectivity, adsorption method becomes the ideal method of extracting lithium from the liquid. Especially ion-sieve adsorbent which has the ability of memory is considered to be suitable for extracting lithium from the liquid. And among the adsorption material of extracting lithium, spinel manganese oxide lithium ion-sieve is most promising.Lithium ion-sieve precursor was mainly prepared with KMO₄, EtOH and LiOH·H₂O through hydrothermal synthesis method. Lithium extraction rate and manganese dissolving loss rate of lithium ion-sieve precursor were investigated under different conditions to determine the optimal conditions of acid pickling. The optimal conditions were that the experimental temperature was 30℃, the stirring speed was 400 r/min, pickling time was 12 h, concentration of HCl was 0.1 mol/L and the liquid-solid ratio was 500 mL/g. Lithium extraction rate could reach 98% and manganese dissolving loss rate was less than 3% under the conditions. The precursor and the lithium ion-sieve presented spinel structure through XRD and SEM test. Adsorption properties and selectivity of adsorbent H_1.6Mn_1.6O₄ were investigated at the best pickling conditions. Results showed that:The adsorption capacity of lithium ion-sieve adsorbent H_1.6Mn_1.6O₄ can reach 62.20 mg/g when the pH was 12.6 and lithium concentration was 500 mg/L. The adsorption capacity is higher than others which was reported in literatures; After 5 times adsorption and desorption experiment, the adsorption capacity can reach 45 mg/g. It is obvious that adsorption material is stable and recycled. In the selective experiments, the K⁺, Na⁺, Mg²⁺ three metal ions influence on Li⁺ adsorption were respectively investigated, results show that the selective of adsorbent is higher than others. The fitting of dynamic model and isothermal adsorption curve suggest that ion-sieve adsorption process is complicated, mainly including chemical adsorption, along with physical adsorption. Adsorption is not uniform and the adsorbate will interact with each other in the solution.