Study On Lithium Extraction From Salt Lake Brineby Adsorption

Lithium is a widely used metal element,and its extraction process has received increasing attention.The domestic lithium resources are mainly brine type,and the extraction of lithium from brine has a clear competitive advantage in terms of cost.However,lithium extraction is difficult due to the high ratio of magnesium and lithium brine in China.Related research shows that aluminum-based lithium adsorbents have the characteristics of high selectivity for lithium and environmental friendliness.Therefore,it is necessary to develop aluminum-based lithium adsorbents with good cycle performance and high capacity for high magnesium-lithium-to-brine brine.The salt brine in China has diversity.In the past,the research object of the aluminum-based lithium adsorbent was single,and there was a lack of comparative research.in different actual brine systems.In this paper,the aluminum-based lithium adsorbent with good performance was prepared by precipitation method,tested and characterized,and the performance differences of the prepared samples in three different regions and different types of high magnesium lithium ratio brine systems were compared and studied.The further practical application of aluminum-based lithium adsorbent provides an effective experimental basis.Samples were prepared by NaAlO2 and AlCl3 as aluminum source,LiCl as lithium source,and cocurrent dropwise addition,and the synthesis conditions were studied.The final test results showed that the samples prepared after optimized conditions had good crystal structure and adsorption cycle The performance is excellent.There is no dissolution loss and crystal form transformation in the 20-cycle experiment,and the adsorption-rinsing capacity is kept above 5.0 mg.mL-1,and no significant decrease is seen.The experimental results examining the efect of three real brines on the adsorption of prepared samples show that:the time,pH,liquid-solid ratio influence curve and adsorption isotherm of the sample in the three brines are the same change rule.And all show a high selectivity for Li+,the adsorption process is dominated by chemical adsorption and monolayer,but the adsorption capacity of three kinds of brine is significantly different;the adsorbent capacity gradually increases with the increase of Li+concentration in brine;the effect of temperature on adsorption capacity varies slightly with brine the difference.The leaching experiment showed that after the sorbent was rinsed with water for 60 minutes,the Li+concentration in the eluent tended to be gentle,and the leaching capacity increased significantly with increasing temperature,but was less affected by pH,the liquid-solid ratio increases,the capacity becomes larger,but the solution concentration becomes lower,and the kinetic and isothermal curve fitting indicates that the adsorbent has the characteristics of chemical adsorption and monolayer adsorption in the equilibrium process of lithium in the water system.The preliminary identification results of the prepared granular adsorbent show that:under the condition of adsorption contact time of 5min and adsorption volume of 50BV,the adsorption capacity is 2.16 mg.mL-1;when the contact time of 10 min is selected,the peak of elution appears at 1.5 BV nearby.The adsorbent can maintain a lithium exchange capacity of about 2.0 mg.mL-1 in 20 adsorption-wash cycle,and there is no obvious damage.Through the SEM images of the sample surface morphology before and after the cycle,no significant changes were found.It shows that the aluminum-based lithium adsorbent for brine with high magnesium to lithium ratio has very good industrial application value.