| With the development of science and technology, the demand of lithium is becoming larger and larger. Traditional extracting from lithium ore can’t meet the demand. Extracting lithium from brine is getting rapid development. Iron-sieve adsorption is regarded as the most promising method extracting lithium from brine. Ion-sieve MnO2·0.5H2O’s Performance is the most good. In this thesis, it was mainly studied on the synthesis method of MnO2·0.5H2O, the choice and application of picking acid, the adsorption performance of MnO2·0.5H2O.Using the orthogonal experimental method, the effect of synthesis factors on the performance of lithium ion-sieve adsorbentMnO2·0.5H2O were studied. The mainly synthesis factors are hydrothermal temperature, Li:Mn molar ratio, hydrothermal reaction time, calcination temperature and calcination time. It showed a significant effect on absorption capacity of lithium ion-sieve while the conditions changed, but for the loss ratio of dissolved Mn had no significant effect. The optimal conditions for preparation of Lithium ion-sieve had been obtained, such as hydrothermal temperature230℃, lithium-manganese molar ratio of5:1, reaction time13h, calcination temperature450℃and calcination time6h. It was performed ten cycles absorption-desorption experiments that the lithium ion-sieve prepared under optimal conditions. The absorption capacity in first absorption process was37.18mg/g. The absorption capacity remained36.11mg/g after ten consecutive cycles of absorption desorption process. The loss ratio of dissolved Mn was low in these processes. The samples, which before and after absorption-desorption processes, were characterized by XRD. The results showed the samples had maintained a Li1.6Mn1.6O4spinel structure before and after the processes.Using sulfuric acid and hydrochloric acid as pickling acid to elute self-made lithium-rich lithium ion-sieve. According the extraction ratio of Li+and the loss ratio of dissolved Mn2+to choose suit pickling acid. Determining the pickling acid concentration, under the premises of low loss ratio of dissolved Mn, high extraction ratio of Li, high lithium concentration in the picking acid. Finally The result show that:For self-made lithium ion-sieve, the comprehensive effects will be best when choosing1.25mol/L sulfuric acid as pickling acid; the concentration of lithium can be enriched to14.27g/L.Studied the influence of pH, reaction temperature and reaction time on the adsorption property. pH has a great influence on adsorption property. The adsorption property is good under alkaline solution. Brine is a week acid buffer system, ion-sieve still has a good lithium adsorption capacity in brine. Ion-sieve has a strong selective adsorption ability. The order is Li+>>a+>K+>Mg2+. The adsorption capacity of powdered ion-sieve gradually into balance after two hours in brine. Increasing temperature can improve the adsorption property. The lithium adsorption capacity is25.05mg/g after adsorb24h in50℃brine. Ionic sieve in brine meet the Langmuir adsorption isotherm, monolayer suck, in line with the pseudo secondary dynamics, chemical adsorption process. Adsorption apparent activation energy, Ea=41.27kJ·mol-1. Lithium adsorption process is not controlled by a single control steps.The lithium adsorption capacity of ion-sieve is decline after granulated. The lithium absorption capacity is12.9mg/g at30℃, only64.3%of powdered ion-sieve. Increasing reaction temperature and appropriate diluting the brine can improve the adsorption property of granulated ion-sieve. The cycle performance of granulated ion-sieve is good. The lithium adsorption capacity is11.3mg/g after10times cycle,88.3%of the initial. |
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