Study On The Granulation Of Ion-Sieve Type Lithium Adsorbent And Its Capability

The XRD illustrative atlas of the precursor, the ion-sieve and its adsorbent were compared. It was proved that their structure was not changed and they were all spinel structure. The cell dimension was different somewhat only. The losing rate of ion-sieve would increase and it had little effect on raising the purity when increasing the acid washing times. The particle size was among 300nm and 500nm by SEM analysis. The adsorptive law of the ion-sieve was determined when pH value was 1, 3, 5, 7, 9, 11 in lithium solution. Its adsorptive capacity was from 0.7mg per gram ion-sieve to 16.55mg per gram ion-sieve when the pH value of solution was changed from 1 to 11. The effect of the pH value on the capacity can be seen obviously.Through the granulation research by using tetramethoxysilane, kaoline, Alta-mud, Autobang Atlapulgite Clay and PVC as the granulating reagent, we picked out the appropriate material-PVC. By changing PVC's proportion during the granulation process, we found that the granules' losing rate was low in the water when the ratio of PVC was 20%. When chosen 0.45-0.90mm adsorbent granule, its adsorptive capacity reached 15.56mg per gram adsorbent in the pure lithium solution. And its available adsorption rate was over 80 percent. It was found that all of the elution rate of the hydrochloride acid to the adsorbent was very high(over 85%) and the concentration of elution solution decreased quickly when the concentration of hydrochloride acid changed from 0.50mol · L-1 , 0.20mol · L-1, 0.05mol · L-1 to 0.02mol· L-1. But when the dissolving rate of manganese was concerned the concentration of acid of 0.05mol L"' was appropriate. Four times of recycling experiments were done and showed that the adsorptive capacity was slightly decreased because of the little dissolve of ion-sieve.The experiment of the granular adsorbent extracting lithium from seawater was done, and it was found that the granular adsorptive capacity was 5.68mg per gram adsorbent. This is higher than the capacity reported in the Japanese papers (4.80mg · g-1). The concentration of rich lithium solution was 200 times compared with the lithium concentration in seawater when using hydrochloride acid of 0.05mol L-1 as the elution solution. And the rich lithium solution hardly contained other positive ion except lithium ion. Through different condition experiments, it was proved that when Na+and the K+exist in the solution the adsorptive capacity of the adsorbent to lithium was near to the capacity in pure lithium solution. But the adsorptive capacity was decreased to the half when magnesium existed in lithium solution.