Sun Ying, Yun Rongping, Zang Yufeng, Pu Min, Xiang Xu
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Materials (Basel). 2019 Jun 19;12(12):1968. doi: 10.3390/ma12121968.
Lithium extraction from salt lake brine is critical for satisfying the increasing demand of a variety of lithium products. We report lithium recovery from pre-synthesized LiAl-layered double hydroxides (LDHs) via a mild solution reaction. Lithium ions were released from solid LiAl-LDHs to obtain a lithium-bearing solution. The LiAl-LDHs phase was gradually transformed into a predominantly Al(OH) phase with lithium recovery to the aqueous solution. The lithium recovery percentage and the concentration of the lithium-bearing solution were dependent on the crystallinity of LiAl-LDHs, the initial concentration of the LiAl-LDHs-1 slurry, the reaction temperature, and the reaction time. Under optimized conditions, the lithium recovery reached 86.2% and the Li concentration in the filtrate is 141.6 mg/L. Interestingly, no aluminum ions were detected in the filtrate after solid-liquid separation with high crystallinity LiAl-LDHs, which indicated the complete separation of lithium and aluminum in the liquid and solid phases, respectively. The Al NMR spectra of the solid products indicate that lithium recovery from the lattice vacancies of LiAl-LDHs affects the AlO coordination in an octahedral configuration of the ordered Al(OH) phase. The XPS O 1 spectra show that the O peak intensity increased and the O peak intensity decreased with the increasing lithium recovery, which indicated that the Al-OH bond was gradually formed and the metal-oxygen-metal bond was broken.
从盐湖卤水中提取锂对于满足各种锂产品不断增长的需求至关重要。我们报道了通过温和的溶液反应从预合成的锂铝层状双氢氧化物（LDHs）中回收锂。锂离子从固态锂铝层状双氢氧化物中释放出来，得到含锂溶液。随着锂回收到水溶液中，锂铝层状双氢氧化物相逐渐转变为主要为氢氧化铝相。锂的回收百分比和含锂溶液的浓度取决于锂铝层状双氢氧化物的结晶度、锂铝层状双氢氧化物-1浆料的初始浓度、反应温度和反应时间。在优化条件下，锂回收率达到86.2%，滤液中的锂浓度为141.6毫克/升。有趣的是，用高结晶度的锂铝层状双氢氧化物进行固液分离后，滤液中未检测到铝离子，这表明锂和铝分别在液相和固相中完全分离。固体产物的铝核磁共振谱表明，从锂铝层状双氢氧化物的晶格空位中回收锂会影响有序氢氧化铝相八面体构型中的铝氧配位。X射线光电子能谱O 1光谱表明，随着锂回收率的增加，O峰强度增加而O峰强度降低，这表明铝-氢氧键逐渐形成，金属-氧-金属键断裂。
