NiPO_4/LiNiPO_4离子筛盐湖提锂热力学分析  

Thermodynamic Analysis of Li-Extraction from Salt Lake by NiPO_4/LiNiPO_4 Ion-Sieve

作　　者：陈浩[1] 何利华[1] 刘旭恒[1] 

机构地区：[1]中南大学冶金与环境学院,湖南长沙410083

出　　处：《稀有金属》2016年第10期1045-1052,共8页Chinese Journal of Rare Metals

基　　金：国家自然科学基金联合项目(U1407137)资助

摘　　要：基于锂离子电池充放电过程的可逆氧化还原反应原理,提出利用NiPO_4/LiNiPO_4电极对盐湖卤水进行锂镁分离的思路。运用同系线性规律对Me(Li,Na,K,Mg)-Ni-P-H_2O中NiPO_4,Ni_3(PO_4)_2,LiNiPO_4,Na NiPO_4,KNiPO_4,Mg_(0.5)NiPO_4的标准吉布斯自由能进行了估算。在热力学计算的基础上绘制了298.15 K时,Me(Li,Na,K,Mg)-Ni-P-H_2O系的φ-p H图,讨论了NiPO_4对盐湖卤水中主要金属离子(Li^+,Na^+,K^+,Mg^(2+))的选择性吸附行为。结果表明:水溶液中存在LiNiPO_4,Na NiPO_4,KNiPO_4的稳定区,还原电位(vs SHE)分别为0.2379,-0.0291,0.0209 V,不存在Mg_(0.5)NiPO_4的稳定区。在实际盐湖卤水(Mg/Li质量比为67)离子浓度条件下,NiPO_4/LiNiPO_4电极对仍具有良好的选择性提锂功能。而天然卤水的p H一般在7左右,表明此时无需添加酸或碱来调节卤水的p H,这与节能减排和环境保护的理念不谋而合,不断重复脱嵌锂过程即可从盐湖卤水中选择性提取锂。NiPO4/LiNiPO4 electrode was selected to separate lithium and magnesium from salt lake brine based on the principle of re- versible redox reaction in lithium ion battery during charging and discharging process. The standard Gibbs free energies of NiPO4, Ni3 （PO4） 2, LiNiPO4, NaNiPO4, KNiPO4 and Mg0.5NiPO4 in Me（Li, Na, K, Mg）-Ni-P-H2O system were estimated by congeneric linearity rule. The φ-pH diagrams of Me（ Li, Na, K, Mg）-Ni-P-H2O system at 298.15 K were plotted and the selectivity of adsorption of main metal ions （ Li ＋ , Na ＋ , K ＋ , Mg2 ＋ ） by NiPOa/LiNiPO4 in brine were discussed according to thermodynamic calculation. The resuits showed that LiNiPO4, NaNiPO4 and KNiPO4 could exist steadily in aqueous solution and the reduction potentials（ vs SHE） were 0. 2379, -0. 0291,0. 0209 V, respectively, while the stable region of Mg0.5 NiPO4 did not exist in the studied range . Under the condition of real brine concentration, in which the mass ratio of Mg/Li was as high as 67, the calculation result showed that NiPOJLiNi- PO4 electrode still presented favorable selective adsorption characteristics. The pH of brine was generally about 7, indicating that there was no need to add acid or base to adjust pH, which coincided with the concept of energy saving and environmental protection. Lithium could be extracted from salt lake brine selectively by repeating the process.

关 键 词：Me-Ni-P-H2O系 NI PO4/Li NI PO4 盐湖提锂 热力学 

分 类 号：TF801.1[冶金工程—有色金属冶金] TF803.2