含锂离子筛膜型吸附剂的制备及其在盐湖卤水提锂中的应用研究

Lithium and its compounds are widely used in many fields, especially in rapid expansion of rechargeable batteries, which increases the demand of lithium resources. Salt lake brine contain vast amounts of lithium. The recovery of lithium from brine has attracted great interest in recent years. The adsorption method has been recognized as one of the most promising method for lithium recovery from salt lake brine owing to the most cost-effective and environment-friendly advantages. Among the inorganic adsorbents, spinel manganese oxides (derived from spinel-type lithium manganese oxide) are promising lithium ion-sieves adsorbents for extracting lithium from brine with extremely high selectivity and capacity, low toxicity, low cost and high chemical stability. However, most lithium ion-sieves are in powder form leading to larger pressure drop, loss of powder and high energy consumption in column operation, which limits their industrial application. Membranization are conventionally introduced to overcome this shortage. A membrane-type adsorbent has the merit in that the adsorption module can be constructed easily by stacking or coiling membranes. That could avoid the column method and would not require a high pressure. Therefore, the membrane-type adsorbent would be suitable for continuous operation and industrial application. This project will prepare the "localized" or "free" of lithium ion-sieve containing membrane adsorbent by immobilizing H1.6Mn1.6O4 into the membrane layer or enveloping H1.6Mn1.6O4 into the cavity of hollow fiber membrane, respectively. The membrane adsorbent will be used to recovery Li+ from salt lake brine. This project can provide new ideas and theoretical basis for the technology development of extracting Li+ from salt lake brine.

锂资源作为一种重要的战略资源备受各国重视，然而，陆地上锂矿资源含量远不能满足市场需求。目前世界锂盐生产中盐湖卤水提锂占总产量的80%，而我国盐湖卤水提锂仅占总产量的25%。因此，发展盐湖卤水提锂技术将是锂产业的主要发展方向。尖晶石型锂离子筛H1.6Mn1.6O4对锂的选择性较高，是目前吸附量最高的吸附剂。然而锂离子筛为粒径微米级的粉末状，因为存在高压力降和难分离的问题，很难实现填柱吸附或直接加入水体中，限制了其工业化应用。而将锂离子筛引入聚合物中制备膜型吸附剂，可以克服粉末状吸附剂的缺点。此外，膜可以直接缠绕或叠加，不再局限于柱式操作，适合于大量生产和连续操作。本项目拟将H1.6Mn1.6O4固载到膜层中或者填充到中空纤维膜的空腔内，制备“定域型”和“自由型”的锂离子筛膜型吸附剂，并研究其在盐湖卤水中对Li+的吸附性能及吸附机理。本课题的实施可以为盐湖卤水提锂技术的发展提供新思路和理论依据

本课题的通过造粒和成膜对粉末状吸附剂进行成型研究，制备出对盐湖卤水中的锂具有高吸附选择性、高吸附容量、适合大规模工业化应用的吸附剂。以PVC为粘结剂，利用相转化法制备了PVC锂离子筛平板膜。通过静态吸附实验确定吸附参数，采用正渗透设备、卷曲填充柱式及平板挂膜浸泡法考察动态连续吸附的性能，确定最佳的制备条件和吸附脱附条件，为盐湖卤水中锂资源提取技术的发展提供新思路和理论依据。采用静电纺丝技术将锂离子筛吸附剂粉末固载到纳米纤维膜中，对锂离子具有较高个吸附性能。制备了钛型锂离子吸附剂，提高了在自然水体酸碱环境下的吸附量，对钛型吸附剂进行磁化改性，实现了吸附剂的固液分离。