盐湖提锂副产氢氧化镁绿色合成镁基层状复合氢氧化物

Green Route of MgAl Layered Double Hydroxides Using By-product of Magnesium Hydroxide Produced by Lithium Extraction from Salt Lakes

青海盐湖资源丰富,在盐湖提锂过程中副产了大量含锂Mg(OH)_(2)镁渣,由于利用条件和工艺的限制,其大部分被企业堆置放弃,造成资源的严重浪费和生态环境的破坏,因此提锂副产镁渣的高值化利用具有重要的意义。本研究仅采用盐湖提锂副产镁渣和可溶性铝盐作为原料,采用水热法成功制备了SO^(2-)和CO_(3)^(2-)插层的镁基层状复合金属氢氧化物(LDHs)。并通过XRD、FT-IR、Raman、TG-DTG等手段对产物的结构、形貌等进行了表征。制备过程中不需要加入其他碱作为沉淀剂,不产生钠盐或铵盐等副产物,产物只需少量水洗涤即可,是一种绿色、经济的制备工艺。此外,在反应过程中可将镁渣中90%的锂进行回收,不仅实现了副产镁渣的高值化利用,还回收了夹带的锂,对盐湖镁锂资源综合高效利用提供了一种有效途径。

The salt lake resources are rich in Qinghai.In the process of lithium extracting,a large amount of by-products of Mg(OH)_(2) containing lithium produced.However,limited by cost and technology,most Mg(OH)_(2) was abandoned directly.In this study,the by-product Mg(OH)_(2) is used as raw material and hydrothermal synthesis method is employed to prepare MgAl-LDHs.The structure and morphology of the MgAl-LDHs were characterized by XRD,FT-IR,Raman and TG-DTG.This process only uses Mg(OH)_(2) and soluble aluminum salts as raw materials,and it’s not necessary to add alkali as a precipitating agent.In addition,there are few by-products produced and only a small amount of water needed to wash the product.Meanwhile,about 90%Li+in by-product Mg(OH)_(2) entered the liquid phase after the reaction,which could be further recycled.This process finally realized the goal of waste recycling and efficient utilization of salt lakes resources.