A review of in coal-based lithium resources:Distribution,occurrence characteristics,and extraction separation

PAN Jinhe; ZHANG Lei; ZHOU Maiqiang; ZHOU Changchun

doi:10.16186/j.cnki.1673-9787.2022070008

Abstract：Lithium is a strategical metal with broad areas of application,which is of great significance for na-tional security,national economy and scientific and technological development.Objectives China's lithium resources are facing the dilemma of imbalanced supply and demand,and there is an urgent need to find new lithium sources.The lithium content in Chinese coal is high and widely distributed.Coal gangue and coal fly ash,which are coal-based by products,have high lithium content and are expected to become alter-native resources for traditional resources.The recovery of lithium from coal gangue and coal fly ash can broaden the existing production routes of lithium,and realize the high value utilization of coal gangue and coal fly ash as resources.Methods This paper reviewed the current research progress on the distribution characteristics and modes of occurrence of lithium in coal deposit and migration laws of lithium elements in coal measures during combustion.It also summarized the leaching and purification recovery methods of coal-based lithium elements,which can provide reference for extracting and recovering lithium resources from coal-based by-products.Results The content of lithium was high in the coal-rich regions of North and South China,and the main lithium bearing minerals were clay minerals such as kaolinite and illite.In some mining areas,the lithium content of gangue-bearing coal,roof and floor was higher than that of coal seams.After coal combustion,the secondary enrichment of lithium was realized.Lithium mainly combined with alumino-silicate,occured in the glass phase,and tended to be enriched in fine fly ash.Leaching and separation were necessary way to realize the recycling of coal-based lithium resources.However,the existing process was complicated,with low lithium concentration in the leaching solution and severe interference from impurity ions in the separation and purification process.Conclusions The future development of coal-based lithium resources should strengthen the differential enrichment of lithium elements in gangue and coal during the mining and selection process,with a focus on exploring the migration and transformation laws of lithium dur-ing the combustion process,emphasizing the efficiency of leaching and the selectivity of separation and puri-fication processes.The exploit and recovery of lithium from coal-based resources contribute to the high-value utilization of coal resources and promote green and sustainable development.