Enhancement of lithium extraction from coal gangue based on the deep dissociation of coal components and acid leaching

Extracting lithium from coal measures can alleviate the shortage of strategic metal resources. However, the lattice substitution characteristics of lithium in carrier minerals and its extremely fine intercalation and entrainment behavior are the challenges that constrain the extraction efficiency of lithium from coal series. This study focuses on improving the separation efficiency between lithium-containing minerals and other minerals and the release behavior of lithium in the liquid phase. First, the feasibility of extracting lithium from carrier minerals is confirmed based on the occurrence state and the process mineralogy characterized by Bgrimm process mineralogy analyzing system (BPMA) and Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS). The optimal selective grinding behavior is achieved within 15 min, allowing Li carrier minerals, including chlorite, kaolinite, and halloysite, to deliver the best dispersion effect with other minerals. Thus, the enriched lithium carrier minerals have been preenriched through screening. The leaching efficiency of Li has reached 97.43% under 1 mol/L hydrochloric acid, 15 g/L pulp density, 70°C, and 20 min. Leaching kinetics studies indicate that the decrease in apparent energy validates the impact of grinding on metal leaching, aligning with the rate-controlling step of a chemical reaction. The process proposed in this study achieves the coordinated control of size and components in coal gangue and actualizes the effective selective enrichment of lithium through its low energy consumption and environmentally friendly nature.