Lithium extraction from hard rock lithium ores (spodumene, lepidolite, zinnwaldite, petalite): Technology, resources, environment and cost

This paper focuses on the research progress of extracting lithium from spodumene, lepidolite, petalite and zinnwaldite by acid, alkali, salt roasting and chlorination methods, and analyzes the resource intensity, environmental impact and production cost of industrial lithium extraction from spodumene and lepidolite. It is found that sulfuric acid method has high lithium recovery rate, but with complicated process and high energy consumption; Alkali and chlorination methods can directly react with lithium ores, reducing energy consumption, but need to optimize reaction conditions and safety of equipment and operation; Salt roasting method has large material flux and high energy consumption, so require adjustment of sulfate ratio to increase the lithium yield and reduce production cost. Compared with extracting lithium from brine, extracting lithium from ores, calcination, roasting, purity and other processes consume more resources and energy; and its environmental impact mainly comes from the pollutants discharged by fossil energy, 9.3~60.4 times that of lithium extracted from brine. The processing cost of lithium extraction from lepidolite by sulfate roasting method is higher than that from spodumene by sulfuric acid due to the consumption of high value sulfate.