Innovations in Liquid-Liquid Solvent Extraction for the Efficient Recovery of Critical Minerals and Rare Earths

B. Cross
Koch Modular Process Systems,
United States

Keywords: Extraction, Critical Minerals, Rare Earths


Liquid-liquid extraction (LLE) or Solvent Extraction (SX) is a separation process that has for many years been applied in industrial chemical processes in areas such as bulk & specialty chemicals, polymers, pharmaceuticals, food & flavors, and metals/mining. More recently it is being used much more often in the production of bio and renewable chemicals, in clean energy processes, and other areas such as recycle metals extraction and plastic recycling. Additionally, LLE has become an attractive unit operation for decarbonizing existing processes. Whereas distillation leverages differences in relative volatility between compounds to make a separation, LLE relies on differences in molecular structure. There are three key aspects for applying LLE to a separation process. The first is the selection of an appropriate solvent that is immiscible or only partially miscible with the bulk feed and will selectively extract the components required. Next comes the selection of the appropriate extraction technology for the given process. Finally, a well-designed and operated pilot test will de-risk the extraction process and ensure that accurate scale-up data is developed. Over the years we have had ample project success using our LLE technology to replace mixer settlers for a number of different chemical processes. This knowhow can be applied to design columns for many metals extraction processes including Lithium. Benefits of switching from a traditional mixer-settler to extraction columns include: • Smaller Area/Footprint • Reduced Solvent Inventory • Shortened Time to Reach Equilibrium • Improved Safety/Emissions Minimization of Emulsification • Improved Control of Challenging Interface • Improved Control of the Continuous/Disperse Phases Relevant published articles available upon request. Thank you