To separate refined fluorene from coal tar, domestic and foreign production processes generally use crystallization, centrifugal separation, solvent recrystallization and drying, but the solvents used for recrystallization are different. The single crystal reagent factory of the former Soviet Union Kharkov Academy of Sciences uses three-stage recrystallization in isopropanol to produce refined fluorene with a melting point of 112.5°C, but the product yield only accounts for 17% of the fluorene fraction, and the operation process has low production capacity and production time. Up to 70 hours. Japan used the crystallization method to extract refined fluorene with a melting point of 113.5°C from the fluorene fraction at 70-100°C. There are also reports that 88.3% of industrial fluorene is recrystallized in three phases using xylene and water at 27°C to produce refined fluorene with a purity of 99.4% and a yield of 75%. Angang Chemical Plant uses fluorene as the raw material, toluene as the solvent, and the solvent crystallization method to prepare refined fluorene. The purity of refined fluorene can reach more than 99%, and the yield can reach 90%.
