Device for recovering benzoic acid from biphenyl substances

The utility model provides a device for recovering benzoic acid from biphenyl substances. The device comprises a heater, an extraction mixer, an extraction layering tank, a back extraction mixer, a back pressure valve, a back extraction layering tank, a water tank and a water injection pump which are connected through pipelines. Taking hot water as an extraction agent, continuously injecting biphenyl substances and hot water into an extraction mixer, enabling a mixed phase to enter an extraction layering tank for layering, enabling a light-phase benzoic acid aqueous solution to overflow from the top of the extraction layering tank to a back-extraction mixer, and discharging heavy-phase biphenyl substances from the bottom of the extraction layering tank; toluene serving as a back-extractant and benzoic acid aqueous solution are continuously injected into a back-extraction mixer, a mixed phase enters a back-extraction layering tank for layering, a light-phase benzoic acid toluene solution overflows from a back