PURPOSE: To separate and recover a lubricating oil and a cleaning agent to be used in the stage of cold drawing a metallic pipe by using a vacuum distillator and a centrifugal separator in separating and recovering the waste liquid mixture composed of the lubricating oil and the cleaning agent.

CONSTITUTION: The lubricating oil used in the stage of cold drawing sticks on a steel pipe 5 which is produced by cold drawing with roll dies 1 of Piller rolls and a mandrel 3 and therefore the bundle of the steel pipes is dipped in a tank 6 contg. a methylene chloride soln. as a cleaning agent in a cleaning device 8 to clean the lubricating oil sticking thereto, whereafter the bundle is pulled from the soln. The methylene chloride liquid increased in volume with the lubricating oil overflows into an evaporation tank 8 and is heated in a heater 9, by which methylene chloride is evaporated and the steel pipe bundle is cleaned by the same. The methylene chloride vapor is cooled in a cooling pipe 7 and is condensed to a liquid form which is again recovered in the tank 6. The liquid thickened by the lubricating oil remaining in the tank 8 is evaporated of the residual ethylene chloride in a vacuum distillator. The vapor is condensed to a liquid in a condenser and is returned into the tank 6. The remaining oil is removed of the mud, iron powder, contained therein by a centrifugal separator 15 and is recovered and is again utilized as the lubricating oil.