Waste Oil Recycling and Reuse

Waste oil can be fully reused through regeneration, which both saves energy and protects the environment. The regeneration principle is as follows: utilizing the characteristics that oil and water are difficult to dissolve in each other and that water has a lower boiling point than oil, water is separated by heating and settling; concentrated sulfuric acid is used for its oxidizing property to remove organic matter; activated clay is used to adsorb pigments, and mechanical impurities are then removed by filtration. The specific operation process is as follows. Water Removal: Collect waste oil into an oil collection tank, remove water, then place it in an oil refining kettle. Heat to 70°C–80°C and stop heating, let it settle for 24 hours, and drain off the free water completely; then slowly heat to 120°C to evaporate the moisture. After about two hours, when the oil stops churning, the process is complete. Acid Washing: After the oil cools to room temperature, slowly add sulfuric acid while stirring; after all the acid is added, continue stirring for half an hour, then let it settle for 12 hours and drain off the acid sludge completely. Alkali Washing: Heat the acid-washed oil to 80°C, add soda ash while stirring, mix thoroughly, and let it settle for 1 hour; when test paper shows the oil is neutral, let it settle for more than 4 hours and drain off the alkali sludge completely. Activated Clay Adsorption: Heat the oil to 120°C–140°C, stir at a constant temperature, add activated clay, continue stirring for half an hour, then let it settle at a constant temperature of 110°C–120°C overnight, and filter while hot the next day. Filtration: Use an oil filter machine for filtration to obtain regenerated oil; if no oil filter machine is available, the cloth bag hanging filtration method can also be used. During the operation, the process should be flexibly applied according to actual conditions: if the impurities and moisture content are very low, the first step (water removal) can be omitted; if the oil color is already normal after acid and alkali treatment, there is no need to use activated clay for decolorization and adsorption.