Waste Oil Recycling and Reuse

Waste oil can be fully utilized through regeneration, which both saves energy and protects the environment. The regeneration principle leverages the facts that oil and water are immiscible and that water has a lower boiling point than engine oil, using heating and settling to separate water; utilizing the oxidizing property of concentrated sulfuric acid to remove organic matter; and employing activated clay to adsorb pigments, followed by filtration to remove mechanical impurities. The operation process is as follows: Water Removal: Collect waste oil into an oil collection tank, remove water, then place it in a refining kettle. Heat to 70°C–80°C and stop heating, let it settle for 24 hours, drain off free water completely, then slowly heat to 120°C to evaporate the moisture. After about two hours, when the oil stops churning, it is done. Acid Washing: After the oil cools to room temperature, slowly add sulfuric acid while stirring. Once the acid addition is complete, 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 indicates the oil is neutral, let it settle for more than 4 hours, then 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. Filter while hot the next day. Filtration: Use an oil filter machine to filter, obtaining regenerated engine oil. If no oil filter machine is available, a cloth bag hanging filtration method can also be used. During the operation process, it should be applied flexibly based on actual conditions. If 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, activated clay decolorization and adsorption are unnecessary.