Used motor oil is cleaned through a re-refining process that removes contaminants and restores the oil's lubricating properties. This process involves several key steps to purify the oil and make it suitable for reuse.
Re-Refining Process
The re-refining process for used motor oil is complex and typically includes the following stages:
Pre-treatment
- Initial removal of water and sediments through gravity separation or heating
- Reduction of lighter contaminants like fuel and antifreeze through various methods.
Main Purification Steps
These steps work to remove a range of impurities and restore the oil's base quality:
| Step | Purpose |
|---|---|
| Propane De-asphalting | Removes heavier, bituminous fractions. |
| Distillation | Physically separates the components of the oil by their boiling points. |
| Solvent Extraction | Uses solvents to dissolve and remove undesirable compounds. |
| Hydrofinishing | Improves the physical properties of the re-refined base oil. |
Detailed Explanation of Each Step:
- Propane De-asphalting: This process uses propane to separate heavy asphalt-like components from the used oil. The propane acts as a solvent, dissolving the oil while leaving the heavier asphaltenes behind.
- Distillation: The oil is then heated in a distillation tower. Different components of the oil vaporize at different temperatures. This process physically separates the oil into fractions based on their boiling range, allowing for the separation of the desired lubricating oil components.
- Solvent Extraction: Following distillation, the oil can be subjected to solvent extraction to remove any remaining unwanted compounds, such as oxidation products and additives, which might have been present after distillation.
- Hydrofinishing: The final stage is hydrofinishing, where the oil is treated with hydrogen under high pressure and temperature. This process removes any remaining impurities and improves the oil’s physical properties like color, stability, and oxidation resistance, resulting in a high-quality base oil.
After Re-Refining
The re-refined base oil can be used in various applications, including:
- Formulating new lubricating oils for vehicles and machinery
- Industrial applications requiring lubrication
- Producing hydraulic fluids
- Fuel oil component
By using these methods, used motor oil is effectively recycled, reducing waste and promoting resource conservation.
