Re-refining of used oil, an important aspect of waste oil recycling, prevents environmental pollution. Re-refining returns used oil to a state nearly equivalent to that of new oil, thus allowing its subsequent use in engines or industrial settings. A general rundown of how re-refining works is given below:
1. Collection of Used Oil
Used oils are sourced from automotive service centers, various industries, and households.
These oils can sometimes be contaminated by dirt, water, fuel, metal, and chemicals.
2. Pre-Treatment (Separate Contaminants)
The first filtration of used oils removes the gross contaminants of dirt and metal particles.
This is followed by some other processes such as coagulation or flocculation for the separation of water and some other chemicals.
This stage may involve centrifugation and vacuum distillation to separate the unwelcome elements present in oil.
3. Vacuum Distillation (Dehydration and Separation)
The medium of oil is heated so that under a vacuum lighter fractions like water and volatile impurities are expelled away from heavier fractions like the base oil.
This would create an oil clean from unwanted hydrocarbons and contaminants.
Light fractions thus collected will be separately, while the heavier oil will go on for further refining.
4. Clay Treatment / Absorption
Afterward, oil is treated with absorbents like activated clay or fuller’s earth to remove its color, odor, and other contaminants.
At this stage, the oil is purified and its appearance and quality improved.
5. Optional Hydrotreating or Hydrogenation
Sometimes after clay treatment, hydrotreating, which is a reaction with hydrogen gas at elevated temperatures and pressures, is employed for this purpose.
It allows doing the cleaning of sulfur, nitrogen, and some aromatic compounds and improving the stability and performance of oil.
6. Final Filtration
After clay treatment and hydrogenation, the oil is passed through a final filter to remove any fine impurities left behind.
7. Blending with Additives
At this stage, where necessary, some additives are blended into the oil, such as detergents, dispersants, antioxidants, and antiwear agents, to restore needed properties for application as lubricants or industrial oils.
8.Finished Product
The re-refined oil is ready for use, having been returned to a high-quality lubricant that is applicable in automotive engines, machinery, and industrial uses in various ways.
Benefits of Re-refining:
Environmental Protection: Less waste and less pollution due to disposing of used oil from landfills and water bodies.
Energy-Efficient: Less energy is consumed during re-refining of used oil as compared to refining of crude oil, which is less environmentally friendly.
Cost-Effective: Re-refined oils are cheaper to produce than crude oil-based oils; thus, re-refined oils provide cost-effective alternatives to virgin oils.
Resource Conservation: This procedure conserves natural resources, such as crude oil, by reusing available resources.
