Base Oil Polishing

Vacuum distillation recovers base oil from waste lubricants, but the distillate often still carries colour and odour that limit its market grade. Reaching water-white, oxidation-stable base oil requires a polishing step. Modern base oil polishing has shifted away from acid washing and clay filtration toward solvent extraction, and the reason is economic as much as chemical.

Why Clay Treatment Falls Short

Clay adsorption is cheap to install but costly over time. It traps recoverable oil in the spent filter cake, generates hazardous waste that requires disposal, and does little to remove the sulfur and nitrogen compounds that cause colour to return during storage. Those hidden costs accumulate year after year.

The Solvent Extraction Advantage

Solvent extraction works on solubility rather than adsorption, selectively removing aromatics and polar contaminants while leaving the paraffin matrix intact. Because no solid medium retains the oil, product recovery is high, and the extracted impurities can be recovered as a separate, valuable stream instead of being discarded.

Controlling Quality Parameters

Achieving a consistently low colour number depends on the solvent-to-oil ratio and a closed-loop solvent recovery system that strips and reuses the solvent. Keeping replenishment costs low while holding a tight specification steady is what separates a premium polishing line from an ordinary one.

The Hidden ROI of By-Products

The extract stream removed during polishing is energy-dense and can be blended into fuel oil or used as an asphalt modifier. What was once a disposal burden becomes an additional product line, improving the overall economics of the refinery rather than simply adding cost.

Learn More:

• Feasibility Studies for Waste-to-Value Projects
• Turn-Key EPC Delivery
• Plant Design & Engineering
• Facility Efficiency Upgrades
• Resource Recovery Projects

Polish product, not just colour.

Solvent extraction lifts oxidation stability and viscosity index while recovering by-products that clay simply throws away.

Klean Industries engineers polishing stages that reach premium grades with minimal waste and solvent loss.

Considering a base oil polishing project?

Contact Klean Industries about base oil polishing » GO.