Group I Base Oil Production

New project developers often frame the choice as distillation versus extraction, but that framing misreads the process. In practice these two technologies sit in sequence, not in competition. Group I base oil production from used lubricants needs deep vacuum fractionation to make the heavy cut, then a solvent finishing step to strip the colour and unstable aromatics that a purely physical split cannot reach.

Why Vacuum Does the Cutting

Used oil is a dirty matrix of degraded chains, water, light fuels, oxidation products and spent additives. Boiling the heavy molecules under a few millibars of absolute pressure lets them vaporise far below the temperature that would crack and foul them. The column then separates the vapor into viscosity-targeted cuts while the poly, carbon and encrustation-heavy metals drop out as residue. What distillation cannot do is tell a clean paraffin from an oxidized or sulfur-bearing molecule with the same boiling point, so the raw cut comes off dark and unstable.

Extraction Brings the Purity

That is the job of liquid solvent finishing. Group I base oil is defined by leaving a portion of aromatics behind rather than eliminating them entirely, and polar solvents such as furfural or an NMP-type agent carry away the aromatics, the sulfur and the colour bodies while the clean paraffinic raffinate stays behind. The two phases split in a settler, the solvent is stripped from both and recycled through a closed loop. What remains is a clearer, stable, higher-VI base oil that keeps the additive solvency Group I is valued for. It is a gentler step than full hydrotreating, preserving the solvency Group I depends on.

Sequencing the Steps

The two steps must follow the flash dehydration and fuel stripping so each stage is head-fed a clean stream. Dehydration protects the vacuum pumps, the vacuum column spares the extraction loop from metals and polymer, so no stage poisons the next.

Experience and the Clay Alternative

The older finishing rival is clay polishing, which is cheap to start but generates a spent clay that continues to carry oil in its weight and counts as hazardous waste to track and dispose of. Solvent extraction removes the contaminant chemically instead of storing it in a filter case.

Learn More:

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

Get your distillation and solvent stage in the right order

Group I base oil sells only when the sequence protects the product, not when steps compete.

Klean engineers combined treating flows that turn used oil into grade stock.

Considering a group I base oil production project?

Contact Klean Industries about group I base oil production » GO.