Solvent Extraction for
Upgrading Base Lube Distillates

Adapted from crude oil refining technology for the used oil recovery sector, Hamsa offers Solvent Extraction to upgrade recovered base lube distillates (or VGO) to base lube oils having Group I / Group II properties. Our Solvent Extraction Process effectively improves typical recovered oil by:

  • Increasing the saturates by 3 – 5+%

  • Decreasing Sulfur levels 

  • Dramatically improving oil color from ASTM 4.0 – 7.0 (medium to
    dark amber), down to ASTM less than 1.0 – 1.5 (pale to light gold) 


  • Significantly enhancing base oil stability (no color deterioration or gum formation in storage)

  • Effectively dropping PAH content to BDL (below detectable levels)

  • Markedly reducing odor.

Concept & Process

Many of the color and odor bodies present in typical recovered oil are actually high boiling aromatics. These aromatics have a strong preferential affinity for the solvent used in the solvent extraction process. By contacting the recovered oil with the solvent in the extractor, the vast majority of the color bodies, odor bodies and other aromatics are removed (extracted) from the oil, substantially improving its properties and quality.

The solvent phase and the oil phase separate after contacting in the extractor. There is a small percentage of the solvent (~5%) remaining in the raffinate (the oil product from which the aromatics, color bodies and odor bodies have been removed). 


The raffinate is then processed to remove virtually all of the remaining solvent traces (typically down to 0.05%) and produce the polished base lube product. 

The extract (the solvent containing the removed aromatics, color bodies and odor bodies and some of the other components) is also processed further to separate and recover the solvent from the aromatics, and other contaminants. The recovered solvent is returned for reuse in the extraction stage of the process, the aromatics are collected separately for sale (as TDAE), or for in-plant use (as a fuel), and the wastewater stream (a very small volume) is collected separately for proper disposal.

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Pragmatic Environmental Solutions Inc., Virginia, USA