Oil sludges are multicomponent physicochemical systems consisting mainly of hydrocarbons, water, and solids such as sand, clay, and metals which are produced during the production, transport and processing of oil. In recent years, there has been a tightening of legislation governing the disposal of oil sludges, due to environmental concerns. In response, the petroleum industry has implemented various technological solutions aimed at the treatment of oil sludges.


In some unique cases, such as the tar sands industry, specialized techniques have been developed to separate the hydrocarbons from solid-hydrocarbon-water mixtures and to produce a hydrocarbon rich stream that can be further processed. However, most of these processes are not sufficiently efficient and effective for recycling of oil sludges. Many of these tar sand extraction processes either have a high cost to the environment, due to the volumes of waste that are produced, or else have poor economic feasibility, due to the high operating costs.


Chemical engineering researchers from the School of Engineering at the University of KwaZulu-Natal (UKZN) have developed the SuperFextTM supercritical fluid extraction process for the extraction and recycling of hydrocarbons from oil sludges. The SuperFextTM process consists of a supercritical extraction vessel that operates at high pressures, a stripping column, from which the extracted oil is recovered, and the solvent is recycled, and a product polishing vessel.  The process uses fluorocarbon gases as solvents, as opposed to the more commonly employed carbon dioxide.


The advantages of the SuperFextTM process include:

  • Oil-dry solids that are completely free of hydrocarbons
  • Simple solvent recovery and recycle
  • Reduced energy costs as the process operates at near ambient temperatures
  • Ease of cleaning
  • Simplified process equipment

Principle Investigator: Dr Mark Williams-Wynn