The air-assisted solvent extraction (AASX) concept uses a solvent-coated bubble to contact the organic and aqueous phases. Compared to conventional solvent extraction, a high contact area can be created using less solvent and the natural buoyancy provided by the air core promotes phase separation. A method of producing coated bubbles exploiting foaming properties of kerosene-based solvent is introduced. Coating thickness is estimated at approximate to3 mum on a 0.44 cm diameter bubble giving a solvent specific surface area of approximate to3000 cm(2)/cm(3), equivalent to a solvent droplet of approximate to20 mum. Such a droplet would have very poor phase separation properties. In extraction tests (500 mg/l Cu solution), high aqueous/organic ratios could be used (e.g., 75:1) while phase separation remained excellent. This shows the potential for AASX to treat large volume, low concentration streams such as acid mine drainage. (C) 2004 Elsevier Ltd. All rights reserved.