An improved low temperature process for extracting oil from oil-bearing materials by extracting the oil-bearing material in an extraction zone with a normally gaseous solvent selected from propane, butane, and mixtures thereof. As the resulting solvent/oil mixture is passed through the bed of extracted...http://www.google.fr/patents/US5525746?utm_source=gb-gplus-shareBrevet US5525746 - Method for selective extraction of compounds from carbonaceous materials
Method for selective extraction of compounds from carbonaceous materials
