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Solvent extraction and deasphalting processes—or solvent deasphalting (SDA) as it is commonly known—use hydrocarbons such as propane, butanes, pentanes, or a mixture of these to extract light, paraffinic components from heavy residue streams. Regardless of the level of impurities in the feedstock, these processes effectively produce deasphalted (DAO) or demetallized oil (terms that are used interchangeably). DAO product quality and yield are dependent upon the solvent that is selected for the process; i.e., the quality (metals, sulfur, nitrogen and Conradson carbon levels) of the products—which can be used as lubricating oil base stock or cracker feedstock—decreases with increasing yield and with the use of heavier solvents. The heavy, highly-aromatic asphalt raffinate (pitch) can be used in a number of ways (e.g., coker feed, gasification feed, road bitumen, etc. Log-in for complete content
