Abstract: A method for dedusting synthetic oil is disclosed. A feed of dust-laden synthetic oil is dissolved in a non-polar solvent of at least one alkane containing from 4 to 7 carbon atoms and aggregates of dust material are formed. The dissolved dust-laden synthetic oil is then gravitationally separated into a substantially dedusted stream in a dust-enriched stream including aggregates formed in the dissolution step. The dissolution and gravitational separation steps are conducted at a temperature and pressure greater than about 150.degree. F. and about ambient pressure and less than about the critical point temperature and pressure of the solvent and the aggregates provide acceptable settling and sludge compression rates. Methods for producing and dedusting oil from synthetic fuel stock are also disclosed.

Abstract: A process is provided to dedust oil derived from solid hydrocarbon-containing material, such as oil shale, coal or tar sand in multi-stage desalters. In the process, water is dispersed into the oil before entering each desalter to form an emulsion. The desalter separates the emulsion into a stream of oil having a substantially lower concentration of dust and a dusty stream of water containing most of the dust. In one embodiment, the sludge-like dusty stream from the first desalter is combusted in a lift pipe and used as heat carrier material in the retort. In other embodiments, the dusty stream from the first desalter is centrifuged or filtered and thereafter heated in a dryer to remove residual oil and water from the stream before the stream is combusted in the lift pipe and used as heat carrier material in the retort and dryer. Effluent water from the second and third desalters as well as from the centrifuge or filter are recycled upstream and dispersed in the oil.