Pyrolysis of oil shale from the Whiterocks tar sand deposit in a rotary kiln

The recovery of hydrocarbon values from the oil sands of Utah can be accomplished by any of several mining-surface recovery techniques. These processing strategies include aqueous separation, diluent-assisted aqueous separation and solvent extraction of the bitumen from the sand, and pyrolysis of the oil sand to produce a bitumen-derived hydrocarbon Liquid. The rotary kiln process was evaluated as a possible option for the thermal processing of mined Utah oil sands, and a series of continuous-flow pyrolysis experiments were successfully conducted in a rotary-kiln reactor. The rotary-kiln reactor utilized is a semi-pilot scale, continuous-flow pyrolysis reactor. The process variables investigated included the pyrolysis reactor temperature, the solids retention time in the pyrolysis zone, the sweep gas flow rate, and the bitumen content of the feed sand. The experimental results indicated that the pyrolysis temperature, and the solids retention time in the pyrolysis zone were the two most important variables affecting the hydrocarbon liquid and gas yields in the rotary kiln. The liquid product (C5) yield generally decreased with increasing reactor temperature. Concomitant with this decline in the liquid yield, there was an increase in the light gas (C^-C^) yield. The liquid product yield increased with decreasing the solids retention time while the light gas yield decreased. No significant effect of the sweep gas flow rate on the product distribution and yields was observed. The quality of the bitumen-derived liquids was significantly better than that of the native bitumen. A preliminary process kinetics model which conforms to the observed trends has been developed.