Pilot evaluation of an aqueous/nonaqueous hybrid bitumen extraction process for mineable oil sands

Abstract

An aqueous/nonaqueous hybrid bitumen extraction (HBE) process for mined oil sand has the potential to reduce thermal energy demand and greenhouse gas emissions while integrating the productivity and robustness of the current commercial process. The process involves the application of a small amount of solvent to pre-soak the mined ore prior to slurry conditioning, followed by the currently used water-based process, albeit at a lower temperature (e.g. 20 °C) and with no need for caustic addition. In this work, the HBE technology is advanced to the testing of a pilot continuous flow system of 100 kg per hour. This communication describes the extraction outcomes of a series of pilot HBE flotation tests conducted at various extraction conditions, and determination of the respective residual solvent contents in the extraction tailings. Results showed that bitumen recoveries and froth qualities from the pilot HBE process depended on the type and dosage of solvent used to soak the ore prior to slurry conditioning, as well as on the slurry conditioning and residence time. Importantly, lower-temperature HBE could produce comparable or higher bitumen recoveries than those achieved using standard Clark hot water extraction; bitumen froth generated from ambient HBE contained lower fines or water contents. The amount of residual solvent in the tailings produced from the pilot hybrid extractions largely correlated to the unrecovered bitumen percentage. For good-processing ores, for which over 90% bitumen recoveries were achieved, the amount of solvent lost to the tailings was below the regulatory limit even without the use of a tailings solvent recovery unit.