Extraction of bitumen from oil sands with hot water and pressure cycles

Abstract

Hot water extraction of bitumen from oil sands has been commercially applied for decades. Required caustics and other reagents adversely impact handling and disposal of byproducts of the process. We have developed a new extraction process that accelerates the recovery of bitumen, requiring no intense agitation, caustics, or other chemical additives that aggravate subsequent treatment and disposal issues. The technique involves compression and decompression cycles, which during decompression create expanding microbubbles to dislodge bitumen from the sands. Process parameters including pressure, number of cycles, temperature, water-to-solid volume ratio, gas type, and oil sands type were investigated. Recovery >92% was achieved within 5min for a solid slurry of 1:1 (water/solid) volume ratio by 4 pressure cycles of air at 6.9atm (100psi) and 105°C. The use of CO2 in lieu of air makes recovery at lower temperature or pressure possible, albeit with increased number of cycles at milder conditions (e.g., >90% recovery with 20 cycles at 55°C and 6.9atm, or at 85°C and 3.4atm). The new process requires less water and heating and results in high yields and no problematic end products. It shows promise as a new extraction technique.