Separation and Recovery of Bitumen from Oil Sand by CO₂ Desorption of Amine Solution

Bitumen extracted from oil sand has garnered increasing attention as an alternative energy source for fossil resources. Since oil sand consist of a mixture of bitumen (10-15 wt. %), water (4 wt. %), and sand (80 wt. %), the separation and recovery of bitumen from oil sand are essential for their utilization. Hot alkaline conditions enhance bitumen separation from sand, but they are unfavorable for the traditional bitumen flotation method using air, as the bitumen surface becomes hydrophilic under alkaline conditions. CO2 has been shown to effectively attach to bitumen droplets under alkaline conditions, but the injection of CO2 decreases solution pH and inhibits bitumen separation. This study applied CO2 desorption of a CO2-loaded amine solution for high-efficiency bitumen recovery. The amine solution remained alkaline even after CO2 loading and maintained a high pH during CO2 desorption, which is beneficial for bitumen separation. Furthermore, the desorbed CO2 bubbles formed evenly in the solution, increasing the opportunity for bubble-bitumen attachment and enhancing bitumen flotation. Pretreatment of oil sand using an amine solution of the same concentration was also conducted for more effective separation of bitumen and sand before flotation. As a result, high purity of 0.92 and a recovery ratio of 0.85 bitumen were achieved using the proposed method on real Canadian oil sand at 95 °C and 1 atm. Additionally, considering the integration of the CO2 desorption stage in the CCS process with the proposed method, a significant amount of energy for heating hot water for bitumen separation could be saved, which could reduce greenhouse gas emissions.