Simulation-Based Integration of Thermal Drying of Fluid Fine Tailings for Tailings Management and Freshwater Conservation in Oil Sands Mining

Abstract

This study developed a two-stage direct thermal contact (2sDTC) process to dewater fluid fine tailings (FFT) from oil sands tailings ponds integrated into ore processing/bitumen extraction plants. The integration aims to recover heat and water from FFT thermal dewatering, thereby reducing FFT storage and freshwater usage while maintaining plant energy efficiency. Employing air-fired natural gas combustion, the process initially involves direct contact between the combustion gas and sprayed FFT, yielding dried solids and steam-rich hot gas. This gas was then mixed with recycled pond effluent water, producing hot water by capturing heat and moisture from FFT dewatering. Case studies using HYSYS simulation assessed the integration feasibility for an extraction plant producing 200,000 barrels daily. Benefits include dewatering 3.36–3.94 million tonnes of FFT annually, conserving a freshwater equivalent to 0.2 barrels per barrel of oil produced. Importantly, these benefits incur no additional energy cost, as the integration eliminates the energy penalty and CO₂ emissions associated with FFT dewatering. Further enhancement using centrifuge-concentrated FFT with approximately 50 wt % solids, which remains pumpable as revealed by this study, increases annual dewatering capacity to 8.05–9.53 million tonnes of FFT, conserving 0.58 barrels per barrel of oil produced, with energy consumption limited to powering the centrifuge machinery.

The two-stage direct thermal contact (2sDTC) process and its integration reduces oil sands tailings stored in ponds, conserving freshwater and energy, crucial for sustainable resource extraction and environmental preservation.