Enhancing bitumen froth quality with sodium citrate: Mechanistic insights from synchrotron-based micro CT imaging

In water-based oil sands extraction, producing cleaner bitumen froth with reduced solids content during primary separation is critical for maintaining high throughput and minimizing downstream solvent loss. This study investigated sodium citrate (Na 3 Cit) as a chemical aid for bitumen froth flotation using synchrotron-based micro-computed tomography (micro-CT) imaging, supported by complementary characterization methods, to elucidate the mechanisms responsible for solids reduction. The addition of Na 3 Cit (150 g/t) reduced the total solids carried to bitumen froth by 18.4 wt% and decreased the solid-to-bitumen (S/B) ratio from 1.15 to 0.97, indicating a significant improvement in froth quality. Micro-CT image segmentation showed that Na 3 Cit selectively influenced sand flotation while leaving the flotation of heavy minerals largely unaffected. In addition, the reduction in solids carryover was primarily associated with decreased water entrainment and reduced true flotation of bitumen-coated sands. The reconstructed X-ray images further suggested enhanced bitumen coalescence accompanied by a notably larger air bubble size and increased total air holdup when Na 3 Cit was used, supporting the hypothesis that Na 3 Cit weakens and softens bitumen-water interfacial film.