The Potential for Carbon Dioxide Sequestration in Oil Sands Processing Streams

The consolidated tailings (CT) process involves chemical amendments to combine the clays and fines in oil sands mature fine tailings or thickened tailings with the coarser sand components to create a nonsegregating tailings (NST) mixture that will rapidly consolidate. Over the years, several amendment chemicals have proved useful in controlling the fluid tailings properties so that they may support sand loading and remain non-segregating. Suncor has several years of commercial-scale operating experience with gypsum as the CT process aid and in the years leading up to the commercialization of the CT process at Suncor, carbon dioxide was also investigated as a CT process aid. With the concerns over carbon dioxide related to the Kyoto Protocol, the extent to which carbon dioxide is trapped and chemically sequestered in the CT process has been investigated. The mechanism by which carbon dioxide addition affects the strength of the mature fine tailings or fluid tailings component has been investigated, and the potential for carbon dioxide sequestration has been quantified. Depending upon the availability of gypsum as a CT or NST additive, carbon dioxide could be a useful alternative.