The Potential For Carbon Dioxide Sequestration in Oil Sands Processing Streams
Notice bibliographique
Résumé
Abstract The CT or consolidated tailings 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 proven to be useful in controlling the fluid tailings properties so that they may support a sand loading and remain nonsegregating. 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. Introduction Creation of a suitable CT mixture involves creation of a nonsegregating mixture of sand, clay, and water; rapid initial settling (water release) of the mixture; and ultimate consolidation of the mixture. Extensive studies by Scott et al.1 have demonstrated that there is a wide range of sand-to-fines ratios, solids contents, and gypsum addition levels where these criteria are met. Poor control of calcium levels in the release water and the scaling problems associated with high calcium and bicarbonate concentrations have been major problems associated with gypsum CT. To circumvent these problems, polymeric flocculants and aluminum salts (alum) have been investigated at Syncrude Research2 and CANMET3 as substitutes for gypsum, with alum showing some promise. In these studies, the dewatering rate and segregation index of alum CT were shown to be similar to those for gypsum CT. Calcium ion concentrations in the release water of alum CT are significantly lower than in the release water of gypsum CT. However, there is a decrease in the release water alkalinity (bicarbonate) with alum - CT, which can potentially increase the caustic demand in extraction where bicarbonate alkalinity has been shown to improve the conditioning and flotation process. The bicarbonate ion disperses the clays, improving oil sand conditioning and flotation. The potential for using CO2 as a substitute for gypsum was evident from high viscosities observed in CO2- saturated MFT4. Under normal circumstances, high MFT viscosity is essential for good CT production. In fact, one would need about 3000 ppm of gypsum in the MFT to match the viscosity produced by CO2-saturated MFT. In the highly buffered CT mixture, pH reduction associated with CO2 addition quickly reverts to the initial pH of the MFT. At low clay-to-water ratios, (C:W), the nonsegregating property of a CT mixture is controlled by the extent to which clay flocs can support sand grains. Divalent cations achieve this strength through double-layer compression, which promotes coagulation of the clays3.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».