Role of Fine Solids in Solvent Recovery from Reconstituted Alberta Oil Sands Gangue
Notice bibliographique
Résumé
Non-aqueous solvent extraction of bitumen from oil sands has the potential to replace the existing hot-water extraction process. The benefit of non-aqueous extraction process includes high bitumen recovery, reduction of fresh water demand for extraction and the elimination of resulting tailing ponds associated with the use of water. Other advantages include a significant reduction in energy consumption as well as greenhouse gas emission that are associated with ozone depletion and global warming. In the non-aqueous extraction process, bitumen is recovered from the ore using an organic solvent, leaving behind a gangue (solid waste) that contains residual bitumen, solvent, and water initially present in the ore. Despite its numerous advantages, a major limitation to NAE process is in minimizing the loss of solvent to the gangue. Recovery of solvent from the gangue is important to the economics of the non-aqueous extraction process and for environmental impact. Solvent recovery from the gangue involves a drying process in which the volatile solvent is evaporated from the porous gangue matrix in the presence of the water. Fine solids in oil sands are known to have a detrimental effect on water-based extraction. Their role in non-aqueous extraction process has not been fully investigated. In this study, we examine the effect of fine solids content on the recovery of solvent from the gangue. Results from the compositional analysis of extracted gangue revealed that the composition of the gangue varies with each extraction. This presented a challenge to studying the interaction of solvent with other gangue components. A proper analysis of the effect of gangue components on solvent recovery from the gangue required well-defined parameters and a systematic control of the gangue composition. As such, a protocol was developed to make synthetic sample (reconstituted gangue) whose drying behaviour (fluid transport mechanism) simulated that of the extracted gangue. The reconstituted gangue was important as samples whose composition could be controlled to enable analysis and a definitive assessment of the effect of the components on solvent recovery from the gangue. Thus, the reconstituted gangues served as perfect substitutes for the extracted gangue. Rich-grade solids (10% fines) and Low-grade solids (~20% fines) were used to prepare reconstituted gangue containing (i) 12% cyclohexane and (ii) 12% cyclohexane and 3.7 %* water (solvent free basis). Drying experiments were conducted on the samples in a fume hood at ambient temperature and pressure. All the drying experiments for samples containing only cyclohexane displayed a two stage drying process, with a fast initial rate drying stage and second slower drying stage. The first stage corresponded to the stage 1 evaporation of the solvent, in which liquid films maintain capillary connectivity to the external surface. In the slower second stage, liquid films had receded below the surface, and mass transfer occurred by diffusion within the porous media. For samples containing water, a third stage dominated by water diffusion followed the solvent-dominated drying stage. A comparison of drying curves for samples with similar liquid composition revealed that solvent removal was slower in low-grade samples compared to rich-grade samples. The particle size distribution and wettability of gangue solids were analyzed, and it was found that fine solids are more hydrophilic than coarse solids for each gangue. The effect of particle size distribution and wettability of solids of solids on the drying of porous media was investigated. Further experiments were performed for reconstituted gangue containing (i) 12% cyclohexane and (ii) 12% cyclohexane and 3.7% water (solvent free basis) for 0%, 10%, and 20% fines solids in each gangue grade. Results indicated that wettability of the fine solids had a dominant role on the drying of the gangue. An increase in fine solids content corresponded to a reduction in the solvent recovery and thus, an increase in solvent retention.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».