Metal transport by oil: Application to ore genesis
Notice bibliographique
Résumé
This thesis describes the results of an experimental study designed to measure and interpret the solubility of palladium oxide in crude oil, and the modification of a method for analyzing metal concentrations in crude oils. An approach that has been employed previously in the analysis of crude oils is to combust (dry ash) them and then leach the residues with acids to prepare an aqueous solution that can be analysed instrumentally. This method of preparation, however, has been criticized as being inaccurate because it led to underestimates of the metal contents of crude oil standards to which it was applied. In this study, modifications were introduced that now permit its reliable application. The modifications involved the use of PyrexTM tubes instead of platinum crucibles and addition of nitric acid and hydrogen peroxide to ensure that any residues remaining after dry ashing were completely oxidized. This modified method was tested by analyzing the nickel and vanadium concentrations of certified crude oil standards using this dry-wet-ashing preparation, leaching the residues with concentrated HCl, diluting them in Milli-Q™ water and measuring the concentrations of Ni, V in the resulting solutions using ICP-MS. The results show that the concentrations of the standards can be reproduced to ± 5% for concentrations ≥ 100 ppm and ± 10 for concentrations down to 1 ppm Ni or V. These results are similar to or better than those using other more costly or less accessible methods of analysis. This suggests, that at least for Ni and V, and probably for most other metals, concentrations of metals in crude oils can be analyzed reliably using the modified dry ashing – ICP-MS method described in this thesis. The solubility of palladium oxide was measured in three crude oils at temperatures of 150, 200 and 250 °C for a duration of seven days, which was shown by kinetic experiments to be sufficient to ensure equilibrium. The selected crude oils varied appreciably in their asphaltene, nitrogen and sulfur contents. Palladium concentration in the lightest crude oil (lowest asphaltene content) decreased systematically from 141 ± 34 ppb to 77 ± 17 ppb between 150 and 250 °C whereas in the other two crude oils, it reached a maximum at 200 °C. The concentration was highest in the heaviest crude oil, reaching 1183 ppb at 200 °C. This suggests that palladium can be dissolved in appreciable concentrations in liquid hydrocarbons and that its solubility is controlled by the proportion of asphaltene macromolecules. The concentration of palladium also increases with increasing nitrogen content and decreasing acidity, suggesting, as has been demonstrated for Ni and V, that it may be dissolved as porphyrin species, which are known to concentrate in the asphaltene fraction. The results of this study show that liquid hydrocarbons have the potential to transport palladium in amounts sufficient to form ore deposits, and emphasize the need for studies of environments in which palladium and hydrocarbons have been shown to be spatially associated.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,000 |
| 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 | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
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 ».