Improving current efficiency in low-temperature aluminum electrolysis with vertical inert electrodes
Notice bibliographique
Résumé
Primary aluminum production is an energy intensive process with an average electric power consumption between 13 – 14 MWh per tonne of aluminum from the electrolysis process alone. Additional energy consumed in the aluminum plant is derived from the carbon anodes used in the process, equating to 3.8 MWh/t Al and contributing to 1.5 tonnes of carbon dioxide emissions for every tonne of aluminum produced. Most aluminum produced today is derived from non-renewable resources, with the aluminum industry emitting approximately 500 million tonnes of carbon dioxide equivalent annually; this constitutes about 1 % of the world’s total CO2 emissions. Countries like Iceland, Norway and Canada use hydroelectric and geothermal power for aluminum production so the only way to achieve substantial reduction in carbon dioxide emissions are to change the anode material. By replacing the carbon-based material with an inert material, oxygen, rather than carbon dioxide, is evolved as the main by-product. Potential materials for inert electrodes have a limited lifetime in the corrosive cryolite electrolyte at 960 °C. This drawback has led to significant research in altering electrolyte composition and lowering bath/electrolyte temperature to improve inert anode stability. The objective of this thesis was to investigate the influence that different operating parameters have on current efficiency in low temperature electrolysis with vertical inert electrodes. \n \nPrimary aluminum production is an energy intensive process with an average electric power consumption between 13 – 14 MWh per tonne of aluminum from the electrolysis process alone. Additional energy consumed in the aluminum plant is derived from the carbon anodes used in the process, equating to 3.8 MWh/t Al and contributing to 1.5 tonnes of carbon dioxide emissions for every tonne of aluminum produced. Most aluminum produced today is derived from non-renewable resources, with the aluminum industry emitting approximately 500 million tonnes of carbon dioxide equivalent annually; this constitutes about 1 % of the world’s total CO2 emissions. Countries like Iceland, Norway and Canada use hydroelectric and geothermal power for aluminum production so the only way to achieve substantial reduction in carbon dioxide emissions are to change the anode material. By replacing the carbon-based material with an inert material, oxygen, rather than carbon dioxide, is evolved as the main by-product. Potential materials for inert electrodes have a limited lifetime in the corrosive cryolite electrolyte at 960 °C. This drawback has led to significant research in altering electrolyte composition and lowering bath/electrolyte temperature to improve inert anode stability. The objective of this thesis was to investigate the influence that different operating parameters have on current efficiency in low temperature electrolysis with vertical inert electrodes. \n \nFurther research is needed before implementing inert anode technology on an industrial level, therefore parameter optimization should continue to be the focus during experimentation for improving current efficiency. Future electrolysis experiments at Innovation Center Iceland should consider using the following parameters: \n \n• An extended cathode with an alumina sleeve to limit aluminum reoxidation \n• A reasonable superheat value \n• A sodium-rich electrolyte with potassium additives \n• Low copper content anodes of homogeneous microstructure which are pre-oxidized prior to experimentation \n \nKeywords: aluminum electrolysis, current efficiency, vertical inert electrodes, low-temperature electrolyte, operating parameters \n \n \nThis thesis has restricted access and will remain closed to the public until June 2022.
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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 | 0,001 |
| 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 ».