Notice bibliographique
Résumé
Rare earth elements (REE) comprise the fifteen elements of the lanthanide series as well as yttrium, and may be found in over 250 different minerals. These elements are required for many different applications such as high-strength permanent magnets, catalysts for petroleum refining, metal and glass additives and phosphors used in electronic displays. REE are abundant in the earth's crust, yet deposits with economically extractable concentrations are much less common. This thesis examines the separation techniques that are currently employed for REE bearing mineral (REM) beneficiation, identifies areas in need of further research, employs characterisation techniques to examine fundamental properties of certain REM, and then applies this knowledge to the beneficiation of the Nechalacho REE deposit in the Northwest Territories of Canada.In order to build up the knowledge of the physicochemical properties of important REM, pure samples of minerals such as bastnäsite, allanite, fergusonite and zircon were acquired along with common gangue minerals in the Nechalacho deposit such as magnetite, hematite and quartz. After characterisation experiments were completed for each of these minerals, lab-scale separation experiments were conducted on a bulk sample from the Nechalacho deposit involving a series of gravity and magnetic separations. A pre-concentration flowsheet was then selected with the resultant product being used for downstream flotation experiments. As the feed sample for flotation was concentrated in many REM, it provided an excellent opportunity for assessing flotation kinetics of these minerals in a multi-mineral system as well as investigating different reagent additions which may be applicable to the development of an industrial flotation process.The major findings from characterisation experiments include the verification of the paramagnetism of REM, the identification of hydroxamates as an ideal flotation reagent for the concentration of bastnäsite from silicate gangue as well as the finding that hydroxamates are not suitable for the flotation of allanite, a silicate REM. Additional work was undertaken to develop a means of floating allanite using alternative reagents such as dodecylamine and the addition of metal ion activators. The concentration of REM from the Nechalacho deposit using physical separation was successfully achieved using a Knelson centrifugal gravity separator and a low intensity magnetic drum separator. The resultant product had a grade of 7.50 wt. % rare earth oxide (REO) and a REO recovery of 11.8 %. An additional finding from this work was that the concentration of the most valuable heavy REE is upgraded in the coarse size fractions after grinding to a P80 of 40 µm.Subsequent ore flotation experiments using this material found that the kinetics of REM flotation from this deposit using hydroxamates are strongly dependent on mineral solubility and metal cation content. Additionally, the addition of lead cations to this system improves the recovery of less floatable REMs such as allanite, and the staged addition of hydroxamates results in improved REM grade and recovery.The implications of this research work includes an improved understanding of fundamental REM properties as well as multiple strategies for improving industrial process designs for the Nechalacho deposit. Implementing selective comminution strategies to upgrade the concentration of the most valuable REE could have a profound effect on any future process by providing a simple means of beneficiation as well as minimizing energy losses in overgrinding. Two different flotation reagent strategies have been investigated with different outcomes. The staged addition of hydroxamate targets REM with rapid flotation kinetics whereas the addition of lead ions is able to improve the recovery of REM with slower flotation kinetics. These reagent schemes may have applications in different stages of an industrial flotation process.
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 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 ».