Mineral weathering and water chemistry of pyrrhotite- and serpentine-bearing mine wastes under freeze-thaw cycles
Notice bibliographique
Résumé
The mineralogical composition of mine wastes is generally considered to be the most important determinant of mine water geochemistry. However, environmental factors can significantly modify the weathering behavior of these materials, and the failure to consider these factors in experimental work may yield biased results. This is a particularly important consideration for mines in arctic and sub-arctic regions, where environmental conditions are far from those of a typical laboratory. The present study focuses on evaluating the influence of ambient thermal conditions on the weathering of pyrrhotite- and serpentine-rich tailings. To this end, laboratory-scale leached columns were used to simulate weathering of tailings over 544 days either at room-temperature or under freeze-thaw cycles (−20 °C/+20.5 °C). Microbiological analyses performed as part of the initial material characterization were unable to detect microbial communities. Although this result was unexpected and unusual, we found that elemental sulfur, which is stable in the absence of sulfur-oxidizing bacteria, had accumulated in the weathered tailings, representing up to 89–92 % sulfur products from pyrrhotite oxidation. Thiosulfate and sulfate were important oxidation products in leachates under both thermal conditions; however, freeze-thaw cycling appeared to enhance the stability of thiosulfate. The dominance of elemental sulfur and thiosulfate, which are produced via non-acid-generating reactions, suggests that the hydrolysis of Fe 3+ and Al 3+ may have been comparatively important sources of acid generation. Serpentine dissolution was more extensive at room-temperature but likely provided little to no alkalinity under freeze-thaw conditions due to slower dissolution kinetics. Calcite and dolomite were the principal buffering phases despite their low abundance. The mobility of Zn seemed to not be limited in either test, whereas Fe and Ni were effectively sequestered via adsorption and/or coprecipitation with ferrihydrite and gibbsite. Under room-temperature conditions, depletion or passivation of the carbonate minerals gave rise to a new buffering regime controlled by gibbsite. Although this maintained the pH around 5.1, aqueous Fe and Ni concentrations spiked (max = 7.6 and 1.5 mM, respectively) as they were released or desorbed from the gibbsite. Leachate pH values remained slightly elevated in the freeze-thaw tests and had not yet stabilized by the end of the experiment; the sequestration of Fe and Ni was not disrupted.
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 ».