Mobility of cobalt in mine waste: Evidence from a historic silver mining district in Canada
Notice bibliographique
Résumé
Historical mine tailings in the Cobalt Mining Camp in northern Ontario are both a source of environmental contamination and a potential resource of critical metals. Widespread mining in the Cobalt area during the 20th century resulted in dozens of unremediated mine sites and at least 18 unconfined tailings deposits, which contain potentially hazardous metals and metalloids, including arsenic (As). Economic metals, including cobalt (Co), also occur in the waste and could be recovered. Geochemical and mineralogical analyses of tailings and pond sediments were performed to assess the mobility of Co and other metal(loid)s in different depositional environments and implications for reprocessing of the mine wastes. Tailings from four sites and benthic sediments from a pond impacted by tailings were characterized using ICP-ES/MS, various mineralogical techniques, and shake flask experiments. Cobalt concentrations in the tailings and sediments (96.8–8900 mg kg −1 Co; median = 470 mg kg −1 ) exceed Canadian environmental quality guidelines for residential soils (50 mg kg −1 Co) at all sample sites. Mineralogical investigations reveal that Co is hosted in oxidized alteration phases in near-surface tailings along with primary sulfide and arsenide minerals, which persist in this environment. In submerged tailings, Co is contained mainly within primary sulfide and arsenide minerals and reduced secondary phases. Cobalt-bearing chlorite is a major host of Co in half of the tailings samples, containing up to 50 wt% of the total Co content; the presence of Co-bearing chlorite may impact potential recovery of Co from the tailings in the future. The mineralogy of the benthic pond sediments is heterogeneous; however, Co is sequestered in both primary sulfide and arsenide minerals and authigenic reduced phases such as Co-bearing sulfide. The results of shake flask experiments reveal that Co in the tailings and sediments dissolves in deionized water under oxidizing conditions. The concentration of Co in the leachate (30–126,000 μg L −1 Co) consistently exceeds Canadian water quality guidelines for Co (1 μg L −1 ). The results of this study provide new insight about the controls on metal(loid) mobility, including the processes which impact metal(loid) cycling in reduced pond sediments and the occurrence of Co-bearing chlorite in the tailings. In addition to characterizing the risks associated with mine waste contamination and informing long-term waste management decisions, the results of this study may be applied to understand the potential for future Co recovery from mine waste and sediments in the Cobalt area. • Cobalt mobility is controlled by mineralogy and local biogeochemical conditions. • Chlorite is a major host of cobalt in tailings from the Cobalt Mining Camp. • Interaction with oxygenated water may release cobalt from tailings and sediments. • Mineralogy may impact remediation or reprocessing of cobalt-bearing mine waste.
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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 | 0,000 |
| 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 ».