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TitreEconomic geology models 2. Tantalum and niobium: Deposits, resources, exploration methods and market Ð A primer for geoscientists
AuteurSimandl, G J; Burt, R O; Trueman, D L; Paradis, S
SourceGeoscience Canada vol. 45, 2, 2018 p. 85-96, (Accès ouvert)
Séries alt.Ressources naturelles Canada, Contribution externe 20182439
ÉditeurAssociation géologique du Canada
Documentpublication en série
Mediapapier; en ligne; numérique
ProgrammeMétaux de base - sources et processus, Initiative géoscientifique ciblée (IGC-5)
Diffusé2018 07 12
Résumé(disponible en anglais seulement)
The worldÕs main tantalum (Ta) resources are in pegmatites (e.g. Wodgina, Australia), rare element-enriched granites (e.g. Abu Dabbab, Egypt), peralkaline complexes (e.g. Nechalacho, Canada), weathered crusts overlying the previously mentioned deposit types, and in placers. Niobium (Nb) resources with the highest economic potential are in weathered crusts that overlie carbonatite complexes (e.g. Catalo I and II, Brazil). Brazil accounts for 90% of the global Nb mine production with another 9% coming from the Niobec Mine, Canada (a hard-rock underground mine). However, at least 17 undeveloped carbonatite complexes outside of Brazil have NI-43-101 compliant Nb resource estimates (e.g. Aley carbonatite, Canada). Concentrates from most carbonatites are used to produce ferroniobium (FeÐNb alloy), and Ta is not recovered. The Ta and Nb contents of some carbonatites (e.g. Upper Fir deposit and Crevier dyke, Canada) are of the same order of magnitude as that of pegmatite ores; however, concentrates from carbonatites have a higher Nb/Ta ratio. Historically, 10Ð12% Ta2O5 in Nb concentrates has not been recovered in ÔwesternÕ smelters because of the hydrofluoric acid cost. Western countries perceive Ta and Nb supplies to be at risk. Tantalum market downturns resulted in several mines in Australia and Canada closing, at least temporarily, and a resultant shortfall has been filled by what is now recognized as Ôconflict-free columbite-tantaliteÕ from Central Africa. The lack of ore will not be a key factor in future Ta and Nb supply disruption. For example, more than 280 Nb-and 160 Ta-bearing occurrences are known in Canada alone, and more resources will likely to be discovered as geophysical and geochemical exploration methods are optimized. © 2018 GAC/AGC¨.