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The solubility and speciation of molybdenum in water vapour at elevated temperatures and pressures : implications for ore genesis

The solubility of molybdenum trioxide in liquid-undersaturated water vapour has been investigated experimentally at 300, 320, and 360°C and 48 to 163 bars. Results of these experiments show that the solubility of MoO3 in the vapour phase is between 1 and 23 ppm, which is 19-20 orders of magnitude higher than that in a water-free system. Molybdenum solubilities increase linearly with fH2O , indicating that the metal forms a gaseous hydrated complex of the type MoO3·nH2O by the reaction: MoO3g+nH 2Og=MoO3· nH2Og A1 The hydration number, n, is interpreted to have a value of 2.6 at 300ºC, 2.5 at 320ºC, and 3.0 at 360ºC. Values of log K for this reaction are 16.9 at 300ºC, 16.5 at 320ºC, and 12.5 at 360ºC. / Calculations based on the extrapolated solubility of MoO 3 in equilibrium with molybdenite at 600ºC and 500 bars, using average H2O and total S fluxes of actively degassing volcanoes, with fO2 and fS2 controlled by the assemblage hematite-magnetite-pyrite, indicate that the vapour phase can transport sufficient Mo in about 900,000 years (within the life of some geothermal systems) to form a deposit of 336 Mt, with an average grade of 0.087% Mo (e.g., the Endako Mo-porphyry deposit, Canada).

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.82411
Date January 2004
CreatorsRempel, Kirsten U.
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Formatapplication/pdf
CoverageMaster of Science (Department of Earth and Planetary Sciences.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 002210686, proquestno: AAIMR12526, Theses scanned by UMI/ProQuest.

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