Aqueous speciation of iron and manganese chlorides in supercritical hydrothermal solutions

Etsuo Uchida, Yuichi Goryozono, Masahiro Naito, Masahito Yamagami

研究成果査読

13 被引用数 (Scopus)

抄録

Aqueous speciation of iron and manganese chlorides in supercritical hydrothermal solutions was determined by monitoring the effects of NaCl and KCl on the Ca/(Ca + Fe) and Ca/(Ca + Mn) ratios of aqueous chloride solutions in equilibrium with scheelite and ferberite and with scheelite and huebnerite, respectively. The experiments were carried out under supercritical conditions of 400 and 600°C, and 1 kbar. The ratios decrease significantly with increasing NaCl and KC1 concentrations at both 400°C and 600°C. This is attributable to the formation of higher-order aqueous chloride complexes of Fe and Mn, presumably FeCl3 - aqand MnCl3 - aq. Based on the thermodynamic analysis of the experimental results using published dissociation constants for NaClaq, KClaqand CaCl2aq, logarithms of the formation constants for FeCl3 - aqwere obtained to be 0.2(NaCl) and 1.2(KCl) for 400°C, and 1.9(NaCl) and 1.9(KCl) for 600°C, and those for MnCl3 - aqto be 0.4(NaCI) and 1.1 (KCl) for 400°C and 2.3(NaCl) and 2.3(KCl) for 600°C. This means that the supposition of m(MeCl2aq) = Σmmefor supercritical hydrothermal solutions is invalid.

本文言語English
ページ(範囲)175-188
ページ数14
ジャーナルGEOCHEMICAL JOURNAL
29
3
DOI
出版ステータスPublished - 1995

ASJC Scopus subject areas

  • 地球物理学
  • 地球化学および岩石学

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