Complexation of Cu2+ in oxidized NaCl brines from 25 degrees C to 175 degrees C: results from in situ EXAFS spectroscopy

MD Collings*, DM Sherman, KV Ragnarsdottir

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

Abstract

In order to understand the significance of Cu2+ transport in oxidized brines and in secondary enrichment processes, we studied the speciation of 0.1 M CuCl2 in 0, 2, and 5 M NaCl solutions from 25 degrees C to 175 degrees C using in situ EXAFS spectroscopy. No chloro-copper complexation is observed in solutions containing 0.2 and 2.2 M Cl at temperatures up to 75 degrees C Between 125 degrees C and 175 degrees C, The dominant species are CuCl+ and CuCl20. At very high Cl-concentrations (5 M NaCl), CuCl+ is the dominant species at 25 degrees C and 75 degrees C, becoming CnCl(3)(-) and CuCl42- at 125 degrees C. However, between 125 degrees C and 175 degrees C, there is a transition to only CuCl+ and CuCl20. This may result from the competitive ion-association of Na+ and Cl-. CuCl42- may be an important species in fluids associated with the formation of red-bed copper deposits. (C) 2000 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)65-73
Number of pages9
JournalChemical Geology
Volume167
Issue number1-2
Publication statusPublished - 5 Jun 2000
EventSymposium on Direct Observation and Measurement of Hydrothermal Reactions held at the 8th VM Goldschmidt Conference - TOULOUSE, France
Duration: 30 Aug 19983 Sep 1998

Keywords

  • copper
  • aqueous speciation
  • EXAFS
  • high temperature
  • chloride
  • X-RAY-ABSORPTION
  • COPPER(II) CHLORIDE SOLUTIONS
  • HYDROTHERMAL SOLUTIONS
  • AQUEOUS-SOLUTION
  • THERMODYNAMIC PROPERTIES
  • METAL-COMPLEXES
  • TEMPERATURES
  • 1000-DEGREES-C
  • 350-DEGREES-C
  • DIFFRACTION

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