A study on the formation of smectite in silica scales precipitated from geothermal water: The effect of magnesium

Yoshinobu Aramaki, Takushi Yokoyama, Yoshihiro Okaue, Akira Imai, Koichiro Watanabe

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Silica scales containing large amounts of smectite were recently found in the pipelines for geothermal water at a geothermal power plant. To elucidate the mechanism of smectite formation, seven silica scale samples were characterized by powder X-ray diffraction, chemical analysis and 27Al MAS NMR. Smectite was present in samples with MgO levels above 10 wt% and Al2O3 levels below 10 wt%. In 27Al MAS NMR spectra, peaks assigned to both tetrahedrally and octahedrally coordinated aluminum (Al(4) and Al(6)) were observed for Mg-rich samples, whereas a peak due to Al(4) alone appeared in Mg-poor samples. From these observation and comparison between 27Al MAS NMR spectra for synthesized precipitates of Al2O3-SiO2 containing MgO and not containing MgO, it is concluded that magnesium plays an important role in the stabilization of Al(6), and results in the formation of smectite.

Original languageEnglish
Pages (from-to)281-284
Number of pages4
JournalResource Geology
Volume55
Issue number3
DOIs
Publication statusPublished - Jan 1 2005

Fingerprint

Silicon Dioxide
smectite
Magnesium
MAS
magnesium
silica
nuclear magnetic resonance
Water
Nuclear magnetic resonance
Geothermal power plants
water
geothermal power
Aluminum
X ray powder diffraction
chemical analysis
Precipitates
power plant
stabilization
Stabilization
Pipelines

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

Cite this

A study on the formation of smectite in silica scales precipitated from geothermal water : The effect of magnesium. / Aramaki, Yoshinobu; Yokoyama, Takushi; Okaue, Yoshihiro; Imai, Akira; Watanabe, Koichiro.

In: Resource Geology, Vol. 55, No. 3, 01.01.2005, p. 281-284.

Research output: Contribution to journalArticle

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AB - Silica scales containing large amounts of smectite were recently found in the pipelines for geothermal water at a geothermal power plant. To elucidate the mechanism of smectite formation, seven silica scale samples were characterized by powder X-ray diffraction, chemical analysis and 27Al MAS NMR. Smectite was present in samples with MgO levels above 10 wt% and Al2O3 levels below 10 wt%. In 27Al MAS NMR spectra, peaks assigned to both tetrahedrally and octahedrally coordinated aluminum (Al(4) and Al(6)) were observed for Mg-rich samples, whereas a peak due to Al(4) alone appeared in Mg-poor samples. From these observation and comparison between 27Al MAS NMR spectra for synthesized precipitates of Al2O3-SiO2 containing MgO and not containing MgO, it is concluded that magnesium plays an important role in the stabilization of Al(6), and results in the formation of smectite.

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