TY - JOUR
T1 - A study on the formation of smectite in silica scales precipitated from geothermal water
T2 - The effect of magnesium
AU - Aramaki, Yoshinobu
AU - Yokoyama, Takushi
AU - Okaue, Yoshihiro
AU - Imai, Akira
AU - Watanabe, Koichiro
PY - 2005/1/1
Y1 - 2005/1/1
N2 - 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.
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.
UR - http://www.scopus.com/inward/record.url?scp=27744497858&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=27744497858&partnerID=8YFLogxK
U2 - 10.1111/j.1751-3928.2005.tb00248.x
DO - 10.1111/j.1751-3928.2005.tb00248.x
M3 - Article
AN - SCOPUS:27744497858
VL - 55
SP - 281
EP - 284
JO - Resource Geology
JF - Resource Geology
SN - 1344-1698
IS - 3
ER -