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How well suited are current thermodynamic models to predict or interpret the composition of (Ba,Sr)SO₄ solid-solutions in geothermal scalings?

Heberling, Frank; Schild, Dieter; Degering, Detlev; Schäfer, Thorsten

In this study, we report results of the analysis of a particularly interesting scaling sample
from the geothermal plant in Neustadt-Glewe in northern Germany, which contained
19% Galena (PbS) and 81% of a heterogeneous assemblage of (Ba,Sr)SO₄ crystals with
varying compositions, 0.15 < X$_{Ba}$ < 0.53. A main fraction of the sample (~56%) has a
barite content of X$_{Ba}$ ≈ 0.32. We try to relate the solid composition of the (Ba,Sr)SO₄
solid-solution to the conditions at the geothermal plant concerning temperature,
pressure, and solution composition, and discuss it with respect to the challenges in
modelling the composition of (Ba,Sr)SO₄ solid-solutions on the basis of thermodynamic
mixing models. We note that considerable uncertainties are related to the description
of (Ba,Sr)SO₄ formation by means of thermodynamic models. The scaling composition
observed in this study would be in line with endmember solubilities as predicted by
the PhreeqC-Pitzer database for 70 °C and an interaction parameter, a0 = 1.6. According
to such a model, the scaling heterogeneity would reflect bimodal precipitation
behaviour due to vari ... mehr

Zugehörige Institution(en) am KIT Institut für Nukleare Entsorgung (INE)
Publikationstyp Zeitschriftenaufsatz
Jahr 2017
Sprache Englisch
Identifikator DOI: 10.1186/s40517-017-0068-x
ISSN: 2195-9706
URN: urn:nbn:de:swb:90-712641
KITopen ID: 1000071264
HGF-Programm 35.14.01; LK 01
Erschienen in Geothermal Energy
Band 5
Heft 9
Seiten 16 S.
Lizenz CC BY 4.0: Creative Commons Namensnennung 4.0 International
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