Partition coefficient of Ra in gypsum

Radium removal in a large scale evaporitic system

“…Partition coefficients for Ra in gypsum, which were evaluated in laboratory experiments, span the range of 0.01-0.36 (Gnanapragasam and Lewis, 1995;Yoshida et al, 2009). Gnanapragasam and Lewis (1995) suggested that the partition coefficient increases as the molar ratio of [Ra]/[Ca] in the solution decreases.…”

“…The similar ionic radii of Ra 2+ and Ba 2+ , electronegativities, electronic configuration and the identical crystallographic structure of pure RaSO 4 and barite (Curti, 1999;Zhu, 2004) make barite an almost ideal host mineral for Ra. However, the precipitation of Ra with other minerals such as gypsum (CaSO 4 Á2H 2 O), anhydrite (CaSO 4 ), calcite (CaCO 3 ) and aragonite (CaCO 3 ) was also studied (Langmuir and Riese, 1985;Chan and Chung, 1987;Gnanapragasam and Lewis, 1995;Yoshida et al, 2009). Field observations indicate that Ra partitioning occurs preferentially with barite (e.g., Paytan et al, 1996;van Beek et al, 2004;Ř anda et al, 2010) but also with other minerals such as Mn and Fe hydrous oxides (Kronfeld et al, 1991), alunite (KAl 3 (SO 4 ) 2 (OH) 6 ) and jarosite (KFe(III) 3 (OH) 6 (SO 4 ) 2 ) (Dickson and Herczeg, 1992).…”

Co-precipitation of radium in high ionic strength systems: 2. Kinetic and ionic strength effects

“…Instead, Ra 2+ co-precipitates with a phase that can reach saturation (henceforth referred to as the host mineral phase). Minerals considered to be appropriate hosts for Ra or that have been found to contain Ra include rock-forming minerals such as gypsum (CaSO 4 Á2H 2 O), anhydrite (CaSO 4 ), calcite (CaCO 3 ) and aragonite (CaCO 3 ) (Langmuir and Riese, 1985;Chan and Chung, 1987;Gnanapragasam and Lewis, 1995;Yoshida et al, 2009) and minor and trace minerals such as barite (BaSO 4 ) (e.g., Doerner and Hoskins, 1925;Gordon, 1955;Gordon and Rowley, 1957), celestine (SrSO 4 ) (Langmuir and Melchior, 1985), Mn and Fe hydrous oxides (Kronfeld et al, 1991), alunite (KAl 3 (SO 4 ) 2 (OH) 6 ) and jarosite (KFe (III) 3 (OH) 6 (SO 4 ) 2 ) (Dickson and Herczeg, 1992a).…”

“…Yoshida et al (2009); (8)Langmuir and Riese (1985); (9) Curti (1999); (10)Curti et al (2010). a Considered by…”

Radioactivity, Geochemistry, and Health

“…With the exception of sparingly soluble RaCO 3 and RaSO 4 (Langmuir and Melchior, 1985), most radium-bearing solids have high solubilities. Typically, groundwater concentrations of radium are too low for precipitation of pure RaSO 4 , but radium can coprecipitate with barium as (Ba,Ra)SO 4 , or with calcium in gypsum in groundwater containing moderate-to-high sulfate concentrations (Beddow et al, 2006;Kaplan et al, 2010;Langmuir and Melchior, 1985;Yoshida et al, 2009). In groundwater with high alkalinity, radium may coprecipitate with calcium during calcite precipitation (Yoshida et al, 2008).…”