Investigation of Cs, Sr, U(VI) sorption on analcime and mica-layer phases at elevated T and P
Book
·
OSTI ID:100786
- Russian Academy of Science, Moscow (Russian Federation). Inst. of the Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry
Experimental studies on ion exchange of Na and K for Cs, Sr and U(VI) in illite-smectite (Ill-Sm) and that of Na for Cs and Sr in analcime-bearing buffered assemblages were carried out at 250 and 300 C and 1,000 bars in 1 m Cl{sup {minus}} solution for the first phase and at 250 C and P{sub sat} and 0.1 m total Cl{sup {minus}} for the second phase. The formation of illite-smectite from Na-montmorillonite was established, the former having a high Cs content of about 7--10%, a moderate Sr content (1--1.5%) and low U(VI) content of (<1%). Ion exchange of Na for Cs and Sr in analcime changes the Si/Al ratio. The compositions of end members for these series might be Cs{sub 0.95}Al{sub 0.79}Si{sub 2.17}O{sub 6}*H{sub 2}O and Sr{sub 0.645}Al{sub 1.41}Si{sub 1.62}O{sub 6}**H{sub 2}O. The Cs ion diffuses 15--20 microns into the crystal Na-analcime after 30 days. Based on the composition of the aqueous chloride solutions, the thermodynamic properties of illite-smectite minerals and Cs, Sr, and Na analcimes were determined. By using these thermodynamic data the equilibria with water of Cs- and Sr-bearing illite-smectite contained in the alkali silicate-bearing and albite- (Cs, Sr, Na) analcime assemblages, were calculated at 250 C. In line with the above, the minimum solubility of Cs and Sr Ill-Sm situated at the Qtz-Ab-Ms-Ill-Sm assemblage. The analcime-albite assemblage can act as a complete sorption barrier to the path-way of Cs and Sr migration from HLW owing to the insolubility of Cs and Sr bearing analcimes and may be used for previous fixation in the latter as in a matrix.
- OSTI ID:
- 100786
- Report Number(s):
- CONF-930906--; ISBN 0-7918-0691-X
- Country of Publication:
- United States
- Language:
- English
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