The ion-exchange capacity and Cs, Sr leachability of natural clinoptilolites at 200--300 C and PH{sub 2}O{sub sat}
- Russian Academy of Sciences, Moscow (Russian Federation). Inst. of the Geology of Ore Deposits
- Geological Survey, Reston, VA (United States)
Clinoptilolites of three US clinoptilolite-rich tuff deposits, with different alkali and alkaline earth element mole ratios, were used for experimental investigation. The runs on stability and sorption ability were carried out in water and 0.3 molal chloride solution, using individual minerals and using assemblages containing microcline and analcime at 200 to 300 C and PH{sub 2}O{sub sat} water (duration of one month and two weeks). The clinoptilolites showed different behavior, unrelated to exchange capacity, when run under similar conditions. It was also found that Cs-bearing clinoptilolites contained 12--14 wt.% Cs after runs in 0.1mNaCl+0.1mKCl+ 0.1mCsCl, whereas Sr-bearing clinoptilolite contained about 3--5% Sr in 0.1mNaCl+0.1mKCl+0.05mSrCl{sub 2}. The compositional trend showed some linear variation between Sr and Cs content and Si/Al mole ratio up to Si/Al=5.0. Thermal investigation showed that (Na-K)rich clinoptilolite completely decomposes at 325 C, (Na-Mg) rich at 350 C and (Ca-Mg) rich at 375 C in runs of 2 weeks duration in pure water. Na-analcimes associated with clinoptilolites have low Cs and Sr adsorption capacity relative to the clinoptilolites. Na-Sr -bearing analcimes have an inverse dependence of Sr/(Sr+Na+K) mole ratio with Si/Al in the reaction of heterovalent exchange in analcime, where Na and Si replace Sr and Al. Thermodynamic calculation was done for the solubility of Cs and Sr-bearing clinoptilolites at 300 C, PH{sub 2}O{sub sat}. It was established that under some conditions Sr leachability from Sr-bearing clinoptilolite is insignificant whereas Cs-bearing clinoptilolite leachability is considerably higher.
- OSTI ID:
- 182966
- Report Number(s):
- CONF-950917--; ISBN 0-7918-1219-7
- Country of Publication:
- United States
- Language:
- English
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