Hollandite is a ceramic
used for the confinement of cesium. In this study, we synthesized a hollandite
of chemical formula: K0.28Ba0.76Ti7.10Cu0.9O16,
where K simulates cesium. This new formulation of a copper-containing hollandite
was synthesized by a double calcination; the first one at 950°C during 18 h,
and the second one at 1000°C during 6 h. The mineral was identified by X-ray
diffraction. Various leaching tests are employed in order to assess the
chemical durability of this mineral. The static test MCC1 gave elemental leaching
rates of: 7.097 10-5 g cm-2 d-1 for Cu, 5.592
10-7 g cm-2 d-1 for Ti and 4.630 10-6
g cm-2 d-1 for Ba, after 42 days. This corresponds to
dissolved elements percentages of: 5.7% Cu, 0.0007% Ti and 0.2% Ba. The
equivalent amount of dissolved K is 0.0029%. A static test in the presence of a
clay barrier, gave the best leaching rates (at 42nd day, NR<3.704
10-7 g cm-2 d-1 of Cu, and <1.11 10-9
g cm-2 d-1 of Ti and <3.67 10-9 g cm-2
d-1 of Ba). This corresponds to 0.030% of Cu, 10-6 % of
Ti and 0.002 % of Ba, and about 0.002% of K. In MCC5 dynamic test, the leaching
rates of Cu, Ti and Ba reached 2 10-6, 1,468 10-7, and
1.084 10-5 g cm-2 d-1, respectively,
corresponding to 0.028% Cu, 0.0003% Ti, and 0.082% Ba, after seven days. The
estimated K leaching rate is 3.613 10-6 g cm-2 d-1,
ie 0.082% K dissolved in the leachate. There is no passivation layer formation.
The MCC5 test is considered as a dissolution test.
Primary Language | English |
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Subjects | Environmental Engineering |
Journal Section | Research Articles |
Authors | |
Publication Date | June 30, 2019 |
Submission Date | August 14, 2018 |
Acceptance Date | March 13, 2019 |
Published in Issue | Year 2019 |