Study of the chemical durability of a hollandite mineral leached in both static and dynamic conditions

Authors : Fairouz AOUCHİCHE, Nourelhayet KAMEL, Dalila MOUDİR, Yasmina MOUHEB, Soumia KAMARİZ

Pages : 85-92

Doi:10.35208/ert.453417

View : 9 | Download : 8

Publication Date : 2019-06-30

Article Type : Research Paper

Abstract :Hollandite is a ceramic used for the confinement of cesium. In this study, we synthesized a hollandite of chemical formula: K 0.28 Ba 0.76 Ti 7.10 Cu 0.9 O 16 , 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 insert ignore into journalissuearticles values(at 42 nd 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.
Keywords : Hollandite, Cesium, Leaching, MCC1, MCC5