A novel hydrothermal method to convert incineration ash into pollucite for the immobilization of a simulant radioactive cesium.
A novel hydrothermal method to convert incineration ash into pollucite for the immobilization of a simulant radioactive cesium.
复制标题
DOI：
10.1016/j.jhazmat.2015.12.024
复制
发表时间：
2016-04
影响因子：
13.6
通讯作者：
Z. Jing;Wenbo Hao;Xiaojun He;Jun-jie Fan;Y. Zhang;J. Miao;Fangming Jin
中科院分区：
文献类型：
--
作者：
Z. Jing;Wenbo Hao;Xiaojun He;Jun-jie Fan;Y. Zhang;J. Miao;Fangming Jin
2011年3月11日发生的日本福岛核事故产生了大量铯污染的焚烧灰，常规的固化方法似乎不适合处理大量铯污染的焚烧灰。采用水热法将铯污染的焚烧灰（稻壳灰）直接转化为铯榴石，并原位转化为铯榴石晶体结构。结果表明，在较宽的Cs添加量范围内（Cs/Si = 0.2-0.6），铯榴石的合成较为容易;当Cs/Si ≥ 0.5时，铯的添加量越大，生成的铯铝硅酸盐（CsAlSiO 4）越少，其对Cs的固载性能越差。即使在短固化时间（1小时）或低固化温度（150 °C）下也可以形成铯榴石。然而，较高的固化温度或较长的固化时间有利于纯铯榴石的形成。添加氢氧化钙后，可获得抗折强度约为22 MPa的坚韧试样，表明该技术可直接应用于铯污染焚烧灰的固化。水榴石和雪硅钙石的形成提高了固化体的强度，同时形成的铯榴石稳定地存在于基质中。淋溶实验表明，合成样品中Cs的淋溶量很低（0.49 × 10−5 ~ 2.31 × 10−5），甚至低于参比的富奥朗德合成岩石（2.0 × 10−2），但合成铯榴石样品中Cs的含量（6.0-31.7%）高于参比样品（3.7%）。因此，铯污染的焚烧灰水热转化为铯榴石可以直接应用于铯。
The Fukushima nuclear accident in Japan on March 11, 2011 produced huge amounts of Cs-polluted incineration ashes; conventional solidification methods seem unsuitable for the treatment of large amounts of Cs-polluted ashes. A novel hydrothermal method was developed to directly convert Cs-polluted incineration ash (rice husk ash) into pollucite to immobilize Cs in its crystal structure in situ. Results revealed that pollucite could be synthesized readily over a wide range of added Cs (Cs/Si = 0.2–0.6); the addition of more Cs (Cs/Si ≥ 0.5) caused the formation of a small amount of cesium aluminosilicate (CsAlSiO4), which exhibits poor immobilization behavior for Cs. Pollucite could be formed even for a short curing time (1 h) or at a low curing temperature (150 °C). However, a high curing temperature or a long curing time favored the formation of a pure pollucite. With the added calcium hydroxide, a tough specimen with a flexural strength of approximately 22 MPa could be obtained, which suggested that this technology may be applied directly to the solidification of Cs-polluted incineration ashes. Hydrogarnet and tobermorite formations enhanced the strength of the solidified specimens, and meanwhile the formed pollucite was present in a matrix steadily. Leaching test demonstrated that the amount of Cs that leached from the synthesized specimens was very low (0.49 × 10−5–2.31 × 10−5) and even lower than that from the reference hollandite-rich synroc (2.0 × 10−2), although a higher content of Cs was found in the synthesized pollucite specimens (6.0–31.7%) than in the reference (3.7%). Therefore, the hydrothermal conversion of Cs-polluted incineration ash into pollucite can be applied to immobilize Cs directly.