In the process of leaching of ionic rare earth ore, the leaching agent ammonium ions exchange the rare earth ions adsorbed on the clay mineral surface by the adsorption of ammonium ions. The adsorption mechanism of ammonium ion on the alumina surface and silica surface of kaolinite with and without water was studied using quantum chemistry calculation method based on density functional theory. The results showed that ammonium ions are most likely to adsorb around the lying hydroxyl groups on the alumina surface and the centre of the six-membered ring on the silica surface. Ammonium ions were mainly adsorbed onto the kaolinite surface by electrostatic interaction and hydrogen bonding. The presence of water molecules can make the adsorption energy of ammonium ions on the alumina surface decrease greatly, but little change on the silica surface. Ammonium ions were more easily adsorbed on the silica surface. The adsorption energy of ammonium ions on the kaolinite in the presence of water was less than that of rare earth lanthanum ions.%在离子型稀土矿浸取过程中,浸取剂铵离子通过在黏土矿物表面的吸附作用交换出被吸附的稀土离子.采用基于密度泛函理论的量子化学计算方法,研究铵离子在无水和有水高岭石的铝氧面和硅氧面上的吸附机理.结果表明:铵离子主要通过静电作用和氢键作用吸附到高岭石表面上.在高岭石铝氧面上,铵离子最容易吸附在平躺的羟基组分周围,而在硅氧面上铵离子更容易吸附在表面六元环中心处.水分子的存在会使铵离子在铝氧面上吸附能显著降低,在硅氧面上变化不大,铵离子更易吸附在硅氧面上.在有水的高岭石铝氧面和硅氧面上,铵离子的吸附能均小于稀土镧离子的吸附能.
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