稀土浸出过程溶质传递的格子Boltzmann模拟

Numerical Study on Solute Transport in Leaching Process of Rare Earth by Lattice Boltzmann Method

采用耦合传质的格子Boltzmann方法模拟风化壳淋积型稀土矿中稀土浸出的溶质传递过程,在验证模型有效性的前提下,获得了稀土矿填充孔隙中流体流动的速度分布和伴随流动过程的溶质浓度分布.通过考察浸取流速对溶质传递过程的影响,得到最佳浸取流速,约为0.25～0.35 mm/s,使溶质传递效率最高.浸取流速小于0.2 mm/s导致浸取周期过长、浸取剂消耗量大;浸取流速大于0.4 mm/s引起沟流,导致稀土不能有效地浸出.此外,模拟所得传质舍伍德数Sh随雷诺数Re的变化关系与经验关系式吻合,表明提出的模型可用于预测稀土浸出过程的溶质传递规律.

The solute transport in the leaching process of rare earth from weathered crest elution-deposited rare earth ore is investigated by a lattice Boltzmann method coupling with mass transfer. Both distributions of flow velocity and solute concentration at pore scale are obtained after the validation of the proposed model. Meanwhile, the effect of leaching velocity on the solute transport process is studied. The result shows that there exists an optimal leaching flow rate at 0.25~0.35 mm/s for achieving the best efficiency of solute transport. The long leaching time and large dosage of leaching agent are required when the leaching flow rate is less than 0.2 mm/s, while the leaching efficiency is reduced with the emergence of channeling phenomenon in the packed column when the leaching flow rate is greater than 0.4 mm/s. Moreover, the simulated result of Sherwood number as a function of Reynolds number fits well with the previous empirical correlation, which indicates that the proposed model can be used to predict the solute transport mechanism in the leaching process of rare earth ore.