离子型稀土矿渗滤浸出过程模拟与分析

发布时间：2018-05-17 16:18

本文选题：稀土 + 浸出　；参考：《江西理工大学》2015年硕士论文

【摘要】：对于离子型稀土矿渗滤浸出工艺中存在的问题,目前绝大部分研究者都采用实验的方法进行研究。然而,由于受到检测手段或检测仪器的精度限制,通过实验的方法无法对稀土矿填充孔隙内部的反应传递等现象进行准确的描述,也难以得到浸出过程中瞬变的非平衡态数据,这对稀土浸出过程的强化和创新造成了很大的障碍。随着计算机科学的迅速发展,数值模拟方法相比于实验方法的优势逐渐凸显,这就为稀土渗滤浸出过程的数值模拟提供了可能。针对目前实验研究方法存在的不足,本研究在验证了模型和程序有效性的基础上,首先采用格子Boltzmann模型对离子型稀土矿浸出的流体流动过程开展了数值模拟,从而观察到了稀土矿复杂孔隙中流体绕稀土矿颗粒流动的绕流现象和沿着大孔隙集中流动的优势流现象,发现了稳态时平均孔隙流速随着填充稀土矿的轴向孔隙率波动变化而在流速值2.0 mm/s上下波动,说明了填充稀土矿的孔隙结构对流体的孔隙流速有明显的影响作用。在此基础上尝试将耦合传质的格子Boltzmann模型用于稀土浸出溶质传递过程的模拟研究,得到了稀土浸出溶质传递过程中伴随流体流动的溶质浓度分布;并探讨了不同浸出流速和温度条件对溶质传递过程的影响,发现浸出流速的增大将引起平均孔隙流速增大以及平均浸出液浓度减小,然而升高温度虽然可以使平均浸出液浓度增大但也存在一定的限制,从而确定了在浸出流速为0.25~0.35 mm/s、浸出温度为25℃的条件下溶质传递效率最高;此外还验证了模拟所得舍伍德数Sh随雷诺数Re的变化关系与多孔介质传质的经验关系式吻合,说明了耦合传质的模型可以比较准确地预测稀土浸出过程的溶质传递规律。接着实现了耦合反应的格子Boltzmann模型并对离子交换化学反应过程进行模拟,在观察到浸出剂溶液于浸出柱内自上而下呈现浓度分带现象的同时得到了流出曲线;然后以稀土单颗粒浸出反应为例,对未反应收缩核模型描述的固相更新过程实现了模拟,由此发现了未反应固体核的界面因受到流体流动的影响而在各方向上产生不均等缩进的现象,并验证了模拟所得舍伍德数Sh随雷诺数Re的变化关系与单颗粒传质的经验关系式吻合;最后,通过模拟还可以得到浸出剂在扩散层的扩散系数sk、扩散层的有效厚度?,浸出剂的扩散速率J、反应速率常数rk以及离子交换反应速率rV等实验方法难以获得的反应动力学参数,这就为确定稀土浸出过程的速率控制步骤提供了有效判据。
[Abstract]:For the existing problems in the leaching and leaching process of ionic rare earth ore, most researchers have used the experimental method to study it. However, due to the precision limitation of detection means or detection instruments, the experimental method can not accurately describe the reaction transfer in the pores filled in the rare earth ore. The non equilibrium data of the transient in the leaching process has caused great obstacles to the strengthening and innovation of the rare earth leaching process. With the rapid development of computer science, the advantages of the numerical simulation method are gradually prominent compared with the experimental method. This provides the possibility for the numerical simulation of the rare earth leaching leaching process. On the basis of validating the validity of the model and program, this study first uses the lattice Boltzmann model to simulate the fluid flow process of the leaching of the ionic rare earth ore, thus the flow around the particles of the rare earth ore in the complex pore of the rare earth ore is observed and the concentration of the fluid along the large pore is concentrated. The flow dominant flow phenomenon shows that the average pore flow velocity fluctuates at the velocity value of 2 mm/s with the variation of the axial porosity in the filled rare earth ore, which indicates that the pore structure of the filled rare earth ore has an obvious influence on the pore flow velocity of the fluid. On this basis, we try to use the lattice Boltzmann model of the coupled mass transfer. The distribution of solute concentration in the solute transfer process of rare earth leaching is obtained by the simulation of the transfer process of rare earth leaching solute. The influence of different leaching velocity and temperature on the solute transfer process is discussed. It is found that the increase of the leaching velocity will cause the increase of the average pore flow velocity and the decrease of the average leaching solution concentration. However, although the increase of temperature can increase the concentration of the average leaching solution, but there is a certain limit, it is determined that the solute transfer efficiency is the highest under the condition of the leaching velocity of 0.25~0.35 mm/s and the leaching temperature of 25 C. Furthermore, the relationship between the Sherwood number Sh with the Reyno number Re and the mass transfer of the porous medium is also verified. The model of the coupled mass transfer can accurately predict the solute transfer of the rare earth leaching process. Then the lattice Boltzmann model of the coupling reaction is realized and the ion exchange chemical reaction process is simulated. The concentration zoning phenomenon is observed from the top down of the leaching agent in the leaching column. At the same time, the outflow curve was obtained. Then the solid phase renewal process described by the unreacted shrinkage nucleus model was simulated with the rare earth single particle leaching reaction, and the unequal shrinkage of the interface of the unreacted solid core was found in all directions due to the influence of fluid flow, and the Sherwood number S was verified. The relationship of H with Reynolds number Re is consistent with the empirical formula of the mass transfer of single particles. Finally, the diffusion coefficient sk of the diffusion layer, the effective thickness of the diffusion layer, the diffusion rate of the leaching agent, the rate constant of the leaching agent, the reaction rate constant rk and the rate rV of the ion exchange reaction can not be obtained by simulation. This provides an effective criterion for determining the rate control steps of rare earth leaching process.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD955

【参考文献】