本文選題：稀土 + 浸出��； 參考：《江西理工大學(xué)》2015年碩士論文

【摘要】：對(duì)于離子型稀土礦滲濾浸出工藝中存在的問題,目前絕大部分研究者都采用實(shí)驗(yàn)的方法進(jìn)行研究。然而,由于受到檢測(cè)手段或檢測(cè)儀器的精度限制,通過實(shí)驗(yàn)的方法無法對(duì)稀土礦填充孔隙內(nèi)部的反應(yīng)傳遞等現(xiàn)象進(jìn)行準(zhǔn)確的描述,也難以得到浸出過程中瞬變的非平衡態(tài)數(shù)據(jù),這對(duì)稀土浸出過程的強(qiáng)化和創(chuàng)新造成了很大的障礙。隨著計(jì)算機(jī)科學(xué)的迅速發(fā)展,數(shù)值模擬方法相比于實(shí)驗(yàn)方法的優(yōu)勢(shì)逐漸凸顯,這就為稀土滲濾浸出過程的數(shù)值模擬提供了可能。針對(duì)目前實(shí)驗(yàn)研究方法存在的不足,本研究在驗(yàn)證了模型和程序有效性的基礎(chǔ)上,首先采用格子Boltzmann模型對(duì)離子型稀土礦浸出的流體流動(dòng)過程開展了數(shù)值模擬,從而觀察到了稀土礦復(fù)雜孔隙中流體繞稀土礦顆粒流動(dòng)的繞流現(xiàn)象和沿著大孔隙集中流動(dòng)的優(yōu)勢(shì)流現(xiàn)象,發(fā)現(xiàn)了穩(wěn)態(tài)時(shí)平均孔隙流速隨著填充稀土礦的軸向孔隙率波動(dòng)變化而在流速值2.0 mm/s上下波動(dòng),說明了填充稀土礦的孔隙結(jié)構(gòu)對(duì)流體的孔隙流速有明顯的影響作用。在此基礎(chǔ)上嘗試將耦合傳質(zhì)的格子Boltzmann模型用于稀土浸出溶質(zhì)傳遞過程的模擬研究,得到了稀土浸出溶質(zhì)傳遞過程中伴隨流體流動(dòng)的溶質(zhì)濃度分布;并探討了不同浸出流速和溫度條件對(duì)溶質(zhì)傳遞過程的影響,發(fā)現(xiàn)浸出流速的增大將引起平均孔隙流速增大以及平均浸出液濃度減小,然而升高溫度雖然可以使平均浸出液濃度增大但也存在一定的限制,從而確定了在浸出流速為0.25~0.35 mm/s、浸出溫度為25℃的條件下溶質(zhì)傳遞效率最高;此外還驗(yàn)證了模擬所得舍伍德數(shù)Sh隨雷諾數(shù)Re的變化關(guān)系與多孔介質(zhì)傳質(zhì)的經(jīng)驗(yàn)關(guān)系式吻合,說明了耦合傳質(zhì)的模型可以比較準(zhǔn)確地預(yù)測(cè)稀土浸出過程的溶質(zhì)傳遞規(guī)律。接著實(shí)現(xiàn)了耦合反應(yīng)的格子Boltzmann模型并對(duì)離子交換化學(xué)反應(yīng)過程進(jìn)行模擬,在觀察到浸出劑溶液于浸出柱內(nèi)自上而下呈現(xiàn)濃度分帶現(xiàn)象的同時(shí)得到了流出曲線;然后以稀土單顆粒浸出反應(yīng)為例,對(duì)未反應(yīng)收縮核模型描述的固相更新過程實(shí)現(xiàn)了模擬,由此發(fā)現(xiàn)了未反應(yīng)固體核的界面因受到流體流動(dòng)的影響而在各方向上產(chǎn)生不均等縮進(jìn)的現(xiàn)象,并驗(yàn)證了模擬所得舍伍德數(shù)Sh隨雷諾數(shù)Re的變化關(guān)系與單顆粒傳質(zhì)的經(jīng)驗(yàn)關(guān)系式吻合;最后,通過模擬還可以得到浸出劑在擴(kuò)散層的擴(kuò)散系數(shù)sk、擴(kuò)散層的有效厚度?,浸出劑的擴(kuò)散速率J、反應(yīng)速率常數(shù)rk以及離子交換反應(yīng)速率rV等實(shí)驗(yàn)方法難以獲得的反應(yīng)動(dòng)力學(xué)參數(shù),這就為確定稀土浸出過程的速率控制步驟提供了有效判據(jù)。
[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.
【學(xué)位授予單位】：江西理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TD955

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本文編號(hào)：1902025