本文關(guān)鍵詞： 濕法磷酸 熔融結(jié)晶 洗滌塔 Aspen Material Studio　出處：《華東理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：濕法磷酸是重要工業(yè)原料,但雜質(zhì)含量高,必須凈化后才能應用于下游行業(yè)。工業(yè)上大規(guī)模采用萃取法凈化磷酸,存在溶劑難以去除的問題。與萃取法相比,結(jié)晶法不使用溶劑,可簡化工藝流程、降低能耗、而且環(huán)境友好,符合工業(yè)發(fā)展趨勢,是一種極具潛力的方法。但結(jié)晶法多為間歇操作,凈化效率和產(chǎn)能有限,難以滿足工業(yè)化需要。因此,開發(fā)連續(xù)化結(jié)晶技術(shù)是結(jié)晶法凈化濕法磷酸技術(shù)工業(yè)化的關(guān)鍵。為此,本研究采用連續(xù)化懸浮熔融結(jié)晶逆流洗滌工藝凈化濕法磷酸。采用虹吸技術(shù)實現(xiàn)了晶漿的穩(wěn)定輸送,固液預分離環(huán)節(jié)強化了逆流洗滌過程,成功解決了連續(xù)化熔融結(jié)晶逆流洗滌操作過程的關(guān)鍵問題。并研究了洗滌塔的晶體沉降速度、融化速率等性能,為該技術(shù)的工業(yè)化實踐奠定了基礎(chǔ)。本文首先用Aspen plus模擬了磷酸體系的密度和黏度,驗證了Aspen plus模擬獲取磷酸的物性參數(shù)及相圖的可行性。用Material Studio模擬軟件的morphology模塊預測H3PO4·0.5H2O晶體的理論形貌,AE模型所得與實際形貌最接近。通過分子動力學計算磷酸體系中典型雜質(zhì)擴散系數(shù),得出Cl-的擴散系數(shù)最大。用離子間的徑向分布函數(shù)(RDF)解釋了體系中離子與水分子的微觀作用。用discover模塊計算雜質(zhì)對H3PO4·0.5H2O晶體各晶面的影響,結(jié)果表明陽離子中Fe2+,陰離子中S042-對各晶面生長速率的影響較大。其次,本文通過對比靜態(tài)與懸浮熔融結(jié)晶過程得出懸浮熔融結(jié)晶所得晶體顆粒小,分布均勻,便于輸送,適宜于連續(xù)化操作。兩種操作方式雜質(zhì)去除率都隨結(jié)晶時間增長而增大。懸浮熔融結(jié)晶對于Fe3+和F-的去除率高于靜態(tài)熔融結(jié)晶,同時多級重結(jié)晶能更有效提純晶體。最后,在本研究所設計的結(jié)晶設備中,洗滌塔的沉降段實現(xiàn)晶體的逆流洗滌過程,通過實驗得到晶體沉降速率在6.61mm/s,與在T=293.2K,dp=3mm條件下理論計算得到的沉降速率6.88mm/s相近。通過洗滌塔的洗滌,晶體除雜率為50%左右,且回流比越大,提純效果越好,在回流比R=6時,除雜率能達到60%。
[Abstract]:Wet process phosphoric acid is an important industrial raw material, but its impurity content is high, it must be purified before it can be used in downstream industry. The crystallization process without solvent can simplify the process process, reduce energy consumption, and is environmentally friendly and in line with the trend of industrial development. It is a promising method. However, the crystallization process is mostly batch operation, and the purification efficiency and capacity are limited. It is difficult to meet the needs of industrialization. Therefore, the development of continuous crystallization technology is the key to industrialization of purification of wet phosphoric acid by crystallization. In this study, the continuous suspension melt crystallization countercurrent washing process was used to purify the wet phosphoric acid. The siphon technology was used to realize the stable transportation of the crystal slurry, and the solid-liquid pre-separation process strengthened the countercurrent washing process. The key problem of continuous melt crystallization countercurrent washing operation has been solved successfully, and the properties of the crystal sedimentation rate and melting rate of the scrubber have been studied. In this paper, the density and viscosity of phosphoric acid system were simulated by Aspen plus. The feasibility of obtaining physical parameters and phase diagrams of phosphoric acid by Aspen plus simulation was verified. The theoretical morphology model of H3PO4 路0.5H2O crystal was predicted by morphology module of Material Studio simulation software. The diffusion coefficient of typical impurity in the system, It is concluded that the diffusion coefficient of Cl- is the largest. The microcosmic interaction between ions and water molecules in the system is explained by the radial distribution function between ions. The influence of impurity on the crystal faces of H _ 3PO _ 4 路0.5H _ 2O crystal is calculated by discover module. The effect of S042- in anion on the growth rate of each crystal plane is great. Secondly, by comparing the static and suspended melting crystallization processes, it is found that the crystal particles obtained by suspension melt crystallization are small, uniform distribution and easy to transport. The removal rate of impurities increases with the increase of crystallization time. The removal rate of Fe3 and F- in suspension melt crystallization is higher than that in static melt crystallization, and multi-stage recrystallization can purify the crystal more effectively. In the crystal equipment designed in this paper, the sedimentation section of the washing tower realizes the process of crystal countercurrent washing. The crystal sedimentation rate is 6.61 mm / s through experiment, which is close to that calculated theoretically under the condition of 3mm T _ (293.2KN) dpg ~ (3 mm), and the washing through the washing tower, The impurity removal rate of the crystal is about 50%, and the higher the reflux ratio is, the better the purification effect is. When the reflux ratio is 6:00, the impurity removal rate can reach 60%.
【學位授予單位】：華東理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ126.35

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