本文選題：亞熔鹽 + 高純氧化鋁　； 參考：《中國(guó)科學(xué)院研究生院(過程工程研究所)》2016年博士論文

【摘要】：本論文在亞熔鹽法氧化鋁清潔生產(chǎn)技術(shù)平臺(tái)的基礎(chǔ)上,以工業(yè)冶金級(jí)氫氧化鋁為原料,通過研究硫酸鋁銨的結(jié)晶過程及結(jié)晶中的雜質(zhì)行為,對(duì)結(jié)晶過程進(jìn)行調(diào)控,來制備高純度的硫酸鋁銨,進(jìn)而制得高純度的氧化鋁產(chǎn)品,以實(shí)現(xiàn)工業(yè)粗產(chǎn)品的高值化利用。另一方面,針對(duì)亞熔鹽法處理赤泥工藝過程中硅酸鈉鈣易分解的問題,研究了硅酸鈉鈣NaCaHSiO4在鋁酸鈉溶液中的分解規(guī)律,為亞熔鹽法處理赤泥的實(shí)際工業(yè)生產(chǎn)操作提供理論依據(jù)和現(xiàn)實(shí)指導(dǎo)。論文主要研究?jī)?nèi)容與研究成果如下：測(cè)定了硫酸鋁銨結(jié)晶誘導(dǎo)期與介穩(wěn)區(qū),并分析了硫酸鋁銨結(jié)晶過程的成核與生長(zhǎng)機(jī)理。根據(jù)經(jīng)典成核理論與介穩(wěn)區(qū)理論分析,得出硫酸鋁銨結(jié)晶成核過程屬于連續(xù)成核,且符合三維成核機(jī)理。根據(jù)表面熵因子理論及模型判定方法,判定硫酸鋁銨晶體的生長(zhǎng)過程屬于連續(xù)生長(zhǎng)機(jī)理。此外,還計(jì)算了硫酸鋁銨晶體在過飽和溶液中的界面張力、表面熵因子、臨界晶核半徑與臨界自由能的值,以及與溶質(zhì)在溶液中擴(kuò)散相關(guān)的活化能。以工業(yè)冶金級(jí)氫氧化鋁為原料,通過硫酸鋁銨結(jié)晶及洗滌進(jìn)行兩步除雜,制備出純度在99.99%以上的高純氧化鋁,工藝簡(jiǎn)單,實(shí)現(xiàn)了工業(yè)粗產(chǎn)品的高值化利用。研究表明結(jié)晶工藝參數(shù),包括硫酸鋁溶液的初始濃度、過飽和度、溫度及結(jié)晶方式,對(duì)硫酸鋁銨晶體中雜質(zhì)的含量有著顯著的影響。通過靜置自然冷卻結(jié)晶的方式可以大幅降低硫酸鋁銨晶體中的雜質(zhì)含量。研究了Na+、K+、Mg2+及Fe3+對(duì)硫酸鋁銨結(jié)晶成核動(dòng)力學(xué)的影響。研究表明,溶液中K+及Fe3+的存在縮短結(jié)晶誘導(dǎo)期、減小介穩(wěn)區(qū)寬度,促進(jìn)成核；溶液中Mg2+的存在延長(zhǎng)結(jié)晶誘導(dǎo)期、增大介穩(wěn)區(qū)寬度,抑制成核；溶液中Na+的存在對(duì)硫酸鋁銨結(jié)晶成核無明顯的促進(jìn)或抑制作用。根據(jù)介穩(wěn)區(qū)理論方法計(jì)算了硫酸鋁銨的初級(jí)成核動(dòng)力學(xué)參數(shù)。以高純硫酸鋁銨為原料,通過碳酸鋁銨焙燒熱解制備出純度達(dá)99.9%、顆粒尺寸小于1μm且尺寸分布均勻的超細(xì)高純氧化鋁。主要研究了碳酸鋁銨的制備條件對(duì)產(chǎn)物中K含量的影響,以及碳酸鋁銨的焙燒與氧化鋁的洗滌除雜。研究了NaCaHSiO4在鋁酸鈉溶液中的分解反應(yīng)過程。當(dāng)NaCaHSiO4在鋁酸鈉溶液中發(fā)生分解時(shí),NaCaHSiO4轉(zhuǎn)變?yōu)榉解c石Na8Al6Si6O24(OH)2(H2O)2和加藤石Ca2.93Al1.97(Si0.64O2.56)(OH)9.44,繼而降低亞熔鹽法處理赤泥工藝中提鋁的效率。
[Abstract]:In this paper, on the basis of sub-molten salt process alumina cleaner production technology platform, using industrial metallurgical grade aluminum hydroxide as raw material, the crystallization process and impurity behavior of ammonium aluminum sulfate were studied to regulate the crystallization process. In order to realize the high value utilization of industrial coarse products, the high purity aluminum oxide products were prepared by the preparation of high purity ammonium aluminum sulfate. On the other hand, in view of the problem that sodium and calcium silicate decompose easily in the process of treating red mud by submolten salt process, the decomposition law of sodium silicate calcium NaCaHSiO4 in sodium aluminate solution is studied. It provides theoretical basis and practical guidance for the practical industrial operation of submolten salt treatment of red mud. The main contents and results are as follows: the induction period and metastable region of ammonium aluminum sulfate crystallization were determined, and the nucleation and growth mechanism of ammonium aluminum sulfate crystallization process were analyzed. Based on the analysis of classical nucleation theory and metastable zone theory, it is concluded that the crystallization nucleation process of ammonium aluminum sulfate is continuous nucleation and accords with three-dimensional nucleation mechanism. According to the theory of surface entropy factor and the method of model determination, it is determined that the growth process of ammonium aluminum sulfate crystal belongs to the mechanism of continuous growth. In addition, the interfacial tension, surface entropy factor, critical nucleation radius and critical free energy of ammonium aluminum sulfate crystal in supersaturated solution were calculated, as well as the activation energy related to solute diffusion in the solution. High purity alumina with purity over 99.99% was prepared by crystallization and washing of ammonium aluminum sulfate with industrial metallurgical grade aluminum hydroxide as raw material. The process was simple and the high value utilization of industrial coarse products was realized. The results show that the crystallization process parameters, including initial concentration, supersaturation, temperature and crystallization mode of aluminum sulfate solution, have a significant effect on the content of impurities in ammonium aluminum sulfate crystal. The impurity content in ammonium aluminum sulfate crystal can be greatly reduced by static natural cooling crystallization. The effects of Na ~ (2 +) K _ (2) mg _ (2) and Fe _ (3) on the nucleation kinetics of ammonium aluminum sulfate were studied. The results show that the existence of K and Fe _ 3 in solution shortens the induction period of crystallization, reduces the width of metastable zone and promotes nucleation, while mg _ 2 prolongs the induction period of crystallization, increases the width of metastable zone, and inhibits nucleation. The presence of Na in the solution has no obvious effect on the nucleation of ammonium aluminum sulfate. The kinetic parameters of primary nucleation of ammonium aluminum sulfate were calculated according to the theory of metastable zone. Using high purity ammonium aluminum sulfate as raw material, ultrafine and high purity alumina with purity 99.9, particle size less than 1 渭 m and uniform size distribution was prepared by calcination pyrolysis of ammonium aluminum carbonate. The effects of preparation conditions of ammonium aluminum carbonate on K content in the product, roasting of ammonium aluminum carbonate and washing and impurity removal of aluminum oxide were studied. The decomposition process of NaCaHSiO4 in sodium aluminate solution was studied. When NaCaHSiO4 was decomposed in sodium aluminate solution, NaCaHSiO4 was transformed into sodium aluminite Na8Al6Si6O24 (OH) 2 (H2O) 2 and katenite Ca2.93Al1.97 (Si0.64O2.56) (OH) 9.44.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院(過程工程研究所)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TQ133.1

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