本文選題：Fe(OH)3膠體　切入點(diǎn)：水合氧化鐵　出處：《南華大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：溶浸采鈾工藝目前通常采用過(guò)氧化氫、氧氣等做氧化劑,氧化劑首先將溶液中的Fe2+氧化為Fe3+,再由Fe3+氧化U4+為UO22+。由此可見(jiàn),鐵的行為在溶浸采鈾中起著重要作用。鐵在溶浸采鈾中充當(dāng)氧化劑的同時(shí),還會(huì)與溶浸劑(無(wú)論是酸性、堿性、中性)發(fā)生化學(xué)反應(yīng),并在一定的溫度與壓力作用下,生成含鐵元素的化合物,經(jīng)過(guò)分析,主要為Fe(OH)3膠體和水合氧化鐵。含鐵化合物可能對(duì)鈾礦物產(chǎn)生包裹,影響溶浸液與礦物界面的接觸和反應(yīng),影響鈾的浸出速度和浸出率。同時(shí),可能附著在礦石表面,影響鈾的浸出和礦層滲透性。本文在實(shí)驗(yàn)室條件下模擬制備了Fe(OH)3膠體和水合氧化鐵,研究其對(duì)鈾的吸附機(jī)理,主要研究?jī)?nèi)容和成果如下:(1)在混合溶劑中模擬制備得到氫氧化鐵膠體,進(jìn)行鈾酰離子吸附實(shí)驗(yàn),研究了p H值、初始鈾濃度及吸附時(shí)間等對(duì)Fe(OH)3膠體吸附鈾的影響。采用準(zhǔn)一級(jí)、復(fù)合二級(jí)與Elovich動(dòng)力學(xué)模型對(duì)數(shù)據(jù)進(jìn)行了動(dòng)力學(xué)計(jì)算與分析,結(jié)果表明Elovich動(dòng)力學(xué)方程更適合描述Fe(OH)3膠體對(duì)鈾的吸附行為;采用Freundlich與Langmuir等溫吸附方程對(duì)實(shí)驗(yàn)數(shù)據(jù)進(jìn)行了熱力學(xué)分析和擬合,結(jié)果表明Freundlich模型更適合描述Fe(OH)3膠體對(duì)鈾的吸附行為。綜合兩種模型的結(jié)論推測(cè),推測(cè)Fe(OH)3膠體對(duì)鈾的吸附屬于不均勻表面的單層物理吸附。根據(jù)激光粒度分析與SEM圖分析結(jié)果,推測(cè)Fe(OH)3膠體對(duì)鈾具有較強(qiáng)的吸附性能,吸附主要是表面吸附。(2)以Fe SO4·7H2O為主要原料模擬制備水合氧化鐵,進(jìn)行了鈾酰離子吸附實(shí)驗(yàn),得出在p H=5時(shí),水合氧化鐵的吸附作用發(fā)揮到最大。在吸附一小時(shí)內(nèi),水合氧化鐵對(duì)鈾具有很高的吸附速率,并在5小時(shí)后達(dá)到吸附平衡。對(duì)吸附行為進(jìn)行動(dòng)力學(xué)擬合,發(fā)現(xiàn)準(zhǔn)二級(jí)動(dòng)力學(xué)方程最適合用來(lái)描述鈾在水合氧化鐵上的吸附行為,擬合相關(guān)系數(shù)R2為0.994,推算平衡吸附量為55.40 mg·g-1與實(shí)驗(yàn)數(shù)據(jù)52.78 mg·g-1相吻合。(3)探究了Fe(OH)3膠體與水合氧化鐵協(xié)同吸附鈾的效果,結(jié)果表明:氫氧化鐵膠體與水合氧化鐵單獨(dú)作為吸附劑時(shí),吸附效果良好;但隨著復(fù)合比的增加,兩者之間的相互干擾作用就越明顯,吸附量會(huì)隨著復(fù)合比的增加而減少。
[Abstract]:At present, hydrogen peroxide and oxygen are usually used as oxidants to oxidize Fe2 in solution to Fe3 and then U4 to UO22 by Fe3. The behavior of iron plays an important role in the leaching of uranium. When iron acts as an oxidant in leaching uranium, it also reacts with the leaching agent (acid, alkaline, neutral) and acts at a certain temperature and pressure. The formation of iron-containing compounds is mainly composed of Fe(OH)3 colloid and hydrated ferric oxide. The iron-containing compounds may encapsulate uranium minerals and affect the contact and reaction between leaching solution and mineral interface. The leaching rate and leaching rate of uranium are affected. At the same time, it may be attached to the surface of ore, which may affect the leaching of uranium and the permeability of ore bed. In this paper, Fe(OH)3 colloid and ferric oxide hydrate were prepared under laboratory conditions, and the adsorption mechanism of uranium was studied. The main contents and results are as follows: (1) Ferric hydroxide colloid was prepared in mixed solvent. The adsorption experiments of uranyl ions were carried out. The effects of pH value, initial uranium concentration and adsorption time on the adsorption of uranium by Fe(OH)3 colloid were studied. The complex second-order and Elovich kinetic models were used to calculate and analyze the data. The results show that the Elovich kinetic equation is more suitable to describe the adsorption behavior of uranium by Fe(OH)3 colloid. The thermodynamic analysis and fitting of the experimental data with Freundlich and Langmuir isotherm adsorption equations are carried out. The results show that the Freundlich model is more suitable for describing the adsorption behavior of uranium by Fe(OH)3 colloids. It is inferred that the adsorption of uranium by Fe(OH)3 colloid is a single layer physical adsorption on heterogeneous surface. According to the results of laser particle size analysis and SEM diagram analysis, it is inferred that Fe(OH)3 colloid has strong adsorption property for uranium. Fe SO4 路7H 2O was used as the main raw material to simulate the preparation of hydrous iron oxide. The uranium ion adsorption experiments were carried out. The results showed that the adsorption of hydrated iron oxide reached its maximum at 5:00, and within one hour of adsorption, The adsorption rate of uranium is very high and the adsorption equilibrium is reached after 5 hours. The kinetic fitting of the adsorption behavior shows that the quasi-second-order kinetic equation is the most suitable for describing the adsorption behavior of uranium on the hydrated iron oxide. The correlation coefficient R2 was 0.994, and the calculated equilibrium adsorption capacity of 55.40 mg 路g -1 coincided with the experimental data of 52.78 mg 路g -1. The effect of Fe(OH)3 colloid on synergistic adsorption of uranium with hydrated ferric oxide was investigated. The results showed that when the colloid of ferric hydroxide and ferric hydroxide were used as adsorbents alone, The adsorption effect is good, but with the increase of the composite ratio, the interaction between the two is more obvious, and the adsorption amount will decrease with the increase of the composite ratio.
【學(xué)位授予單位】：南華大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TD868

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