本文選題：鋁酸鹽結構熒光粉 + 堿熔　； 參考：《北京科技大學》2017年博士論文

【摘要】：從廢舊稀土熒光粉中回收稀土元素,可以有效解決我們所面臨的稀土資源問題。鋁酸鹽結構的稀土熒光粉具有很好的發(fā)光效率和實用價值,是被廣泛應用的熒光粉。鋁酸鹽結構的稀土藍粉和綠粉結構穩(wěn)定,難以回收其中的稀土元素,導致稀土回收率低。堿熔是一種有效處理鋁酸鹽結構熒光粉的工藝手段,兩步酸解法工藝主要采用堿熔方法處理難溶廢舊熒光粉,有效提高了稀土浸出率。但是現(xiàn)階段堿熔機理并不完善,堿熔工藝流程還可以進一步改進。本文通過對藍粉和綠粉堿熔過程的物相分析,計算堿熔反應的活化能,對整個堿熔過程進行熱力學分析。通過藍粉、綠粉分別和不同堿熔劑(KOH,NaOH,Ca(OH)2,NaCl,Na2CO3和Na2O2)的對比反應,從離子作用的角度解釋反應過程。本文認為破壞鋁酸鹽熒光粉的官能團是含氧陰離子(OH-,CO32-,O22-),稀土離子與游離的含氧陰離子結合以逃離結構,導致熒光粉結構被破壞。這一觀點可用來解釋藍粉和綠粉中稀土元素的回收原理及移動軌跡。本文在實驗分析的基礎上,提出陰-陽離子協(xié)同作用理論,更加全面的說明鋁酸鹽熒光粉的堿熔理論。在鋁酸鹽稀土熒光粉堿熔時,陽離子會取代鏡面層的稀土離子,而陰離子的存在會保證取代能夠發(fā)生,由于電價不匹配,晶體結構發(fā)生畸變,結構崩塌。這一理論說明了鋁酸鹽結構熒光粉結構變化的過程,補充了堿熔的基礎理論。通過中試實驗和模擬實驗的結果,本文評價了兩步酸解法工藝的可行性�；谔幚�1t廢舊熒光粉的中試實驗結果,經(jīng)濟分析表明產(chǎn)品價值約為直接輸入消耗的4倍,說明工藝本身是富有價值的;環(huán)境評價指出,工藝對環(huán)境最大的影響來自水資源的消耗以及能源消耗產(chǎn)生的溫室氣體。根據(jù)工藝的評價分析,提出了熒光粉除硅預處理,來改進兩步酸解法工藝。對廢舊熒光粉進行300目物理篩分,可除去56%的二氧化硅,可節(jié)省0.215 t的片堿,0.538 t鹽酸和0.8 m3的水。廢水和廢渣的產(chǎn)生量也會相應地減少,由硅酸膠體吸附導致的稀土元素損失也會降低。稀土資源短缺是世界面臨的共同問題,從替代、法規(guī)、減量和循環(huán)等方面對稀土資源管理進行合理安排,加強對基礎理論和回收工藝的研究,對我們應對類似的資源短缺問題有重要意義。
[Abstract]:The recovery of rare earth elements from waste rare earth phosphors can effectively solve the problem of rare earth resources. The rare earth phosphors with aluminate structure have good luminescence efficiency and practical value and are widely used as phosphors. The structure of rare earth blue powder and green powder with aluminate structure is stable, so it is difficult to recover rare earth elements, resulting in low recovery of rare earth elements. Alkali melting is an effective process for the treatment of aluminate structure phosphors. The two-step acid hydrolysis process is mainly used to treat refractory waste phosphors, which effectively improves the leaching rate of rare earths. However, the mechanism of alkali melting is not perfect at present, and the technological process of alkali melting can be further improved. In this paper, the activation energy of alkali melting reaction is calculated by analyzing the phase of alkali melting process of blue powder and green powder, and the thermodynamic analysis of the whole alkali melting process is carried out. The reaction process was explained from the point of view of ion action by comparing the blue powder and green powder with different alkali fluxes (Koh) and NaCl-Na _ 2CO _ 3 and Na _ 2O _ 2 respectively. It is considered that the functional group that destroys the aluminate phosphors is the oxygen anion (OH-OH-CO32-O22-N). The rare earth ions combine with the free oxygen-containing anions to escape from the structure, resulting in the destruction of the phosphor structure. This view can be used to explain the recovery principle and moving track of rare earth elements in blue and green powder. On the basis of experimental analysis, this paper puts forward the theory of anion-cation synergistic action, and explains the alkali melting theory of aluminate phosphors more comprehensively. In the alkaline melting of aluminate rare earth phosphors, cations will replace the rare earth ions in the mirror layer, and the existence of anions can guarantee the substitution. Because of the mismatch of electricity price, the crystal structure is distorted and the structure collapses. This theory explains the process of structure change of aluminate phosphors and complements the basic theory of alkali melting. In this paper, the feasibility of two-step acid hydrolysis process is evaluated by the results of pilot and simulation experiments. Based on the pilot experiment results of treating 1 t waste phosphor powder, the economic analysis shows that the product value is about 4 times of the direct input consumption, which shows that the process itself is of great value, and the environmental evaluation indicates that, The greatest impact of technology on the environment comes from the consumption of water and the greenhouse gases generated by energy consumption. According to the evaluation and analysis of the process, the pretreatment of removing silicon from phosphor powder was put forward to improve the two-step acid hydrolysis process. By physical screening of waste phosphors for 300 mesh, 56% of silica can be removed, and 0.215 tons of tablet alkaloid 0.538 t of hydrochloric acid and 0.8 m3 of water can be saved. The amount of waste water and waste residue will be reduced correspondingly, and the loss of rare earth elements caused by silica colloid adsorption will also be reduced. The shortage of rare earth resources is a common problem facing the world. The management of rare earth resources should be rationally arranged from the aspects of substitution, regulation, reduction and circulation, and the research on basic theory and recycling technology should be strengthened. It is important for us to deal with a similar shortage of resources.
【學位授予單位】：北京科技大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TQ422

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