本文選題：磷灰石 + 密度泛函理論��； 參考：《貴州大學(xué)》2016年碩士論文

【摘要】：作為一種重要的不可再生資源,磷灰石的綜合回收利用是自然界中磷循環(huán)的重要組成部分。然而天然磷礦石在形成過程中常常和其他脈石礦物共生或伴生,例如,石英、白云石、方解石等。這些礦物與磷灰石的物理、化學(xué)性質(zhì)接近,且在形成過程中嵌布復(fù)雜,難以分離,因此長期以來磷礦的分選一直困擾著人們。目前浮選被認(rèn)為是分離磷礦石中有價磷資源最有效的方法之一,然而浮選工藝常常受制于浮選藥劑,同時常規(guī)浮選藥劑帶來的生態(tài)問題也是磷礦石分選工作不得不面對的問題。因此,探索磷礦石浮選綠色高效的浮選藥劑已迫在眉睫。本論文基于密度泛函理論(DFT)的第一性原理,研究了兩種磷灰石的晶體結(jié)構(gòu)和表面浮選行為機理。考察了氟磷灰石和氯磷灰石體相及(001)面的結(jié)構(gòu)及電子性質(zhì);重點研究了兩種磷灰石浮選過程中水分子和捕收劑的作用機理。主要研究結(jié)果如下:1.氟磷灰石和氯磷灰石的禁帶寬度分別為5.667 eV和5.154 eV,兩種磷灰石的態(tài)密度分布的差異主要顯示在通道原子。相對于F,Cl的能帶整體移向高能級方向,其3s和3p態(tài)均較F 2s和2p能級高,且Cl 3p態(tài)更寬,更接近費米能級,即氯磷灰石穩(wěn)定性不如氟磷灰石。研究表明,F得電荷能力強于Cl,對應(yīng)F 2s和2p態(tài)荷電分別是1.96 e、5.72 e;Cl 3s和3p態(tài)得電荷分別是1.94 e和5.65 e。兩種磷灰石中的O—P長度接近,但是氟磷灰石的F—Ca結(jié)合作用明顯強于氯磷灰石的Cl—Ca作用,同時氯磷灰石中的O—Ca較氟磷灰石的短。進(jìn)一步研究顯示O—P具有較強的化合鍵性質(zhì),對應(yīng)原子間作用也最強;F—Ca、O—Ca和Cl—Ca呈現(xiàn)更多的離子性,且鍵長更長。2.氟磷灰石的Ca終端面和氯磷灰石的Ca-Cl終端面分別為對應(yīng)表面能最小的終端面,其值分別為3.86 eV/cell和3.72 e V/cell。弛豫分析顯示,這幾種終端面中位于獨立層的Ca原子表現(xiàn)出較大的位移,但位移仍不足以引起表面原子的重構(gòu)。進(jìn)一步研究顯示氟磷灰石的Ca終端面和氯磷灰石的Ca-Cl和Ca終端面的性質(zhì)更接近于各自的體相。3.氟磷灰石的F-A構(gòu)型吸附能最大,對應(yīng)值為-69.541 kJ/mol;最小的是F-B構(gòu)型,對應(yīng)值為-123.817 kJ/mol。氯磷灰石的最大值為Cl-A構(gòu)型,其值為-67.033kJ/mol;最小值為Cl-D構(gòu)型的-118.996 kJ/mol。態(tài)密度分析顯示,單個水分子在兩種磷灰石表面的吸附對其表面性質(zhì)產(chǎn)生了一定的影響,這種作用主要表現(xiàn)為物理作用。單層水分子膜吸附研究顯示,水分子在磷灰石表面的作用呈現(xiàn)出一種有規(guī)律的無序排列。4.捕收劑(CH_3(CH)_2COO)分子在磷灰石(001)面的吸附只存在一種構(gòu)型,即在最外層的Ca1位點,對應(yīng)氟磷灰石(001)面和氯磷灰石(001)面的吸附能分別是-137.515 kJ/mol和-134.733 kJ/mol。Mulliken電荷布居顯示,吸附后捕收劑末端O86與Ca6的影響最為明顯。Mulliken鍵布居顯示捕收劑分子在磷灰石表面吸附后,原來圍繞在Ca1位點的O被彈開,Ca—O變長,即藥劑分子在磷灰石表面的作用時一個排開水分子吸附的過程。進(jìn)一步研究顯示,Ca6與O75、O77、O78的作用被削弱;捕收劑末端O86與Ca6在臨近費米能級附近存在較強的成鍵作用。
[Abstract]:As an important non renewable resource, the comprehensive recovery and utilization of apatite is an important part of the phosphorus cycle in nature. However, the natural phosphate rock is often associated with or associated with other gangue minerals, such as quartz, dolomite, calcite, etc., such as quartz, dolomite, calcite, etc.. These minerals are closely related to the physical and chemical properties of apatite and are in shape. It is complicated and difficult to separate in the process of formation, so the separation of phosphate rock has been perplexing people for a long time. Flotation is considered as one of the most effective methods to separate phosphorus resources from phosphate rock. However, flotation process is often controlled by flotation reagents. At the same time, the ecological problem brought by conventional flotation reagents is also not necessary for the separation of phosphate rock. Therefore, it is imminent to explore the flotation reagent of green and efficient flotation of phosphate rock. Based on the first principle of density functional theory (DFT), the crystal structure and surface flotation behavior mechanism of two kinds of apatite are studied. The structure and electronic properties of fluorapatite and chlorapatite body phase and (001) surface are investigated. The mechanism of water molecules and collector in the flotation process of two kinds of apatite is studied. The main results are as follows: the forbidden band width of 1. fluorapatite and chlorapatite is 5.667 eV and 5.154 eV respectively. The difference of the density distribution of the two apapatite is mainly shown in the channel atom. Relative to F, the energy band of the Cl is shifted to the high energy level, and its 3S The 3P state and the 3P state are higher than the F 2S and 2p energy levels, and the Cl 3P state is wider and closer to the Fermi level, that is, the stability of the chlorapatite is not as good as the fluorapatite. The study shows that the charge capacity of F is stronger than that of Cl, and the corresponding F 2S and 2p state charge are 1.96 e, 5.72 respectively. The binding effect of F - Ca of limestone is stronger than the Cl - Ca effect of chlorapatite, while O - Ca in chlorapatite is shorter than that of fluorapatite. Further studies show that O P has strong bonding properties and the interaction between atoms is also the strongest. F Ca, O Ca and mercury are more ionic, and the bond length is longer. The Ca-Cl terminal surface of the surface and chlorapatite is the terminal surface with the smallest corresponding surface energy, respectively, the values of 3.86 eV/cell and 3.72 e V/cell. relaxation analysis show that the Ca atoms in the independent layer show a larger displacement in these terminal surfaces, but the displacement is still not enough to cause the reconstruction of the surface proon. Further research shows the C of the fluorapatite. The properties of Ca-Cl and Ca terminal surfaces of a end faces and chlorapatite are much closer to the F-A configuration of.3. fluorapatite in their respective body phases, the corresponding values are -69.541 kJ/mol, the smallest is F-B configuration, and the maximum value of -123.817 kJ/mol. chlorapatite is Cl-A configuration. J/mol. state density analysis shows that the adsorption of single water molecules on the surface of two apatite has a certain effect on its surface properties. This effect is mainly physical. The study of monolayer water molecular membrane adsorption shows that the action of water molecules on the apatite surface presents a regular disordered arrangement of.4. collector (CH_3 (CH) _2COO). There is only one configuration in the adsorption of apatite (001) surface, that is, at the outermost Ca1 site, the adsorption energy for the fluorapatite (001) surface and the chlorapatite (001) surface is -137.515 kJ/mol and -134.733 kJ/mol.Mulliken, respectively. The influence of O86 and Ca6 at the end of the collector is most obvious after the adsorption of.Mulliken bond. After the adsorbents were adsorbed on the apatite surface, the O was opened around the Ca1 site, and the Ca - O became longer, that is, the adsorption process of the molecules on the apatite surface. Further studies showed that the effects of Ca6 and O75, O77, O78 were weakened, and the terminal O86 and Ca6 were strong near the near Fermi level. Bonding.
【學(xué)位授予單位】：貴州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TD97
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本文編號：2053644