黃銅礦表面性質(zhì)及CN~-在其表面吸附的密度泛函理論研究
發(fā)布時間：2018-11-05 20:57
【摘要】：我國金銀礦山氰化尾渣中的黃銅礦由于受到氰化物的強(qiáng)烈抑制,未能有效地綜合回收,造成了嚴(yán)重的資源浪費和環(huán)境污染問題,且目前我國對氰化尾渣中銅資源的綜合利用水平較低,關(guān)于黃銅礦氰化抑制機(jī)理的研究不足,為這部分銅礦物的回收帶來困難。論文采用基于密度泛函理論的平面波贗勢法,系統(tǒng)地研究了黃銅礦表面性質(zhì)及氰根離子的吸附,討論了CN~-在其表面的吸附機(jī)理,并采用單礦物浮選試驗、XPS測試對密度泛函理論計算結(jié)果進(jìn)行了驗證分析。密度泛函理論研究結(jié)果顯示,黃銅礦晶體屬于直接帶隙的p型半導(dǎo)體,Fe原子與Cu原子的化合價之比接近3:1,S-Fe鍵的穩(wěn)定性較S-Cu鍵高。結(jié)構(gòu)優(yōu)化后,黃銅礦(0 0 1)-M、(0 0 1)-S、(1 1 2)-M、(1 1 2)-S和(1 1-2)-M面都發(fā)生了明顯的表面重構(gòu)現(xiàn)象,僅(1 1-2)-S面發(fā)生小幅的表面馳豫,表面重構(gòu)使黃銅礦表面生成了S_2~(2-)和S_n~(2-),并出現(xiàn)不同程度的S元素富集現(xiàn)象,使黃銅礦表現(xiàn)出良好的天然可浮性。在各計算表面中,黃銅礦(1 1 2)-M面的表面能最低,具有較高的熱力學(xué)穩(wěn)定性,因此(1 1 2)-M面是黃銅礦的最穩(wěn)定解理面。CN~-能夠自發(fā)地吸附在黃銅礦(1 1 2)-M面上,其中最穩(wěn)定的吸附位點為表面Fe-Fe穴位,吸附能達(dá)-335.90 kJ/mol,為化學(xué)吸附。氰根離子通過C原子與黃銅礦表面的Fe原子相互作用,C原子的2s軌道與Fe原子的4s軌道和4p軌道形成共價s鍵,Fe原子3d軌道的電子轉(zhuǎn)移到C原子上,占據(jù)了C原子空的反鍵p軌道,形成d-p反饋p鍵。單礦物浮選結(jié)果表明,當(dāng)氰化鈉濃度較低時,對黃銅礦的浮選影響較小,當(dāng)氰化鈉濃度達(dá)到0.8%時,黃銅礦的浮選回收率下降到20%以下,對其產(chǎn)生了強(qiáng)烈的抑制作用。黃銅礦回收率隨著浸出時間的延長出現(xiàn)小幅增長的趨勢,這主要是由于黃銅礦表面Cu~(2+)的溶解,消耗了一部分氰化鈉,對黃銅礦產(chǎn)生了一定的活化作用。XPS分析結(jié)果表明,黃銅礦各原子化合價構(gòu)型為Cu~+Fe~(3+)(S~(2-))_2,且黃銅礦表面存在S_2~(2-)和S_n~(2-),這與黃銅礦表面性質(zhì)的理論計算結(jié)果相一致。氰化鈉在黃銅礦表面吸附后,表面O元素的相對含量大幅降低,表明氰化鈉的吸附阻礙了氧分子與礦物表面的作用。氰化鈉能夠與黃銅礦表面的金屬原子形成親水性物質(zhì)鐵氰絡(luò)合物和氰化亞銅,并且優(yōu)先與Fe原子作用,當(dāng)氰化鈉濃度較高時,能夠與表面Cu原子反應(yīng),對黃銅礦產(chǎn)生顯著的抑制作用。
[Abstract]:Chalcopyrite in cyanide tailings of gold and silver mines in our country has been restrained strongly by cyanide and has not been recovered effectively, which has caused serious waste of resources and environmental pollution. At present, the comprehensive utilization of copper in cyanide tailings in China is relatively low, and the research on the mechanism of cyanidation inhibition of chalcopyrite is insufficient, which brings difficulties to the recovery of copper ore. In this paper, the surface properties of chalcopyrite and the adsorption of cyanide ions on the surface of chalcopyrite are systematically studied by using the plane wave pseudopotential method based on density functional theory. The adsorption mechanism of CN~- on its surface is discussed, and the flotation test of single mineral is used. The results of density functional theory (DFT) are verified by XPS test. The results of density functional theory show that chalcopyrite crystal belongs to p-type semiconductor with direct band gap, and the valence ratio of Fe atom to Cu atom is close to 3: 1, the stability of S-Fe bond is higher than that of S-Cu bond. After structural optimization, the surface reconstruction of chalcopyrite (0.01) -M, (0.01) -S, (112) -M, (112) -S and (1.1-2) -M has been observed. Only a small surface relaxation occurred on the (11-2) -S surface, and the surface reconstruction resulted in the formation of S2- and Sn2- on the chalcopyrite surface, and the enrichment of S elements in the surface of chalcopyrite was observed in varying degrees. Chalcopyrite shows good natural floatability. Among the calculated surfaces, chalcopyrite (112) -M plane has the lowest surface energy and high thermodynamic stability. Therefore, the (112) -M plane is the most stable cleavage surface of chalcopyrite. CN~- can spontaneously adsorb on the chalcopyrite (112) -M surface, and the most stable site is the surface Fe-Fe acupoint, and the adsorption energy is up to-335.90 kJ/mol,. For chemisorption. The C atom interacts with the Fe atom on the surface of chalcopyrite. The 2s orbital of the C atom forms a covalent s bond with the 4s orbital and 4p orbital of the Fe atom, and the electrons of the 3D orbital of the Fe atom transfer to the C atom. The d-p feedback p bond is formed by occupying the antibond p orbital of the C atom space. The results of single mineral flotation show that when the concentration of sodium cyanide is low, the effect on the flotation of chalcopyrite is small. When the concentration of sodium cyanide reaches 0.8, the flotation recovery of chalcopyrite decreases to less than 20%, which has a strong inhibitory effect on the flotation of chalcopyrite. The recovery rate of chalcopyrite increases slightly with the prolongation of leaching time, which is mainly due to the dissolution of Cu~ (2) on the surface of chalcopyrite, which consumes a part of sodium cyanide and activates chalcopyrite to some extent. The results of XPS analysis show that, The valence configuration of each atom of chalcopyrite is Cu~ Fe~ (3) (S2-) 2, and there are S2- and Sn- on the surface of chalcopyrite, which is in agreement with the theoretical calculation results of surface properties of chalcopyrite. After the adsorption of sodium cyanide on the surface of chalcopyrite, the relative content of O element on the surface of chalcopyrite decreases significantly, which indicates that the adsorption of sodium cyanide hinders the interaction between oxygen molecule and mineral surface. Sodium cyanide can form a hydrophilic iron cyanide complex and copper cyanide with metal atoms on the surface of chalcopyrite, and react with Fe atoms preferentially. When the concentration of sodium cyanide is high, it can react with Cu atoms on the surface. It has significant inhibitory effect on chalcopyrite.
【學(xué)位授予單位】：江西理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TD952;O647.31
本文編號：2313435
[Abstract]:Chalcopyrite in cyanide tailings of gold and silver mines in our country has been restrained strongly by cyanide and has not been recovered effectively, which has caused serious waste of resources and environmental pollution. At present, the comprehensive utilization of copper in cyanide tailings in China is relatively low, and the research on the mechanism of cyanidation inhibition of chalcopyrite is insufficient, which brings difficulties to the recovery of copper ore. In this paper, the surface properties of chalcopyrite and the adsorption of cyanide ions on the surface of chalcopyrite are systematically studied by using the plane wave pseudopotential method based on density functional theory. The adsorption mechanism of CN~- on its surface is discussed, and the flotation test of single mineral is used. The results of density functional theory (DFT) are verified by XPS test. The results of density functional theory show that chalcopyrite crystal belongs to p-type semiconductor with direct band gap, and the valence ratio of Fe atom to Cu atom is close to 3: 1, the stability of S-Fe bond is higher than that of S-Cu bond. After structural optimization, the surface reconstruction of chalcopyrite (0.01) -M, (0.01) -S, (112) -M, (112) -S and (1.1-2) -M has been observed. Only a small surface relaxation occurred on the (11-2) -S surface, and the surface reconstruction resulted in the formation of S2- and Sn2- on the chalcopyrite surface, and the enrichment of S elements in the surface of chalcopyrite was observed in varying degrees. Chalcopyrite shows good natural floatability. Among the calculated surfaces, chalcopyrite (112) -M plane has the lowest surface energy and high thermodynamic stability. Therefore, the (112) -M plane is the most stable cleavage surface of chalcopyrite. CN~- can spontaneously adsorb on the chalcopyrite (112) -M surface, and the most stable site is the surface Fe-Fe acupoint, and the adsorption energy is up to-335.90 kJ/mol,. For chemisorption. The C atom interacts with the Fe atom on the surface of chalcopyrite. The 2s orbital of the C atom forms a covalent s bond with the 4s orbital and 4p orbital of the Fe atom, and the electrons of the 3D orbital of the Fe atom transfer to the C atom. The d-p feedback p bond is formed by occupying the antibond p orbital of the C atom space. The results of single mineral flotation show that when the concentration of sodium cyanide is low, the effect on the flotation of chalcopyrite is small. When the concentration of sodium cyanide reaches 0.8, the flotation recovery of chalcopyrite decreases to less than 20%, which has a strong inhibitory effect on the flotation of chalcopyrite. The recovery rate of chalcopyrite increases slightly with the prolongation of leaching time, which is mainly due to the dissolution of Cu~ (2) on the surface of chalcopyrite, which consumes a part of sodium cyanide and activates chalcopyrite to some extent. The results of XPS analysis show that, The valence configuration of each atom of chalcopyrite is Cu~ Fe~ (3) (S2-) 2, and there are S2- and Sn- on the surface of chalcopyrite, which is in agreement with the theoretical calculation results of surface properties of chalcopyrite. After the adsorption of sodium cyanide on the surface of chalcopyrite, the relative content of O element on the surface of chalcopyrite decreases significantly, which indicates that the adsorption of sodium cyanide hinders the interaction between oxygen molecule and mineral surface. Sodium cyanide can form a hydrophilic iron cyanide complex and copper cyanide with metal atoms on the surface of chalcopyrite, and react with Fe atoms preferentially. When the concentration of sodium cyanide is high, it can react with Cu atoms on the surface. It has significant inhibitory effect on chalcopyrite.
【學(xué)位授予單位】：江西理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TD952;O647.31
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