Water-oxygen interaction on marcasite (1 0 1) surface: DFT calculation

Marcasite (FeS₂) is widespread in nature, its oxidation plays a vital role in acid mine drainage, mineral resource recovery, and photoelectric material applications. In this paper, the oxidation mechanism of marcasite has been studied for the first time using density functional theory (DFT). It is found that, unlike the oxidation of pyrite, the oxidation of marcasite merely occurs at surface S atoms. Under the coexistence of water and oxygen, S atoms around surface Fe atoms are replaced by O atoms. The surface S sites are initially oxidized to form S==O bonds, and continue to adsorb oxygen to gradually generate SO₃^2?, SO₄^2? species, and eventually FeSO₄. In this process, H₂O molecules participate in neither oxidation nor dissociation, and they are adsorbed on surface Fe sites in the form of molecules, i.e., all O atoms in SO₄^2? derive from oxygen rather than water molecules.     

Calculation of electron structure by density function theory and electrochemical process of surface （100） of FeS2

The electron structure of FeS2 surface (100) was computed by DFT (density function theory) and the process of electron transfer in sulfide flotation was simulated through ab-initio calculation. The results show that the interaction between xanthate and FeS2 is controlled by the energy of valence band. The products and degree of the reaction depend on the density of state of valence band and concentration of positive hole in valence band. Interaction between xanthate and pyrite can be changed by modifying the election structure of the surface of pyrite. Xanthate is adsorbed on the surface of intrinsic pyrite. But the amount of xanthate adsorbed on the surface of the pyrite with sulfur vacancy is more than that on the surface of the intrinsic pyrite due to the higher electron and vacancy density. Xanthate is not adsorbed on the surface of pyrite with Fe vacancy because of its high Fermi energy.     

C, N在γFe中扩散激活能的计算

在固体与分子经验电子理论基础上提出了用结构弛豫模型计算C,N在γFe中的扩散激活能.首先,加以约束,间隙原子挤入鞍点位置,电子的杂化台阶保持不变.然后,解除约束,原子在库仑排斥力作用下松弛,达到平衡.第一步所需的能量可以由第二步来部分地补偿.用这种方法,计算了C,N在γFe中的扩散激活能,与实验值的相对误差＜5%,这是目前同类理论得到的较好结果.     

Oxygen adsorption on pyrite （100） surface by density functional theory

Pyrite (FeS2) bulk and (100) surface properties and the oxygen adsorption on the surface were studiedby using density functional theory methods. The results show that in the formation of FeS2 (100) surface, there exists a process of electron transfer from Fe dangling bond to S dangling bond. In this situation, surface Fe and S atoms have more ionic properties. Both Fe^2 and S^2- have high electrochemistry reduction activity, which is the base for oxygen adsorption. From the viewpoint of adsorption energy, the parallel form oxygen adsorption is in preference The result also shows that the state of oxygen absorbed on FeS2 surface acts as peroxides rather than O2.     

Density Functional Theory Study of Oxygen Atom Adsorption on Different Surfaces of Pyrite

We discussed the oxidation differential and mechanisms on different planes of pyrite. The experimental results show that the oxidation priority is:(222) plane(200) plane(200) plane, and there is no direct correlation between the crystal plane index, the atom numbers, and the oxidation priority. However, with more exchanged charge among atoms, the oxidation could be conducted more easily, and the distribution rule of the electric charge conforms with the variation trend of adsorption energy, which will provide more overall cognition on the oxidation mechanism of pyrite from the atomic scale.     

原子簇NiFeB_2的结构及催化性能

利用DFT（密度泛函理论）方法,对原子簇NiFeB_2的10余种可能构型在单重态下进行优化计算,分析比较了优化结果的能量、成键、电荷分布情况及不同构型的催化性能。结果表明：原子簇NiFeB_2以B-B键较长的三角锥形1构型最稳定,是原子簇NiFeB_2最有可能存在的构型,B-B在Ni-Fe异侧的平面四边形2构型次之;Ni-B,Fe-B原子问有强烈的成键作用且Fe-B间作用力比Ni-B间作用力大;各构型中电子由B转向Ni,Fe;在形成原子簇NiFeB_2的过程中Fe,B原子的所有轨道均参与成键,Ni原子的4p,4s在其成键中起主要作用;除了B-B键较短的三角锥形3构型外的其它构型中Fe原子的催化活性高于Ni原子,B-B键较短的三角锥形3构型和直线型4构型可能具有较好的催化性能;在催化加氮和加氢上直线型4构型具有较好的催化活性。     

Density Function Theory Studies on the Structure of AMT Inhibitor

Density function theory （DFT） at the B3LYP/6- 311 ＋ ＋ G（2d） （5D, 7F） level of theory was calculated to predict the geometry structures, toted energy and net charges of four kinds of dynamic isomer molecules of 2-aminino-5 mercapto- 1,3,4-thiodizole （ AA/IT for short）. The fact that the atoms in four kinds of dynamie AMT isomer molecules lie in a plane and one kind of AMT is most stable is approved. The results also indicate that the pentogon ring in four kinds of dynamic AMT isomer molecules are aromatics, and the AMTc and Cu corrosion mitigation film produces as a result of the bonds form one by one of the covalent bond of Cu（1） with 7 N atom in AMTc amd the coordinate bond of Cu with 2S atom in ATMc. The resonant vibration frequencies and IR intensity for the four kituds of dynamic isomer of AMT are also calculated and their IR spectra are shown.     

Electronic structure and FIM imaging mechanism of Fe-Al intermetallic compounds

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噻吩与Mo(100)和W(100)面相互作用的EHMO研究

本文用EHMO法确定了Mo(100)和W(100)面吸附噻吩的最优几何构型,结合能,净电荷分布等。同时分析了吸附体系的成键特征,结果表明:噻吩的硫原子键合到四重轴空位上,且到第二层金属原子的距离为0.133nm,噻吩分子的π轨道与顶层金属成键。同时分子倾斜平面与金属面法线成18°定位,所得的吸附构型与实验基本一致。     

非晶Fe—P合金的价电子结构

本文在“固体与分子经验电子理论”的基础上,通过推广的键距差分析,对非晶Fe-P合金的价电子结构进行了分析。结果表明,偏径向分布函数的峰位可视为实验健距,而偏径向分布函数第一峰下的面积可作为等同健距数目,所得结论在一级近似下是合理的。计算结果指出,Fe为B型双态杂化的13阶杂化,而P位于杂化态的第Ⅰ阶,Fe-P之间有很高的共价结合。     

纤锌矿AlN中反位和间隙点缺陷电子结构的最大局域化Wannier函数方法研究

结合第一性原理计算方法,利用最大局域化Wannier函数方法研究了纤锌矿AlN中反位和间隙点缺陷引起的电子结构变化及成键性质.研究发现:在N反位缺陷结构中,反位N原子只与[0001]方向上最近邻的N原子成键,未成键的孤对电子局域在反位N原子及其余最近邻的3个N原子附近;在Al反位缺陷中,反位Al原子与垂直于[0001]方向的底面上3个最近邻Al原子成键.研究同时发现:在反位和间隙缺陷中,N间隙对电子结构影响最小,间隙N原子与下方最近邻的3个Al原子成键;尽管Al间隙对电子结构影响最大,但间隙Al原子并不与周围原子成键.无疑,相比于传统的电子结构分析方法,最大局域化Wannier函数方法更加直观便捷,能给出清晰的物理图景.     

碳纳米管超晶格结构吸附Fe原子的电子机理

为了提高碳纳米管与Fe基体之间的润湿性,构造出N掺杂有限长碳纳米管超晶格结构.第一性原理能量计算结果表明,新型超晶格结构的埋置能正向升高,结构稳定性降低,但可以显著提高外壁对Fe原子的吸附能力.差分电荷密度结果表明,掺杂体系中N原子与邻近C原子间的π键出现了畸变,使得N原子易与Fe原子发生结合.布居数和电荷转移情况表明,N原子的掺入导致Fe原子失电子能力降低,但Fe—N间共价键强度提高.超晶格结构在一定的扭转和剪切变形下仍能保持对Fe原子的吸附能力.     

Influencing factors of pyrite leaching in germ-free system

The effect of mineral particle size, pulp potential and category of oxidant on pyrite leaching was studied. The results show that a smaller mineral particle size leads to a higher leaching rate of pyrite, and the optimum result with pyrite leaching rate of 2.92% is obtained when mineral particle size is less than 0.037 mm. The pulp potential reflects the leaching process. The increase of pulp potential can improve pyrite leaching. The leaching rate and velocity of pyrite can be enhanced rapidly by adding strong oxidant. The kind and the method of adding oxidant have important effect on the pyrite leaching. Appropriate concentration of Fe3 can enhance pyrite leaching but the precipitation generated by high concentration of ferric ion covers the surface of pyrites and prevents the leaching process. The leaching rate increases with the constant addition of H2O2.     

镀膜玻璃衬底表面结构的分子动力学模拟

为考察硅酸盐玻璃衬底的表面结构以及温度对玻璃衬底表面结构的影响，模拟研究了500～1 000 K温度范围内及Al质量分数为0.5%～1.5%的玻璃衬底结构.采用Born-Mayer势函数,使用分子动力学方法，模拟了玻璃体相结构向表面结构转化的结构驰豫过程.结果表明，结构驰豫使系统能量下降，原子向表面一侧扩散.在500～1 000 K温度范围内，玻璃成份中Na原子的驰豫最为明显，Ca原子次之，Si、O原子最小，玻璃衬底表面的Na原子的质量分数高于体相.随着玻璃成份中Al质量分数的减小，玻璃衬底表面层的能量增加，活性增强，有利于沉积原子的吸附.     

石油的激光荧光光谱测量

描述了用光学光谱分析仪（ＯＳＡ）对水面浮油的激光激发荧光光谱进行的测量．结果表明不同品种的油类，其荧光光谱强度的波长分布，峰值波长，相对光强都不相同，具有自己的特征．以此为依据可用于航空遥感相关分析方法探测海面油溢污染及海底油矿贮藏探测的研究．     

Zr对Nd2Fe14B/α-Fe快淬纳米复合永磁材料的影响

主要研究了Zr对Nd2Fe14B/Fe快淬纳米复合永磁材料的影响.研究发现,Zr元素的添加提高了快淬薄带的非晶热稳定性,晶化处理后的矫顽力和磁滞回线的方形度.三维原子探针分析发现,快淬薄带晶化后Zr在硬磁性相内部以及晶粒之间分布不均匀,有利于细化晶粒、提高的矫顽力以及改善磁滞回线的矩形度.     

煤中黄铁矿表面细菌氧化的XRD及SEM/TEM研究

借助于XRD和SEM/TEM 等表面分析测试技术,对煤中黄铁矿表面经氧化亚铁硫杆菌作用前后的表面微观结构的变化进行了研究.作为对比,同时采用了氧化剂（H2O2）对黄铁矿表面进行氧化试验.结果表明,氧化亚铁硫杆菌在黄铁矿表面的氧化形式与氧化剂（H2O2）在黄铁矿表面的氧化形式不同.从黄铁矿表面微观结构的变化来看,氧化剂氧化的结果多出现钮扣状的片起,表现为较为剧烈的直接强氧化作用,而氧化亚铁硫杆菌氧化则呈现坑蚀,表现为相对缓和的吸附氧化作用.这为研究细菌对煤中黄铁矿表面的作用机理提供了一定的参考.     

Action time effect of lime on its depressive ability for pyrite

Two sample groups of bulk concentrates consisting mainly of pyrite and chalcopyrite from Daye and Chenghchao Mines in Hubei Province of China were used to investigate the effect of the action time of lime on its depressive ability for pyrite. The experimental results conducted with different samples and collectors showed that the action time between lime and pyrite markedly influences the depressive ability of lime. The depressive ability of lime increased with the action time increasing. It was also proved that the depressive results obtained at a large lime dosage after a shorter action time are similar to those obtained at a small lime dosage after a longer action time. The increase of depressive ability of lime after a longer action time is because that there are different mechanisms in different action time. The composition on the surface of pyrite acted for different time with lime was studied by using ESCA (Electron Spectroscopic Chemical Analysis). The results showed that iron hydroxide and calcium sulphate formed on the pyrite surface at the presence of lime in the pulp but the amounts of iron hydroxide and calcium sulphate were different at different action time. At the beginning action time the compound formed on the pyrite surface was mainly calcium sulphate and almost no iron hydroxide formed; but with the action time increasing, iron hydroxide formed. The longer the action time, the more iron hydroxide and the less calcium sulphate formed. It was considered that the stronger depressive ability of lime after a longer action time is because more iron hydroxide forms on the pyrite surface.     

脂类捕收剂DLZ对黄铜矿和黄铁矿浮选的选择性作用

通过浮选实验、吸附量和红外光谱测定,考察了捕收剂DLZ对黄铜矿和黄铁矿浮选性能的影响及作用机理.结果表明:DLZ在pH=2.7～12.05时对黄铜矿的捕收能力强,最大回收率95.7%,而对黄铁矿的捕收能力弱,且PH=6.9～12.05时其回收率小于10%.用CaO作pH调整剂时,在pH=7～11时黄铜矿的回收率与用NaOH调PH相差不大,但黄铁矿可浮性被抑制,回收率低于5%.DLZ在黄铜矿上的吸附量比在黄铁矿上的大,特别是强碱条件下;其吸附量随用量的增加而增大.DLZ与矿物作用的红外光谱分析表明:黄铜矿与DLZ作用后出现了DLZ的相关特征吸收峰,而黄铁矿与DLZ以及Cu~(2+)作用前后的红外光谱曲线基本没有变化,可见DLZ在黄铜矿表面的吸附属于化学吸附,在黄铁矿表面的吸附属于物理吸附.     

Influences of collector DLZ on chalcopyrite and pyrite flotation

The interaction mechanism of collector DLZ in the flotation process of chalcopyrite and pyrite was investigated through flotation experiments, zeta potential measurements and infrared spectrum analysis. Flotation test results indicate that DLZ is the selective collector of chalcopyrite. Especially, the recovery of chalcopyrite is higher than 90% in neutral and weak alkaline systems, while the recovery of pyrite is less than 10%. When using CaO as pH regulator, at pH=7-11, the floatability of pyrite is depressed and the recovery is less than 5%. Zeta potential analysis shows that the zeta potential of chalcopyrite decreases more obviously than that of pyrite after interaction with DLZ, confirming that collector DLZ shows selectivity to chalcopyrite and pyrite. And FT1R results reveal that the flotation selectivity of collector DLZ is due to chemical absorption onto chalcopyrite surface and only physical absorption onto pyrite surface.