高纯超细活性γ-Al2O3的应用及其研究进展

从γ-Al2O3的结构和特性出发介绍了高纯超细活性γ-Al2O3在高性能特种陶瓷合成、催化剂或其载体及化学机械抛光等方面的应用，综述了国内外有关高纯超细Al2O3多种制备方法的研究现状和发展趋势。     

Bioleaching of chalcocite by mixed microorganisms subjected to mutation

Mixed microorganisms with elevated activity of chalcocite-leaching were screened by mutation methods. The original microorganisms collected from acid mine drainage of different sites were mixed and then treated with mutagens NO₂⁻, diethyl sulfate (DES), UV and their combinations, respectively. Five groups of mixed microorganisms with much stronger ore-leaching ability were obtained by screening on the leaching media. Among them, group E of mixed microorganisms (treated with 1% DES for 60 min) with the best performance on chalcocite-leaching, increases the content of Cu²⁺ by 101.4% in 20 d of leaching compared with the control culture. In addition, group E is more tolerant to Cu²⁺ in media than the control without mutation treatment. Analysis for the diversity of microbial clones indicates that half of operational taxonomic units (OTUs) in group E are Acidithiobacillus ferrooxidans. These observations suggest that group E might have potentials for industrial application. Foundation item: Project(50321402) supported by the National Natural Science Foundation of China; Project(2004CB619201) supported by the Major State Basic Research and Development Program of China     

Bioleaching of pyrrhotite by Sulfobacillus thermosulfidooxidans

The bioleaching of pyrrhotite was investigated using Sulfobacillus thermosulfidooxidans.The effects of pH,pulp concentration,inoculation amount,external addition of ferrous and ferric ions were examined.The pH is found to exert a profound effect on the leaching process for controlling the bacterial activity and precipitation of ferric ions mainly as jarosite.The results show that low pulp content increases the leaching rate of iron.The inoculation amount from 1×107 cell/mL to 1×108 cell/mL has positive effects on the leaching rate.The results also imply that addition of ferrous sulfate（1 g/L） is required for the bacteria to efficiently drive the extraction of iron,however,the leaching efficiency has no obvious enhancement when 2 g/L ferrous sulfate was added.Comparatively,addition of ferric sulfate（2 g/L） significantly inhibits the bioleaching process.At the end of bioleaching,jarosite and sulfur are observed on the surface of pyrrhotite residues by using XRD and SEM.With the passivation film formed by jarosite and sulfur,the continuous iron extraction is effectively blocked.     

2-氨基-5-巯基-1,3,4-噻二唑缓蚀剂结构的密度泛函计算

采用密度泛函量子化学计算方法,获得了在B3LYP/6-311 G(2d)(5D,7F)理论水平上2-氨基-5-巯基-1,3,4-噻二唑(简称AMT)4种互变异构体的平衡几何构型、能量和电荷分布,证实了4种互变异构体的所有原子处于同一平面,且有一种异构体最稳定.研究结果表明:AMT4种异构体中的环骨架具有芳香性,AMTc与Cu形成的缓蚀膜层是Cu(Ⅰ)与AMTc中的7N和2S原子分别形成共价键和配位键相互交错而成.计算了AMT4种异构体的谐振频率和红外光谱强度.     

DFT research on activation of sphalerite

Activation of sphalerite ZnS, (Zn, Fe)S, (Zn, Cu)S were carried out using the density functional theory (DFT) method. The electronic structures and related properties of three kind of zinc sulfide compounds were investigated. In addition, the relation between electronic structure and flotation behavior was discussed. The results show that, ZnS has a broader band gap than (Zn,Cu)S and (Zn,Fe)S do, and it has low electrochemistry activity to react with flotation collectors to render the surface hydrophobic. When the Zn atom in ZnS is replaced by Cu atom,the band gap will be reduced, and the top valence band will be occupied by Cu 3d orbit, thus it is beneficial to the interaction between mineral surface and collector.     

Cu~(2+)对Fe~(2+)在T.f菌修饰粉末微电极上氧化行为的影响

Fe2 + 的氧化在细菌浸矿过程中具有重要作用 ,细菌浸铜过程中 ,Cu2 + 的存在对T .f菌的生长代谢和其氧化Fe2 + 的能力有一定影响。制备了T .f菌修饰碳粉粉末微电极 ,研究了Cu2 + 存在下Fe2 + 在T .f菌修饰粉末微电极上氧化的电化学反应机理 ,并测定了相应的电极过程动力学参数。循环伏安研究表明 ,Cu2 + 的存在不影响Fe2 + 在T .f菌修饰粉末微电极上的氧化反应的可逆性。对电极稳态及暂态过程研究表明 ,当Cu2 + 浓度在 12mmol/L以下时 ,Cu2 + 的存在不会抑制Fe2 + 在T .f菌修饰粉末微电极上的氧化 ,适量Cu2 + 加强T .f菌氧化Fe2 +的作用是在于其加快了电荷传递速率     

高岭石脱水反应的非等温热重法研究

在系统分析非等温固相反应特点的基础上,建立了非等温脱水反应速率方程.采用非等温热重法、通过计算机辅助计算,对高岭石脱水反应动力学规律进行了研究.结果表明:由于高岭石晶体结构中内、外羟基脱除的顺序不同,其脱水反应机制在反应分数(α)为0.7左右时发生改变.在反应前期(0＜α＜0.7)时,脱水反应遵循二维扩散控制规律,脱水反应表观活化能为159.682 kJ/mol、表观频率因子为1.007×10 10/min.     

Flotation performances of polymorphic pyrrhotite

The floatability of different crystalline structures of pyrrhotite (monoclinic and hexagonal) was studied. It is shown that the floatability of monoclinic and hexagonal has obvious difference, and that the flotation recovery of monoclinic pyrrhotite is larger than that of hexagonal pyrrhotite using different collectors. When butyl dithiophosphate is used as the collector, the recovery is larger than that by sodium butyl xanthate and sodium diethyl dithiocarbamate. At the pH values ranging from 6 to 9, monoclinic pyrrhotite can be floated well, and the flotation recovery is higher than 90%. Monoclinic and hexagonal pyrrhotites are more easily activated by Cu²⁺ in acidic conditions than in alkaline conditions. But Cu²⁺ cannot activate hexagonal pyrrhotite using sodium diethyldithiocarbamate as the collector. By the measurement of contact angle, it is indicated that monoclinic and hexagonal pyrrhotites float well and are easily activated by Cu²⁺ when dithiophosphate is used as the collector. Using sodium diethyl dithiocarbamate as a collector, the relationship between potential and pH range for pyrrhotite flotation is established. At pH 5, the optimal potential range for flotation of monoclinic pyrrhotite is about 125–580 mV (vs SHE), with the maximum flotation occurring at about 350 mV (vs SHE); the optimal potential range for flotation of hexagonal pyrrhotite is 200–580 mV (vs SHE), with the maximum flotation occurring at about 300 mV (vs SHE).     

丁基黄原酸甲酸乙酯的合成及对黄铜矿浮选研究

考察了不同条件对丁基黄药合成丁基黄原酸甲酸乙酯(BXEF)的影响。研究结果表明,合成BXEF反应的最佳工艺参数为：反应温度25℃,反应时间200 min,n(丁基黄药)：n(氯甲酸乙酯)=1．04：1。在此条件下,BXEF的产率可以达到94．5%。对江西永平铜矿硫化物矿石的浮选试验结果表明,与丁基黄药相比,BXEF对硫化铜矿有更高的浮选回收率,而且铜精矿中铜的品位更高。对丁基黄药和BXEF的量子化学计算结果表明,BXEF比丁基黄药有更低的能量,稳定性更强。     

BaO-SiO2-B2O3-TiO2系统玻璃的电子自旋共振研究

采用电子自旋共振(ESR)方法研究了钛在BaO-SiO2-B2O3-TiO2系统玻璃中的价态及Ti3+的结构状态.结果表明在正常空气气氛下熔制的玻璃中,钛主要以Ti4+形式存在,所产生的顺磁信号归因于玻璃的本征缺陷和熔制时TiO2中氧的逸出而形成的氧空位捕获电子引起,且随温度升高,氧空位浓度减少;在微还原性气氛下,有部分Ti3+形成,出现g┃=1.9954,g┸=1.9823两处顺磁峰,它们对温度有着不同的依从性,即随温度升高g┃ 峰增强,g┸峰降低;根据Ti3+的g┃ 、g┸)参数的性质,认为Ti3+是处于带四方畸变的八面体配位场中,形成[TiO6];即便在液氮温度下,也难以观察到Ti3+的超精细结构谱线.