高分子絮凝剂在赤铁矿和尾矿表面的吸附动力学

应用紫外－可见光分光光度计，采用淀粉－三碘络合物显色法，对阴离子聚丙烯酰胺Magnafloc139、Magnafloc525和 M1017在赤铁矿和尾矿表面的吸附动力学进行了详细的研究，获得一些规律性的认识，可为实际生产应用奠定基础，提供科学依据。     

The Mechanism of the Thermal Transformation From Goethite to Hematite

Synthetic pigments of goethite (Bayferrox^R) of different particle size were investigated by DTA, IR, DSC, TG and X-ray diffraction measurements. It follows that a so-called ‘hydrohematite’ described in the literature does not exist as a discrete intermediate during the dehydration course from goethite to hematite. Instead we observed a dependence of the dehydration mechanism on the particle size. Transformation enthalpies and activation energies for the dehydration process will be given. A plausible dehydration mechanism, which is compatible with our DTA/DSC results, is deduced from TEM investigations. This revised version was published online in August 2006 with corrections to the Cover Date.     

油酸包裹对不同尺寸纳米α-Fe_2O_3晶体Morin相变影响的Mssbauer研究

用 Mossbauer方法研究了冻油酸中的 35nm与 6 0 nm均匀α- Fe2 O3 微晶的 Morin相变温度 ,发现它比未包裹样品分别高了 50 K和 2 4 K     

Synthesis and Characterization of a Novel Ternary Hematite Nanocomposites Structure with Fullerene and 2D‐Electrochemical Reduced Graphene Oxide for Superior Photoelectrochemical Performance

In this study, a novel ternary hematite nanocomposites photoanode structure with superior photoelectrochemical (PEC) performance consisting of fullerene (C₆₀) and 2D‐electrochemical reduced graphene oxide (eRGO) used as the effective surface passivators is developed. The introduction of both the electron scavenging C₆₀ and highly conducting eRGO has mitigated the high interfacial recombination rate of hematite and led to the superior enhancement in PEC performance. UV–vis analysis reveals that the incorporation of C₆₀ and eRGO can provide a stronger light absorption at the visible light (400 nm < λ < 700 nm) and near infrared (IR) region (λ > 700 nm). Through the electrochemical impedance spectroscopy measurements, it can be concluded that the introduction of C₆₀ and eRGO onto hematite photoanode improves electron transfer and collection, reduces charge‐carrier recombination efficiency, and enhances PEC activity. The resultant ternary hematite photoanode structure exhibits 16.8‐fold enhancement in photocurrent density and 0.8‐fold reduction in charge transfer resistance when compared to the bare hematite structure only. This study has shown that the application of C₆₀, 2D‐eRGO, or in combination as a ternary structure provides the plasmonic effect that can enhance the PEC performance in hematite photoanode structure.     

Artificial neural network approach to assess selective flocculation on hematite and kaolinite

Because of the current depletion of high grade reserves, beneficiation of low grade ore, tailings produced and tailings stored in tailing ponds is needed to fulfill the market demand. Selective flocculation is one alternative process that could be used for the beneficiation of ultra-fine material. This process has not been extensively used commercially because of its complex dependency on process parameters. In this paper, a selective flocculation process, using synthetic mixtures of hematite and kaolinite in different ratios, was attempted, and the adsorption mechanism was investigated by Fourier transform infrared (FTIR) spectroscopy. A three-layer artificial neural network (ANN) model (4-4-3) was used to predict the separation performance of the process in terms of grade, Fe recovery, and separation efficiency. The model values were in good agreement with experimental values.     

难选鲕状赤铁矿深度还原-磁选实验研究

针对国内某种难选鲕状赤铁矿的特点,进行了深度还原--磁选实验研究,探讨了还原温度、还原时间、二元碱度、磨矿细度和磁场强度等不同实验条件对渣铁分离效果和产品指标的影响.通过光学显微分析、X射线衍射分析、SEM和化学分析等手段确定了原矿与产品的物相组成与特点.在还原温度为1200℃、还原时间为2h及二元碱度为0.2的工艺条件下,获得了品位为91.94%、回收率为95.85%的铁精矿粉.分析表明,所得铁精粉的品位高,有害杂质少.     

Mössbauer spectroscopy on Mars: goethite in the Columbia Hills at Gusev crater

In January 2004 the USA space agency NASA landed two rovers on the surface of Mars, both carrying the Mainz Mössbauer spectrometer MIMOS II. The instrument on the Mars-Exploration-Rover (MER) Spirit analyzed soils and rocks on the plains and in the Columbia Hills of Gusev crater landing site on Mars. The surface material in the plains have an olivine basaltic signature [1, 5] suggesting physical rather than chemical weathering processes present in the plains. The Mössbauer signature for the Columbia Hills surface material is very different ranging from nearly unaltered material to highly altered material. Some of the rocks, in particular a rock named Clovis, contain a significant amount of the Fe oxyhydroxide goethite, α-FeOOH, which is mineralogical evidence for aqueous processes because it is formed only under aqueous conditions. In this paper we describe the analysis of these data using hyperfine field distributions (HFD) and discuss the results in comparison to terrestrial analogues.     

聚氧化乙烯絮凝微细粒高岭石强化赤铁矿反浮选脱硅机理研究

通过矿物浮选试验并结合激光粒度测试、扫描电镜(SEM)、矿物Zeta电位及XPS等检测方法对赤铁矿反浮选过程中聚氧化乙烯絮凝细粒高岭石的行为及机理进行了研究.矿物絮凝浮选试验表明：添加聚氧化乙烯可以提高高岭石的单矿物回收率和人工混合矿分离效率,促进赤铁矿和高岭石反浮选分离.激光粒度测试和扫描电镜检测结果表明：聚氧化乙烯不絮凝赤铁矿,但絮凝高岭石颗粒,使其表观粒径增大.Zeta电位测试和XPS分析表明：聚氧化乙烯在高岭石颗粒表面发生化学吸附,并使其Zeta电位正移.因此,开展聚氧化乙烯对硅酸盐矿物絮凝的研究对赤铁矿和高岭石反浮选分离具有意义.     

Micro‐analysis on Chinese over‐glaze red decoration of Linshui Kiln from Jin dynasty (1115–1234 ad)

Red and green over‐glaze decoration on Chinese porcelains from the Song‐Jin periods is critical to the development for Chinese ceramics. To characterize the identity, crystal size, and band gap width of the red colorant, red and green porcelain shards from the Linshui kiln produced in the Jin dynasty (1115–1234 ad ) are investigated using Raman spectroscopy, X‐ray diffractometry, and diffuse reflectance measurements. The colorant is shown to comprise hematite crystallites with the average diameter around 30 nm, and its crystal lattice is distorted as the result of the low firing of the decoration. The use of crystal size estimations coupled with band gap width calculations are believed to be employed for the first time on the study of Chinese archeological artifacts. Copyright © 2014 John Wiley & Sons, Ltd.     

Hydrothermal Synthesis and Properties of Controlled α‐Fe2O3 Nanostructures in HEPES Solution

A facile, template‐free, and environmentally friendly hydrothermal strategy was explored for the controllable synthesis of α‐Fe₂O₃ nanostructures in HEPES solution (HEPES=2‐[4‐(2‐hydroxyethyl)‐1‐piperazinyl]ethanesulfonic acid). The effects of experimental parameters including HEPES/FeCl₃ molar ratio, pH value, reaction temperature, and reaction time on the formation of α‐Fe₂O₃ nanostructures have been investigated systematically. Based on the observations of the products, the function of HEPES in the reaction is discussed. The different α‐Fe₂O₃ nanostructures possess different optical, magnetic properties, and photocatalytic activities, depending on the shape and size of the sample. In addition, a novel and facile approach was developed for the synthesis of Au/α‐Fe₂O₃ and Ag/α‐Fe₂O₃ nanocomposites in HEPES buffer solution; this verified the dual function of HEPES both as reductant and stabilizer. This work provides a new strategy for the controllable synthesis of transition metal oxide nanostructures and metal‐supported nanocomposites, and gives a strong evidence of the relationship between the property and morphology/size of nanomaterials.