一步法由钛铁矿生产优质人造金红石

本文详细介绍用恒沸恒酸一步法由钛铁矿生产优质人造金红石及副产铁粉的过程。母液闭路循环。     

Surface modification of ilmenite by a novel surfactant dodecyliminodimethylenediphosphoinc acid and its sequent influence on ilmenite floatability

ABSTRACT

In the study, a novel compound of dodecyliminodimethylenediphosphoinc acid was synthesized, and its adsorption mechanism onto ilmenite surface was investigated by zeta potential, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscop (XPS) measurements. The zeta potential measurement results indicated that dodecyliminodimethylenediphosphoinc acid (DDDA) could adsorb onto ilmenite surface, and the optimum pH range for adsorption was 4–8 (similar to the flotation behavior). The FTIR analyses further confirmed that DDDA chemisorbed onto ilmenite surface and formed metal–DDDA complex, rendering the hydrophobic media for flotation. The XPS results provided strong evidences that DDDA species chemisorbed onto ilmenite surface and reacted with Fe ions rather than Ti ions.     

Investigation into high-pressure behavior of MnTiO3: X-ray diffraction and Raman spectroscopy with diamond anvil cells

The structural stability of manganese titanate MnTi03 at high pressure was investigated by X-ray diffraction and Raman spectroscopy with diamond anvil cells. Ilmenite-type MnTiO3 is stable at least to 26.6 GPa, and lithium niobate type MnTi03 reversibly transforms at room temperature to perovskite at 2.0 GPa. Bulk moduli (K300) of ilmenite, lithium niobate and perovskite are 174(4) GPa, 179 (8) GPa, and 208(5) GPa, respectively (at fixed first pressure derivative K'＝4). The Gruneisen parameter y has been estimated to be 1.28 for ilmenite and 1.75 for perovskite. In ilmenite phase, Ti06 octahedra become more regular with increasing pressure. In perovskite phase structural distortion increases with pressure increase.     

含钛铁尾矿制纳米级TiO2的结构及性能

以贵州某低品位细粒难选钛铁矿还原焙烧-弱磁选选铁尾矿为原料,采用酸化焙烧-水解工艺制得高品位纳米级TiO2粉末,采用XRD、SEM、TEM和BET等手段对TiO₂粉末进行了结构表征,并以难降解酚类化合物4-硝基酚为对象,评价了TiO₂样品光催化降解4-硝基酚的性能。结果表明：所制备的TiO₂粉末属纳米级锐钛矿精矿,颗粒粒径在几十纳米;TiO2粉末呈介孔结构,平均孔径在5 nm左右;TiO₂粉末对4-硝基酚显示了很好的光催化降解性能,240 min的降解率超过60%。     

Behavior of ilmenite as oxygen carrier in chemical-looping combustion

For a future scenery where will exist limitation for CO₂ emissions, chemical-looping combustion (CLC) has been identified as a promising technology to reduce the cost related to CO₂ capture from power plants. In CLC a solid oxygen-carrier transfers oxygen from the air to the fuel in a cyclic manner, avoiding direct contact between them. CO₂ is inherently obtained in a separate stream. For this process the oxygen-carrier circulates between two interconnected fluidized-bed reactors. To adapt CLC for solid fuels the oxygen-carrier reacts with the gas proceeding from the solid fuel gasification, which is carried out right in the fuel-reactor. Ilmenite, a natural mineral composed of FeTiO₃, is a low cost and promising material for its use on a large scale in CLC.The aim of this study is to analyze the behavior of ilmenite as oxygen-carrier in CLC. Particular attention was put on the variation of chemical and physical characteristics of ilmenite particles during consecutive redox cycles in a batch fluidized-bed reactor using CH₄, H₂ and CO as reducing gases. Reaction with H₂ was faster than with CO, and near full H₂ conversion was obtained in the fluidized-bed. Lower reactivity was found for CH₄. Ilmenite increased its reactivity with the number of cycles, especially for CH₄. The structural changes of ilmenite, as well as the variations in its behavior with a high number of cycles were also evaluated with a 100 cycle test using a CO + H₂ syngas mixture. Tests with different H₂:CO ratios were also made in order to see the reciprocal influence of both reducing gases and it turned out that the reaction rate is the sum of the individual reaction rates of H₂ and CO. The oxidation reaction of ilmenite was also investigated. An activation process for the oxidation reaction was observed and two steps for the reaction development were differenced. The oxidation reaction was fast and complete oxidation could be reached after every cycle. Low attrition values were found and no defluidization was observed during fluidized-bed operation. During activation process, the porosity of particles increased from low porosity values up to values of 27.5%. The appearance of an external shell in the particle was observed, which is Fe enriched. The segregation of Fe from TiO₂ causes that the oxygen transport capacity, R_OC, decreases from the initial R_OC = 4.0% to 2.1% after 100 redox cycles.     

Sputtering deposition of amorphous cadmium stannate as transparent conducting oxide

In this work we studied deposition conditions by RF sputtering of ternary oxides of Cd and Sn, starting from Cd₂SnO₄ target and varying substrate temperature, sputtering power and deposition gas (from inert Ar to oxidizing 50% Ar-50% O₂ atmosphere). The aim of this study was to obtain thin films for use as Transparent Conducting Oxide (TCO). TCOs are oxides that couples low sheet resistance and high transparency that find application in many fields like solar cells, light emitting diodes and transparent thin film transistors.Thin films functional properties were characterised by means of sheet resistance and transmittance measurements in the visible region, and film composition and structure were investigated by total reflection X ray fluorescence and glancing incidence X ray diffraction. Morphology was studied by Atomic Force Microscopy and Scanning Electron Microscope and showed very smooth surface suitable for solar cells application. Composition and phase analysis allowed us to discuss possible correlation of film structure with functional properties. Deposition in inert atmosphere at 400 °C substrate temperature was selected for its low sheet resistance and high transparency that are comparable to the ones of commercial TCOs like indium tin oxide or SnO₂: F. The thin film obtained in these conditions was amorphous, and it crystallized into CdSnO₃ ilmenite phase when annealed at 700 °C; segregation of Sn₃O₄ was also observed. Since sheet resistance of thin films increases after annealing treatments, amorphous thin film was selected for future applications.     

攀枝花选钛厂细粒级钛铁矿回收途径探讨

简要介绍了“七五”、“八五”攻关期间研究的几种工艺流程和设备的分选指标，综合分析了细粒级钛铁矿回收率低的原因，主为采用强磁－浮选程选别细太铁是适宜的。     

SLon磁选机分选南非红河钛铁矿的半工业试验

以ＳＬｏｎ－１０００立环脉动高梯度磁选机为主体选别设备，对南非红河钛铁矿的选别工艺进行了产工业试验研究，结果表明，采用全磁流程，可以获得合格的铁精矿和钛精矿。     

Mathematical Simulation on Oxidation of Ilmenite in Fluidized Bed

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Catalytic reforming of tar during gasification. Part I. Steam reforming of biomass tar using ilmenite as a catalyst

Ilmenite, a natural iron-containing mineral, has been investigated as an inexpensive catalyst for the steam reforming of volatiles (tar) from the pyrolysis of mallee woody biomass. The results indicate that ilmenite has good activity for the steam reforming of tar into gases due to its highly dispersed iron-containing species. The supply of external steam, in addition to the H₂O and CO₂ produced during the pyrolysis of biomass, plays an important role in minimising the formation of coke on the catalyst surface and thus the catalyst activity. The catalyst deactivation due to coke formation has more adverse effects on the reforming of larger aromatic ring system with steam than that of smaller ones. In addition, the supply of additional oxygen at low concentration changed the outcomes of tar reforming mainly because oxygen activated the smaller aromatic ring systems and polymerised them into larger aromatic ring systems in the gas phase.