Papers by Keyword: Magnetite

Abstract: A new magnetitediatomite compositions was synthesized by co-precipitation diatomite with Fe²⁺ and Fe³⁺ in the presence of diatomite. Magnetic compositions of diatomite were investigated using XRD and SEM. Comprehensive analysis for SEM and XRD data shows that the most favorable magnetic particle including to the diatomite pores in DM-15 and DM-30. Increasing of content of maghemite in compositions causes reduction of the proportion of smectite and mica, which is associated with the destruction of the crystal lattice. Determined by the interaction between the diatomite surface and including particles of magnetite and maghemite can be hydrogen bonds between the SiOH and SiOH₂⁺-groups of the diatomite surface and the iron (II) and iron (III) oxides.

Abstract: A new type of column magnetic separator has been developed, and a series of experiments have also been carried out in this paper. The structureseparating mechanismexperiments of column magnetic separator are introduced. The results show that the separator can produce concentrate from rough grinding products directly. The findings of orthogonal experiment show that the cycle of magnetic-field, the electrical current intensity and the position of magnetic system have remarkable effect on the experiment results. The optimized cycle of magnetic system is 0.2s, the optimized volume flow of the feed is 10cm³/s, the optimized electrical current is 11A ; the optimized water flow velocity is 11.1mm/s; the optimized position of magnetic system 20mm from the edge of cleaning area. Under the condition of the feed containing 47.99% TFe, an iron concentrate containing 66.27% TFe with 61.63% Weight ratio are obtained by using it to separate the rough grinding products of Nanfen ore dressing plant.

Abstract: This test used countercurrent bubble contact flotation column in reverse flotation to improve the grade of magnetic concentrate. By the tests of operating conditions and reagent system experiment, when the ore grade of concentrate after magnetic separation is 42.15%, after one roughing ,we can obtain the grade is 65.82% and recovery rate is 62.79% of the concentrate.

Abstract: Electromagnetic wave absorbing properties in GHz region were investigated for magnetite prepared by hydrogen reduction of hematite, which was synthesized via drip thermal oxidation using a fluidized bed. The magnetite powder product showed better absorption ability when the precursor hematite was prepared at a higher bed temperature, which also induced an improvement in morphology. This morphological enhancement is believed to result from the rapid thermal oxidation treatment of the hematite powder in the bed along with an accelerated evaporation of aqueous FeCl₂ solution.

Abstract: The paper describes two methods of syntheses of iron oxides, microstructure and morphology of magnetite nanoparticles. Nanocomposite thin films of SiO₂/Fe₃O₄ have been prepared with sol-gel dip coating technique: dip-coating from SiO₂/Fe₃O₄ sol and encapsulation magnetite between two SiO₂ layers. Structural and morphological characteristics of iron oxides particles and prepared film were analyzed by X-Ray Diffraction, SEM, FTIR, DTA, AFM. AFM topography of surface and measurements of roughness has shown that using iron oxide encapsulation between two SiO₂ layers to provide the even distribution of iron oxide, results as high quality films with low R_q values 1.5 2.7 nm.

Abstract: The situation of a pilot experiment of magnetite concentration from yunnan province was introduced.After five days of continuous production, magnetite concentrate is of good quality and the process is stability, the contents of mainly impurities are low. The beneficiation process has strong adaptability. The technical index is advanced and the test time and operation conform to the standard. The data of experiment can be used as a basis for industrial design. This test to increase enterprise efficiency and reduce the environmental pressure is of much benefit.

Abstract: The paper presents results of X-ray measurements of the texture of a magnetite (Fe₃O₄) layer formed on 10CrMo9-10 steel during 100,000 hours operation at the temperature of 575°C (in a flowing medium environment). The formed oxide layer was ≈140µm thick. Measurements of texturing were performed on the oxide surface and also at the depth of ≈50µm from the surface (1st polishing) and ≈100µm (2nd polishing). X-ray studies were carried out using the radiation of a cobalt anode tube, λ_Co=0.17902nm, for (311) and (400) Fe₃O₄ reflections, using a radiation beam collimated to φ=2mm. The study was aimed at determination of correlation between the texturing and the structure on the magnetite layer cross-section. A clear texturing of {111} and {111} type for the magnetite in the initial state and after the second polishing was found. Instead, after the first polishing there was a substantial texturing of {034} and {015} type. A different nature of the texture may result from a diversified morphology of magnetite at various depths (caused inter alia by a differentiated temperature on the tube wall cross-section during the material operation), which is related among other things to the crystallites size. The magnetite structure and texture changes can affect the magnetite porosity and cleavage.

Abstract: Materials with both electrical and magnetic properties are required for various applications ranging from electric and magnetic shields, molecular electronics, and sensors to microwave absorbers. Conducting polymers with the addition of magnetic oxides composites are suitable for such uses. Such is the case of the polyaniline (PANI), an organic polymer, mixed with magnetite. We have prepared through a new chemical method a PANI/ Fe₃O₄ composite with different amount of magnetic oxide from 0.3% m/m on the composite up to 42% m/m. The final product is a powder with good solubility in some organic solvents as chloroform. Structural morphological studies, transport properties (the electrical conductivity as a function of temperature) and magnetic characterization were performed on the oxides, on PANI and on the composites. We have explored the answer of these composites as absorbers in the microwave region to determine its potential technological application. An interesting magnetoresistance (MR) behavior was observed. The results are related to the particle size and to the influence of the percentage of oxide in the composite.

Abstract: Superparamagnetic iron oxide nanoparticles were synthesized using co-precipitation, hydrothermal and ultrasonic routes from Fe²⁺/Fe³⁺ ions and NaOH. The average diameter for the sample prepared using co-precipitation, hydrothermal and ultrasonic method is 33, 9 and 30 nm, respectively with surface area of 85, 117 and 87 m²/g, respectively. Although the results showed all the magnetite nanoparticles were superparamagnetic, but their saturation magnetization and coercitivity are different, depending on the method of synthesis. This study shows that method of synthesis is important that influence the physico-chemical properties of the resulting magnetite iron oxide nanoparticles.

Abstract: Malaysian low grade iron ore is unsuitable as raw material for domestic iron making due to high energy consumption which correspond to low iron content. The present agricultural residues from domestic palm oil industry are attractive proposition as energy source for iron making. This work describes the use of ash produced from pyrolysis of palm oil Empty Fruit Bunch (EFB) to magnetize the low grade iron ore. A briquette composite of iron ore and ash is subjected to reduction process using an electric tube furnace under argon atmosphere at 873K and 1073K. The ore was successfully magnetized through reduction process as carbon in EFB ash act as reductant. The results showed that the reduction degree was greatly enhanced with increasing of temperature and time. The significant phase changes of iron ore from a non-magnetic material of goethite to a strong magnetic material of magnetite was detected in XRD patterns. The process indicated that substitution of coal with EFB ash as an energy source has a potential in replacing fossil fuel by magnetizining the iron ore as well as encourage waste management control.