Advanced Materials Research Vols. 455-456

Abstract: The content of carbonate minerals in Dong Anshan iron ore was increasing in recent years, which deteriorated reverse flotation indices or even resulted in unclear separation between concentrate and tailing. In dodecylamine and sodium oleate systems, reverse flotation tests were undertaken with artificial mixed minerals of martite, quartz and siderite. Based on mineral flotation tests, the effect mechanism of siderite on reverse flotation were investigated in terms of SEM and EDS. Results showed that siderite was weakly depressed by starch, and the adsorption of siderite on hematite and quartz was the main cause for reverse flotation difficulties. In reverse flotation in dodecylamine system, the adverse effect of siderite on reverse flotation could be reduced when the amount of starch increased, and iron minerals and quartz were separated effectively. Therefore, the reverse flotation in dodecylamine system could be considered to realize separating effectively iron minerals and quartz of Donganshan iron ore containing carbonates, but which had high requirements on pH. Other methods were siderite being separated prior to reverse flotation or inventing flotation agents capable of effectively activating or depressing siderite.

Abstract: The bubble disintegration is of great scientific importance in metal refining, In order for further improvement, Research on bubble disintegration and dispersion becomes necessary, The intensification of bubble disintegration experiment that we have done in cold water model by study absorption rate ,The purpose is to research bubble disintegration under difference experimental condition . In this paper, we use mass transfer coefficients stand for absorption rate, we also study utilization rate, we want to research the best experimental condition which can enhance mass transfer coefficients and utilization rate. On the basis of experimental result, Provided a scientific and experimental basis to high-temperature experiment of bubble dispersion and disintegration .Experimental results show:the rate of absorption of CO2 injected in aqueous NaOH solution can be increased greatly by mechanical stirring when the positive-reverse rotation mode is adopted. Dispersion of small bubbles in the liquid is very effective for increasing the absorption rate.

Abstract: High nitrogen stainless steels with excellent mechanical and corrosion resistance properties is focused on to develop a new class of engineering material. The manufacture process of high nitrogen stainless steels under high nitrogen pressure is complicated. There are some theoretical problems to be solved for large scale melting and cast high nitrogen stainless steels. The thermodynamic calculation models of nitrogen solubility in the liquid phase, δ ferrite phase and γ austenitic phase built can well predict the nitrogen solubility and analyze the effect of temperature, alloy components and nitrogen pressure on the nitrogen solubility. The minimum nitrogen pressure for preventing the nitrogen porosity formation has been calculated by the micro-segregation. By the analysis nitrogen behavior of melting and cast high nitrogen stainless steels, it is possible to produce high nitrogen stainless steels in a large scale in China.

Abstract: Nb-doped TiO2 powders with different concentrations of Nb have been synthesized by a sol-gel method and characterized by a series of technologies including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The photocatalytic activity of Nb-doped TiO2 is evaluated by degradation efficiency of methyl orange in aqueous solution. The results indicate that the photocatalytic activity of Nb-doped TiO2 synthesized with a Nb/Ti molar ratio of 5% is higher than that of TiO2 under the visible light.

Abstract: Magnetic Fe3O4@SiO2 composite microspheres were prepared using hydrolyzation of tetraethoxysilane and Fe3O4 nanoparticles as seeds, and then the resultant composite particles were modified with silane coupling agent 3-methacryloxypropyltrimethoxy silane. The products were characterized by scanning electron microscope, X-ray powder diffraction, fourier transform infrared spectroscopy, and vibrating-sanple magnetometry, respectively. The results clearly show that the magnetic particles have favorable superparamagnetism and remain strong magnetic response. Moreover, the duplex bonds of carbon functional groups from 3-methacryloxypropyltrimethoxy silane was introduced onto the suface of Fe3O4@SiO2 composite particles.

Abstract: In published papers, the experimental researches have been carried out on heat transfer in Oscillatory Flow Reac-tors (OFRs) with annular baffles in both batch and continuous modes. It’s found that even with low net flow rates (or without net flow) the heat transfer properties of OFR can match turbu-lent pipe flow. But there’s no paper shows the micro-structure of temperature field in OFRs to illustrate the heat transfer mechan-ism. In this paper, we report our 3-dimensional numerical simu-lation results of heat transfer of OFR with novel conic ring baf-fles which is particularly suitable for liquid-solid systems. The temperature field of conic baffled OFR was obtained by using the commercial CFD package CFX11.0. It’s found that in “soft” mix-ing region the maximum temperature gradient lies approximate-ly in the middle of each cell, i.e. between the two pairs of vortices. It can be speculated that the convection caused by the intense vortex interaction leads to heat transfer essentially. When it’s global mixing, severe bias flow occurs. The temperature field becomes more chaotic and the heat convection is caused by more disordered vortex interaction.

Abstract: The energy saving, waste water reduction and economic performance of a novel process for purifying methanol, which employs dividing wall column and double effect distillation, was investigated by steady state simulation in comparison with two-column conventional distillation process and three-column double effect distillation process. Results showed that the novel process could reduce steam consumption by 34% comparing to the two-column process and had comparative ability in energy saving with three-column double effect process. Meanwhile it can reduce waste water by 20% and 20%, period for recovery of investment by 8.6% and by 5.1%, comparing to the two processes above respectively.

Abstract: Using industrial material and synthetic test instrument for the physical characteristics of slag, the effects of NaF on melting temperature, viscosity, fluidity, surface tension and Al2O3 inclusion adsorption of mould flux for thin slab continuous casting were studied. The results showed that with the increase of NaF content, melting temperature, viscosity and surface tension decreased obviously, and fluidity and Al2O3 inclusion adsorption increased. The effects of basicity on properties should be taken into account. NaF could play effective role when its content was less than 9%. The results would play a guiding role in designing of mould flux for thin slab continuous casting.

Abstract: To increase the production and improve the quality of dried agricultural products, a new drying system with a hybrid driving power system was developed and tested. The system with total collector area of 100m2 is consisted of 10 drying units and each of them is consisted of 5 identical air collectors and a greenhouse-like drying chamber. Each of collectors in the system is equipped with a DC fan, powered by either 120W solar modules or a 300W wind turbine, and an AC fan, directly powered by the electricity from grid. Such drying system can operate in all time of any day and avoid any possible spoilage of dried products as found in conventional solar dryers due to the formation of mould on the surface of dried materials in the events of consecutive rainy days. Field test for the drying of 9 fruits was conducted from November to December in 2005. The results indicated that the system was very effective for the drying of fruits and the solar drying time for most of the materials to be investigated was only one third of that required in the natural sun drying. Test results also showed that the nocturnal ventilation of drying chambers at the early stage of drying exercise was necessary for materials with high initial moisture content in order to further shorten the solar drying time.

Abstract: Based on the study of diagnosis principle of OBD, this paper probes into the pressure drop characteristics of wall-flow DPF, puts forward the failure diagnosis strategy of DPF based on the pressure drop characteristics of DPF, and actual vehicle tests have revealed that the devised diagnosis strategy can accurately identify various failure faults of DPF.