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Shang X.,Kunming University of Science and Technology | Shang X.,Key Laboratory of Unconventional Metallurgy | Shang X.,National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology | Chen J.,Kunming University of Science and Technology | And 2 more authors.
High Temperature Materials and Processes | Year: 2016

This paper proposes an analytical approach to optimize the thickness of refractories for achieving maximum microwave power transmission in microwave heating based on the analysis of power transmission coefficient (PTC). The microwave PTCs of alumina (Al2O3) ceramics over the temperature range of 22-1,379°C at 2,450 MHz, mullite ceramics in the temperature range of 27-1,027°C at 2.45 GHz and 400-1,300°C at 915 MHz are studied. The results show that there are several transmission peaks in the PTC patterns. The transmission peak amplitude depends sensitively on the thickness of the refractory and the peak shifting towards a smaller thickness as the temperature of the refractory increases. We also show that high microwave transmission can only be achieved in a refractory with a small thickness corresponding to a slight transmission peak shift in the entire microwave heating (less than one eighth wavelength in the refractory). © 2016 by De Gruyter.


Chen G.,Key Laboratory of Unconventional Metallurgy | Chen G.,Kunming University of Science and Technology | Chen J.,Key Laboratory of Unconventional Metallurgy | Chen J.,Kunming University of Science and Technology | And 2 more authors.
Metalurgia International | Year: 2011

Temperature rising characteristics of titania-rich slag under microwave irradiation were obtained. The effects of microwave power, mean particle sizes of samples and sample weight on temperature rising characteristics of titania-rich slag were systematically investigated. The crystalline compounds of sample before and after microwave heating were characterized by X-ray diffractometry. The results show that the titania-rich slag has a good microwave absorption property. The titania-rich slag sample can be reach 1200 °C after 60 min at 3.0 kW in microwave field. The XRD characterization results show that untreated titania-rich slag mainly consists of crystalline compounds of anatase TiO2 phase; while the microwave heating treated sample is mainly composed of crystalline compounds of rutile TiO2 phase. It can be inferred that anatase TiO2 phase is completely converted to rutile TiO2 phase in microwave heating.


Chen G.,Key Laboratory of Unconventional Metallurgy | Chen G.,Kunming University of Science and Technology | Chen J.,Key Laboratory of Unconventional Metallurgy | Chen J.,Kunming University of Science and Technology | And 2 more authors.
Metalurgia International | Year: 2011

In this paper, the effects of mechanical activation on the microwave absorbing characteristics of ilmenite were systematically investigated using the microwave cavity perturbation technique and the digital signal processing technique. The relationships between dielectric loss and the microwave absorbing characteristics of the mechanical activated ilmenite were studied. The crystal structures and surface chemical functional groups of ilmenite were characterized using XRD and FT-IR, respectively. The results indicated that the microwave absorbing characteristics of mechanical activated ilmenite are better than that of untreated ilmenite. The optimum experiment parameters were found as follows: mechanical activation time of 120 min.


Yin S.,Kunming University of Science and Technology | Yin S.,Key Laboratory of Unconventional Metallurgy | Li S.,Kunming University of Science and Technology | Li S.,Key Laboratory of Unconventional Metallurgy | And 5 more authors.
Chemical Engineering Research and Design | Year: 2015

The lanthanum (La) extraction kinetics from chloride medium containing two complexing agents lactic acid (HLac) and citric acid (H3cit) by D2EHPA (H2A2) have been investigated using constant interfacial area cell with laminar flow. The stoichiometry of the complex formation reaction between La and H2A2 has been evaluated. The extraction kinetics data have been analyzed in terms of pseudo-first order constants. From the effects of stirring speed, temperature and specific interfacial area on the extraction rate, it is found that the extraction process is a diffusion-controlled kinetics process with an interface reaction. The rate-determining step is made by predictions derived from interfacial reaction models, and the rate equation has been evaluated from analysis of the experimental results, also, the extraction model has been proposed. © 2015 The Institution of Chemical Engineers.


Yin S.-H.,Kunming University of Science and Technology | Yin S.-H.,Key Laboratory of Unconventional Metallurgy | Li S.-W.,Kunming University of Science and Technology | Li S.-W.,Key Laboratory of Unconventional Metallurgy | And 6 more authors.
RSC Advances | Year: 2014

In order to develop a novel separation technology superior to the current extraction systems, the extraction behaviors of Ce(iii) and Pr(iii) from chloride medium with P204 in the presence of two complexing agents lactic acid (LA) and citric acid (H3cit) have been reported. The distribution ratios increase with the increase of the equilibrium pH and the ratio of [H3cit]:[LA] under certain conditions. The separation factors of Ce(iii) and Pr(iii) increase with the ratio of [H3cit]:[LA] at fixed pH, and the maximum value is as high as 5.78 in this complexing system. The maximum saturated extraction capacity is 27.08 g L-1 which is close to that in the current saponified P507 extraction system. The equilibrium constants and thermodynamic functions, ΔG, ΔH and ΔS have been calculated. Lactic acid and citric acid can be effectively recycled and enriched, providing possibilities for dissolving minerals in the circular process. By comparison with the experimental results, this complexing extraction method could be regarded as an effective strategy for separating REs. © The Royal Society of Chemistry 2014.

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