| 1. |
- Peng, Jianhui, et al.
(författare)
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Achieving ultra-high electromagnetic wave absorption by anchoring Co0.33Ni0.33Mn0.33Fe2O4 nanoparticles on graphene sheets using microwave-assisted polyol method
- 2018
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 44:17, s. 21015-21026
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Tidskriftsartikel (refereegranskat)abstract
- The Co0.33Ni0.33Mn0.33Fe2O4/graphene nanocomposite for electromagnetic wave absorption was successfully synthesized from metal chlorides solutions and graphite powder by a simple and rapid microwave-assisted polyol method via anchoring the Co0.33Ni0.33Mn0.33Fe2O4 nanoparticles on the layered graphene sheets. The Fe3+, Co2+, Ni2+ and Mn2+ ions in the solutions were attracted by graphene oxide obtained from graphite and converted to the precursors Fe(OH)(3), Co(OH)(2), Ni(OH)(2), and Mn(OH)(2) under slightly alkaline conditions. After the transformations of the precursors to Co-Ni-Mn ferrites and conversion of graphene oxide to graphene under microwave irradiation at 170 degrees C in just 25 min, the Co0.33Ni0.33Mn0.33Fe2O4/graphene nanocomposite was prepared. The composition and structure of the nanocomposite were characterized by X-ray diffraction (XRD), inductive coupled plasma emission spectroscopy (ICP), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), transmission electron microscopy (TEM), etc. It was found that with the filling ratio of only 20 wt% and the thickness of 2.3 mm, the nanocomposite showed an ultra-wide effective absorption bandwidth (less than -10 dB) of 8.48 GHz (from 9.52 to 18.00 GHz) with the minimum reflection loss of - 24.29 dB. Compared to pure graphene sheets, Co0.33Ni0.33Mn0.33Fe2O4 nano particles and the counterparts reported in literature, the nanocomposite exhibited much better electromagnetic wave absorption, mainly attributed to strong wave attenuation, as a result of synergistic effects of dielectric loss, conductive loss and magnetic loss, and to good impedance matching. In view of its thin thickness, light weight and outstanding electromagnetic wave absorption property, the nanocomposite could be used as a very promising electromagnetic wave absorber.
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| 2. |
- Ye, Lei, et al.
(författare)
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Preparation of Metallized Pellets from Blast Furnace Dust and Electric Arc Furnace Dust Based on Microwave Impedance Matching
- 2020
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Ingår i: 11th International Symposium on High-Temperature Metallurgical Processing. - Cham : Springer Nature. - 9783030365400 - 9783030365394 ; , s. 569-579
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Konferensbidrag (refereegranskat)abstract
- Blast furnace dust and electric arc furnace dust are two typical solid wastes in iron and steel industry. In order to overcome the shortcomings of traditional processes, such as low metal recovery efficiency and high secondary pollution, microwave energy was applied in this study to intensify the self-reduction of core-shell BF dust-EAF dust composite pellets based on impedance matching for realizing highly efficient migration and separation of iron, zinc, and lead. By reducing the composite pellets in microwave field, it was found that under the optimal conditions of proportion of EAF dust in shell to all EAF dust in the pellet of 20%, reduction temperature of 1000 degrees C, and dwell time of 15 min, metallized pellets with the total iron content of 68.73 wt %, iron metallization degree of 95.87%, zinc removal percentage of 88.78%, lead removal percentage of 94.38%, and compressive strength of 190.4 N/p were obtained.
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| 3. |
- Ye, Lei, et al.
(författare)
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Toward environmentally friendly direct reduced iron production : A novel route of comprehensive utilization of blast furnace dust and electric arc furnace dust
- 2021
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456. ; 135, s. 389-396
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a novel method for producing direct reduced iron (DRI) powders based on microwave-assisted self reduction of core-shell composite pellets composed of blast furnace (BF) dust and hazardous electric arc furnace (EAF) dust followed by magnetic separation was reported. The proper core-shell structure of the composite pellets was designed according to the rule of impedance matching and properties of BF dust and EAF dust by adjusting the thickness of shell (i.e., thickness of impedance matching layer) via controlling the C/O molar ratio of the raw materials from 0.55 to 0.70. The results showed that the EAF dust with high content of CaO was beneficial to the mechanical strength of green, dried, and metallized pellets (collected after reduction), while the BF dust with high content of carbon enabled sufficient microwave-assisted reduction of the pellets, facilitating subsequent magnetic separation and also the removal of zinc from EAF dust. By reduction of the core-shell BF dust-EAF dust composite pellets with the C/O molar ratio of 0.65 at 1050 degrees C for 15 min, the resulting metallized pellets showed superior reduction and magnetic separation indexes with higher removal percentages of zinc and lead, in comparison with conventional metallized pellets. The DRI powders obtained after magnetic separation had total iron content of 91.2 wt%, iron metallization degree of 95.8%, yield of 68.1%, and iron recovery of 88.0%. This study provided a good example for efficient and environmentally friendly comprehensive utilization of typical and hazardous wastes in the iron and steel industry.
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| 4. |
- Ye, Qing, et al.
(författare)
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Microwave-assisted self-reduction of EAF dust-biochar composite briquettes for production of direct reduced iron
- 2020
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Ingår i: Powder Technology. - : ELSEVIER. - 0032-5910 .- 1873-328X. ; 362, s. 781-789
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Tidskriftsartikel (refereegranskat)abstract
- This study applied microwave energy for rapid self-reduction of electric arc furnace (EAF) dust-biochar composite briquettes to produce powdered direct reduced iron (DRI). based on the good electromagnetic response of EAF dust-biochar composite briquettes. The reduction experimental results showed that the iron-bearing components in the dust were reduced to metallic iron, leading to a high iron metallization degree of the reduced briquettes (94.7%). Meanwhile, the zinc-containing phases of EAF dust in the composite briquettes were converted to metallic zinc which then volatilized together with lead in the form of PbCl2. The volatilization percentages of zinc and lead were 99.6% and 92.9%, respectively, after reduction with the mass ratio of biochar to EAF dust of 0.25 and heating rate of 25 degrees C/min at 1050 degrees C for 15 min. By magnetic separation of the reduced briquettes, a magnetic concentrate with iron content of 91.32 wt% and recovery of 87.36% was obtained, meeting the quality requirements of DRI. (C) 2019 Elsevier B.V. All rights reserved.
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| 5. |
- Ye, Qing, et al.
(författare)
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Thermodynamic Analysis of Carbothermic Reduction of Electric Arc Furnace Dust
- 2019
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Ingår i: 10th International Symposium On High-Temperature Metallurgical Processing. - Cham : Springer International Publishing. - 9783030059552 - 9783030059545 ; , s. 117-124
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Konferensbidrag (refereegranskat)abstract
- Electric arc furnace (EAF) dust is a kind of secondary resource which contains multiple metallic elements, including Fe, Mn and Cr. Pyrometallurgical processes for recovering metal elements from EAF dust have been investigated for many years although they are suffered from high energy consumption due to the spinel-structured components of EAF dust. In this study, the thermodynamic analysis of carbothermic reduction of EAF dust was performed. The main components of EAF dust were magnetite (Fe3O4), hausmannite (Mn3O4) and chromate spinel (FeCr2O4). The gangue minerals were mainly composed of magnesium silicates. The thermodynamic analysis indicated that magnetite and hausmannite can be reduced to metallic iron and MnO, respectively. Meanwhile, the chromate spinel will be reduced to chromium oxide and then to form CaCr2O4. The results also demonstrated that the gangue components can promote the separation of Fe and Cr, agreeing well with the experimental results.
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