| 1. |
- Fahimi, A., et al.
(author)
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Poultry litter ash characterisation and recovery
- 2020
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In: Waste Management. - : Elsevier Ltd. - 0956-053X .- 1879-2456. ; 111, s. 10-21
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Journal article (peer-reviewed)abstract
- This paper reports a complete characterisation of poultry litter ash and its potential use as a heavy metal stabiliser. We propose a novel approach, in which the ashes deriving from municipal solid waste incineration (MSWI) are combined with poultry litter ash, rather than with coal combustion flue gas desulfurisation (FGD) residues. Heavy metals stabilisation was demonstrated by comparing the elemental concentrations in the leaching solutions of the starting raw and stabilised materials: leachable Pb and Zn showed a reduced solubility. The characterisation was conducted by total reflection X-ray fluorescence (TXRF), X-ray diffraction (XRD), micro-Raman spectroscopy and scanning electron microscopy combined with energy-dispersive X-ray spectrometry (SEM-EDX). The results showed that the poultry litter ash was Ca-, P-, K- and S-rich (>29 g/kg). It contained amorphous materials (i.e. fly ash economiser (FAECO) 73% and fly ash cyclone (FACYC) 61%) and soluble phases (e.g. arkanite and sylvite; up to 13% FAECO and 28% FACYC), as well as resilient crystalline (up to 2% of FAECO and FACYC) and amorphous phases (e.g. hydroxyapatite). After two months, the Pb and Zn concentrations in the leachate solutions were below the limit set by the European regulations for waste disposal (<0.2 mg/L and 1.5 mg/L, respectively). We propose a mechanism for the heavy metals stabilisation based on the carbonation process and high amounts of P, Ca and reactive amorphous phases. In conclusion, it is demonstrated that poultry litter ash can be an effective secondary source of heavy metals, allowing their immobilisation through P- and Ca-based reactive amorphous phases.
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| 2. |
- Fu, Yifeng, 1984, et al.
(author)
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Templated Growth of Covalently Bonded Three-Dimensional Carbon Nanotube Networks Originated from Graphene
- 2012
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In: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 24:12, s. 1576-1581
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Journal article (peer-reviewed)abstract
- A template-assisted method that enables the growth of covalently bonded three-dimensional carbon nanotubes (CNTs) originating from graphene at a large scale is demonstrated. Atomic force microscopy-based mechanical tests show that the covalently bonded CNT structure can effectively distribute external loading throughout the network to improve the mechanical strength of the material.
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| 3. |
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| 4. |
- Ye, Guozhu, et al.
(author)
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Association of halogens in electric arc furnace dust and zinc oxide fume before and after leaching
- 1999
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In: REWAS '99. ; , s. 1503-1510, s. 1503-1510
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Conference paper (peer-reviewed)abstract
- Pilot-scale tests were conducted at MEFOS for the production of zinc oxide from Electric Arc Furnace (EAF) dust using a DC arc furnace with a hollow electrode suitable for the processing of fine-grained materials. The association of halides in Electric Arc Furnace (EAF) dust and zinc oxide fume before and after water leaching was investigated by XRD, SEM, and TEM analysis. In EAF dust, chlorine and fluorine were found to exist primarily as NaCl, KCl, and CaF2. After water leaching of the zinc oxide fume the halide concentrations were reduced to about 200 ppm Cl and 200 ppm F, mostly in the form of CaF2 and chlorine-containing silicate phases.
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| 5. |
- Ye, Guozhu, et al.
(author)
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Elimination of zinc ferrite for hydrometallurgical recovery of zinc from EAF dust
- 2006
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In: 2006 TMS Fall Extraction and Processing Division: Sohn International Symposium. - 0873396332 - 9780873396332 ; , s. 397-411
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Conference paper (peer-reviewed)abstract
- Hydrometallurgical zinc recovery from EAF dust has several advantages compared to pyrometallurgical alternatives in terms of low temperature operation, lower energy consumption and higher flexibility. Many hydrometallurgical processes have been suggested and tested over the years without success. The main reasons are: - Low leaching yield of zinc due to the fact that a high fraction of ZnO in the EAF dust exists in the zinc ferrite structure which makes selective leaching of ZnO not possible - Many of the proposals could not handle the halide in the EAF dust To eliminate these two disadvantages, two zinc ferrite elimination concepts have been tested and developed in the REZIN project of the EU 5 th Framework Programme. The two concepts for zinc ferrite elimination could be shortly described by the following chemical reactions: A. ZnOFe 2O 3 + 2CaO = Ca 2Fe 2O 5 + ZnO free B. ZnOFe 2O 3 + C = Fe met + CO/CO 2 + ZnO free These two concepts were investigated in details in combination with a subsequent leaching step using the novel EZINC process for recovery of zinc from EAF dust. Leaching of pretreated samples has shown great increases of a zinc recovery yield. A zinc recovery of over 90 % could be reached, as compared to about 50 % for no-pretreated samples. This paper will describe the two concepts in details.
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