Fly ash utilization for the development of low NOx bed materials

Screening tests for NO catalytic decomposition and NO catalytic reduction by CO on a series of fly-ash-derived materials have been carried out at FBC temperatures in a fixed bed quartz reactor. The samples prepared directly from biomass fly ashes appeared to have very high catalytic effects toward NO reduction by CO. Meanwhile, no activity was observed for catalytic decomposition of NO on the tested samples. © Tran et al.; Licensee Bentham Open

X-ray fluorescence tomography of individual waste fly ash particles

Fluorescence tomography is a non-destructive, non-invasive technique that provides information about the internai spatial distribution of each element that emits a detectable fluorescence signal from the measured slice of the sample. The reconstruction proMem for fluorescence tomography is much more difficult than it is for transmission tomography, due to the absorption of thé photons within the excitation and détection paths. The present work présents a reconstruction technique that is based on the SART (Simultaneous Algebraic Reconstruction Technique) algorithm, which has been modified in order to take into account absorption corrections. This technique has been applied to the analysis of individual waste fly ash particles of about 80-150 micron diameters, which have been scanned using an X-ray beam of V*H=2*5 pjn spot-size and placing an energy dispersive Si (Li) X-ray detector at 90 degrees to the incoming excitation beam. From previous scanning i-SRXRP measurements it is clear that the elemental distribution within individual fly ash particles is highly inhomogeneous but no information could be obtained on the location of the différent investigated elements (within/on the surface of the particle). On the other hand thé location of toxic elements within individual fly ash particles affects the possible fate of thèse elements during e.g. fly-ash recycling. Thus the aim of this study was to investigate the 2D interna) elemental distribution of the particles, with spécial attention to that of the toxic metals, such as Zn, Cd, Pb

X-ray fluorescence tomography of individual municipal solid waste and biomass fly ash particles

Information about Cd distribution inside single municipal solid waste and biomass fly ash particles is fundamental since it affects its leachability. The internal 2D distributions of the main and trace elements in such highly inhomogeneous matrixes were successfully determined by means of the combined synchrotron radiation induced micro X-ray fluorescence (μ-SRXRF) and tomography (μ-SRXRFT) techniques. Scanning μ-SRXRF measurements show Cd elemental distribution within single fly ash particles to be inhomogeneous, but no information can be obtained about its internal distribution. During μ-SRXRFT analysis, single fly ash particles are successively measured by a rotational-translational scan in a VH = 2 × 5 μm2 microbeam. The 2D internal elemental distribution images, obtained by the modified simultaneous algebraic reconstruction technique algorithm, provide the size and the location of Cd-containing areas together with the location of other measurable elements. Results showed Cd concentration to be higher in the core of the fly ash particles analyzed rather than on the surface of the particles. Moreover, in both ashes, Ca-containing matrixes are found to be the main Cd-bearing phases. A possible mechanism for Cd adsorption on the fly ash particles is proposed based on the obtained results