Analysis of Pulverized Coal by Laser-Induced Breakdown Spectroscopy

Abstract

Laser-induced breakdown spectroscopy (LIBS) has been used to detect atomic species in various environments. The quantitative analysis (C, H, 0, N and S) of representative coal samples are being carried out with LIBS, and the effects of particle size are analyzed. A powerful pulse Nd:YAG laser is focused on the coal sample at atmosphere pressure. and the emission spectra from laser-induced plasmas are measured by time-resolved spectroscopy, and the intensity of analyzed spectral lines is obtained through observing the laser plasma with a delay time of 0.4 ps. The experimental results show that the slope of calibration curve is nearly 1 when the concentration of the analyzed element is relatively low, and the slope of curve is nearly 0.5 when the concentration of C is higher than other elements. In addition, using the calibration-free model without self-absorption effect, the results show that the decreasing of particle size leads to an increase of the plasma temperature.

Semi-quantitative analysis of metal alloys, brass and soil samples by calibration-free laser-induced breakdown spectroscopy: recent results and considerations

“…The analysis of pulverized coal for the elements C, H, O, N and S has been reported by Liangying et al, 16 where the dependence of the particle size was also investigated. Finally, in a recent paper, 17 Wang et al described a variant called ''controlled calibration LIBS'' in which the concentration of the elements can be calculated from a reference element whose concentration is known.…”

“…6,7 Since its inception, the CF-LIBS approach, as well as more or less sophisticated variants of it, have been applied by several research groups to the analysis of different types of samples of varying degrees of complexities. [8][9][10][11][12][13][14][15][16] One of the first applications of the CF-LIBS technique dealt with the analysis of aluminum alloys and ambient air. 6,7 All the elements in the Al alloy were detected and quantitatively determined in a wide dynamic range from 250 ppm Cu up to 96% Al, with errors ranging from 0.4% (Al), 38% (Si) and 2-55% (minor sample components).…”

Application of laser-induced breakdown spectroscopy to the analysis of secondary materials in industrial production

“…Coarse-grained powders have been analyzed directly by LIBS without pressing the sample material into pellets or fi xing the powder on a supporting tape. Examples are powders of CaCO 3 , KBr (particle diameter up to 0.1 mm), and coal (Rusak et al , 1997;Oki et al , 2004;Liangying et al , 2005). Plate VIII (see color section between pages 278 and 279) shows optical photographs of the laser-induced plasma and the laser-induced ejection of particles from the loose Fe 2 O 3 powder target ).…”

Examination of the capability of the laser-induced breakdown spectroscopy (LIBS) technique as the emerging laser-based analytical tool for analyzing trace elements in coal

“…Several works on the application of LIBS to coal analysis has been reported [6][7][8]. However, the works mostly dealt with major and minor constituents, not trace element.…”