AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Size-Segregated Chemical and Morphological Analysis of Three Gold Mine Dusts
Lauren Chubb, EMANUELE CAUDA, Traci Lersch, Gary Casuccio, NIOSH
Abstract Number: 638 Working Group: Health Related Aerosols
Abstract Characterization of physicochemical attributes of discrete size ranges of mine-generated dust can facilitate the development and improvement of monitoring techniques and control technologies with regard to crystalline silica exposure. Detailed characterization of size-segregated airborne dust as well as of individual particles can be accomplished using a combination of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS).
Three gold mine dusts were each aerosolized in a calm air chamber and their size distributions characterized via aerodynamic and scanning mobility particle sizers (APS, SMPS). Particles were size-segregated using a ten-stage micro-orifice uniform deposit impactor (MOUDI). Samples were collected on PVC filters for the quantification of silica via FTIR and XRD analyses, and on Nuclepore filters or copper mesh carbon film TEM grids for single particle analysis of morphology and elemental composition via SEM-EDS. An automated SEM-EDS method facilitated the analysis of approximately 1500 particles on each MOUDI stage, in contrast to manual acquisition where significantly fewer particles could be analyzed in a similar period of time. The automated approach yields a more complete data set that is representative of the particular dust and size fraction, and enables comparison between characteristics of silica-containing particles and non-silica-containing particles from each size fraction.
Initial FTIR and XRD results indicate that silica is not uniformly distributed in all size ranges of dust particles, and comprises a higher proportion of some size fractions than of others; the contribution will give comparisons of this trend across the three different dusts. SEM-EDS analysis is underway, and the contribution will summarize single-particle elemental composition and morphological characteristics for each size fraction, highlighting characteristics that distinguish silica from non-silica particles.