On the Occurrence and Persistence of Coal-Mineral Microagglomerates in Respirable Coal Mine Dust

A previous effort to characterize respirable coal mine dust in 16 US mines turned up a curious finding: particle-based analysis using scanning electron microscopy (SEM) tended overpredict the abundance of sourced from rock strata, and underpredict coal, when compared mass-based thermogravimetric (TGA). One possible explanation is occurrence coal-mineral microagglomerates (MAGs). Coal particles covered with fine mineral could be mostly by mass but classified as minerals SEM due their surface elemental content. In current study, subset previously analyzed samples was re-examined, images mapping showed that MAGs are indeed present. Furthermore, were created sampled passively laboratory, demonstrating MAG formation can occur generation processes sampling environment, rather than mere artifact procedures. Finally, experiments conducted evaluate dispersibility liquid suspensions, which might shed some light on fate upon inhalation. Results indicated sonication deionized water effective for dispersion, solution mimics natural lung surfactant also appeared enhance dispersibility. An understanding important terms exposure assessment.