Abstract
Respirable coal mine dust (RCMD) particles, particularly the nano-sized fraction (<1 μm) of the RCMD if present, can cause severe lung diseases in coal miners. Characterization of both the particle size and chemical composition of such RCMD particles remains a work in progress, in particular, with respect to the nano-sized fraction of RCMD. In this work, various methods were surveyed and used to obtain both the size and chemical composition of RCMD particles, including scanning electron microscopy (SEM), scanning transmission electron microscopy (S-TEM), dynamic light scattering (DLS), and asymmetric flow field-flow fractionation (AsFIFFF). It was found that the micron-sized fraction (>1 μm) of RCMD particles collected at the miner location, from an underground coal mine, contained more coal particles, while those collected at the bolter location contained more rock dust particles. Two image processing procedures were developed to determine the size of individual RCMD particles. The particle size distribution (PSD) results showed that a significant amount (~80% by number) of nano-sized particles were present in the RCMD sample collected in an underground coal mine. The presence of nano-sized RCMD particles was confirmed by bulk sample analysis, using both DLS and AsFIFFF. The mode particle size at the peak frequency of the size distribution was found to be 300–400 nm, which was consistent with the result obtained from SEM analysis. The chemical composition data of the nano-sized RCMD showed that not only diesel particles, but also both coal and rock dust particles were present in the nano-sized fraction of the RCMD. The presence of the nano-sized fraction of RCMD particles may be site and location dependent, and a detailed analysis of the entire size range of RCMD particles in different underground coal mines is needed.
Highlights
In the coal mining industry, respirable coal mine dust (RCMD) is generated during mining operations [1]
Individual dust particles deposited on the filter were characterized for chemical composition using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX)
The results indicate that the RCMD samples consisted of, micron-sized dust particles, and nano-sized dust particles
Summary
In the coal mining industry, respirable coal mine dust (RCMD) is generated during mining operations [1]. The Mine Safety and Health Administration (MSHA) in the United States set a lower respirable dust standard of 1.5 mg/m3 for underground coal mining operations Compliance with this standard is monitored through periodic collections of occupational dust samples. The conventional sampling approach uses a gravimetric-based device that collects the respirable fraction of the coal mine dust particles. The collected coal dust samples were characterized to determine both the size and composition of individual dust particles using scanning electron microscopy (SEM) and scanning transmission electron microscopy (S-TEM). Imaging and elemental composition analyses of dust particles on the filters were conducted using scanning electron microscopy (SEM). The particle size and chemical composition of individual dust particles on the filters were determined using SEM coupled with energy-dispersive X-ray spectroscopy (EDX). The others were particles that contained heavy metals, such as iron
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
