Review of Respirable Coal Mine Dust Characterization for Mass Concentration, Size Distribution and Chemical Composition

Abstract

Respirable coal mine dust (RCMD) exposure is associated with black lung and silicosis diseases in underground miners. Although only RCMD mass and silica concentrations are regulated, it is possible that particle size, surface area, and other chemical constituents also contribute to its adverse health effects. This review summarizes measurement technologies for RCMD mass concentrations, morphology, size distributions, and chemical compositions, with examples from published efforts where these methods have been applied. Some state-of-the-art technologies presented in this paper have not been certified as intrinsically safe, and caution should be exerted for their use in explosive environments. RCMD mass concentrations are most often obtained by filter sampling followed by gravimetric analysis, but recent requirements for real-time monitoring by continuous personal dust monitors (CPDM) enable quicker exposure risk assessments. Emerging low-cost photometers provide an opportunity for a wider deployment of real-time exposure assessment. Particle size distributions can be determined by microscopy, cascade impactors, aerodynamic spectrometers, optical particle counters, and electrical mobility analyzers, each with unique advantages and limitations. Different filter media are required to collect integrated samples over working shifts for comprehensive chemical analysis. Teflon membrane filters are used for mass by gravimetry, elements by energy dispersive X-ray, rare-earth elements by inductively coupled plasma-mass spectrometry and mineralogy by X-ray diffraction. Quartz fiber filters are analyzed for organic, elemental, and brown carbon by thermal/optical methods and non-polar organics by thermal desorption-gas chromatography-mass spectrometry. Polycarbonate-membrane filters are analyzed for morphology and elements by scanning electron microscopy (SEM) with energy dispersive X-ray, and quartz content by Fourier-transform infrared spectroscopy and Raman spectroscopy.

Particle size and mineralogy distributions in respirable dust samples from 25 US underground coal mines

“…Though these finer particles might contribute relatively little to the respirable dust mass, at high number concentrations their increased surface area could have significant implications for exposure response (Oberdörster et al, 2005;Mischler et al, 2016;Riediker et al, 2019;Zhang et al;. Data on dust constituents and particle sizes is not only critical for informing engineering and administrative controls and monitoring programs in mines, but also the understanding of health outcomes (National Academies, 2018; Abbasi et al, 2021). However, most available data on respirable coal mine dust stems from regulatory compliance sampling efforts, which are practically limited to mass-based measures.…”

“…1 Due to non-normal distributions, data in the following classes was transformed using the cube root: ASK, ASO, SLO, S, M, CB, O…”

Respirable Coal Mine Dust: A Review of Respiratory Deposition, Regulations, and Characterization

“…For example, Polycarbonate-membrane (PC) filter is used for morphological and elemental analysis by scanning electron microscopy (SEM). Quartz fiber filter is used for organic analysis of RCMD, or Teflon filter is used for mineralogic analysis by X-ray diffraction (XRD) [112]. The efficiency captured by collector should be maximum for those filters since the total mass of the RCMD collected on a filter is assumed to all become the miner's exposure dose.…”

Geochemical and Morphological Evaluations of Organic and Mineral Aerosols in Coal Mining Areas: A Case Study of Santa Catarina, Brazil

“…Several studies have previously signaled that transitional elements such as bioavailable iron or nickel are culpable for the incidence of severe health problems [13][14][15][16]. However, the precise chemical nature and compositional information about the materials inhaled in coal mining areas remain scanty [17][18][19]. This knowledge gap is mainly because most published works on coal and potentially hazardous elements (PHEs) geochemistry focus on the toxic emissions and residues produced during combustion in coal power plants [19,20].…”