Respirable silica particles in coal mine dust: image library
This dataset comprises an image library and corresponding elemental data for 282 respirable silica particles. The particles were identified in samples of respirable coal mine dust (RCMD) collected in a group of US underground mines, and samples of lab-generated respirable dust that were created using the primary dust source materials obtained from those mines. Details regarding sample collection are given in [1,2]. A limited number of particles were also identified in samples generated from silica-containing reference materials, namely: Min-U-Sil 5 or Sil-Co-Sil (US Silica, Katy, TX; these are high purity quartz products), VCAS-160 (Vitro Minerals, Jackson, TN, USA; this is a high purity aluminosilicate glass powder), and Ball Clay (The Ceramic Shop, Norristown, PA, USA; this is an aluminosilicate powder that has moderate silica content). The dataset can inform the understanding of real respirable silica particles in coal mine environments, including their texture and morphology, variation in aluminum content between the particle surface and core, and association with other particles (e.g., as agglomerates). The Respirable Silica Particle Image Library (.docx file) is presented in a single table, formatted with two columns (i.e., such that two particles are presented per row.) For each particle, a pair of SEM images (micrographs) is shown; one image was captured at 5 kV and the other at 20 kV, and Si (green) and Al (red) maps overlaid are overlaid. Additionally, the sample identifiers and the particle number are reported, along with the SEM magnification and the measured Si and Al% at 5 and 20 kV. If only one silica particle in the image was analyzed, the image is centered on that particle; if multiple particles were analyzed, the particle for which elemental values are reported is marked with +. (Sample identifiers include: Type (all samples) = respirable coal mine dust “RCMD”, lab-generated respirable sample from mine dust “source” material, or lab-generated respirable sample from “reference” material; Mine (RCMD and source samples) = mine number between 10-24; Location (RCMD samples) = intake, production, roof “bolter”, “feeder” breaker, or return; Source for source samples = run-of-mine coal “ROM coal”, ROM rock, bolter dust or rock dust; Material (reference samples) = Min-U-Sil 5 or Sil-Co-Sil, VCAS-160, and Ball Clay.) The associated Normalized Atomic % Values table (.xlsx file) gives elemental data (i.e., % O, Al, Si, C, Mg, Ca, Ti, Fe) at both 5 and 20 kV for each of the 282 silica particles included in the library. Data can be cross-referenced to the library by particle number and sample identifiers. References  C. Keles, N. Pokhrel, E. Sarver, A study of respirable silica in underground coal mines: Sources. Minerals. 12 (2022) 1115. https://doi.org/10.3390/min12091115  C. Keles, E. Sarver A Study of Respirable Silica in Underground Coal Mines: Particle Characteristics. 12 (2022) 1555. https://doi.org/10.3390/min12121555
Steps to reproduce
All data was collected using a FEI Quanta 600 FEG environmental scanning electron microscope (ESEM) (Hillsboro, OR, USA) equipped with a backscatter electron detector (BSD) and a Bruker Quantax 400 EDX spectroscope (Ewing, NJ, USA), and Bruker Esprit software (version 1.9.4). Silica particle identification was done directly on the sample filter at 15 kV and magnification of 5000x per the method described in . Then, each silica particle was imaged and analyzed at both low (5 kV) and high (20 kV) accelerating voltage. For this, SEM micrographs were captured at high magnification (i.e., 5,000-20,000×) and overlaid with elemental maps to visually indicate relative Si and Al content; and spectra were also collected to determine Si and Al % in each particle (normalized atomic % considering eight elements: C, O, Al, Si, Ca, Mg, Fe, Ti).