Mining Contract: Size-dependent Metric Analysis of Respirable Coal Mine Dust (RCMD)

Contract #	75D30122C14732
Start Date	9/15/2022
Research Concept	The metrics of respirable coal mine dust (RCMD) particles, such as particle size and elemental composition, have been determined by imaging individual particles on polycarbonate or polyvinyl carbonate filters using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry. The scanning electron microscopy method enables a characterization of dust particles down to a top size of 600 nanometers. Below that size range, particle characterization is challenging. To continue characterization of RCMD, obtaining samples of RCMD at operating coal mines are necessary. One easy method to potentially obtain a large number of samples is to collect filters used in continuous personal dust monitors (CPDM). Today, continuous personal dust monitor (CPDM) devices are routinely used in underground coal mines, and dust-loaded CPDM filters are available after each shift. They are normally discarded after compliance checks. However, metric analysis of dust particles collected on CPDM filters could provide broad but useful information on dust compositions at various underground coal mines.
Topic Areas	Respirable Dust Respiratory Diseases

Contract Status & Impact

This contract is ongoing. For more information on this contract, send a request to mining@cdc.gov.

The first objective of this contract research is to develop a beyond-compliance approach of characterizing size-dependent metrics of RCMD particles and address one recommendation by the National Academies of Sciences (NAS) committee on particle size information of RCMD particles. The metrics of RCMD particles include particle size information as well as elemental and mineral compositions at different size fractions.

The second objective is to develop a protocol for the characterization of RCMD particles collected on CPDM filters that are normally discarded after each shift. The goal is to generate a large quantity of datasets on the metrics of RCMD from various operating underground coal mines in the United States.

These objectives will be pursued by way of accomplishing the tasks described below.

A literature review will be conducted on previous work on surface analysis of CPDM-tapered element oscillating microbalance (TEOM) filters. A report will be generated, to include the planned protocol for direct on-filter analysis and indirect dispersed-particle analysis. Because TEOM filters are not enclosed and are subjected to contamination as well as a loss of dust particles, a customized cap will be fabricated using a 3D printer. This cap will be developed and tested, and the mass loss of dust particles during the sample transportation will be evaluated.
For direct on-filter analysis, SEM and micro X-ray fluorescence and other appropriate methods will be used to determine the ability to characterize the particles on the CPDM TEOM filters. This work will be performed at University of Utah, Michigan Tech, and Virginia Tech to develop initial protocols for analysis.
For indirect dispersed-particle analysis, a non-destructive dispersion of particles from CPDM TEOM filters in the aqueous solutions will be conducted. An initial protocol will be developed to disperse particles in aqueous solutions. Success will be measured by the ability to disperse sufficient particles without loss of materials from the CPDM TEOM filters (i.e., at least 90% of material will be removed from the TEOM filter), and without contamination of quartz fibers from the filters.

These primary tasks will be followed by a report and the completion of other related tasks, with the ultimate goal being to develop a protocol that enables a recovery of dust particles from CPDM filters and a determination of metrics for the dust particles collected on those filters. Results from this work will provide information on elemental and mineralogical compositions of RCMD collected from different underground coal mines as well as information on silica and silicate content and soluble minerals content in various dust samples from different coal mines.