Direct-on-Filter α-Quartz Estimation in Respirable Coal Mine Dust Using Transmission Fourier Transform Infrared...

Area of Science:

• Occupational Health and Safety
• Analytical Chemistry
• Mineralogy

Background:

• Silicosis is a significant health risk for miners, necessitating accurate measurement of airborne respirable crystalline silica (RCS).
• Current methods for RCS quantification involve multiple sample preparation steps, limiting field applicability.
• Fourier transform infrared (FT-IR) spectrometry is a potential tool for on-site analysis, but mineral interferences like kaolinite must be addressed.

Purpose of the Study:

• To evaluate the feasibility of a direct-on-filter (DoF) FT-IR method for end-of-shift measurement of α-quartz in coal mine dust.
• To compare two quantification approaches, ordinary least squares (OLS) and partial least squares (PLS) regression, for RCS determination.
• To assess the efficacy of these methods in the presence of kaolinite, a common confounding mineral.

Main Methods:

• Analysis of 66 coal mine dust samples using FT-IR transmission spectrometry.
• Quantification of RCS using an OLS calibration approach, similar to the MSHA P7 method.
• Quantification of RCS using a PLS regression approach.
• Evaluation of both methods' ability to account for kaolinite interference.

Main Results:

• Both OLS and PLS methods successfully accounted for kaolinite interference.
• The OLS method showed good correlation with P7 results but was limited by kaolinite presence.
• The PLS approach demonstrated better accuracy and no bias due to kaolinite, correlating well with the P7 method.
• PLS showed decreased sensitivity to mineral and substrate confounders, simplifying analysis.

Conclusions:

• FT-IR spectrometry is effective for silica determination in coal mine dust, even with kaolinite present.
• The PLS regression method is a promising approach for automated, accurate, and field-deployable RCS measurement.
• This DoF FT-IR method, particularly using PLS, could enhance miner safety by enabling rapid on-site monitoring and reducing silicosis risk.