Development of a Portable Coal Dust Analyzer for Silica by Laser Induced Breakdown Spectroscopy

Christopher B. Stipe (1), Arthur L. Miller (2), Gregg A. Lithgow (3), and Steven G. Buckley (3)

(1) Seattle University (2) National Institute for Occupational Health and Safety (3) Photon Machines, Inc.

     Abstract Number: 464
     Last modified: May 12, 2010

Abstract
Exposure of mine workers to crystalline silica dust can lead to silicosis, which is an incurable and often fatal lung disease. Currently, silica in coal dust is measured by method MSHA P7, which is a lab based infrared absorption technique requiring filter samples from a gravimetric dust sampling system. In our study, laser induced breakdown spectroscopy (LIBS) was performed on coal dust laden filter samples to quantify the concentration of silica. LIBS is advantageous in that it can be performed on-site as a field portable instrument with little sample preparation. A calibration curve for silica was obtained by measuring known concentrations of pure silica. Silica in kaolinite, a clay deposit often interbedded within coal layers and a potential interference source of silica, was accounted for using a correction factor based on the ratio of aluminum to silicon peaks. Five loadings (six replicates) of coal dust were measured and a detection limit below 0.7 micro-g/cm2 was attained.