Particle size distributions in underground coal mines

Area of Science:

• Occupational Health and Safety
• Environmental Science
• Mining Engineering

Background:

• Underground coal mining generates respirable dust, posing significant health risks to workers.
• Accurate characterization of particle size distribution is crucial for assessing inhalation exposure and implementing effective controls.

Purpose of the Study:

• To determine particle size distributions in underground coal mines.
• To evaluate the effectiveness of newly developed personal cascade impactors for sampling airborne particles.

Main Methods:

• A sampling program was conducted by the National Institute for Occupational Safety and Health (NIOSH).
• Newly developed cascade impactors, compatible with personal sampling pumps, were utilized.
• Particle size distribution samples were collected from 10 continuous mining sections across three states.

Main Results:

• Mass frequency distributions indicated a potential bimodal particle size distribution.
• A primary size mode of approximately 17 microns was consistently measured.
• A secondary size mode of approximately 5 microns was also consistently measured, particularly away from continuous miner operations.

Conclusions:

• The study identified distinct particle size modes in underground coal mine environments.
• The findings suggest that particle generation sources may differ depending on proximity to mining machinery.
• The results provide valuable data for understanding worker exposure to airborne particulates in coal mines.