PURPOSE:  The objective of this research project is to lower the risk of developing debilitating lung diseases by reducing respirable dust exposure to mine workers at longwall mining operations.

RESEARCH SUMMARY:  Longwall mining operations now account for approximately 51% of the coal produced underground in the United States. Unfortunately, substantial increases in coal extraction rates also result in the generation of more respirable dust. From 1996 through 2000, compliance dust samples exceeding the federal dust standard of 2.0 mg/m3 were 18% and 15% for jack setters and shearer operators, respectively. Health surveillance data also indicates that overexposure to respirable dust in underground coal mines continues to lead to the development of lung disease.

Laboratory research has been conducted to evaluate and optimize control parameters that impact dust generated by the shearer. These results provide operators with guidance on dust control resulting from changes in face air velocity, water spray pressure, water quantity, spray system design and cutting direction. Additional laboratory testing will be conducted to optimize external sprays system designs for high coal operations.

Laboratory testing has also been completed to evaluate shield dust entrainment in high velocity airstreams up to 2000 fpm. Results have shown that significant increases in respirable dust levels were observed as air velocity increased. Future tests will evaluate the ability of water sprays to reduce respirable dust entrainment in these high velocity airstreams.

Benchmarking surveys have been conducted on six longwall faces across the country to quantify dust levels from various sources, define current operating practices, and determine the relative effectiveness of existing control technologies. Four additional surveys will be completed and a “best practices” document produced to assist operators in applying effective control technologies.

Successful completion of this research project will result in developing improved dust control technologies/practices that can be adopted by longwall operators throughout the United States. The goal is to reduce dust exposure of longwall mine workers by 30% over a 5-year period as these controls are implemented.