Coal Mine Dust Mitigation through Novel Scrubber Development and Numerical Modeling

Dust generation resulting from mining activities remains a problem, particularly in underground coal mines. Coal dust is both a health and safety hazard. Coal Worker’s pneumoconiosis (CWP), colloquially known as ‘black lung’, is a chronic respiratory disease resulting from extended exposure to respirable coal dust. Measures to mitigate CWP, resulting from the Federal Coal Mine Health and Safety Act of 1969 (Public Law 91-173, 1969), have significantly reduced the incident rates over the last four decades. Continuing efforts are needed to control this hazard. A recent study by the National Institute for Occupational Safety and Health (NIOSH, 2008) highlighted the ongoing health hazards that remain within the coal mining industry due to respirable dust. Aside from being a health hazard, coal dust can form explosive mixtures when mixed with air and possibly methane, posing a potentially catastrophic safety hazard. Dust generated through mining activities, when not captured at the source, is advected through the ventilation airways. This dust settles onto all surfaces of the mine ventilation airways. The significant safety hazard comes when insufficient rock dust is applied to those same surfaces. The forces resulting from a methane ignition can disturb this dust causing it to participate in and greatly enhance the destructive impact of the explosion. Such an event occurred at the Upper Big Branch Mine explosion according to the forensics report (U.S. Department of Labor, 2011). The problem of dust in underground coal mines is being addressed in this research through two means. The first method is removal of the dust with a scrubber and the second method is numerical modeling of the migration of dust through the mine ventilation network. The removal of coal dust from the air at the face mitigates the probability of two major health and safety hazards. For dust that remains in the air, it is necessary to understand the manner in which it flows through the ventilation network and becomes deposited to the surface of the mine ventilation airways. This understanding would provide guidance for appropriate rock dusting protocols. The objective of task 1 of this research proposal is the control of dust generated at the working face of an underground coal mine. This will be accomplished through the adaptation of the vortecone wet scrubber for coal dust. Though originally developed for removal of paint dust in automotive factories, it offers several compelling advantages over Campbell-type flooded-bed dust scrubbers, such as lower power requirements, higher cleaning efficiency and extended time between service and maintenance. The goal of this task is to identify the necessary modifications to the vortecone wet scrubber design to remove coal dust from the air through computational fluid dynamics modeling and physical prototyping. The objective of task 2 of this research proposal is to predict the flow of dust through the mine ventilation system and the manner in which it deposits on the surface of the airways. This will be accomplished through field surveys of dust conditions in underground coal mines, including dust concentration measurements and the settling rate on surfaces. The data obtained will be incorporated in a network ventilation model that includes the influences of flow through the network and settling. The goal of this task is to develop a network ventilation model that predicts dust concentration levels deposited to the surfaces to provide guidance for rock dusting protocols.