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Emerald Mine field study, NIOSH closing report 10/09/1998; utilizing multiple tracer gas releases to define air movement in gob areas.

Diamond P; Schatzel S; Farcia F; LaScola J; McCall F; Jeran P
NIOSH 1998 Oct; :1-69
A study designed to investigate airflow in longwall gob areas utilizing tracer gas was initiated at Cyprus Emerald Resources Corporation's Emerald Mine with an "Opening Meeting" on March 31, 1997. The objective of the Emerald Mind tracer gas study was to measure gas migration characteristics associated with long wall gobs for use in optimizing methane control strategies. This objective was approached in two ways utilizing tracer gas releases from various locations within the mine environment. The first investigated communication (or the lack there or) between gob gas ventholes and the ventilation system, and between individual god gas ventholes on the same long wall panel. The second determined the overall distribution pattern and average velocities of the tracer gas movement in the gob and old workings. The general concept of the gas flow characterization experiments is to release a defined volume of tracer gas into the ventilation airflow or long wall gob, and then monitor (obtain gas samples) all potential exit points for the gas. By determining the tracer gas concentration (if any) in the periodic gas samples taken at the various monitoring locations, and measuring the associated gas flow rate, the volume of tracer gas passing though each monitoring site can be calculated. Thus, the relative distribution of gas flow to the various outlet points can be determined. The velocities associated with the identified gas flow pathways can be calculated knowing the path length and travel times (first arrival, peak concentration, and tail) for tracer gas flow at each monitoring location. These are the basic gas flow characterization data required for optimizing longwall god methane control strategies. For the underground releases, most of the ventilation air was expected to flow to one or both of the bleeder fans. In addition to monitoring the bleeder fans, operating gob gas ventholes that were in the vicinity of the expected general flow path for the ventilation airflow towards the bleeder fans were also monitored. Therefore, monitoring location for the borehole injection experiment included the other two producing gob gas ventholes on the study panel, one venthole on the previously mined panel to the north, the two bleeder fans, and underground locations which would intercept any tracer gas that might migrate towards the main fan shaft.
Gas-sampling; Ventilation; Airflow; Air-sampling-pump; Underground-tracer-gas; Borehole-injection
Publication Date
Fiscal Year
NIOSH Division
Priority Area
Other Occupational Concerns
Source Name
National Institute for Occupational Safety and Health
Page last reviewed: October 1, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division