Relationship between Area Concentrations and Personal Exposures along Longwall Faces

Abstract

In underground coal mining, the preference for ambient atmospheric dust control and area sampling in comparison to administrative dust control and personal sampling for the assessment of a mine worker's dust exposure is becoming evident. However, the relationship between area concentration and the concentration to which a mine worker is exposed is not fully determined. Among the important issues to be resolved are the locations of these area samplers and the allowable concentrations at these locations. In this article the relationship between area concentration and personal exposure in longwall faces is explored with data from several in-mine studies. Among the conclusions of this study are the following: while the dust weight on the personal sampler filter increases as sampling time increases, the concentrations at the tailgate at longwall faces level off after several hours of sampling. There appears to be no direct relationship between the dust concentration of the shearer operator and the concentration at the tailgate of the face. A major reason for this may be that the shearer operator is working in an area where the air flow contains less dust and/or his use of remote control equipment allows him to work away from the major dust generation source that contributes to the tailgate dust concentration. The exposure of the shearer operator may be estimated as the average of the concentrations observed at three stationary locations in the face. The airborne dust concentration appears to be independent of the production from the shearer. Since the operating conditions change from shift to shift or even within a shift, a good method for evaluating the relationships between area concentration and personal exposure may be studying these relationships in a computer-oriented simulation model for the various conditions.