Abstract
In Polish coal mining the gravimetric dust sampling system has been obligatory since 1980, after a 5-year transition period between conimetric and gravimetric systems. The dust concentrations are measured in fixed points, mainly in outlet air stream in longwalls and on machine operator positions in headings. The dust sampler used is a gravimetric instrument, Barbara 3A, with an air flow of 5 L/min. The sample is taken on the membrane filter. Long-term observations showed that in almost 90 percent of longwalls and 80 percent of headings the dust concentration values are higher than allowable. The number of new cases of pneumoconiosis is about 600 to 900 every year. It appears that a new approach to the respirable dust problem is necessary. The Polish coal industry tends toward the calculation of individual dust loading. The preliminary estimations of differences between individual and fixed-point sampling were made with the use of the CIP-10 personal dust sampler. The goal of the measurement campaign was the determination of: (1) individual dust loading on typical workplaces in the longwall faces; (2) the influence of various dust sources on respirable dust concentrations in longwalls; and (3) the effectiveness of suppression methods. The results of the sampling in different longwalls and different positions are given. The following conclusions are drawn: (1) The respirable dust concentrations on various workplaces differ considerably from that measured at a fixed point 15 m from longwall outlet. (2) The maximum concentration appears in different longwall positions depending on local conditions.