Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Dust sampling strategy for drivages

Trials were carried out to determine whether the assumptions made in the original evolution of the dust sampling strategy for drivages, in the early 1970s, were still valid in view of the vast changes in mining techniques and practices to the present day. Underground trials were carried out at a total of 14 sites, representing the various layouts of ventilation systems, roadway profiles and types of machine in normal use. The overall results from the present trials generally confirmed the findings of the original trials: that with the large day to day and site to site variations, no one sampling position close to the face of the drivage could be statistically shown to be associated with significantly higher dust concentrations than any other. However, it was found that an instrument sited on the machine, beside the machine driver, tended to give marginally higher readings than the Routine instrument. Observations of the dust behaviour also suggested that very localised dust backup could also play a part in the differences between the two positions at some sites. It was therefore concluded that an on machine instrument gives a better overall measure of at least average dust conditions in a drivage while at exhaust ventilated sites it gives a better representation of the man at most risk. It was also concluded that Routine sampling should continue to be carried out using 'fixed point' MRE113A instruments.

Two specific issues were examined during the trials: firstly, the situation with a remote machine operator and secondly, the representation of men who are routinely sited in a position forward of the machine operator during cutting. For remote operators, it was found that an on machine instrument still gave the most reliable result representative of the general workplace. For men sited in front of the driver's position, spotters were not shown to be exposed to greater dust levels than the machine operator but this was not the case for bolting rig operators. Such a situation should be catered for within the sampling system, such that the man at most risk is identified for a particular ventilation layout and the Routine instrument located in his vicinity rather than close to the machine driver. Factors were used in the original derivation of the dust standards to assess the long-term likely maximum dust exposure of an average workman in a drivage. Using the original factors, this figure was calculated to be 3.3 mgm{-3} from a 5 mgm{-3} standard. However, from new factors calculated from the present data the factor was found to be 2.8 mgm{-3}.

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