Method to determine the effects of rotary drilling parameters and overburden rock on silica dust generation.
Trans Soc Min Metal Explor 2003 Dec; 314:102-106
The National Institute for Occupational Safety and Health is conducting research to reduce the silica dust exposure of workers at surface coal mines. One goal of this research is to evaluate the relationship between drilling parameters, rock strata, and silica dust generation. This study involved measuring blast hole emission dust from a rotary drill rig. The drill rig, which produces high concentrations of dust (>400 mg/m3) in high-velocity airstreams, was being sampled for respirable silica dust. To measure dust initially, traditional sampling methods using personal sampling instruments were attempted in and around the shroud area of the drill with no success. Variations in the dust cloud concentrations under the shroud, the condition of the shroud and its orientation over the hole, and ambient air conditions prevented consistent and accurate dust measurements from being obtained. A more consistent dust cloud is necessary for accurate measurements. An area of the drill's dust collector system that consistently draws the emitted airborne dust from the hole is the collector tube. This tube connects the drill collector's vacuum and dust filtration system to the shroud area. Assuming the collector system is working as designed, sampling from the collector tube would enable more consistent and accurate samples to be taken. However, current personal samplers are unable to sample in the concentrations and velocities experienced in the collector tube, so another method had to be devised. To achieve the desired results, an in-stack cascade cyclone was used. Preliminary field testing has shown positive results.
Silica-dusts; Dust-exposure; Surface-mining; Coal-mining; Respirable-dust; Dusts; Dust-sampling; Occupational-diseases; Silicosis
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
Transactions of the Society for Mining, Metallurgy, and Exploration