EVALUATION OF A MACHINE-MOUNTED DUST COLLECTOR.

This paper decscribes field and laboratory investigations conducted on a dust-collection system recently designed for integral use with a continuous mining machine. The results of the field study showed that the average respirable dust concentration measured at the machine operator's position was reduced by about 60% (from 8. 7 to 3. 5 milligrams per cubic meter), and total and respirable dust concentrations in the return air were reduced by approximately 70%. The data indicated that approximately 20% of the dust generated at the face was not passed through the scrubber. The laboratory results showed that the overall efficiency (by particle count) was approximately 80% for total dust concentrations (minus 20 micrometers in size) typical of those encountered underground. Calculations based on total dust concentrations measured during the underground study indicated that the respirable mass concentrations of the effluent from the scrubber would still exceed acceptable levels even if scrubbing of all the air at the face were possible.