Question: for dilution by ventilation a long blasthole stope is experiencing...
For dilution by ventilation, a long blasthole stope is
experiencing a high average respirable dust concentration of about
3.8 mg/m3 downwind of the stope mucking. If the intake air consists
of 50,000 cfm (23.6 m3
/s) of air containing 0.25 mg/m3 of respirable dust, how much air must be coursed through the stope to reduce the respirable dust concentration downwind of the stope to 3.0 mg/m3. Determine the average velocity of the air through the face area after the ventilation is increased, given the opening dimensions to be 8.2 ft. x 9.45 ft. (2.5 m x 2.88 m). Is the velocity acceptable?