Dust deposition in coal mine airways. Technical progress report

The Bureau of Mines conducted an exploratory field survey to determine the amount of airborne coal dust, the size distribution of the dust, and the rate of dust deposition in coal mine airways. The survey was taken at eight underground locations in operating coal mines. The rate of dust deposition in the airways depended upon the concentration of airborne dust and decreased exponentially with distance from the dust source. A sample rock-dusting schedule for that return is presented; that is, the trickle duster should be operated for 3 1/2 hours after every five shifts to protect the average deposit of new float coal dust in the return, but operation after every three shifts is preferred, to protect an occasional heavier deposit.