Abstract
The Federal Coal Mine Health and Safety Act of 1969 has caused the Bureau of Mines to focus a major portion of its research on reducing coal mine respirable dust concentrations to established limits. This paper describes a laboratory investigation conducted to study the effectiveness of doped and undoped sprayed water for controlling respirable coal dust. Dust suppression efficiency was determined for water droplets sprayed into an airborne coal dust cloud traversing a laboratory dust tunnel. The effects of three chemically different surfactants on suppression efficiency were evaluated. A “nozzle parameter,” P, was developed relating spray droplet velocity, quantity of water discharged, and mean volume droplet diameter to suppression efficiency. This parameter now provides a method of selecting spray nozzles that will provide the optimum suppression efficiency based on the quantity of water and line pressures available underground.