Dust Control Handbook for Industrial Minerals Mining and Processing

safety considerations may preclude wetting the blast area during the "tying in" phase of the blastwhere all the individual hole charges are connected together prior to blasting.Water CartridgesWater ampoules or cartridges which are inserted into the blasthole with the explosive have beenused successfully for dust reduction in past underground coal mining blasting operations[ILO 1965]. The water cartridges consist of a properly sized plastic bag which is prefilled withwater or can be filled in the hole. The cartridges can be placed in front of, alongside, or behindthe explosive without causing any adverse effects to fragmentation. There is another type ofcartridge which can be used in the place of stemming as shown in Figure 3.20. This cartridgeuses a PVC bag which is inserted into the hole after the explosive and is then filled with water tomaintain a tight seal with the blasthole. In coal mining operations, the use of these cartridges isclaimed to have reduced dust by 40–60 percent.Figure 3.20. A typical blasthole containing an explosive charge utilizinga water cartridge to suppress dust generated during blasting.Fogger SpraysIn the past, many underground operations used a fogger type spray in the heading where theblasting is conducted, shown in Figure 3.21. This setup uses both compressed air and waterforced through a nozzle to create a fogged-in blast area. The nozzle is located at an approximatedistance of 100 feet from the face, is turned on prior to blast initiation, and remains operationalfor 20 to 30 minutes after the blast [ILO 1965]. While a fogger type spray is effective forunderground blasting, it is not known if such a system would be viable for surface blasting.102 Drilling and Blasting