Blasting is a process of reduction of rocks or hard soil into fragments with the help of explosives. The blasting operation involves drilling of holes, installation of a detonator and charge, detonating the charge, and removal of debris.
In this article, we discuss how to safely conduct blasting operations in hard rock or soil.
Safety Precautions before Blasting
- The blasting operations shall be carried out under the supervision of a responsible authorized blasting engineer.
- In case of blasting with dynamite, the position of all the boreholes to be drilled shall be marked in circles with white paint.
- The boreholes shall be of a size that facilitates the easy passage of cartridge.
- After the drilling operation, the engineer shall inspect the holes to ensure that only the marked locations have been drilled, and no extra hole has been drilled.
- The engineer shall then prepare the necessary charge separately for each borehole.
- The boreholes shall be cleaned thoroughly before the insertion of the cartridge.
- For tamping, only cylindrical wooden tamping rods shall be used. Metal rods with pointed ends shall never be used for tamping.
- Each cartridge shall be placed in the borehole and gently pressed but not rammed down.
- Cartridges shall be added as required to make up the necessary charge for the borehole.
- The topmost cartridges shall be connected to the detonator, which shall, in turn, be connected to the safety fuses of the required length.
- The fuses of the required length shall be cut and inserted into the holes.
- The fuses shall be free of joints but if found unavoidable, a semi-circular nitch shall be cut off from one piece of fuse from the end and inserted into the notch of the other fuse.
- The joint pieces of the fuse shall then be wrapped together with string.
- All joints of the fuses exposed to dampness shall be wrapped with rubber tape.
- The maximum of eight boreholes shall be loaded and fired at one go.
- The charges shall not be fired simultaneously but successively.
- Immediately before firing, a warning shall be given, and the engineer shall see that all the workers have retired to a place of safety.
- The safety fuses of the charged holes shall only be ignited in the presence of the engineer.
- The required count before each blast shall be set by the engineer and others.
- After all the charged boreholes have exploded, the engineer shall inspect the site for anomalies.
Safety Precautions while Blasting
- For the safety of workers, red flags shall be prominently displayed around the area where blasting operations are to be carried out.
- All the workers at the site shall withdraw to a safe distance of at least 200 meters from the blasting site.
- An audio warning by blowing whistle shall be given before igniting the fuse.
- The blasting operation shall be carried out under the supervision of trained personnel.
- The blasting shall not be done within 200m of an existing structure unless permitted explicitly by the engineer in writing.
- All procedures and safety precautions for the use of explosives, drilling, and loading of explosives before and after shot firing and disposal of explosives shall be carried out corresponding to the region and country code.
Precautions against Misfire
- In case of misfire, the safety fuse shall be cut in an oblique direction with a knife.
- All sawdust shall be cleared from the interior of the detonator.
- This shall be carried out either by blowing down the detonator or tapping the open end.
- No metal tools shall be inserted into the detonator for the purpose of cleaning.
- If water is present in the detonator, the junction of the fuse and detonator shall be made watertight by using tough grease or other suitable material as prescribed by the engineer.
- The detonator must be inserted into the cartridge in such a way that about one-third of the copper tube is left exposed.
- The safety fuse in the cartridge above the detonator shall be securely tied in position.
- Waterproof fuse shall only be used when water is present in the borehole or when the borehole is in damp condition.
FAQs on Safety Precaution for Blasting Operation
Blasting is a process of reduction of rocks or hard soil into fragments with the help of explosives. The blasting operation includes drilling of holes, installing a detonator and charge, detonating the change, and removing of broken material.
The maximum of eight boreholes can be loaded and fired at one go.
The safe distance of at least 200 meters from the blasting site shall be maintained during the blasting operation.
Read More:
1. How to Carry out Controlled Blasting of Rocks? [PDF]
2. How to Perform Rate Analysis for Earth Excavation? [PDF]