Drilling is the process of penetrating through the ground and extracting rocks from various depths beneath the surface for confirming the geology beneath and/or providing samples for chemical analysis.
More specifically, drilling also means making a hole or a series of holes in the rock in preparation for blasting.
Drill and blast mining is the most commonly used mining excavation method in the world. Drill and Blast mining is extremely popular for numerous reasons, such as itsΒ cost,Β simplicity, andΒ effectiveness.
Thus, the concepts below are very important as far as drilling is concern:
1. The most effective, and hence most usually adopted, method of destruction of an the object is by blasting.
2. Β This method invariably aims at breaking the object into several small pieces.
3. Explosives are used for the purpose of breaking the object.
4. An explosive is a substance that generates a very high volume of gases and a huge quantity of heat within a very short time span of a few milliseconds as soon as it is ignited.
5. When gases are generated by ignition in this way, very high pressure is exerted
on the surroundings.
6. At the same time, the strength of the surrounding material also reduces considerably due to the heat.
7. As a result of this, cracks develop in the material and the material gets fragmented.
9. When the place of generation of gases is confined, the gases cannot escape to the atmosphere and the intensity of the pressure increases to a considerably higher level.
10. This results in maximum destruction.
For the most effective destruction of surrounding material, a hole is drilled in the material to be destroyed. After completion of drilling, the hole is charged (i.e. filled with explosive material) in a certain predefined manner.
11. A detonator, connected by two copper wires, is kept in the hole while the explosive is filled. The hole is then sealed from the top.
12. Once the appropriateness of all the precautionary measures is verified, an electric current is sent through the wires.
13. The electric current heats the wire in the detonator and the explosive material in the detonator explodes.
14. This explosion causes further detonation in the explosive-filled hole. The hole drilled for filling explosives in this manner is called a blast hole.
15. Β The process of drilling such holes is called blasthole drilling.
16. The process of drilling such holes is called blast-hole drilling. Or often simply a drill.
17. Except cases like breaking a boulder in field etc., a blasthole is seldom drilled in the singular.
18. They are drilled in numbers, perhaps in hundreds, one after another, then charged and blasted simultaneously.
19. The fragmented rock mass formed by blasting is almost always moved away, either to create space, as in civil engineering projects, or to extract a mineral of interest, as in mining or quarrying.
20. If the sizes of the fragments are small they can be moved easily.
21. In order to have a small size rock fragments after a blast, blast holes are required to be located in a properly planned manner.
22. This requires careful design to determine the diameter, depth, and inclination of the holes, and also layout and other relevant parameters of the holes.
