drill

⚒ BASIC CONCEPTS OF DRILLING ⚒

🔷 The most effective, and hence most usually adopted, method of destruction of an the object is by blasting.

🔷 This method invariably aims at breaking the object into several small pieces.

🔷 Explosives are used for the purpose of breaking the object.

🔷 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.

🔷 When gases are generated by ignition in this way, very high pressure is exerted

on the surroundings.

🔷 At the same time, the strength of the surrounding material also reduces considerably due to the heat.

🔷 As a result of this, cracks develop in the material and the material gets fragmented.

🔷 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.

🔹 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.

🔷 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.

🔹Once the appropriateness of all the precautionary measures is verified, an electric current is sent through the wires.

🔹The electric current heats the wire in the detonator and the explosive material in the detonator explodes.

🔹This explosion causes further detonation in the explosive-filled hole. The hole drilled for filling explosives in this manner is called a blast hole.

🔷 The process of drilling such holes is called blasthole drilling.

🔷 The process of drilling such holes is called blast-hole drilling.r often simply a drill.

🔷 Except cases like breaking a boulder in field etc., a blasthole is seldom drilled in the singular.

🔷 They are drilled in numbers, perhaps in hundreds, one after another, then charged and blasted simultaneously.

🔷 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.

🔷 If the sizes of the fragments are small they can be moved easily.

🔷 In order to have a small size rock fragments after a blast, blast holes are required to be located in a properly planned manner.

🔷This requires careful design to determine the diameter, depth, and inclination of the holes, and also layout and other relevant parameters of the holes.