Requirements for drilling tools in blasting hole drilling operations

【Requirements for drilling tools in blasting hole drilling operations】

Drilling is generally described by four characteristics: straightness, depth, straightness and stability.

1.Hole diameter

The diameter of the drilling hole depends on the purpose for which the hole is used.In blasting hole drilling operations, there are many factors that affect the choice of holes.For example: the size of the rock particles required after rock breaking; the type of blasting selected; the “quality” requirements of the rock particles blasted (the surface smoothness of the particles and the proportion of crushing); the degree of surface vibration allowed in the blasting operation, etc.In larger quarries or large open-pit mines, the use of large-aperture blasting operations often reduces the cost of drilling and blasting per ton of rock.In underground rock drilling operations, mining equipment is limited by underground space.In the drilling of water well holes, the size of the rock hole depends on the diameter of the pipe or the diameter requirements of the supporting equipment required by the water pump.In terms of rock formation support holes, the diameters of different bolt rods are the determining factors.

2.Depth of hole

The depth of the hole is affected by the rock drilling equipment, and only short drilling tools can be selected in a limited space.Short drilling tools in the form of threaded connections are very necessary for rock drilling in a limited space.In rock drilling operations for blasting rock holes (horizontal or vertical holes), the depth of drilling is slightly deeper than the theoretical depth or the height of the terraces.Under some rock drilling conditions, the drilling depth is required to be deeper (50-70 meters or deeper). Generally, the DTH rock drilling method is used instead of the top hammer impact rock drilling method. The energy transfer of the DTH rock drilling method and the powder discharge effect under deep hole conditions are more efficient.

3.Straightness of the hole

The straightness of the hole is a factor that varies greatly with the rock type and natural conditions, the selected mining method and the selected mining equipment.In horizontal and inclined rock drilling, the weight of the drill tool will also affect the offset of the hole.When drilling a deep blasting hole, the drilled rock hole must be as straight as possible so that the charge can accurately obtain the ideal blasting effect.

In some types of rock drilling operations, it is often necessary to drill deeper rock holes, and the straightness of the rock holes is very demanding, such as pipe holes or cable holes.Even the requirements for water well holes are very strict so that water pipes and pumps can be installed smoothly.

The use of different types of guide equipment, such as guide drill heads, guide drill pipes and guide drill pipes, will improve the straightness of the hole.In addition to the offset of the rock hole itself, the direction of drilling is also related to factors such as the degree of adjustment of the propulsion beam and the accuracy of the opening.Therefore, considerable accuracy is required in this regard.Studies have shown that more than 50% of the rock hole offset is due to unreasonable propulsion beam adjustment and poor opening.

4.Hole stability

Another requirement for the drilled rock hole is to remain stable until it has been charged or used for other purposes.Under certain conditions, such as when drilling loose materials or soft rock areas (the area has a tendency to degrade and clog rock holes), it is very important to use a drill pipe or hose to go down the drilled rock hole.