Rock Fracturing by Plasma Blasting Technology

There is a great deal of interest in fragmentation of rocks in such areas as tunneling, quarrying and mining. Conventionally, blasting by explosives is the usually employed method in excavation work. Due to problems of vibration, noise, and scattering of stones, this method is prohibited of use near important buildings and residential areas. The alternatives to this method are breakage by such crushing machines as large breakers and by chemical substances. However, such breakage methods are high in cost and the problems of decrease in breaking performance were observed.

Plasma Blasting Technology (PBT) involves the production of a pulsed electrical discharge by inserting a blasting probe in a water-filled cavity drilled in a rock, which produces shocks or pressure waves in die water. These pulses then propagate into the rock, leading to fracture.

Compared with conventional blasting method such as rock drilling machines, the PBT technology is friendlier to the earth, because it causes less vibration, noise, and dust, and uses no chemical substances. In the blasting procedure, a reusable blasting electrode and a power supply main body incorporating capacitors and other devices that are connected by a cable are used.

Newly developed compact blasting equipment it suitable for blasting of platy structures and boulder stones. Holes for blasting can be opened by hand-held tools. Therefore, the blasting procedure is easy and simple. By creating more than one hole in linear orientation and discharge at the same time, the object can be blasted as if it were cut.

This compact blasting equipment is suited for following applications.

• Blasting of thin, platy object (structures such as buildings and furnaces).
  
• Blasting of boulder stones. Digging of riverbed.
  
• Use in places where transportation of heavy load is difficult (such as mountains, slopes, and high places).
  
• Flexible and imprompt blasting under various situations (such as recovery work in a time of disaster).
  
• In the case where blasting like cutting is required, such at finishing of the blasted surface after main excavation work.

The main features of the PBT technology are as follows.

• Low vibration, low noise.
  
• No scattering of stones.
  
• No chemical reaction.
  
• Discharge portion is reusable.
  
• Blasting in the sea is possible.
  
• No heavy machinery is required.

Source: Facilitation Centre for Industrial Plasma Technologies