Plasma blasting method

• US 5,106,164 A
• Filed: 02/26/1991
• Issued: 04/21/1992
• Est. Priority Date: 04/20/1990
• Status: Expired due to Fees

• Current Assignee: Noranda, Inc. (Glencore Plc)
• Original Assignee: Noranda, Inc. (Glencore Plc)
• Inventors: Nantel, Jacques, Kitzinger, Frank
• Primary Examiner(s): MACMILLAN, KEITH D
• Application Number:
  US07/660,767
• Time in Patent Office: 420 Days
• Field of Search: 299/13, 299/14, 175/16, 166/60, 166/63, 166/65.1, 166/299
• US Class Current: 299/14
• CPC Class Codes: E21B 7/007 Drilling by use of explosives underwater drilling using explosives E21B7/1245
• CPC Class Codes: E21B 7/15 of electrically generated heat
• CPC Class Codes: E21C 37/18 by electricity

Abstract

A blasting method which comprises delivering electrical energy at a rate of at least 100 megawatts per microsecond until a peak power of at least 3 gigawatts is reached across the gap of two poles of a coaxial electrode assembly immersed in an electrolyte within a confined area of a substance to be blasted. A dielectric break-down of the electrolyte in the confined area is produced resulting in the formation of plasma within the confined area which creates a pressure sufficient to blast the substance in the manner of a high explosive charge.

Claims

1. A blasting method which comprises drilling a hole in a substance to be blasted, injecting a predetermined amount of electrolyte into the hole, inserting a coaxial electrode having two poles separated by a gap into the hole, the diameter of the coaxial electrode being such as to produce a confined area filled with electrolyte within the hole when the coaxial electrode is inserted in the hole, and delivering electrical energy to the coaxial electrode at a rate of at least 100 megawatts per microsecond until a peak power of at least 3 gigawatts is reached across the gap of the two poles of the coaxial electrode, so as to produce a dielectric break-down of the electrolyte resulting in the formation of plasma within said confined area which creates a pressure sufficient to blast said substance in the manner of a high explosive charge.

2. A method according to claim 1, in which the energy delivery rate is in excess of 200 megawatts per microsecond.

3. A method according to claim 2, in which the peak power is in excess of 4 gigawatts.

4. A method according to claim 1, in which the electrolyte is a solution of copper sulphate.

5. A method according to claim 1, further comprising combining a gelling agent with the electrolyte to increase its viscosity.

6. A method according to claim 5, in which the gelling agent is bentonite.