Patent ID: 6375271
Filing Date: 2002-04-23
Classification: E21C

Abstract:
An apparatus for breaking rock, concrete and other hard materials with a controlled fracturing technique, comprising:a high-pressure foam injection barrel having an entry end and a distal end for inserting into a predrilled hole in a material to be broken; a high-pressure reservoir containing a high-pressure foam, a high-pressure seal mounted proximal the distal end of the barrel for sealing between the barrel and a wall of the hole; a fast-acting, high-flow valve connected to the reservoir and to the entry end of the barrel for releasing the high-pressure foam down the barrel and rapidly pressurizing a bottom of the hole and for fracturing the material through the initiation and propagation of controlled fractures from the bottom of the hole and thus effectively breaking and removing a volume of the material; a foam generator connected to the reservoir wherein the foam properties and volume are tailored, in terms of viscosity, foam quality and pressure for providing an optimum amount of energy to just break the material, without providing excessive energy which would be less efficient and would result in increased noise and thrown material; and an additive supply connected between the generator and the reservoir wherein the foam is designed to obtained by means of delayed chemical and/or thermal reactions an extremely high viscosity, with resultant viscosity being higher than could be pumped through the foam generator but being such as to improve the fracture and excavation of highly fractured rock and/or rock with unusually high fracture toughness.