Method and device for breaking hard compact material
AssigneeAtlas Copco Aktiebolag
InventorErik V. Lavon
Life of this patent
Estimating the term…
Abstract
A hard compact material, such as rock, is broken by maintaining a column of relatively incompressible fluid, such as water, extending from outside into at least one hole which has been pre-drilled in the material to be broken. A shock wave is generated in the column outside the hole and is transmitted through the column into the hole. Due to the energy of the propagated shock wave, cracks are initiated and driven to a free surface of the material to break same. Breakage by the effect of the shock wave may be facilitated by means of an explosive. The explosive is delivered into the hole prior to the admission of fluid thereinto and is initiated by means of the transmitted shock wave.
Claims14
A method of breaking a hard compact material, such as rock, in which at least one hole is pre-drilled, comprising:
- maintaining a column (12) of substantially incompressible fluid having a length which exceeds the hole depth,
- filling the free cross sectional area of the hole with fluid at the one end of said column which directly contacts a surface of the hole.
- accelerating an impact body toward said fluid column by means of an accelerating device to impact said fluid column and generate a shock wave in said column outside the hole, said impact body having a shorter length than that of said column, and
- transmitting the shock wave through said column into the hole to act directly on a surface of the hole, said shock wave having a sufficient amplitude to cause cracks to form in the material,
- said fluid column being of sufficient length with respect to the length of said impact body for preventing a pressure increase caused by occurring shock wave reflections from arising in said column outside said hole.
A method of breaking a hard compact material, such as rock, in which at least one hole is pre-drilled, comprising:
- maintaining a column of substantially incompressible fluid having a length which exceeds the hole depth,
- filling the free cross section area of the hole with fluid at the one end of said column which directly contacts a surface of the hole,
- accelerating an impact body toward said fluid column by means of an accelerating device to impact said fluid column and generate a shock wave therein outside the hole, said impact body having a shorter length than that of said column, said length being chosen so as to create a pressure-time history in the vicinity of the bottom of the hole such that the pressure is highest when the shock wave arrives in the bottom of the hole, whereupon the pressure thereafter decreases, and
- transmitting the shock wave through said column into the hole to act directly on a surface of the hole, said shock wave having a sufficient amplitude to cause cracks to form in the material.
An apparatus for breaking a hard compact material such as rock, having a plurality of pre-drilled holes formed therein, comprising:
- a plurality of barrel means (13;
- 19;
- 35) adapted to be inserted into the respective holes, each of said barrel means having a length which exceeds the hole depth and each of said barrel means having respective mutually varying radial elasticities,
- means for filling the free cross sectional area of the hole with relatively incompressible fluid and for maintaining a column (12) of the fluid extending rearwardly out of the hole inside said barrel means,
- an accelerating device associated with said barrel means, said accelerating device having an impact piston which impinges against the fluid column in said barrel means for generating shock wave energy in said column of a magnitude which exceeds that required to cause cracks to form in the material, said impact piston having a shorter length than that of said column,
- each of said barrel means extending between said means for generating shock wave energy and a respective one of said plurality of pre-drilled holes, and
- said barrel means defining a wave-guide for the propagating shock wave to transmit the generated shock wave energy to act directly on a surface of the hole with sufficient magnitude for causing cracks to form in the material, said wave-guide having a length relative to the length of said impact piston which is sufficient for preventing a pressure increase caused by occurring shock wave reflections from arising in said column outside said hole.
Dependencies are inferred from the claim text.