초록 ▼

Rock and other hard materials, such as concrete, are fragmented by a controlled small-charge blasting process. A cartridge containing an explosive charge is inserted at the bottom of a hole drilled in the rock. The explosive charge is configured to provide the desired pressure in the hole bottom, in

Rock and other hard materials, such as concrete, are fragmented by a controlled small-charge blasting process. A cartridge containing an explosive charge is inserted at the bottom of a hole drilled in the rock. The explosive charge is configured to provide the desired pressure in the hole bottom, including, if desired, a strong shock spike at the hole bottom to enhance microfracturing. The cartridge is held in place or stemmed by a massive stemming bar of high-strength material such as steel which blocks the flow of gas up the drill hole except for a small leak path between the stemming bar and the drill hole walls. The cartridge incorporates additional internal volume designed to control the application of pressure in the bottom hole volume by the detonating explosive.

대표청구항 ▼

[ What is claimed is:] [1.] A device for fracturing a hard material, comprising:a cartridge; anda stemming means for stemming a hole in the material, the hole containing the cartridge, the cartridge being located in a bottom portion of the hole and adjacent to a downhole end of the stemming means an

[ What is claimed is:] [1.] A device for fracturing a hard material, comprising:a cartridge; anda stemming means for stemming a hole in the material, the hole containing the cartridge, the cartridge being located in a bottom portion of the hole and adjacent to a downhole end of the stemming means and including an explosive, wherein the explosive is decoupled from and is positioned at a distance from the downhole end of the stemming means to dissipate a detonation shock wave generated during detonation of the explosive to protect the stemming means from the detonation shock wave, wherein the cartridge includes a cartridge base positioned adjacent to the downhole end of the stemming means, the cartridge base having a second yield strength that is less than a first yield strength of the stemming means, and an outer cartridge housing attached to the cartridge base, at least a first portion of the outer cartridge housing containing the explosive.