Abstract: A method of compacting powder comprising interweldable particles into a solid body by using a shock wave. The shock wave has such an amplitude that interwelding of the particles in the powder is obtained. The shock wave is generated by impact of either a body impacted against the powder or by a capsule containing the powder, which capsule is impacted against a support instead of the body. The velocity at which the body or the capsule is impacted is about 300 to 2000 m/sec. The duration of the compacting pressure following behind the shock wave is determined by the chosen length and the chosen impedance of said body or said capsule and said support. The shock wave is chosen such that it propagates through the powder with a rise time which is shorter than the time necessary for obtaining equalization of the overall temperature. The compacting pressure must be maintained so long that the welds on the surfaces of the powder particles solidify.

Abstract: A hard compact material, such as rock, is broken by directing a high velocity jet of fluid, such as water, into a drill hole in the material to be broken. The jet is generated by a nozzle and is directed into the drill hole through a tubular member, which is associated with the nozzle. Upon having traversed the tubular member, the jet is suddenly arrested in the hole to break the material by the established jet stagnation pressure stemmed by the tubular member.

Abstract: A hard compact material, such as rock, is broken by delivering a hydraulic fluid, such as water, into at least one hole which has been pre-drilled in the material to be broken, the hole functioning as an hydraulic fluid cylinder. A piston is driven into the hole to impact the fluid to generate a high pressure in the fluid and to cause tensile stress cracks in the material by the established pressure. Due to the concentration of the stress at the bottom of the hole, the cracks are initiated and spread generally radially outwardly substantially normal to the principal stress direction. A plurality of said holes may be drilled and the cracks linked together by appropriate choice of form, depth, orientation, spacing and number of the holes. Preferably, the piston is driven into the hole by means of a gun at speeds ranging up to several hundred meters per second.