Abstract: A method for recovering shale oil and gas from subsurface oil shale deposits in which free space is formed in the shale deposit and relieved blasting toward the free space from first shot holes drilled into the shale from the ground surface fills the free space with rubble. In-situ combustion of the rubblized shale decomposes organic material in the shale to form shale oil and gas, which are conveyed by combustion products through the shot holes to the surface, and leave a weak, easily compressible spent shale. After the in-situ combustion, shale surrounding the spent shale is rubblized by explosives detonated in second shot holes blasting toward the previously retorted zone. The second shot holes, which also are drilled from the surface into the shale, are spaced laterally from the first shot holes. The rubblized shale is then retorted by in-situ combustion. The successive rubblizing and in-situ combustion steps can be repeated to move the combustion operation laterally through the shale deposit.

Abstract: A method for driving tunnels in rounds is disclosed in which, after each round, the tunnel is left with an inclined transition to the floor. In the subsequent round, a cut is opened up in the transition towards the floor and the tunnel face is then stepwise drilled and blasted in cycles until the roof is reached and the round is completed. A machine for carrying out the method is disclosed which comprises a plurality of drill-and-blast units that are mounted on a frame that is pivotable about a transverse horizontal axis.

Abstract: Subterranean mineral deposits, such as oil shale or the like, are prepared for in-situ retorting by selectively mining out an area at the base of the deposit leaving an overlying deposit supported in a suitable manner such as by a plurality of pillars. The overlying deposit is expanded in any suitable manner into the underlying area in a fashion to create a predetermined distribution of permeability from an area of low permeability to an area of high permeability. An inlet is provided at the low permeability area and an outlet at the high permeability area. A suitable medium is introduced into the deposit at the low permeability end for extracting and forcing mineral values from the deposit toward the outlet end for recovery.

Abstract: Directed thrusts are generated in rock by detonating explosive charges in groups of drill holes therein, the drill holes being aligned so that the maximum thrust from the substantially simultaneous detonation of charges in a group of holes is exerted in a direction close to one in which the rock has been found to be particularly vulnerable to failure, i.e., a direction that is at an angle of 60.degree. to a representative normal of a densely populated set of joints in the rock and that also is close to a direction of maximum principal tectonic stress should one be found.

Abstract: A method for recovering coal from deeply buried deposits comprising drilling a hole down into a coal seam, filling the hole with water, and periodically detonating an explosive charge at the bottom of the water-filled hole. The water transmits the explosive shock wave to the face of the coal seam, thereby fracturing and dislodging the coal. The resulting suspension of loose coal in water is then pumped to the surface where the coal is recovered and the water is recycled to the mining operation.

Abstract: Free-standing boulders or rocks are fractured and broken down into many smaller pieces by impacting the boulder with a high velocity projectile. The impact energy is delivered to the rock by a blunt nosed projectile in a time which is less than the transit time of a sound signal across the average diameter of the rock.

Abstract: The device has a hollow housing having made therein a chamber adapted to accommoate an explosive charge, separated by a partition made of an elastomeric material for sealing the chamber from the cavity of the housing, communicating with the hole through lateral apertures in the housing. The device further includes a stem of a diameter that is lss than that of the rest of the housing, preferably threadedly secured to the bottom face of the housing. The stem has cut therein axial and radial passsages establishing communication between the cavity of the housing and the external lateral surface of the stem. A ring of an elastomeric material is received about the stem so that it closes off the openings of the radial passages in the external lateral surface of the stem.

Abstract: This invention pertains to recovery of metal values from ore deposits found at great depth; more specifically, the invention pertains to the recovery of metal values from an ore deposit by explosive fracturing of the ore formation at a depth at which the deposit is economically inaccessible by surface mining. Still further, this invention pertains to a method for explosive fracturing of a formation containing metal values at depth whereby hydraulically assisted fracturing is used to propagate an explosive shock wave so as to obtain a more desirable medium in which metal value recovery can be practiced.