Abstract: To prevent the rapid escape of high-pressure explosion gases when an explosive charge is initiated in a borehole, the hole is stemmed with chunks of readily liquefiable and/or vaporizable solid material, preferably chunks of ice and/or chunks of dry ice, piled up one upon the other so as to form a columnar bed of pre-solidified stemming material. The column remains in place during the explosion, and thereafter disappears by melting and/or subliming on absorbing heat from the surrounding formation. A preferred stemming column comprises a combination of ice chunks and chunks of dry ice, e.g., wherein the ratio of dry ice to ice in the column decreases with distance from the explosive charge.

Abstract: The pneumatic loading of essentially free-flowing slurry-bearing ammonium nitrate (AN) prills, i.e., AN prills which carry or support a water gel or water-in-oil emulsion, produces a high-density explosive consisting of the tightly packed whole and crushed slurry-bearing prills. The density of this explosive can be as much as 20% higher than the poured density of the mass of slurry-bearing prills.

Abstract: A method and apparatus for delivering an explosive to the bottom of a borehole containing water without allowing a detrimental amount of mixing between the explosive and the water. More particularly, the present invention allows an ammonium nitrate rich bulk explosive to be placed in a borehole without allowing the explosive composition to change significantly through dissolution of its constituents. The apparatus of the present invention includes a length of collapsible tubing having a plurality of apertures near its base and a weight attached to its base. The tubing is then lowered into a borehole. The weight causes the tubing to extend through any water layer within the borehole and the collapsible nature of the tubing serves to keep any significant amount of water from entering the tube. An explosive can then be flowed into the mouth of the tubing and down through the length of the tubing to the bottom of the borehole.

Abstract: Explosives that are sensitized blends of a water-in-oil emulsion and inorganic nitrate, e.g., AN, particles, such as AN or ANFO prills, have improved stability when their structure hinders the loss of water from the aqueous emulsion phase and transportation of such water across the oil phase to the nitrate particles. Use of an anionic emulsifying agent comprising a fatty acid salt, e.g., as formed in situ during the formation of the emulsion, is the preferred way of forming such a blend-stabilizing structure. Emulsion/nitrate blends stabilized in this manner make satisfactory storage-stable packaged products. Emulsion/nitrate blends made with a new low-viscosity emulsion containing essentially all of the oil required to oxygen-balance the blend and a proportionately larger amount of anionic emulsifying agent to stabilize the emulsion structure constitute preferred bulk products owing to their greater adaptability to pumping.

Abstract: A liquid-type low detonation-velocity explosive composition having reduced shock energy with unhindered bubble energy, and a method for minimizing damage from explosive well stimulation procedure by use of such composition.

Abstract: A pre-packaged explosive charge of the type made up of modules having a threaded male coupling end and a threaded female coupling end is loaded into a bore hole by use of a plug fitting threadably attachable to the uppermost charge module. The fitting is constructed so that the torque required for disconnection of the fitting from the module is substantially less than the torque required to separate one module from another.

Abstract: An apparatus for stimulating a subterranean formation uses a gas generating propellant placed in the well adjacent the formation to be stimulated. The propellant is ignited to generate gas at sufficient pressure and in sufficient volume to fracture the formation to thereby improve its permeability or productivity. The device is designed to generate an initial pressure pulse of substantial amplitude to initiate fractures in the formation. Shortly, the pressure generated by the device falls off to a lower value and is sustained at that value for a relatively substantial length of time.

Abstract: A blasting cap to primer adapter permits the use of any size of a blasting cap and associated shock tube in combination with commercially available primers and detonating cords. In one embodiment, a bracket arrangement and cord tunnel assembly having a plurality of tunnels is employed attachable to a primer having a tunnel through which an associated blasting cap shock tube may be looped, while a length of detonating cord may be similarly directed through the tunnel assembly of the adapter. An ignition of the detonating cord will result in a concurrent ignition of the shock tube to effect the desired explosion of the primer. Through this construction, any number of primers and blasting cap arrangements can be attached to and ignited by a single detonating cord.

Abstract: The invention is a method and apparatus for formulating and delivering emulsion slurry blasting agents in a self-contained, "on-site," movable system, such as a heavy duty truck which houses the necessary apparatus for formulating the emulsion blasting agent. A key part of the apparatus is a blender in which the emulsion phase is formed.

Abstract: A method of charging upwardly extending, large diameter boreholes with cylindrical explosive cartridges is provided employing a longitudinally inflating flexible tube as the pushing mechanism. A fluid-impervious flexible tube is turned over or everted at one end and secured. A fluid, preferably air, at about 3 psi is passed into the tube causing the tube to elongate and the everted tube face to travel along the length of a borehole. An explosive cartridge mounted against the tube face is carried to a desired location in the borehole after which the tube is partly deflated and withdrawn from the borehole.

Abstract: A two-piece, telescopic climber, which is insertable into a drillhole behind cylindrically shaped explosive charges, alternately advances one and then the other of its two telescopic pieces in the direction of the drill hole thereby to urge the charges forwardly thereof into the hole. Each piece has thereon means which expands outwardly against the wall of the drill hole to hold that piece stationary while the other piece advances. At least one of the two pieces can be removed from the drill hole to be used repeatedly.

Abstract: A method of charging a borehole with a column of explosives is described wherein the explosive charge is detonable in time-delay sequence by means of electrically initiated detonators. The method requires providing a loop of an insulated electrical conductor throughout the length of the borehole and, as the borehole is charged with explosives, sliding electrically actuable time-delay detonators along the wire so as to be positioned at intervals throughout the borehole. The detonators are electrically coupled to the looped wire by means of slidable toroidal transformer cores. The wire loop, in turn, is electromagnetically energized by means of a second transformer core and an energy source. The method provides for safe and efficient borehole charging and avoids the hazards associated with usual electric detonator systems.

Abstract: A method for loading explosive charges into blastholes in a subterranean formation for forming a fragmented permeable mass of formation particles in an underground cavity in the formation is provided. Upper and lower voids spaced apart vertically from each other by unfragmented formation are excavated into the subterranean formation. A generally vertical blasthole is formed in the unfragmented formation between the voids. Upper and lower explosive charges, separated from one another by stemming, are formed in the blasthole. Each such explosive charge includes at least one primer operationally connected to an explosive initiating lead that extends from the charge. The explosive initiating lead of the upper explosive charge extends from the top of the blasthole into the upper void and the explosive initiating lead of the lower explosive charge extends from the bottom of the blasthole into the lower void.

Abstract: An explosive charging apparatus for charging controlled amount of explosives sequentially to bores drilled in a rock surface. The charging apparatus includes an explosive charging pipe, a boom mechanism carrying the explosive charging pipe, boom actuators for actuating the boom mechanism so that the explosive charging pipe is moved to a desired position, a control circuit for controlling the boom actuators and the explosive charging pipe.

Abstract: This invention relates to an automatically controlled rock drilling apparatus which performs rock drilling operations as well as post-drilling operations such as explosive charging. Memory means are used during the drilling operation and reused during subsequent operations for follow-up work, specifically the charging of explosive to the drilled bores.

Abstract: Steep dip strong-coal deposits can be broken in an explosive mine environment utilizing a succession of explosive units each of which comprises a core tube surrounded by a body of explosive material which, in turn, is surrounded by an arc-suppressing heat-dissipating fluid. Igniters in the explosive charges have conductors which are lead back out of the bore hole through the tubes of the explosive units which are anchored at spaced locations along the bore hole.

Abstract: An explosive or stemming package is provided which is self-retaining in vertical or inclined up-holes in stable rock. The package containing a flowable material, for example, slurry explosives, consists of a thin-walled cylindrical bag having at least one longitudinal, external pleat held closed by means of an adhered overcovering or tape. With the package held in position in the up-hole by a push rod, the tape is severed by means of a rip cord allowing the pleat to open. The slumping contents press the package closely against the borehole wall for secure retention without additional support. Improved coupling of the explosive charge to the rock is also provided giving enhanced blasting efficiency.

Abstract: The invention provides a container for explosive material comprising a rigid tube (10 FIGS. 1-4, 18 FIGS. 5-8) a closure (13,14; 19,20) at each end of the tube, said tube having a recess (12; 21) in its wall between its ends to receive a detonating cartridge.

Abstract: The detonation gas for gas-detonatable blasting charges used in surface mining and the like is supplied by a portable self-contained delivery unit connected to the blasting charges by a network of small flexible tubing, which unit blends pressurized fuel and oxidizing gases from separate supply sources in predetermined proportions and regulates the separate flows of such gases in response to the backpressure imposed by the tubing network to maintain such proportions in the gas blend delivered to the tubing network. The separate gas flows are controlled by servo-actuated flow control valves actuated by a control gas pressure which is applied or released in response to such backpressure.

Abstract: An explosive booster, useful as a starter for one or more low-energy explosive connecting cords, e.g., low-energy detonating cord (LEDC), comprises a detonating explosive charge in the form of a rod having at least one longitudinal perforation for threading one or more (receiver) cords to be initiated by the booster explosive charge, which in turn is initiated by a blasting cap or preferably by the side-output of a (donor) detonating cord in contact therewith. A preferred rod has multiple perforations for threading multiple receiver cords, and is housed within a rigid plastic connector having a portion of its wall circumferentially cut out to allow a donor cord to contact the thereby-exposed rod therein. A trunkline cord is thereby adapted to initiate multiple downlines via a single booster.

Abstract: Cartridge for bulling mine holes, which is of cylindrical shape, is made of n elastic material and possesses a zone 7 capable of deforming axially and a zone 6 capable of deforming radially, under the effect of an axial or radial pressure exerted on the cartridge or under the effect of an internal pressure variation, in which cartridge the volume of the zone 7 capable of deforming axially is greater than the volume of the zone 6 capable of deforming radially.

Abstract: An apparatus for the charging of rising drillholes (10), preferably large holes of diameter approximately 100 mm or more, with pipecharges (22). The aim is to make it possible to feed charges into the hole in such a way as to fill the hole effectively while making it easy to apply the necessary firing gear (primer and detonator). The charging apparatus comprises a stand (14) capable of being aligned with the mouth (28) of a drillhole by pivoting on a fixed surface (26). The stand includes a lifting means (18) which is provided with a rest (20) capable of travelling towards and away from the drillhole, to carry pipecharges. That part of the stand which is aligned with the drillhole consists of a guide unit (16) which is arranged to guide the pipecharges into the drillhole as the rest travels towards the said drillhole. The pipecharges are retained in place after the lift by retaining means (30).

Abstract: An improved process is provided for blasting in situ oil shale retorts, and oil and gas wells. In the process, a specially formed concrete plug is installed at a desired depth in a bottomless blast hole and an explosive charge is placed upon the plug and detonated to blast the underground formation. The plug is accurately and reliably set by lowering a canister, which releasably houses a bag support assembly supporting a bag of concrete slurry, to a desired depth into the blast hole. The bag support assembly and bag of wet concrete are subsequently dropped a fixed distance below the canister. The bag of concrete expands, dries, and hardens against the walls of the blast hole to form a permanent stationary plug across the blast hole. In the preferred process, the bag support assembly is formed by casting a concrete disc around a drainpipe, and the bag support assembly is lowered and released from the canister with the aid of an electrically powered sequencer.

Abstract: A plugging apparatus is provided to reliably plug a bottomless blast hole in underground oil shale retorts and oil and gas wells. The plugging apparatus has a special electrically powered sequencer which automatically lowers and releases a bag of cementatious slurry, supported by a drainpipe-reinforced concrete disc, from a canister to form a composite blasting plug in the blast hole.

Abstract: Method and apparatus for remotely positioning individual explosive charges at preselected locations in substantially horizontal voids created by mining hard material such as coal are disclosed. The method includes the steps of positioning at least one charge proximate the entry of a void. The charge is then armed as by connecting a detonator cord thereto and inserted into a void to a preselected depth from a remote location. An apparatus is provided for positioning the charges at preselected locations in the voids and includes insert means having a body member for releasably engaging the charges during the positioning operation. The insert means is driven until the body member and charge propelled thereby is moved to a preselected location within the void where the charge is deposited.

Abstract: An explosive charging apparatus for charging explosive pellets to a bore drilled in a rock. The apparatus includes a body having coaxial pellet guiding first and second bores, the second bore being provided with a pellet supplying port. A cylinder is provided and has a piston with its rod extending into the second bore to force the pellet therein when the rod is advanced under an air pressure supplied to the cylinder. The rod is formed with an axial air passage opened to the second bore and adapted to be connected with a pressurized air source when the rod is advanced so as to supply air pressure to the second bore to thereby drive the explosive pellet to the first bore. The first bore is supplied with a lower air pressure which functions to feed the pellet in the first bore to the bore in the rock. The cylinder is associated with a pilot operated valve which receives a returning pilot pressure when the piston is fully advanced and an advancing pilot pressure when the piston is fully retracted.

Abstract: A non-electric delay blasting method is provided which comprises the use of single trunk line of detonating cord having a series of detonating relays, all of the same delay period, connected at spaced intervals along its length. Branch lines of detonating cord are connected in groups to the trunk line in the intervals between the relays and each branch line has a delay detonator of the same delay period attached thereto. The delay period of the relays is shorter than that of the delay detonators. The detonators within the groups detonate in a random manner. The method eliminates the need to use large numbers of different delay period detonators in a multi-charge blast thus simplifying preparation of the charge and reducing inventories.

Abstract: A cast or pressed explosive primer is provided which is adapted for slidable initiating engagement with a detonating cord. The primer comprises two hermetically sealed shells or cups which are connected together. One shell contains a sensor/signal carrier/delay cap combination and the second shell contains the explosive primer charge. Guides are provided on the outside of the shells for the threading therethrough of a detonating cord. The construction provides protection against the ingress of water or other liquids which may desensitize the initiation system.

Abstract: An explosive blasting method and apparatus for producing rock fragmentation and substantially reducing the amplitude of seismic effects (ground vibration) in the vicinity of the blast. An embodiment of the invention utilizes an air gap method and apparatus for superheating the air surrounding the charge in a borehole thereby significantly raising the pressure therein coupled with the use of multiple detonation points along the borehole for the reduction of burn time thereby substantially reducing the quantity of explosives used along with a marked reduction of seismic shock, sound and dust effects to the surrounding area.

Abstract: Bags of explosive are loaded rapidly into deep wellbores by suspending a rigid positioning tube partway into the wellbore, and loading the bags into the tube, the bags being prevented from dropping through the open bottom end of the tube by a cord attached to the lowermost bag and secured at the upper end of the tube when the tube-suspending cable is in tension by a cord-securing/releasing means, e.g., a pivotable bar having a hook on one end. When the bag-laden tube is lowered to the bottom of the wellbore, or to a column of bags previously placed therein, the tension on the cable is relaxed and the cord is released, allowing the positioning tube thereafter to be raised to the surface for re-use, leaving the cord and bags in the wellbore. Freedom of the bag-supporting cord to move with respect to the positioning tube when the latter is raised to the surface is assured by threading the cord through plastic tubing mounted to the wall of the positioning tube and releasable therefrom for re-use.

Abstract: Disclosed are method and apparatus for cutting tubular members from the inside by use of an explosive-induced shock wave. In a particular disclosed embodiment, an electric detonator is used to initiate two equal lengths of linear explosives, each of which initiates a non-electric detonator, to provide dual simultaneous detonation of both ends of an elongate high explosive charge distribution. The resulting collision of detonation shock fronts at or near the center of the explosive charge diverts the shock energy 90.degree. into a 360.degree. distribution about the axis of the charge distribution in a plane perpendicular to that axis to provide the energy to cut a tubular member circumscribing the explosive charge.

Abstract: A bag for explosives is provided that includes an inner liner of plastic material that has a quantity of granular explosive material therein, and wherein a woven outer member has the liner arranged therein, girdle sleeve portions on the lower end of the bag, and wherein the upper and lower end(s) of the bag are closed.

Abstract: Apparatus for detecting ferromagnetic material such as is present in an explosive cartridge being loaded into a borehole, e.g., according to the method described in U.S. Pat. No. 3,986,430, which includes an inductance coil connected in series with a resistor, separately rectifies and amplifies the AC voltages across the coil and resistor and connects them in series opposition. The value of the balancing resistance is adjusted so that the two rectified voltages are equal and opposite when no ferromagnetic material is present. When the unbalance voltage exceeds a threshold value, a signalling device is actuated.

Abstract: An apparatus for retrieving drill collars in an earth boring drill string when stuck. A sub is connected between two drill collars at various points. Each sub is a cylindrical member with a reduced annular or notched area at one point that is no greater in wall thickness than the drill pipe. A locator is secured to a wire line and lowered into the drill string to the vicinity of one of the subs located above the stuck point. The locator carries an explosive charge of capacity sufficient to cut drill pipe. The locator has a pivotal dog that engages a landing in the sub. The landing is spaced above the annular area a distance selected to position the explosive charge adjacent the annular area when the dog engages the landing.

Abstract: A method of charging a borehole with at least first and second separate sections of explosive material, which method comprises the steps of providing a detonating cord extending into the borehole, providing a first primer on a first carrier having a time delay connection between the cord and the first primer, this time delay having a first selected value, providing a second primer on a second carrier having a time delay connection between a cord and the second primer, the time delay of the second carrier having a second selected value different from the first selected value, sliding the first carrier and primer along the cord and into detonation association with the first section of explosive material and sliding the second carrier and primer along the same cord to detonation association with the second section of explosive material.