Abstract: In a non-electric system for initiating explosives, a shock tube is initiated by the detonation of a low-energy detonating cord (LEDC) whose wall has been placed adjacent to an initiation-sensitive region of a thin membrane in the shock tube, or in a capping member to an open end of a shock tube or in a capping member to the detonator itself, wherein the inner surface of the bore of the shock tube or the end-capping member is coated with a reactive composition of an explosive or a deflagrating compound. The end capping member fits over and seals the open end of the shock tube or fits in and seals a detonator with or without a shock tube in it, acting as a shock tube itself. The thin membrane accepts the detonation from the LEDC, whereby the shock tube or capping member is initiated and relays a pressure pulse to the shock tube or the detonator affixed thereto. Novel shock tubes, shock tube/detonator units, and a detonator for use in the hybrid shock tube/LEDC system are disclosed.

Abstract: A formation is blasted with one or more arrays of elongated, chemical, explosive charges so as to produce relatively low levels of ground vibration. The orientation and velocity of propagation of explosion in each charge and the velocity of propagation of vibration in the formation are such that, at a selected outlying location, the onset of vibration from explosion of the first negligably small increment of the charge arrives a finite time before that from explosion of the last negligably small increment. The charges of each array are fired in accurately-timed sequence, with the times between initiations chosen so that, at the outlying location, the onset of vibration from explosion of the last small increment of each charge, except the last charge, arrives a negligably small increment of time before the onset of vibration from explosion of the first small increment of the succeeding charge.

Abstract: An improved connector for holding low energy detonating cord adjacent the percussion-actuation and surface of a detonator comprises a plastic tube having a detonator-receiving bore and one or more cord receiving transverse bores between a plastic end closure for the tube and the end of the bore of the tube. The transverse bore(s) form channels which permit the cord segments therein to span the actuation end surface of the detonator and result in improved reliability of initiation of the detonator.

Abstract: An explosive primer unit adapted to be initiated instantaneously by low energy detonating cord when the unit comprises an explosive primer and an explosive coupler which operatively joins the low energy detonating cord to the primer.

Abstract: A primer assembly for use in the non-electric initiation of cap-insensitive explosives, especially of deck-loaded explosive charges by means of a single downline of low-energy detonating cord (LEDC), includes a percussion-actuated detonator seated in a cavity in a high-energy primer, and an explosive coupler in which a coupling explosive charge, housed in a plastic connecting block, is in initiating proximity to the detonator's percussion-sensitive ignition charge and sufficiently close to a cord-receiving perforation or conduit in or adjacent the primer as to be initiatable by the detonation of LEDC threaded therethrough. A preferred connecting block has means for engaging the detonator, and means for attaching the block to the primer. Preferably the explosive coupler is seated within a block-like cavity in the primer.

Abstract: An explosive primer unit in which the degree of energy coupling between a low-energy detonating cord (LEDC) and an explosive coupling element in a cast explosive primer is maximized; the unit contains (a) a substantially cylindrical charge of cast explosive having a perforation therein aligned substantially parallel to the charge's cylindrical axis, and sized to slidably receive a length of LEDC and (b) embedded in the cast explosive charge along the LEDC-receiving perforation, an explosive coupling element containing a shock-sensitive high-velocity detonating explosive having a tubular body having a wall that surrounds, and a bore that forms, the LEDC-receiving perforation over at least a portion of the perforation's length, the size of the bore of the coupling element's tubular body that forms the LEDC-receiving perforation in the cylindrical charge of cast explosive closely matching the outer diameter of a length of LEDC to be received therein.

Abstract: In emulsion blend explosives, the replacement of coarse salt particles, e.g., prills, by fines, i.e., particles which pass a No. 50 U.S. sieve, increases the water resistance of the explosive without deleteriously affecting its shelf life provided that the explosive, prior to such replacement, is storage-stable as determined by the Salt Extraction and lead compression tests described herein. Products containing a combination of whole and crushed ammonium nitrate prills, and emulsions made with an anionic emulsifying agent such as a fatty acid salt, are preferred. Depending on the fines content and chemical composition, other properties such as sensitivity to initiation and detonation velocity also may be improved.

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: 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: An apparatus for injecting a lubricating liquid, e.g., water, into a conduit as an annular layer around a flowing Bingham solid, e.g., a water gel or water-in-oil emulsion explosive, to facilitate the flow of the Bingham solid has an annular passageway from which the lubricating liquid flows into a cylindrical chamber containing the flowing Bingham solid. The annular passageway has a constricted throat portion of adjustable width, which, along with the flow rates of the Bingham solid and the lubricating liquid, is adjusted to produce a thin film of lubricant which allows lubricated plug flow of the Bingham solid in a descending section of conduit under the propelling force of gravity alone. Low drag permits the delivery of Bingham solid explosives into very deep vertical holes with no increase in the required pumping pressure.

Abstract: Improved uniformity of timing, and particularly reduced sensitivity of timing to minor variations in delay charge size, are achieved in delay detonators by placing a loose load of a flame-sensitive ignition composition between a pressed delay charge and an ignition assembly, e.g., a percussion primer, at the actuation end of the detonator. The loose ignition charge has a free surface and is adapted to be ignited in response to direct contact with flame emitted from the ignition of a charge in the ignition assembly. Preferably, the delay charge is pressed into a plastic carrier which, in a non-electric detonator, has an open end terminating between the walls of the detonator shell and a primer shell that closes the actuation end of the detonator, and the ignition charge is loosely loaded into a metal capsule seated against the delay charge.

Abstract: A percussion-actuated instantaneous or delay detonator transmits a detonation from a first length of low-energy detonating cord (LEDC) transversely positioned adjacent the detonator's percussion-responsive end to a U-shaped segment of a second length of LEDC held with its apex against the base-charge end of the detonator and the arms of the U extending away from the detonator. A directional connector for connecting one or more U-shaped segments of detonating cord adjacent each end of the detonator has identifiable donor- and receiver-cord-housing sections, e.g., the receiver-cord-housing section has the shape of the head, and the donor-cord-housing section the shape of the butt, of an arrow. A connector adapted to hold receiver LEDC and high-energy detonating cord (HEDC) segments is internally configured to receive nested U-shaped segments of LEDC and HEDC only when the LEDC is adjacent the base-charge end of the detonator.

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: Water-bearing explosives comprising oxidizer, fuel, and sensitizer components in a thickened or gelled continuous aqueous phase are stabilized against the degradation of their thickened or gelled structure by the incorporation therein of iodide and/or iodate ions. Preferably, iodide ion is introduced by dissolving ammonium iodide or an alkali metal iodide in an aqueous liquor or sol containing the oxidizer component. The stabilization method is particularly useful in explosives containing a guar gum thickener and flake aluminum in the sensitizer component.

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: Self-supporting water-bearing explosive products, e.g., for use as primers and in blasting and seismic charges, contain discrete cells of an aqueous solution of an inorganic oxidizing salt and/or of an amine salt encapsulated by a crosslinked (thermoset) resin matrix. The products are sensitized by a dispersed solid high explosive and/or gas bubbles or voids. Preferred primers are sensitized by PETN and are rigid. The products are made by crosslinking a liquid polymer in the continuous phase of an emulsion which contains the aqueous solution as a discontinuous phase.

Abstract: The ignition assembly of a non-electric delay detonator which is adapted for field-assembly with a low-energy detonating cord has an expansion shell provided with a cavity into which the cord is inserted at the time of use. The pressure pulse resulting from the detonation of the cord causes the shell to expand and an ignition charge to be actuated as a result of sudden compression between the expansion shell and a rigid ignition capsule. The burning ignition charge causes the ignition of a delay charge, which in turn ignites a priming charge, causing the base charge to detonate. The presence of ignition charge in an annular spacing between the expansion shell and ignition capsule walls, as well as between the shell and capsule ends, and the proper positioning of a cord-gripping means, preferably in the shell cavity, assure actuation of the ignition charge whether or not the cord is shoved to the bottom of the shell.

Abstract: Emulsion-type explosives having improved storage stability are formed by combining an aqueous solution of an inorganic oxidizing salt and an oil in the liquid phase with agitation in the presence of a fatty acid, e.g., oleic or stearic acid, and an ammonium or alkali metal hydroxide, and incorporating dispersed gas bubbles or voids in the resulting water-in-oil emulsion. An emulsifying system including a fatty acid salt is formed in situ. The product contains the fatty acid salt, fatty acid, and hydroxide in a stabilizing equilibrium which permits the product to retain its explosive properties after storage at temperatures as high as 49.degree. C. or more.

Abstract: A chub cartridge has a tubular chamber containing a water-bearing blasting agent, and a longitudinal tunnel adjacent to the tubular chamber and integral therewith. Preferably, the tunnel is full-length and continuous and has holes for threading a detonating cord therethrough and for holding a cord firmly against the tubular chamber for the cord-priming of the cartridges. In primer assemblies, the tunnel also can be used to hold a cap/booster in place, and for lacing cap wires or a low-energy detonating cord. A preferred cartridge is made continuously in a series by wrapping a web of film having a row of holes along one edge so as to form a tube and an outer flap containing the holes, and sealing the tube and the flap so as to form a tunnel containing the holes in its outer portion, the wrapping being performed so that either the inner or outer portion of the tunnel is circumferentially longer than the other.