Abstract: The present invention provides a method of preparing a recycled cementitious material by a phosphogypsum-assisted carbon sequestration pretreatment process. The method includes: (1) placing 100 mass parts of phosphogypsum, 1 to 2 mass parts of grinding aid, 10 to 20 mass parts of sodium-containing alkali component, 150 to 300 mass parts of zirconia balls, and 150 to 300 mass parts of water into a wet grinding tank for wet grinding. After 10 min to 30 min of wet grinding, introducing CO2 at a flow rate of 1.5 to 2.2 mass parts/min to keep a temperature of a wet grinding slurry below 40° C. When the wet grinding slurry reaches pH=10, ending the wet grinding and sieving out a wet grinding slurry; (2) mixing the wet grinding slurry with 700 to 1000 mass parts of slag and 100 to 350 mass parts of water to obtain a recycled cementitious material.

Abstract: The invention provides an apparatus and method for preventing surrounding loose rock fragments from falling or collapsing into a blast hole. The apparatus includes a flexible sheet including a pair of spaced apart longitudinally extending side edges and a pair of spaced apart laterally extending end edges. The sheet has a curved form defining a longitudinal passage extending between openings at longitudinally opposite ends, one end of the curved sheet being insertable into the open end of a blast hole whereby the curved sheet closely faces an internal surface of the blast hole and forms a barrier preventing surrounding loose rock fragments from falling or collapsing into the open end of the blast hole. The invention also provides a bench blasting method and a deployment device for deploying the apparatus into a blast hole.

Abstract: A method of plugging a formation fracture includes drilling, with a drill string configured to flow drilling fluid, a wellbore, where, at a downhole location, the drilling fluid is lost through a formation fracture. The method also includes deploying, through the drill string, a plugging assembly to the downhole location of the wellbore. The plugging assembly includes a flexible fiber sheet releasably coupled to a pumpable dart such that when the plugging assembly reaches the downhole location, the flexible fiber sheet is released from the dart to flow, with the drilling fluid, to the formation fracture to at least partially overlay the formation fracture. The method also includes adding, to the drilling fluid, lost circulation material configured to accumulate on a portion of the flexible fiber sheet to at least partially fluidically plug the formation fracture.

Abstract: An above ground stemming device is described which includes a body configured, in use, to cover an open end of a blast hole loaded with explosives to surface or to within 300 mm of surface. The body has a void containing a stem of superabsorbent polymer gel therein and it is positioned in use to allow the stem of superabsorbent polymer gel to be in contact with the explosives in the blast hole. The body may include a base and an upper portion extending upwardly from the base. The void may extend through the body to an opening in the base. Alternatively, the void may be encased by the body. The body may be fabricated from a rigid material or from a flexible material capable of being inflated with a fluid.

Abstract: Provided is an extensible spacer (14) for an inflatable blasthole plug (10) in the form of a collapsed bag (12). The spacer (14) includes a body (14.1) attached to the bag (12), and an associated leg formation (16) which may include leg segments (16.1, 16.2).

Abstract: A blasthole guard may include a conduit and a cap. The conduit is sized and shaped to allow a hose to pass through. The cap comprises a funnel that narrows to an open end of the conduit. A slot continuously extends from the conduit through the cap such that the slot forms an opening that extends along an entire length of the device.

Abstract: An elastomeric blasting plug and method of using the same are described. The elastomeric blasting plug may include a plurality of stacked units that taper from a base to a stem. A fuse may extend through the elastomeric blasting plug and the elastomeric blasting plug may expand radially after detonating the fuse and explosive charge.

Abstract: An igniter for seismic prospection or for mining applications or for use in the crude oil and natural gas industries is described, including a detonator in which an explosive material, an igniting element and internal wires for initiating the igniting element are arranged, wherein the internal wires lead into a plug which is arranged at one end of the detonator. In order for the user of the igniter to be able to introduce external wires into the plug without having to strip the wires of insulation beforehand, and, in the plug, for the internal wires to be electrically connected to the external wires, without the external wires requiring any plug and socket connector or mating part of a plug and socket connector, the plug is designed as a multifunctional plug.

Abstract: The invention relates to an igniter for seismic prospection or for mining applications or for use in the crude oil and natural gas industries, comprising a detonator in which an explosive material, an igniting element and internal wires for initiating the igniting element are arranged, wherein the internal wires lead into a plug which is arranged at one end of the detonator. In order for the user of the igniter to be able to introduce external wires into the plug without having to strip said wires of insulation beforehand, and, in the plug, for the internal wires to be electrically connected to the external wires, without the external wires requiring any plug and socket connector or mating part of a plug and socket connector, according to the invention, the plug is designed as a multifunctional plug.

Abstract: The invention provides a method of preparing a blast hole which method comprises the steps of: drilling a blast hole; placing explosives in the blast hole; filling the blast hole with a stemming material comprising a cement composition and water wherein the weight ratio of water to solids content of the stemming material is at least about 1:1.

Abstract: The invention provides a method of preparing a blast hole which method comprises the sequential steps of: drilling a blast hole; placing explosives in the blast hole; filling the blast hole with a stemming material comprising a cement composition and water wherein the weight ratio of water to solids content of the stemming material is at least about 1:1.

Abstract: A cylindrical casing (18) has first and second ends (33 and 31), the first end (33) being closed. The casing (18) encloses an accelerant (22) disposed adjacent the first end (33), at least one stemming mechanism (21), and a fuse (14 or 14?) extending from the accelerant (22) out of the second end (31) of the cylindrical casing (18). The cartridge (12) is made of a rupturable cylindrical casing (18) with accelerant (22) and self-stemming mechanism (22) inserted therein. A method of breaking hard (R) materials involves detonating a self-stemming cartridge (12) disposed in a borehole (B).

Abstract: Application of the method and device to a water well will permanently seal the well casing in order to prevent hydraulic cross-contamination with other water wells in the area. The method employs a string to explosive modules in spaced relation along the depth of a well casing. This weighted string of explosive modules is lowered into the well casing, wet concrete should then be introduced into the casing, after which the explosive elements are detonated sequentially, starting at the top of the well. Detonation of the elements in such a manner should force the wet concrete or cement out through the well casing perforations, so that the well casing will be entirely captured within the cured concrete. The individual explosive elements are made from detonating cord and metallic ball bearings wrapped into bundles, and then the bundles are bound in suitable adhesive tape.

Abstract: An inexpensive bullet-shaped plug is shown for use in a blasting hole containing water in the bottom thereof, which plug permits dry powder to be used above the waterline rather than more expensive wet powder. After the blasting holes are drilled, if water accumulates in the bottom thereof, the bullet-shaped plug with a center weight is dropped into the hole, which bullet-shaped plug floats on the water. Small rocks are dropped on top of the bullet-shaped plug causing upper tentacles to flare out to engage the wall of the blasting hole. Dry powder is then loaded into the blasting hole on top of the bullet-shaped plug. A cap is inserted a distance below the surface of the blasting hole. Thereafter, a series of similar blasting holes are blown at one time to create debris that can be removed or further processed.

Abstract: The invention provides a method of preparing a blast hole which method comprises the steps of: drilling a blast hole; placing explosives in the blast hole; filling the blast hole with a stemming material comprising a cement composition and water wherein the weight ratio of water to solids content of the stemming material is at least about 1:1.

Abstract: The invention provides a method of preparing a blast hole which method comprises the sequential steps of: drilling a blast hole; placing explosives in the blast hole; filling the blast hole with a stemming material comprising a cement composition and water wherein the weight ratio of water to solids content of the stemming material is at least about 1:1.

Abstract: Apparatus for plugging a hole, such as a bore hole used in blasting, comprises a platform shaped to fit within the hole and to support material such as explosives or stemming at a desired depth in the hole. The platform takes the form of a plate or tray which is generally ellipsoidal in shape so that it fits snugly within the hole when inclined transversely relative to a longitudinal axis of the hole. The plate has a central load support region and a peripheral region for engaging the wall of the hole. The apparatus includes a locking member, typically a length of rigid pipe, attached movably to the platform. The locking member is moveable between a first position in which it is supported clear of the wall of the hole below the platform, and a second position in which it spans the hole to lock the platform in position in the hole.

Abstract: An apparatus to mechanically stem (plug) a borehole or blast hole to contain or confine the gases generated by explosives is provided, thus preventing the energy generated by explosives to be released to the atmosphere. An assembly of the mechanical stemming apparatus for mining blasting operations according to the present invention comprises 2 pieces, placed one over the other: a base piece (1) and a central piece (6), and additionally includes two lateral wedge pieces (8) and four supporting pivots (11). The mechanical stemming apparatus according to the present invention and the entire apparatus set form a cylindrical body with a diameter lower than the borehole diameter and a length directly proportional to the diameter and depth of the boreholes or blast holes.

Abstract: A tamping device (10) for plugging an open end of a blasting hole used in a mine blasting application comprising an expandable sleeve (20) having a bore. The sleeve is configurable between circumferentially expanded and circumferentially retracted positions. An actuation member (40) having a head section (41) is at least partially locatable inside the expandable sleeve. The head section and the expandable sleeve are adapted in order for relative longitudinal movement between the head section and the expandable sleeve, to cause the sleeve to be manipulated from the retracted position to the expanded position.

Abstract: An inflatable air tube includes a sleeve member arranged concentrically about the upper end portion of the air tube to define a receptacle chamber for receiving a quantity of bulk explosive blasting powder, thereby to add weight to the air tube for positioning and stabilizing the same in the bulk explosive powder during the depositing of the powder into a blasting hole drilled into the ground. According to the method of the present invention, a plurality of accurate blasting patterns may be provided in the blasting powder column by timing the manual or mechanical insertion of the air tubes into the bulk blasting powder relative to the rate of supply of the powder from a source thereof.

Abstract: A method of dampening stress waves propagated from the detonation of an explosive device in a wellbore to protect a device positioned downhole including the steps of positioning a shock dissipater between an explosive device and a package; detonating the explosive device propagating a stress wave toward the shock dissipater and the package; and reflecting a portion of the stress wave in the shock dissipater. The shock dissipater may have one or more interface formed between materials of dissimilar acoustic impedances. The shock dissipater may reflect a compressive portion of the stress wave at one interface and a tensile portion of the stress wave at another interface.

Abstract: The invention relates to a stemming plug (10) which is made from a suitably resilient plastic material and comprises two cup-shaped members (12,14) which face each other with their rims (22) in abutment and means, which extends between the centres of the base portions of the cups (20) in the plug (10), which is adapted to move the bases of the cups (20) towards each other to compress the cups (10) and cause a circumferential zone of the plug (10) on either side of the abutting faces of the cups (20) to increase in radial dimension to be brought into load bearing contact with the side of a predrilled hole (38) in which the plug (10) is to be located, in use, and to enable the bases of the cups (20) to be moved away from each other to allow the plug (10) to be withdrawn from the hole (38) in the event of a misfire of the explosive in the hole (38).

Abstract: A drill hole (350) extends into rock to be blasted. A blasting accessory (310) includes a container portion (312) for holding a predetermined volume of stemming material, and a spacer (330) for spacing the stemming material a predetermined distance from a surface, e.g. a blind bottom of the drill hole. The container portion has a top (320) surrounded by a dilatable, inverted skirt forming a seal (342), and forms a support for a blasting substance like an explosive.

Abstract: A rock breaking cartridge (10) which includes a tubular body (12), spaced inner and outer second caps (14 and 16) inside the tubular body (12), a propellant (20) inside the tubular body (12) between the caps (14 and 16), a radially expansible stemming device (30) inside the tubular body (12) spaced from the inner cap (14), and a filler (34) between the inner cap (14) and the stemming device (30).

Abstract: A blasting arrangement (10) includes drillholes (30) in a rock mass (20). Blind ends (32) are drilled to a desired level and, if necessary, are adjusted as shown at (62) to said level. Each hole (30) is plugged by means of a plug (42), which is protected by non flammable buffer material (44), at a level (40) spaced from the end (32). Explosive (50) is charged above the level (40) and the hole is tamped, shown at (60). The holes are detonated desirably by detonators (52), forcing the plugs (42) downwardly and compressing air in chambers (34) above the ends (32). The weakest part of each hole, around the end (32), is split causing a three dimensional zone of weakness at the level of the ends (32). Air forced into the zone of weakness causes a fracture zone (70) at that level, inhibiting propagation of blasting shock waves and protecting the material underneath the level of the ends (32).

Abstract: Disclosed herein is a rock blasting method using air bladders embedded in explosives. The rock blasting method includes the step of drilling a plurality of loading holes into a rock to predetermined depths in a predetermined arrangement. Thereafter, the loading holes are loaded with a plurality of initial explosives, a plurality of primers and a plurality of explosives in such a way that one or more air bladders are inserted into each of the loading holes and surrounded by the explosives. Thereafter, the loading holes are stemmed with stemming materials in the portions of the loading holes situated over the explosives. The primers are detonated so that the initial explosives and explosives are blown up. Hence, the loading lengths of the explosives are increased in proportion to the lengths of the air bladders so that a projection area formed on the free face of the rock is increased.

Abstract: The present invention is directed to a cartridge that includes a number of advantageous features. For example, the cartridge can include a bulk energetic material, an igniter located in a central portion of the cartridge body, and a low void space in the cartridge.

Abstract: Reinforced borehole plugs useful in the presplitting and blast removal of earth formations, the improvements provided by the invention comprising inflatable devices intended to support stemming, explosives and the like at suspended locations within a borehole to produce desired blast results. The borehole plugs of the invention comprise inflatable sport balls such as are used on playgrounds as toys and which are reinforced according to the invention to maintain inflation within a borehole, a characteristic which playground balls can only inconsistently provide. The borehole plugs of the invention are preferably inflatable through use of valve structures which permit pumping of an inflating fluid into the plugs once the plugs are respectively suspended at desired locations within boreholes prior to filling the boreholes in whole or in part with stemming and/or explosives and the like.

Abstract: A tunnel blasting method is disclosed. The method including the step of drilling blast holes such as cut holes, cut spreader holes, floor holes and roof holes to predetermined depths and in a predetermined hole arrangement. The blast holes are loaded with one or more detonators and explosives, stemming the blast holes with stemming materials. The detonators are detonated using a triggering device. In the hole loading step, one or more air bladders are situated in each of the blast holes so that a front free surface or one or more small free surfaces are formed. As a result, a projective area toward a free surface is enlarged and a total blast pressure is increased to increase the fragmentation rate of a rock and reduce blast vibration.

Abstract: The present invention relates to a stemming arrangement and stemming method for use in blast holes. A rigid but deformable hollow member is located in a blast hole with its curved shape providing a clearance between opposed wall portions. A stemming material is contained within the curved portion. Detonation of the explosive deforms the hollow member outwardly into contact with the opposed wall portions of the blast hole.

Abstract: The present invention is directed to a boom supporting a slide assembly. The slide assembly includes a guide track, a drill, and a stemming member for use in small charge blasting. The drill is initially moved along the guide track to form the drill hole. After the hole is completed, the drill is retracted along the guide track, and the stemming member is moved along the guide track and placed in the drill hole. After the stemming member fractures the rock, the stemming member is retracted along the guide track and the steps repeated to break new material. The stemming member has a breech and barrel that are located in the hole. The breech is either side- or front-discharging.

Abstract: The present invention is directed to a method for selecting pressure wave suppression devices from among a menu of pressure wave suppression devices to satisfy the pressure wave requirements of a given job or application. The present invention is further directed to pressure wave suppression devices that can be used in the hole, at or near the opening of the hole, or at a distance from the hole to perform pressure wave and/or flyrock protection. The invention is particularly useful in suppressing airblast and other excavation equipment noise in urban areas.

Abstract: A rock blasting method is provided in which a series of aligned boreholes are charged with explosives and air tubes in a predetermined pattern. The air tube is a cylindrical flexible tube having a predetermined width and length to be fitted with the borehole. In one preferred form, each borehole is charged with the explosives and detonator with one air tube installed above the explosives. Stemming materials are installed above the air tube. For example, in a 45-millimeter diameter and 2.5-meter long borehole, the length of explosive charging is 0.8 meters, the co-operating charge weight was 0.648 Kg, the total amount of explosive 3.24 Kg, the length of the air tube 1.0 meter, the diameter of air tube 40 millimeters, and the length of stemming 0.7 meters. The explosives and air tube may be alternately charged along the borehole. The use of air tubes, charged above at least one explosive layer allows a quantitative air decking in every blasthole.

Abstract: A conical plug for sealing a blast hole in the earth is provided. The plug is made from a generally circular sheet of elastic material such as plastic or metal and can be folded and releasably locked with a trigger into a conical shape. When in its conical shape, the plug is lowered into a blast hole and, when in position, a release weight is slid down the lowering cable to impact and release the trigger. When the trigger is released, the plug expands and is wedged against the sides of the blast hole forming a plug capable of supporting debris in the upper portion of the blast hole.

Abstract: The present invention is directed to a method for selecting flyrock control devices from among a menu of flyrock control devices to satisfy the flyrock requirements of a given job or application. The present invention is further directed to flyrock devices that can be used in the hole, at or near the opening of the hole, or at a distance from the hole to perform flyrock and/or pressure wave protection. The invention is particularly useful in suppressing flyrock in urban areas.

Abstract: A pyrotechnic cutting device (14) is designed for directly cutting one or two parts (10) made form a nonmetallic material, such as a composite material. The device (14) comprises a pyrotechnic expansion tube (16), which acts on the part or parts (10) to be cut by means of a cutting member (32). This member can act in the manner of a punch or single or double shears. It can also be deformable or non-deformable. In the former case, the cutting member (32) can be integrated into the part (10) during its manufacture, particularly when said part is made from a composite material.

Abstract: A method of stemming a borehole (6) includes the steps of placing a first layer (16) of stemming in the borehole, placing a spherical body (20) in the borehole on top of the layer (16), the body being relatively incompressible and a diameter slightly smaller than the diameter of the borehole, and placing a second layer (18) of stemming in the borehole over the body. The stemming (16, 18) may be placed in the borehole either in direct contact with an explosive (8), or spaced from it by a gas bag (24) or the like form a deck (22). In accordance with an alternate application, the stemming layers (16, 18) may be placed in the borehole prior to placement of an explosive material such that it serves as backfill. Preferably, the stemming includes crushed rock and drill cuttings such as those produced during formation of the borehole. However, other available materials may also be used such as gravel.

Abstract: A device for locating and inflating a blasthole plug comprising; (i) a shroud adapted to enclose at least part of a deflated plug as the deflated plug is passed along a blasthole, (ii) an ejection means for removing the deflated plug from the shroud into a desired location in a blasthole, and (iii) an inflation means adapted to be removably connected to the plug, such that when the deflated plug is removed from the shroud, fluid material may be passed through the inflation means to inflate the plug.

Abstract: 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.

Abstract: A device and process for plugging an explosives blasthole, the device having an inner member (7a, 7b) in the form of a conduit having a valve (9) and being adapted for the passage of fluid bulk explosives and an outer member (1) adapted to engage the walls of the blasthole. The outer member may be made of deformable material or be inflatable. The inner and outer members may be detachable.

Abstract: A stemming plug constructed from a durable, resilient material and comprising a circumferential wall defining an inner cavity, an end wall at the first end and an open second end. In the preferred embodiment, the circumferential wall is fluted so that it can easily compress and seat in a borehole while maintaining a snug friction fit. The plug is inserted in the borehole over the explosive charge. Stemming material, preferably rock, is placed on top of the plug. The stemming material covers the top and slides down around the circumferential wall and is lodged between the circumferential wall and the borehole. Upon explosion, the blast energy is forced into the inner cavity causing the circumferential wall to expand outwardly and thereby engaging the stemming material and the borehole wall to secure the plug in place. The stemming material can also be placed inside the plug, with blast energy inverting the plug end wall to wedge stemming material within the borehole.

Abstract: Rock slabs or pieces are broken from larger rocks or from rock formations with reduced cracking of the broken rock slabs or pieces by drilling bore holes along the desired break lines, placing detonating cord into the bore holes, filling the bore holes with a shock transmitting and moderating composition, and detonating the detonation cord. The shock transmitting and moderating composition is preferably a gel with shock absorbing material such as microspheres or micro gas bubbles suspended therein. Openings in rock can also be formed by drilling at least one bore hole within the desired opening and drilling a plurality of bore holes along the desired periphery of the desired opening.

Abstract: A plug device for absorbing the energy of an explosion generated during a blasting operation in a bore located in a rock formation including a cup-shaped member having an annular sidewall and a closure wall, the cup-shaped member being constructed of a yieldable material that allows the cup-shaped member to form a sealed engagement with the bore thereby forming a barrier to the explosive force, the cup-shaped member includes a corrugated construction on the annular sidewall.

Abstract: A mine shaft closure plug which is created by a self-expanding plastic foam on a platform positioned within the mine shaft. Multiple expansion foam containers are used to provide the foam. Each expansion foam container has two closed waterproof pouches, an inner pouch and an outer pouch, each containing a separate component of the foam. The inner pouch is contained within the outer pouch. Upon breaking the inner pouch, the separate foam components combine within the outer pouch to form a complete expansion foam. The foam expands slowly enough to provide sufficient time for the container to be placed on the platform. Once in position, the expansion foam bursts the outer pouch to form the expansion foam plug above the platform. Either the platform or the expansion foam containers may be lowered into place by attached tethers.

Abstract: A device for internally cladding an outer tube with an inner tube by means of an explosion process. The device includes an outer tubular fixture (1) in which a workpiece in the form of the outer (2) and the inner (3) tubes can be placed; at least one end of the tubular fixture (1) is connected to an expansion chamber (7, 10); and a sealing cap (6) of easily destructed material is located between a respective expansion chamber (7, 10) and the workpiece. The sealing cap or caps (6) is/are intended to retain a liquid pressure-transmitting medium (5), preferably water, in the inner tube (3) prior to detonating an explosive substance (4) placed within the inner tube (3).

Abstract: A stemming agent is provided comprising: A) a neutralized acrylic acid polymer; B) a neutralized mixture of sodium silicate and a silicon oxide-containing material such as sand, clay, stones, volcanic ash, or the like; or C) a mixture of materials A) and B). The stemming agents produced are low cost, easily made, and preferably are free of nitrate salts. Accordingly, the use of these preferred stemming agents eliminates the contamination of ground water by nitrate salts. The stemming agents of the invention may be used in either bulk-delivered or packaged applications.

Abstract: An overbalance technique propagates a fracture in a formation to stimulate hydrocarbon production from a wellbore. A liquid column in the wellbore is driven into the formation by a gas generator to propagate the fracture. The gas generator can be compressed gas or propellant which is placed within the wellbore near or in the liquid column. Preferably the gas generator is placed in the wellbore above the production zone. The gas generator can be conveyed via tubing, wireline, or coiled tubing. Typically the liquid is brine, water or oil. The liquid can be a resin to consolidate a weak formation, sand and gel to prop a fracture, or acid to etch a fracture face. The overbalance technique has applications to cased and openhole wellbores. In cased wellbores, the technique can be performed as the casing is perforated or after the casing is perforated.

Abstract: A borehole decking plug which is created by a self-expanding plastic foam. Two closed waterproof pouches, an inner pouch and an outer pouch, each contain a separate component of the foam. The inner pouch is contained within the outer pouch, and both are contained within a third open external pouch having a tether attachment. Upon breaking the inner pouch, the separate foam components combine within the outer pouch to form a complete expansion foam. The foam expands slowly enough to provide sufficient time for the device to be lowered via the tether down a borehole to a preselected position. Once in position, the expansion foam bursts the outer pouch and escapes upward through the external pouch to form a deck plug at the preselected position.

Abstract: Inflatable devices configured for use particularly in large diameter boreholes and in blasting applications such as vertical cratering, the invention finds utility in blast removal of earth formations wherein the inflatable devices act to suspend explosives and/or stemming materials and the like within a borehole prior to detonation of explosives within said borehole. The inflatable devices are of various shapes and comprise an inner, relatively stretchable inflatable bag enclosed by an outer, relatively non-resilient bag, the inner bag having a valve to allow a fluid such as air to be pumped thereinto with the inner bag expanding to contact inner walls of the outer bag and force the outer bag into contact with walls of the borehole to exert forces against the borehole walls and thus "plug" the borehole at a desired location along the length thereof. Explosive materials and/or stemming materials can thus be suspended at desired locations within the borehole.

Abstract: A method of stemming a blast hole loaded with an explosive charge. The blast hole has side walls, an outwardly opening mouth and a central axis extending longitudinally of the blast hole. The method comprises inserting a conduit having a discharge end inwardly through the mouth of the blast hole and positioning the discharge end of the conduit within the blast hole generally adjacent the explosive charge. Particulate stemming material is forced under pressure through the conduit for exit from its discharge end into the blast hole toward the explosive charge thereby to pack stemming material in the blast hole adjacent the explosive charge. As stemming material is forced out the discharge end of the conduit, the discharge end of the conduit is moved generally axially outwardly relative to the blast hole toward the mouth of the blast hole to simultaneously fill and pack the blast hole with stemming material.