Systems and methods for delivering reduced-density mechanically-gassed explosives

Abstract

Making a bulk explosive material can include obtaining an unsensitized bulk energetic material and processing the material to produce an explosive material. More specifically, such a method can include reducing a density of the bulk energetic material to a target density by injecting a gas into the material in conjunction with one or more dispersing agents. Systems for sensitizing bulk energetic material may provide for the joint injection of gas and a dispersing agent into a stream of the material.

Description

SYSTEMS AND METHODS FOR DELIVERING REDUCED-DENSITY MECHANICALLY- GASSED EXPLOSIVESRELATED APPLICATIONS

[0001] This application claims priority to United States Provisional Application No. 63 / 761,778, filed on Feb. 21, 2025, and titled Systems and Methods for Delivering Reduced-Density Mechanically-Gassed Explosives, and to United States Provisional Application No. 63 / 856,065, filed on August 1, 2025, and titled Systems and Methods for Delivering Reduced-Density Mechanically-Gassed Explosives, each of which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to the field of explosive compositions. More particularly, the present disclosure relates to methods of sensitizing mechanically-gassed explosives and related systems.BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The written disclosure herein describes illustrative embodiments that are non-limiting and non-exhaustive. Reference is made to certain of such illustrative embodiments that are depicted in the figures, in which:

[0004] FIG. 1 is a schematic diagram illustrating one embodiment of a process flow for manufacturing mechanically-gassed emulsion explosive.

[0005] FIG. 2 shows an assembly for sensitizing a stream of bulk energetic material in accordance with one embodiment.

[0006] FIG. 3 shows an assembly for sensitizing a stream of bulk energetic material in accordance with another embodiment.

[0007] FIG. 4A shows an assembly for sensitizing a stream of bulk energetic material in accordance with another embodiment.

[0008] FIG. 4B shows an alternative example according to the embodiment of FIG. 4A.

[0009] FIG. 5A shows an assembly for injecting a gas and a dispersing agent into a stream of bulk energetic material in accordance with one embodiment.

[0010] FIG. 5B shows a detailed view of an element of the embodiment shown in FIG. 5A.

[0011] FIG. 6A shows an assembly for sensitizing a stream of bulk energetic material in accordance with another embodiment.

[0012] FIG. 6B shows a detailed view of an element of the embodiment shown in FIG. 6A.

[0013] FIG. 6C shows a detailed view of a particular element of the structure shown in FIG. 6B.

[0014] FIG. 7A shows a cross-sectional view of a portion of a delivery conduit in accordance with one embodiment.

[0015] FIG. 7B shows a side view of a delivery conduit in accordance with one embodiment.

[0016] FIG 7C shows a detailed cross-sectional view of an element of the delivery conduit shown in FIG 7B

[0017] FIG. 7D shows a detailed cross-sectional view of an alternative arrangement of the element shown in FIG. 7C.14929-7744-3216 1DETAILED DESCRIPTION

[0018] This disclosure generally relates to bulk energetic materials to be used as explosives, along with related systems and methods. The present disclosure primarily discusses water-in-oil (or melt-in-oil) emulsions as an exemplary energetic material for the purposes of illustrating embodiments described herein; however, it will be understood that other explosive mixtures are contemplated, including, but not limited to, water gels, slurry explosives, and blends thereof.

[0019] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.”

[0020] “Emulsion” as discussed herein refers to a dispersion of droplets of an aqueous solution or water-miscible melt (the discontinuous phase) in an oil or water-immiscible organic substance (the continuous phase) The water-in-oil emulsion explosives discussed herein contain a water-immiscible organic fuel as the continuous phase and an emulsified inorganic oxidizer salt solution or melt as the discontinuous phase. The fuel can include a diesel fuel (which may alternatively be referred to as fuel oil), and can be a mixture of fuel and an emulsifier. The oxidizer salt solution can include, for example, ammonium nitrate Othertypes of emulsions can also be used, including hydrogen peroxide emulsions. “Watergel” as discussed herein refers to explosive mixtures comprising an aqueous inorganic oxidizer salt solution forming a continuous phase with solid particulate fuels or organic liquid fuels dispersed throughout and further including one or more thickeners.

[0021] Bulk energetic materials are commonly used in the mining, quarrying, and excavation industries for breaking rocks and ore. Generally, a hole, referred to as a “blasthole” or “borehole,” is drilled in a surface, such as the ground. The bulk energetic material may then be pumped or augered directly into the blasthole or, alternatively, may be packaged before placement in the blasthole. Bulk energetic materials are generally transported to a job site or made on the job site in a form that is too dense to completely detonate. Therefore, in order to detonate successfully the bulk energetic material needs to be “sensitized”, i.e. processed so as to reduce its density. Sensitizing is typically accomplished by introducing small voids into the material. These voids act as hot spots for propagating detonation. These voids may be introduced by: injecting a gas into the emulsion and thereby forming discrete gas bubbles ("mechanical gassing"); adding microspheres or other porous media; and / or injecting chemical gassing agents to react in the material and thereby form discrete gas bubbles (“chemical gassing”).

[0022] In some bulk energetic materials achieving very low densities can be difficult, particularly when sensitizing these materials by mechanical gassing. The density of the explosive material can be lowered by increasing the number of bubbles formed therein; however, as bubble concentration increases beyond a certain point any further reduction in density may be lost due to bubble coalescence. A method of reducing the density of a bulk energetic material can comprise introducing gas bubbles into the material in conjunction with one or more agents selected to minimize or prevent the bubbles from coalescing ("dispersing agents"). In the context of the24929-7744-3216 1present disclosure, dispersing agents act to evenly distribute bubbles throughout the bulk energetic material. Without being bound to a particular theory regarding mechanism of action, dispersing agents can be understood to work by adsorbing onto the surface of the bubbles, thereby creating a barrier that prevents them from clumping together and coalescing. This can be achieved through electrostatic repulsion or steric hindrance The dispersing agents can also be understood to facilitate the initial dispersion of gas bubbles in the material by acting as a wetting agent, i.e. lowering the interfacial tension between the material and the bubbles. Without being bound to a particular theory, the dispersing agents can be localized on or near the surface of the air bubbles, which are distributed throughout the bulk energetic material.

[0023] Exemplary dispersing agents include surfactants having a polar head group, which may be ionic or nonionic, and a nonpolar tail group. Examples of tail groups include hydrocarbons, alkyl ethers, fluorocarbons or siloxanes. Particular examples of suitable surfactants can have a tail group comprising at least 10 carbon atoms, for example a C10-C20 tail group. In some embodiments, the dispersing agent is an oil-miscible compound, examples of which include, without limitation, sorbitan monooleate, mineral oil, fuel oil, lecithin and polyisobutylene succinate anhydride (PIBSA)-based emulsifiers. In some embodiments, the dispersing agent is a water-miscible compound, examples of which include, without limitation, sodium lauryl sulfoacetate, sodium lauryl acetate, sodium lauryl ether sulfate, sodium dodecyl sulfate, phosphatidylcholine, cocamidopropyl betaine and sodium stearoyl lactate. In some embodiments, reducing density of a bulk energetic material can comprise adding at least one oil-miscible dispersing agent and at least one water-miscible dispersing agent.

[0024] Dispersing agent may be added to a bulk energetic material in an amount selected to achieve a target density in the resulting explosive. In various embodiments, the amount of dispersing agent with respect to the bulk energetic material can be from about 0.1 wt% to about 15 wt%, about 0.25 wt% to about 5 wt%, about 1 wt% to about 15 wt%, or about 1 wt% to about 3 wt%.

[0025] In some embodiments where the bulk energetic material is an emulsion, an emulsifier can also be added to reduce interfacial tension between the oil and water phases in the emulsion. Examples of emulsifiers that may be selected for use include alcohol alkoxylates, phenol alkoxylates, poly(oxyalkylene) glycols, poly(oxyalkylene) fatty acid esters, amine alkoxylates, fatty acid esters of sorbitol and glycerol, fatty acid salts, sorbitan esters, poly(oxyalkylene) sorbitan esters, fatty amine alkoxylates, poly(oxyalkylene)glycol esters, fatty acid amides, fatty acid amide alkoxylates, fatty amines, quaternary amines, alkyloxazolines, alkenyloxazolines, imidazolines, alkylsulfonates, alkylarylsulfonates, alkylsulfosuccinates, alkylphosphates, alkenylphosphates, phosphate esters, lecithin, copolymers of poly(oxyalkylene) glycols, and poly(12-hydroxystearic acid). The emulsifier can be different from the dispersing agent. In some embodiments, the emulsifier is added when the emulsion is manufactured, and the dispersing agent is added on the mobile processing unit or during delivery of the explosive to help achieve a required density. In certain embodiments, although not limiting, an emulsifier may be added when the amount of34929-7744-3216 1dispersing agent added to the material is from about 5 wt% to about 10 wt%. Emulsifiers can also be added with other amounts of dispersing agents as desired

[0026] Addition of dispersing agent as described herein can be used to produce a mechanically-gassed explosive material having a significantly lower density than would otherwise be achieved by mechanical gassing alone. In various embodiments, addition of dispersing agent can result in the explosive material having a density below about 1.5 g / cc, below about 1.25 g / cc, or below about 1 g / cc. In some embodiments, addition of dispersing agent can result in the explosive material having a density range of about 0.5 g / cc or about 1 g / cc to about 1.25 g / cc or about 1.5 g / cc. In some embodiments, addition of dispersing agent as described herein to an emulsion matrix can be used to produce an emulsion explosive having a density of about 0.6 g / cc to about 1.5 g / cc, or about 0.8 g / cc to about 1.25 g / cc. In some embodiments, addition of dispersing agent as described herein to a watergel can be used to produce an explosive having a density of about 0.5 g / cc to about 1.25 g / cc.

[0027] In various embodiments, sensitization of the bulk energetic material can be incorporated into the process of delivering the emulsion matrix from a processing unit to the borehole. Accordingly, the present disclosure provides systems and related methods for reducing density in bulk energetic materials in association with such delivery. The following discussion primarily describes emulsions as an exemplary energetic material for the purposes of illustrating various embodiments for sensitizing such materials; however, it will be understood that the operation of said embodiments can be applied to other explosive mixtures such as watergels. It will be readily understood that the modules of the embodiments as generally described below and illustrated in the Figures herein could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of various embodiments, as described below and represented in the Figures, is not intended to limit the scope of the disclosure, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0028] The phrases “operably connected to,” “connected to,” and “coupled to” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Likewise, “fluidically connected to” and “fluid communication” are each used in their ordinary sense, and are broad enough to refer to arrangements in which a fluid (e.g., a gas or a liquid) can flow from one element to another element. Two entities may interact with each other even though they are not in direct contact with each other. For example, two entities may interact with each other through an intermediate entity.

[0029] In accordance with the present disclosure, making an explosive material can comprise obtaining an unsensitized bulk energetic material and processing the material to produce an explosive material More specifically, such a method can comprise reducing a density of the bulk energetic material to a target density by injecting a gas into the material in conjunction with a dispersing agent. In some embodiments the method may further comprise delivering the resulting explosive material to a borehole. In some embodiments, the energetic material can be44929-7744-3216 1manufactured at a facility and then pumped into a storage reservoir of a mobile processing unit (e.g., transport truck) The energetic material can be sensitized and refined to produce a stable explosive.

[0030] Processing an energetic material as described above to produce a bulk explosive can comprise the use of an explosives delivery system In some embodiments, such a system may be substantially contained within a mobile processing unit (e.g., transport truck). FIG. 1 shows a process flow diagram of an explosives delivery system 100 in accordance with the present disclosure. The system can be configured to receive a stream 102 of emulsion matrix 104 from a reservoir 106 The system 100 can comprise a plurality of modules 112-1 - 112-x, where x = 2 to 10, for sensitizing and refining a stream 102 of the emulsion matrix 104. The system 100 can be configured to sensitize the emulsion matrix 104 by introducing gas bubbles into the stream 102. More particularly, the gas bubbles may be mechanically introduced into the stream 102 and combined with the emulsion matrix by one or more modules of the system 100. For example, in the process flow shown in FIG. 1, the system 100 can comprise a gas source 108 fluidically connected to the stream 102 at one or more injection ports 114 configured to deliver a stream of a gas 110 into the flow path. As shown in FIG. 1 , the system 100 may include an injection port at one or more of a plurality of locations along the flow path. In various embodiments, injection port locations may be described with respect to one or more modules. For example, an injection port may be situated upstream or downstream of an individual module, or alternatively incorporated into a module. In some embodiments, gas injection ports may be situated upstream or downstream of multiple modules or all of the modules.

[0031] In various embodiments, the system 100 can further comprise modules configured to add a dispersing agent to the emulsion matrix. For example, in the process flow shown in FIG. 1, the system 100 can comprise a dispersing agent source 116 fluidically connected to the stream 102. In some embodiments, addition of dispersing agent can be coupled with one or more stages of gassing. For example, as illustrated in FIG. 1 , dispersing agent 118 may be added to the stream 102 at a point 119 adjacent to a gas injection port 114 in the upstream or downstream direction, or the dispersing agent 118 may be added at the same point as gas injection In some embodiments, dispersing agent and a gas may be added simultaneously. More particularly, as illustrated in FIG. 1, in some embodiments dispersing agent 118 and gas 110 may be injected through the same injection port 114. In other embodiments, the dispersing agent and gassing agent can be added to the stream 102 at different points or locations. And in still other embodiments, dispersing agent and gassing agent can both be added at a first point, and additional dispersing agent and / or additional gassing agent can be added at second point that is upstream or downstream of the first point

[0032] In various embodiments, one or more modules of the system 100 may be configured to impart shear to the emulsion matrix for refinement purposes, such as to thicken, stabilize or otherwise modify the emulsion matrix. For example, as illustrated in FIG. 1, the flow path can comprise at least one homogenizer 120. In some embodiments, the homogenizer 120 operates by subjecting the emulsion explosive to shear stress. The homogenizer 120 may be configured54929-7744-3216 1to alter the size distribution of oxidizer salt solution droplets in the emulsion explosive. For instance, in some embodiments, the homogenizers may disrupt relatively large droplets of oxidizer salt solution, thereby converting such droplets into smaller droplets that have a more narrow size distribution. Such manipulation of the oxidizer salt solution droplets may cause an increase (e.g. , a significant increase) in the viscosity of the homogenized emulsion explosive. It will be appreciated that each of the gas 110 and / or the dispersing agent 118 can be added to the stream 102 before or after the homogenizer 120, or both before and after the homogenizer 120. In certain embodiments, the gas 110 and / or the dispersing agent 118 is added after the homogenizer 120.

[0033] The system 100 can also comprise a delivery conduit 122 fluidically connected to the homogenizers 120. The delivery conduit 122 may be configured for insertion into a bore hole and for ejecting the stream 102 of energized emulsion matrix into the bore hole. In some embodiments, the delivery conduit 122 may comprise at its distal end a structure or component for directing or controlling ejection of the stream into the bore hole, such as a spray nozzle. In some embodiments, the delivery conduit 122 can include one or more structures or components for gassing or refining the stream 102.

[0034] Methods of reducing density in a mechanically-gassed explosive material according to the present disclosure can comprise injecting a compressed or pressurized gas and a dispersing agent into a stream of energetic material. More particularly, introduction of the gas and the dispersing agent may be closely temporally related in a process of sensitizing a bulk energetic material and delivering the resulting explosive, for example as directly adjacent introduction events or particularly simultaneously in a single introduction event. In various embodiments, introduction can comprise combining the pressurized gas and dispersing agent to create a mixture, particularly an atomized mixture, before injection of the mixture into the material. In some embodiments, dispersing agent may be mixed with pressurized gas and then discharged from a nozzle to create such a mixture, and the mixture is then injected into a stream of energetic material.

[0035] An example of an assembly 200 for injecting a gas and a dispersing agent into a stream of energetic material is shown in FIG. 2. A system may comprise an injection module 202 configured to define a flow path 204 for a stream of an energetic material. The injection module 202 can include an injection port 206 configured to provide a fluidic connection between a nozzle assembly 208 and the flow path 204. The nozzle assembly 208 can comprise an inlet 210 for receiving a pressurized stream of liquid dispersing agent and an inlet 212 for receiving a pressurized gas. The inlets 210, 212 can be configured to direct their respective streams to a mixing chamber 214 More particularly, the inlets 210, 212 can be configured so that their respective streams impinge upon each other in the mixing chamber 214. The vigorous agitation resulting from this high velocity impingement can disperse the dispersing agent throughout the gas, producing an atomized mixture The mixing chamber 214 can be in fluid communication with a nozzle 216 situated in the injection port 206, such that the pressurized mixture in the mixing chamber 214 is forcibly discharged from the nozzle 216, through the injection port 206 into the flow path 204. The gassed energetic material can then pass down the flow path 204 into at least64929-7744-3216 1one downstream module for further processing or refinement. In some embodiments, as illustrated in FIG. 2, the downstream module 218 may comprise a static mixer 220 configured to facilitate mixing and dispersion of the gas and dispersing agent throughout the stream. In some embodiments, the pressurized mixture can be delivered directly to a module configured for introducing the mixture into the energetic material. Such a module may be configured to perform other processing steps coincidentally with sensitizing the energetic material.

[0036] FIG. 3, FIG. 4A and FIG. 4B present additional examples of injection assemblies based on the general design principle illustrated in FIG. 2. Accordingly, like features are designated with like reference numerals, with only the leading digit incremented to specify the figure in which it is depicted.

[0037] FIG. 3 shows an example of an assembly 300 utilizing a plurality of nozzles for injecting a gas and a dispersing agent into a stream of energetic material. The assembly 300 may comprise an injection module 302 configured to define a flow path 304 for a stream of an energetic material. The injection module 302 can include an injection port 306 configured to provide a fluidic connection between a nozzle assembly 308 and the flow path 304. The nozzle assembly 308 can comprise an inlet 310 for receiving a pressurized stream of liquid dispersing agent and an inlet 312 for receiving a pressurized gas. The inlets 310, 312 can be configured to direct their respective streams to a mixing chamber 314. More particularly, the inlets 310, 312 can be configured so that their respective streams impinge upon each other in the mixing chamber 314. The vigorous agitation resulting from this high velocity impingement can disperse the dispersing agent throughout the gas, producing an atomized mixture.

[0038] The mixing chamber 314 can be in fluid communication with a nozzle 316 situated in the injection port 306, such that the pressurized mixture in the mixing chamber 314 is forcibly discharged from the nozzle 316, through the injection port 306 into the flow path 304. In some embodiments, the injection port 306 may further comprise an injection line 318 in fluid communication with the injection port 306 and configured to convey the atomized mixture into the flow path 304. In some embodiments the injection line 318 can be configured to discharge the atomized mixture in a downstream direction. For example, as shown in FIG. 3, the injection line 318 may be an elbow fitting that directs the atomized mixture downstream. The injection line 318 may include an injection nozzle 320 to effect delivery of the atomized dispersing agent into the flow path 304.

[0039] In some embodiments, impingement of the dispersing agent and gas may be accomplished by discharging one or both of these streams from a nozzle. An example of an assembly 400 configured for this approach is shown in FIG. 4A. The assembly 400 can comprise an injection module 402 defining a flow path 404 and having an injection port 406 configured substantially as described in reference to FIG 3. A nozzle assembly 408 can include an inlet 410 for liquid dispersing agent in fluid communication with a dispersing agent nozzle 416 and an inlet 412 for pressurized gas in fluid communication with a gas nozzle 417. Each nozzle is oriented to discharge its respective stream into a mixing chamber 414 so that the streams impinge upon each other at high velocity, producing an atomized mixture. The mixing chamber 414 can be in fluid74929-7744-3216 1communication with the injection port 406. An injection line 418 also in fluid communication with the injection port 406 can be configured to discharge the atomized mixture in a downstream direction. The injection line 418 may be an elbow fitting as shown in FIG. 4A. In some cases, the injection line 418 may comprise tubing or piping as shown in FIG. 4B. In some embodiments the injection line 418 may include an injection nozzle 420 to effect delivery of the atomized dispersing agent into the flow path 404.

[0040] Another example of an assembly 500 for injecting a gas and a dispersing agent into a stream of energetic material is shown in FIG. 5A The assembly 500 can comprise an inlet 502 for receiving a pressurized stream of the liquid dispersing agent and an inlet 504 for receiving pressurized gas. Each of the inlets can be configured to direct their respective streams to a mixing chamber 506. The mixing chamber 506 can be in fluid communication with one or more atomizing nozzles 508, such that the pressurized mixture in the mixing chamber 506 is forcibly discharged from the one or more atomizing nozzles 508. For example, as shown in FIG 5A and FIG. 5B, a plurality of atomizing nozzles 508 may be arranged in a disk 510 situated between the mixing chamber 506 and an outlet 512 of the assembly 500. The disk 510 can include an array of orifices 514 each configured to accommodate and secure an atomizing nozzle 508 in place. In some embodiments, an atomizing nozzle 508 can be removably secured in an orifice 514 so that the atomizing nozzle 508 can be removed and replaced. In various embodiments, the assembly 500 can include one, two, three, four, five, six, or seven atomizing nozzles 508.

[0041] In some embodiments, the outlet 512 can be coupled to an injection port of a module configured for introducing the pressurized mixture into the stream of energetic material. Such a module may be configured to perform other processing steps coincidentally with sensitizing the energetic material. As shown in FIG. 5A, the assembly may optionally comprise a flow control mechanism configured to control delivery of the pressurized mixture, where “control” can include the commencement and cessation of delivery, determining the rate of delivery, or both. For example, as shown in FIG. 5A, a valve 516 may be situated between the outlet 512 and an injection port, e.g. of a processing module, where the valve can be actuated to transition between open state and a closed state.

[0042] Another example of an assembly for injecting a gas and a dispersing agent into a stream of energetic material is shown in FIG. 6A A system may comprise an injection module 602 configured to define a flow path 604 for a stream of an energetic material and to provide a fluidic connection between an injection port 606 and the flow path 604. The injection port 606 is configured to fluidically connect to an atomizing nozzle 608. The atomizing nozzle 608 can comprise a nozzle body 610 that includes an inlet 612 for receiving a pressurized liquid additive such as a dispersing agent as described herein, and an inlet 614 for receiving a pressurized gas (e.g., such as air). A nozzle cap 616 attached to the nozzle body 610 can comprise a dispersing agent outlet 618 fluidically connected by a channel 620 to the inlet 612 The nozzle cap 616 can further comprise one or more gas outlets 624 each fluidically connected by a channel 622 to the inlet 614. As shown, in some embodiments the nozzle cap 616 can comprise a plurality of channels 622 and corresponding gas outlets 624 arranged in an array around the dispersing agent84929-7744-3216 1outlet 618 and its channel 620. As also shown, the plurality of channels 622 may communicate with the inlet 614 via an annular manifold 626. A gasket 628 having orifices 630 each aligned with one of the plurality of channels 622 can be situated between the annular manifold 626 and the nozzle cap 616 (FIG. 6A, FIG. 6C). As also shown, the channels 622 and corresponding gas outlets 624 may be oriented so that gas discharged from the gas outlets 624 will impinge with dispersing agent discharged from dispersing agent outlet 618. Impingement of these streams at high velocity results in atomization of the dispersing agent. A discharge orifice 632 provides for discharge of the atomized dispersing agent from the atomizing nozzle 608 and into the injection port 606. The discharge orifice 632 may be removably secured by a locking nut 634 to the injection port 606 or to a structure coupled thereto. One or more of the elements connecting the atomizing nozzle 608 to the injection port 606 may include threading to provide for removable attachment between said elements.

[0043] The injection module 602 may further comprise an injection line 636 in fluid communication with the injection port 606 and configured to convey the atomized dispersing agent into the flow path 604. In some embodiments the injection line 636 may include a spray nozzle 638 to effect delivery of the atomized dispersing agent into the flow path 604.

[0044] A method of reducing density of a bulk energetic material can comprise adding a dispersing agent to the material in conjunction with mechanical gassing, where a gassing step is incorporated into a process of delivering the energetic material to a borehole. In some embodiments, dispersing agent can be added to the energetic material prior to and / or in conjunction with this gassing step. For example, in some embodiments, dispersing agent may be added to the bulk energetic material at an upstream location, optionally in conjunction with a gassing step as described above. An explosive delivery system can also comprise a delivery device, such as a delivery conduit or hose configured to convey a stream of an energetic material into a borehole. In some embodiments, the delivery conduit may be configured for sensitizing the energetic material at or proximate the downstream end of the delivery conduit, prior to, or in conjunction with, ejecting it into the borehole. Such sensitization can be referred to as end-of-hose gassing In some of such embodiments, the delivery conduit can be configured to add one or both of a gas and a dispersing agent into the energetic material at or proximate the downstream end of the delivery conduit.

[0045] In some embodiments, an example of which is illustrated in FIG. 7A, a delivery conduit 700 may include a hose 702 that defines a flow path 704 for a stream of bulk energetic material. The delivery conduit 700 may also include a separate tube 706 providing a flow path 708 for conveying a stream of compressed gas or, optionally, a pressurized mixture of gas and a dispersing agent. As shown, in some embodiments, the delivery conduit 700 may comprise a section 710 in which the tube 706 is situated directly adjacent the hose 702 so that their respective streams are parallel to each other As shown in the side view of the delivery conduit 700 (downstream from the view in FIG. 7A), the delivery conduit 700 may further comprise a nozzle 712 configured to combine the streams to produce an explosive product. The delivery conduit94929-7744-3216 1700 may further comprise a section 714 for conveying the explosive product from the nozzle 712 to the borehole.

[0046] FIG. 7C shows a cross-sectional view of the delivery conduit 700 showing features of the nozzle 712 in particular An inlet connector 716 can be configured to provide a secure fluidic connection between the hose 702 and the nozzle 712. The nozzle 712 can comprise one or more injection ports 718 in fluid communication with the tube 706 and configured to inject gas (or a gasdispersant mixture) into the flow path 704 of the energetic material. In various embodiments, the nozzle 712 can include from one to 8 injection ports 718. For example, the nozzle 712 can include four injection ports 718 as shown in FIG. 7C. In other embodiments, separate tubes and ports for gas and dispersing agent may be provided. The nozzle 712 can comprise one or more static mixers 720 (e.g., one to five static mixers 720, or one to three static mixers 720) to facilitate mixing and dispersion of the gas (or gas-dispersing agent mixture) throughout the flow path 704. An example of an alternative embodiment is shown in FIG. 7D, in which the nozzle 712' includes additional static mixers 720. The nozzle 712 may include other features to regulate the stream of the sensitized energetic material, for example one or more pressure relief holes 722 and / or a check valve 724 to prevent backflow. An outlet connector 726 conveys the sensitized energetic material out of the nozzle. The outlet connector 726 may be configured to provide a secure fluidic connection to the downstream section 714 of the delivery conduit

[0047] Gas and / or dispersing agent can thus be added to the energetic material at various locations during the explosive delivery process. For instance, in an embodiment, a dispersing agent and a gassing agent can be added to the energetic material at a location upstream of the delivery conduit. In another embodiment, a dispersing agent (with or without a gassing agent) can be added to the energetic material upstream of the delivery conduit, after which gassing agent (with or without additional dispersing agent) can be added proximate the downstream end of the delivery conduit. And in yet another embodiment, a dispersing agent and a gassing agent can be added to the energetic material proximate the downstream end of the delivery conduit.

[0048] Any methods disclosed herein include one or more steps or actions for performing the described method. The method steps and / or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and / or use of specific steps and / or actions may be modified Moreover, sub-routines or only a portion of a method described herein may be a separate method within the scope of this disclosure. Stated otherwise, some methods may include only a portion of the steps described in a more detailed method.

[0049] Reference throughout this specification to “an embodiment” or “the embodiment” means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment

[0050] Similarly, it should be appreciated by one of skill in the art with the benefit of this disclosure that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the104929-7744-3216 1disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim requires more features than those expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment. This disclosure includes all permutations of the independent claims with their dependent claims.114929-7744-3216 1

Claims

CLAIMSWhat is claimed is:

1. A method of reducing the density of a bulk explosive material, comprising:obtaining an unsensitized energetic material;adding an amount of a dispersing agent to the unsensitized energetic material; sensitizing the energetic material to produce a sensitized explosive material, wherein sensitizing comprises introducing a gas to the energetic material,wherein the energetic material is an emulsion or a watergel; andwherein the sensitized explosive material has a density of less than about 1.5 g / cc.

2. The method of claim 1 , wherein the dispersing agent is added prior to sensitizing.

3. The method of claim 1, wherein sensitizing comprises introducing the gas and the dispersing agent simultaneously4. The method of claim 3, comprising delivering a pressurized stream of the gas and the dispersing agent into the energetic material.

5. The method of claim 3 or 4, comprising:combining a pressurized stream of the gas and a pressurized stream of the dispersing agent to create an atomized mixture; andinjecting the atomized mixture into the energetic material.

6. The method of any one of claims 1 to 5, wherein the sensitized explosive material has a density of about 0.1 g / cc to about 1.5 g / cc.

7. The method of any one of claims 1 to 6, wherein the sensitized explosive material has a density of about 0.5 g / cc to about 1.5 g / cc.

8. The method of any one of claims 1 to 7, wherein the density is less than about 1.25 g / cc.

9. The method of any one of claims 1 to 8, wherein the energetic material is a watergel and the density is about 0.5 g / cc to about 1.25 g / cc.

10. The method of any one of claims 1 to 8, wherein the energetic material is an emulsion and the density is about 0.8 g / cc to about 1.25 g / cc.

11. The method of any one of claims 1 to 10, wherein the dispersing agent is a compound having a polar head group and a C10-20 nonpolar tail group.

12. The method of claim 11, wherein the polar head group is nonionic.

13. The method of claim 11, wherein the polar head group is ionic.

14. The method of any one of claims 1 to 13, wherein the dispersing agent is an oil-miscible compound.

15. The method of claim 14, wherein the dispersing agent is selected from sorbitan monooleate, lecithin, poly(isobutylene) succinic anhydride (PIBSA)-based emulsifiers, fuel oils, and mineral oil.

16. The method of any one of claims 1 to 13, wherein the dispersing agent comprises a water-soluble compound17. The method of claim 16, wherein the dispersing agent is selected from sodium lauryl ether sulfate, sodium dodecyl sulfate, cocamidopropyl betaine, sodium lauryl sulfoacetate, and sodium stearoyl lactylate.124929-7744-3216 118. The method of any one of claims 1 to 17, wherein the amount of the dispersing agent is about 0.1 wt% to about 15 wt% of the energetic material.

19. The method of claim 18, wherein the amount is about 0.25 wt% to about 5 wt%.

20. The method of any one of claims 1 to 19, further comprising:delivering the explosive material to a borehole through a delivery conduit, wherein sensitizing comprises introducing the gas into the energetic material proximate a downstream end of the delivery conduit.

21. The method of claim 20, wherein the dispersing agent is added upstream of the delivery conduit22. The method of claim 20 or 21 , comprising introducing a mixture of the gas and the dispersing agent upstream of the delivery conduit.

23. The method of any one of claims 20 to 22, comprising introducing a mixture of the gas and the dispersing agent proximate the downstream end of the delivery conduit.

24. The method of any one of claims 1 to 23, further comprising:homogenizing the energetic material with a homogenizer, wherein at least one of the dispersing agent or the gas is added to the energetic material before the homogenizer.

25. The method of any one of claims 1 to 23, further comprising:homogenizing the energetic material with a homogenizer, wherein at least one of the dispersing agent or the gas is added to the energetic material after the homogenizer.

26. A system for reducing the density of a bulk energetic material, comprising:a flow path configured to receive and convey a stream of an energetic material; one or more injection ports each providing fluidic access to the flow path;a source of a pressurized gas;a source of a dispersing agent,wherein each source is flu id ically connected to at least one of the one or more injection ports, anda delivery conduit configured to convey the energetic material to a borehole.

27. The system of claim 26, further comprising:an injection module configured to introduce the pressurized gas and the dispersing agent into the energetic material.

28. The system of claim 27, wherein the injection module further comprises an injection assembly configured to:combine a stream of the pressurized gas with a stream of the dispersing agent to create a mixture; anddeliver the mixture into the injection port.

29. The system of claim 28, wherein the mixture is an atomized mixture.30 The system of claim 28 or 29, wherein the injection assembly comprises:an inlet for receiving the stream of the pressurized gas;an inlet for receiving the stream of the dispersing agent; anda mixing chamber fluidically connected to both inlets,134929-7744-3216 1wherein the inlets are arranged so that the streams impinge upon each other in the mixing chamber.

31. The system of claim 30, wherein the injection assembly further comprises one or more nozzles fl u id ically connected to the mixing chamber and situated to discharge the mixture into the injection port.

32. The system of claim 31, wherein the one or more nozzles comprises an atomizing nozzle.

33. The system of claim 31 or 32, wherein the injection assembly comprises a plurality of said nozzles.

34. The system of claim 33, wherein the injection assembly comprises 3 to 7 of said nozzles.

35. The system of any one of claims 28 to 34, further comprising an injection line fluidically connected to the injection port and situated in the flow path and configured to discharge the mixture into the flow path36. The system of claim 35, wherein the injection line comprises a spray nozzle.

37. The system of any one of claims 30 to 36, wherein each inlet is connected to a nozzle configured to discharge the stream received by the inlet into the mixing chamber.

38. The system of claim 28, wherein the injection assembly includes an atomizing nozzle comprising:an inlet for receiving the stream of the pressurized gas and fluidically connected to a plurality of gas outlets;an inlet for receiving the stream of the dispersing agent and fluidically connected to a dispersing agent outlet,wherein the gas outlets and the dispersing agent outlet are arranged so as to discharge their respective streams to impinge and create an atomized mixture.

39. The system of any one of claims 28 to 38, further comprising a flow control valve through which the injection assembly is connected to the injection port.

40. The system of any one of claims 27 to 39, further comprising a static mixer downstream of the injection module.

41. The system of any one of claims 26 to 40 wherein the delivery conduit comprises:a hose fluidically connected to the flow path and configured to receive the stream of energetic material;a tube fluidically connected to the source of pressurized gas and defining a flow path for a stream of the pressurized gas;a nozzle fluidically connected with a downstream end of the hose and the tube and configured to combine the stream of pressurized gas with the stream of energetic material.

42. The system of claim 41, wherein the source of dispersing agent is fluidly coupled to one or more injection ports in the flow path upstream of the delivery conduit43 The system of claim 41 or 42, wherein the nozzle is further configured to combine dispersing agent with the stream of energetic material.

44. The system of claim 43, wherein the tube conveys dispersing agent together with the pressurized gas.144929-7744-3216 145. The system of any one of claims 41 to 44, wherein the nozzle includes at least one static mixer.

46. The system of claim 45, wherein the nozzle includes one to three static mixers.

47. The system of claim 46, wherein the nozzle includes three static mixers48. The system of any one of claims 26 to 47 further comprising:a homogenizer for homogenizing the energetic material, wherein at least one of the source of a dispersing agent or the source of a pressurized gas is fluidically connected to an injection port that is before the homogenizer154929-7744-3216 1

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