Method and arrangement for multi deck blasting

Abstract

A blast-hole loading method for commercial blasting applications, the method including: providing a first explosive deck of bulk explosive material in a blast-hole; providing at least one explosive second deck of bulk explosive material in the blast-hole; providing stemming between the first explosive deck and the or each second explosive deck to protect the or each second explosive deck from blast effects generated by initiation of the first explosive deck; and providing a water-excluding compressible deck between the stemming and the first explosive deck to protect the or each second explosive deck from a dynamic pressurisation event generated by the initiation of the first explosive deck, wherein the water-excluding compressible deck absorbs and / or reflects at least a portion of energy of the dynamic pressurisation event when it is compressed by the dynamic pressurisation event.

Description

METHOD AND ARRANGEMENT FOR MULTI DECK BLASTINGRELATED APPLICATION

[0001] The present application is related to the following patent application, the specification of which is hereby incorporated by reference in its entirety: Australian Provisional Patent Application No. 2024903108 entitled “Method and apparatus for multi deck blasting”.TECHNICAL FIELD

[0002] The present disclosure relates to a blast-hole loading method for commercial blasting applications and an arrangement in a blast-hole for commercial blasting applications, including multi deck blasting, e g., mining, quarrying, tunnelling, demolition (for instance, dams) and / or construction. Also disclosed herein is a commercial blasting method.BACKGROUND

[0003] Explosives are commonly used in mining. When detonated / initiated, explosives release a significant amount of energy into the rock mass surrounding the explosive: this released energy is directed by a blast designer to achieve a desired outcome, e.g., fragmenting a rock mass, or moving material. The explosives are often in the form of a bulk explosive material in a blast hole (or "blast-hole"). The dynamic pressure of the blast is controlled by the size and location of the blast-hole (typically in an array of blast-holes), the location of the bulk explosives within the blast-hole (e g , between stemming and a toe of the blast-hole), water (if present), ground conditions, and the geology.

[0004] In "multi deck blasting", also referred to as "decked blasting", two or more decks of the bulk explosive material, typically separated by stemming, are loaded into a blast-hole, and fired at different times. Stemming generally includes inert material, such as sand, gravel or crushed rock, packed into the blast-hole above the bulk explosive material, and is used to confine the explosive energy of the blast, directing it into the surrounding rock rather than out of the blast-hole. The deeper deck can be fired before the shallower deck, or vice versa Indecked blasting, it is generally desirable to have the second (and subsequent) deck or decks, each of which include bulk explosive material and an initiating system (typically electronic), and possibly blast monitoring equipment, survive initiation of the first deck, including surviving the dynamic pressures generated by the blast. The initiating system (or “blasting equipment”) in each deck may include blast controllers, detonators, initiators and primers.

[0005] The highest amplitude dynamic pressure experienced by the second (and subsequent) deck or decks is typically caused by movement of material within the blast-hole being blasted, e.g., stemming and / or water in the blast-hole. Mitigating undesirable effects of this dynamic pressure on the second (and subsequent) deck or decks may be particularly difficult in certain conditions, including when the blast-holes contain water, and / or when the ground / rock is harder.|0006| Previous mitigation measures for this dynamic pressure have previously relied on pressure-resistant devices, such ORICA's PROTECT-E booster, and / or on de-watering of blast-holes. However, the pressure-resistant devices do not protect the surrounding / nearby material (e g , bulk explosive), and / or may only provide modest improvements to initiating system survivability, depending on the blasting application. Furthermore, de-watering blastholes during loading does not ensure that water will not re-enter (e g , the stemming region) at a later stage, and de-watering is time-consuming and expensive.100071 It is desired to address or ameliorate one or more disadvantages or limitations associated with the prior art, or to at least provide a useful alternative.SUMMARY

[0008] One or more embodiments of the present invention include a blast-hole loading method for commercial blasting applications, the method including: providing a first explosive deck of bulk explosive material in a blast-hole; providing at least one explosive second deck of bulk explosive material in the blasthole;providing stemming between the first explosive deck and the or each second explosive deck to protect the or each second explosive deck from blast effects generated by initiation of the first explosive deck; and providing a water-excluding compressible deck between the stemming and the first explosive deck to protect the or each second explosive deck from a dynamic pressurisation event generated by the initiation of the first explosive deck, wherein the water-excluding compressible deck absorbs and / or reflects at least a portion of energy of the dynamic pressurisation event when it is compressed by the dynamic pressurisation event.

[0009] Each explosive deck may include: the bulk explosive material and at least one device to be protected from the dynamic pressurisation event. The or each water-excluding compressible deck may be arranged / held adjacent to the or each corresponding stemming when in the blast-hole, optionally by a weight. The water-excluding compressible deck may be non-explosive. The blast-hole loading method may include: providing more than two explosive decks in the blast-hole, including at least two second decks; providing further stemming between each sequential pair of the second decks to protect one of the second decks in each pair from blast effects generated by the other second deck in the pair; and providing further one or more water-excluding compressible decks between the further stemming portion and the other second deck in each pair to protect the one of the second decks in each pair from a dynamic pressurisation event generated by the initiation of the other second deck in each pair. The dynamic pressurisation event may include a pressurizing effect that is caused by the initiation of the first deck, including one or more of: a p-wave, a compression wave, a pressure wave, a displacement wave, a water hammer through a column in the blast-hole, a blast-hole collapse, and / or pressurization of existing water channels / soil / clay. The dynamic pressurisation event may have a time duration of less than 1 second, optionally substantially 100s of milliseconds. The dynamic pressurisation event may have a speed between 80 m / s and 500 m / s, optionally substantially 500 m / s. The blast-hole loading method may include providing weight, optionally rocks or stemming, to hold thecompressible deck from floating in water in the hole, wherein the weight is of lower mass than the stemming portion.

[0010] One or more embodiments of the present invention include an arrangement in a blasthole, the arrangement including: a water-excluding compressible deck; and a stemming portion, arranged / held adjacent to the water-excluding compressible deck, such that the arrangement, when provided between a first deck and a second deck of bulk explosive material in the blast-hole, protects the second deck from: blast effects generated by initiation of the first deck; and a dynamic pressurisation event generated by initiation of the first deck.

[0011] The arrangement may include a weight arranged hold the water-proof compressible deck under water if the blast-hole has water between the stemming and the first deck. The water-excluding compressible deck may be sized to substantially extend across a cross- sectional area of the blast-hole to mitigate portions of the pressure pulse travelling around the water-excluding compressible deck. The water-excluding compressible deck may include at least an outer material that withstands degradation due to the bulk explosive material in the first deck and / or due to water in the blast-hole The water-excluding compressible deck resists compression by other matter placed thereon in the blast-hole before the explosion of the first deck. The water-excluding compressible deck may be configured to withstand multiple shocks within the blast-hole when there are more than two decks of bulk explosive material in the blast-hole, wherein the water-excluding compressible deck includes an elastic water-proof compressible material.

[0012] The water-excluding compressible deck may include one or more of: a water-proof material containing a gas; a foam with gas bubbles or material beads in a matrix, optionally a polymer matrix, polyurethane, polyethylene, polystyrene, ethylene vinyl acetate (EVA), and / or polyvinyl chloride (PVC); and an explosive emulsion with at least 30% voidage. The foam may include a syntactic foam or an integral skin foam. The water-proof materialcontaining a gas may include: at least one gas-filled water-proof ball; and / or at least one gas- filled bag. The water-excluding compressible deck may resist a pressure of at least 10 bar for at least 7 days when in the blast-hole. The water-excluding compressible deck may be substantially compressible when in the blast-hole in order to absorb and / or reflect a substantial fraction of energy from the dynamic pressurisation event, wherein the substantial fraction is at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95%.

[0013] Also disclosed herein is a method including: providing a first deck of bulk explosive material in a blast-hole; providing at least one second deck of bulk explosive material in the blast-hole; providing a stemming portion between the first deck and the second deck to protect the second deck from blast effects generated by initiation of the first deck; and providing water-excluding compressible material between the stemming portion and the first deck to protect the second deck from a dynamic pressurisation event generated by the initiation of the first deck.

[0014] Also disclosed herein is an apparatus or arrangement including: water-proof compressible material; and a stemming portion, arranged / held adjacent to the water-proof compressible material, such that the apparatus can be provided between a first deck and a second deck of bulk explosive material in a blast-hole in order to protect the second deck from: blast effects generated by initiation of the first deck; and a dynamic pressurisation event generated by initiation of the first deck.

[0015] Also disclosed herein is a method including: providing two or more explosive decks of bulk explosive material in a blast-hole;providing a stemming portion between each sequential pair of the explosive decks, wherein the stemming portion is configured to protect a second deck of each sequential pair from blast effects generated by initiation of a first deck of each sequential pair; and providing water-excluding compressible material between the stemming portion and the first deck of each sequential pair to protect the second deck of each sequential pair from a dynamic pressurisation event generated by the initiation of the first deck of each sequential pair.

[0016] Also disclosed herein is a commercial blasting method including: providing in a blast-hole having a collar, a toe, and a length between its collar and its toe, and a plurality of decks of explosive material along the length of the blast-hole, each deck separated from an adjacent deck by a water-excludable compressible composition / material and a stemming material portion, wherein for a given deck that is to be explosively initiated prior to the initiation of an adjacent deck along the length of the blast-hole: the given deck is a donor deck and the adjacent deck is an acceptor deck with respect to the explosive initiation of the donor deck causing the transfer or propagation of a dynamic pressurisation event toward, to, or into (a) the acceptor deck as well as (b) the water-excludable compressible composition / material and the stemming material portion separating the donor deck and the acceptor deck, and the water- excludable compressible composition / material is configured to protects the acceptor deck and / or devices carried therein from a dynamic pressurisation event generated by way of the explosive initiation of the donor deck.

[0017] Also disclosed herein is a commercial blasting method including: providing in a blast-hole having a collar, a toe, and a length between its collar and its toe, and a plurality of decks of explosive material along the length of the blast-hole, each deck separated from an adjacent deck by a water-excludable compressible composition / material and a stemming material portion; and sequentially explosively initiating each deck of explosive material along the length of the blast-hole, wherein for a given deck that is explosively initiated prior to the initiation of an adjacent deck along the length of the blast-hole: the given deck is a donor deck and the adjacent deck is an acceptor deck with respect to the explosive initiation of the donor deck causing the transfer or propagation of a dynamic pressurisation event toward, to, or into (a) the acceptor deck as well as (b) the water-excludable compressible composition / material and the stemming material portion separating the donor deck and the acceptor deck, and the water-excluding compressible composition / material protects the acceptor deck and / or devices carried therein from a dynamic pressurisation event generated by way of the explosive initiation of the donor deck.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Some embodiments of the present invention are hereinafter described with reference to the accompanying drawings in which:FIG. 1 shows an example configuration of a compressible deck in a wet blasthole to protect the acceptor deck (including the acceptor bulk explosive material and / or an initiator device in the acceptor deck) from dynamicpressure caused by explosion of the donor deck (including donor bulk explosive material);FIG. 2 is a series of diagrams of a side view of a blast-hole at a plurality of stages of the loading method disclosed herein for a top-initiating blast-hole with the compressible deck adjacent the donor deck;FIG. 3 is a series of diagrams of a side view of a blast-hole at a plurality of stages of the loading method disclosed herein for a bottom-initiating blast-hole with the compressible deck adjacent the donor deck; andFIG. 4 is a flow chart of a method for selecting a compressible deck for a blasting application.DETAILED DESCRIPTION

[0019] Deck loading is a method of loading blast-holes (or “blast-hole loading method”) in which two or more explosive charges (each including a bulk explosive and an initiating system), referred to as “decks” or “deck charges” and intended to be blasted at mutually different times, are loaded into the same blast-hole

[0020] Disclosed herein is a method and an arrangement for combating undesired effects of intra-hole dynamic pressure by reducing energy transmitted between decks of explosive charges.

[0021] The method includes a blast-hole loading method that includes, with reference to the blast-hole 102 in Fig. 1 : providing a first deck 104 (also referred to herein as a "donor deck" because it is the first deck to be fired) of bulk explosive material (thus “donor explosive”) in the blasthole 102; providing at least one second deck 110 (also referred to herein as an "acceptor deck" because it is fired after the donor desk, so needs to accept (and survive) the blast fromthe donor deck), wherein the at least one second deck 1 10 can include two or more acceptor decks, each separated by stemming, wherein the second deck 110 includes bulk explosive material (thus “acceptor explosive”) in the blast-hole 102; providing a stemming portion 108 (which may be referred to as “stemming” or the "main stemming" protecting the acceptor deck 110 from the donor deck's blast effects), e.g., including rocky aggregate stemming, between the donor deck 104 and the acceptor deck 110 to protect the acceptor deck 110 from blast effects generated by initiation of the donor deck 104 (due to explosion of the donor deck 104, including a seismic p-wave and detonation products including heat and gasses); and providing a water-excluding compressible deck 106 (which is, in some embodiments, an “air deck”) in the blast-hole 102, between the stemming 108 and the donor deck 104, to protect the acceptor deck 110 from a dynamic pressurisation event (also referred to as a “dynamic pressure event”) generated by the initiation of the donor deck 104.

[0022] In many applications, water is present in the blast-hole 102, so the stemming 108 includes water, and is therefore referred to as “wet stemming” and may be water-saturated stemming. The water-excluding compressible deck 106 includes, and is substantially formed by, at least one water-excluding compressible material 107. "Water-excluding" means a sealed against ingress of water, and includes sealed water-proof containers, e.g., containing air, and solid water-proof materials, e.g., elastic polymers. The water-excluding compressible deck 106 excludes water sufficiently such that the dynamic pressurisation cannot be conducted through the compressible deck 106 by water — since water is substantially incompressible, the dynamic pressurisation event would not substantially compress the deck 106 if it were to be water saturated, or substantially water filled. The water-excluding compressible deck 106 excludes water under typical blast-hole temperatures, pressures and in-hole durations, for example (i) at temperatures above 0 degrees Celsius and below 100 degrees Celsius, typically between around 40 degrees and around 55 degrees, (ii) pressures of up to 10 bar, up to 20 bar, up to 30 bar, up to 40 bar, up to 50 bar, up to 60 bar, up to 70 bar, up to 80 bar, up to 90 bar, up to 100 bar, and (iii) up to 90 days or 3 months, upto 60 days or 2 months, up to 30 days or 1 month, up to 15 days or 2 weeks, up to 7 days or 1 week. The water-excluding compressible deck 106 may exclude water equivalent to having an Ingress Protection Rating (TEC 60529) of at least 1P68.

[0023] The water-excluding compressible deck 106 has substantially more compressibility than the stemming portion 108, so is able to absorb and / or reflect more energy from the dynamic pressurisation event than the stemming portion 108.

[0024] The donor deck 104 and the acceptor deck 110 in the blast-hole 102 are referred to herein as forming a “sequential pair” of explosive decks for each initiation event. Thus, in other words, the loading method includes: providing two or more explosive decks 104,1 10 of bulk explosive material in a blast- hole 102; providing a stemming 108 between each sequential pair of the explosive decks104,110, wherein the stemming portion 108 is configured to protect a second deck (or “acceptor deck” 110) of each sequential pair from blast effects generated by initiation of a first deck (or “donor deck” 104) of each sequential pair; and providing the water-excluding compressible deck 106 between the stemming 108 and the first deck 104 of each sequential pair to protect the second deck 1 10 of each sequential pair from a dynamic pressurisation event generated by initiation of the first deck 104 of each sequential pair.

[0025] As described hereinafter, each explosive deck 104,110 includes the bulk explosive material and at least one device (referred to as an "in-hole device", which typically includes at least one electronic device) to be protected from the dynamic pressurisation event.

[0026] As described hereinafter, the or each water-excluding compressible deck 106 is arranged / held adjacent to the or each corresponding stemming 108 when in the blast-hole 102, e.g., by an additional weight object when the water-excluding compressible deck 106 is above the stemming 108.

[0027] The blast-hole loading method is generally followed by a commercial blasting method, which includes: providing in the blast-hole 102, having a collar 112, a toe 114, and a length between its collar 112 and its toe 114, and a plurality of decks 104, 110 of explosive material along the length of the blast-hole 102, each deck 104 / 110 separated from an adjacent deck 104 / 110 by the water-excludable (or “water-excluding”) compressible composition / material (which is provided by the water-excluding compressible deck 106) and the stemming material portion (which is provided by the stemming 108), wherein, for a given explosive deck that is explosively initiated prior to the initiation of the next explosive deck along the length of the blast-hole 102: o the given explosive deck is a donor deck 104 and the next explosive deck is an acceptor deck 110 with respect to the explosive initiation of the donor deck 104, causing transfer or propagation of the dynamic pressurisation event toward, to, or into (a) the acceptor deck 110 as well as into (b) the waterexcluding compressible deck 106 and the stemming material portion 108 separating the donor deck 104 and the acceptor deck 110, and o the water-excluding compressible deck 106 protects the acceptor deck 110 (including devices carried therein) from the dynamic pressurisation event generated by way of the explosive initiation of the donor deck 104.

[0028] The commercial blasting method includes sequentially explosively initiating each deck of explosive material along the length of the blast-hole 102 to form a blast.

[0029] As shown in FIG. 2, the blast-hole loading method can include loading the acceptor deck 110 at or towards the toe 114 of the blast-hole 102 (so the blast is commenced from the collar end). Alternatively, as shown in FIG. 3, the blast-hole loading method can includeloading the donor deck 104 at or towards the toe 1 14 of the blast-hole 102 (so the blast is commenced from the toe end).

[0030] In an example, as shown in FIG. 2, the blast-hole loading method may include a loading process for a top-to-bottom blast, illustrated from the left:- providing the blast-hole 102, which can contain water 202, e.g., by drilling (step (a)); providing a lower acceptor deck 110 by dispensing emulsion into the toe 114 of the blast-hole 102, which raises the level of the water 202 (step (b); providing the stemming 108 above, and adjacent to, the lower acceptor deck 110, which further raises the level of the water 202 (step (c)) — and, due to the water 202, the stemming 108 is wet; deploying the compressible deck 106 until it is arranged / held adjacent to the stemming portion 108, which additionally raises the level of the water 202, and the compressible deck 106 may be deployed by a pole / hose 204 extended into the blasthole 102, and optionally held in place by a weight (step (d)) — when the compressible deck 106 reaches its location adjacent to the stemming 108, it operates in combination with the stemming 108 to protect the lower acceptor deck 110 from the dynamic pressurisation event that is generated by the initiation of the upper donor deck 104; providing the upper donor deck 104 by dispensing emulsion onto the compressible deck 106, which again raises the level of the water 202 (step (e)); and providing further stemming 206 onto the upper donor deck 104 (step (f)).

[0031] The loaded blast-hole 102 in step (f) of FIG. 2 has a top-to-bottom firing order, thus the upper explosive deck (donor deck 104) is fired before the lower explosive deck (acceptor deck 110), thus the compressible deck 106 and the adjacent stemming 108 (which is above and directly adjacent to the lower explosive deck) protect the lower explosive deck from the blast and the dynamic pressurisation event of the upper explosive deck.

[0032] Tn another example, as shown in FIG 3, the blast-hole loading method may include a loading process for a bottom-to-top blast, illustrated from the left: providing the blast-hole 102, e.g., by drilling (step (a)), and the blast-hole 102 can contain water 202;- providing the lower donor deck 104 by dispensing emulsion into the toe 114 of the blast-hole 102, which raises the level of the water 202 (step (b)); deploying the compressible deck 106 until it is arranged / held adjacent to the lower donor deck 104, which further raises the level of the water (step (c)) — the compressible deck 106 may be deployed by a pole / hose extended into the blast-hole 102 — with the compressible deck 106 in this location adjacent and underneath the stemming 108, the compressible deck 106 and the stemming 108 protect the upper acceptor deck 110 from a dynamic pressurisation event that is generated by the initiation of the lower donor deck 104;- providing the stemming 108 above, and adjacent to, the compressible deck 106, which additionally raises the level of the water (step (d)), wherein the stemming 108 and the compressible deck 106 are arranged / held adjacent to each other by the weight of the stemming — and, due to the water 202, the stemming 108 is wet; providing the upper acceptor deck 110 by dispensing emulsion onto the compressible deck 106, which again raises the level of the water (step (e)); and providing further stemming 206 onto the upper acceptor deck 110.

[0033] The loaded blast-hole 102 in step (f) of FIG. 3 has a bottom-to-top firing order, thus the lower explosive deck (donor deck 104) is fired before the upper explosive deck (acceptor deck 110), thus the compressible deck 106 and the adjacent stemming 108 (which is above and directly adjacent to the compressible deck) protect the upper explosive deck from the blast and the dynamic pressurisation event of the lower explosive deck.

[0034] The dynamic pressurisation event may include any pressurizing effect that is caused by the initiation of the donor deck, e.g., a p-wave, a compression wave, a pressure wave, a displacement wave, a water hammer through a column in the blast-hole, a blast-hole collapse with rock moving from adjacent blast-holes, and / or pressurization of existing water channels / soil / clay. When initiated, the donor deck 104 generates the dynamic pressurisation event in the blast-hole 102, and the dynamic pressurisation event may undesirably damage / effect explosive material and / or equipment in other explosive decks (the acceptor deck or decks 1 10) of the same blast-hole 102.

[0035] The dynamic pressurisation event may have a time duration of substantially 100s of milliseconds, including less than 1 second.

[0036] The dynamic pressurisation event can travel at high speeds, e.g., between 80 m / s and 500 m / s, for instance substantially 500 m / s.

[0037] The blast-hole loading method may further include providing the weight (optionally rocks, or more stemming) to hold the compressible deck 106 from floating in the water 202 in the blast-hole 102, and the weight is of lower mass than the stemming portion. Although some stemming material or stemming-like material in the stemming 108 may be provided on a donor side of the compressible deck 106, e g., rocks acting as the weight to stop the compressible deck from floating in water in the blast-hole 102, the stemming 108 on the acceptor side of the compressible deck 106 is generally of substantially higher mass than the weight in order to block or attenuate any blast effects generated by initiation of the donor deck 104 that are not sufficiently blocked / attenuated by the compressible deck 106 alone.

[0038] The blast-hole loading method may include providing more than two explosive decks in the blast-hole 102, and providing the stemming 108 between each sequential pair of the decks to protect one of the decks in each pair (to protect the "acceptor deck" for that initiation event) from blast effects generated by the other second deck in the pair (from the "donor deck" for that initiation event); and providing the water-excluding compressible deck 106 between each stemming 108 and the other second ("acceptor") deck 110 in each pair toprotect the one ("acceptor") of the decks in each pair from a dynamic pressurisation event generated by the initiation of the other ("donor") deck in each pair.

[0039] The blast-hole 102 may be loaded in the following order for a top-to-bottom blast: the acceptor deck 110, e.g., at the blast-hole toe 114 if the acceptor deck 110 is the deepest; the stemming 108; the water-excluding compressible deck 106; and then the donor deck 104. There may be more than two explosive decks in the blast-hole, in which case the second-to- last loaded deck is the acceptor for initiation of the first deck, and then the donor for initiation of the second deck.

[0040] The blast-hole may be loaded in the following order for a bottom-to-top blast: the donor deck 104, e.g., at the blast-hole toe 114 if the donor deck 104 is the deepest; the waterexcluding compressible deck 106; the stemming 108; and then the acceptor deck 110. There may be more than two explosive decks in the blast-hole, in which case the second loaded deck is the acceptor for initiation of the first deck, and then the donor for initiation of the second deck.

[0041] Each explosive deck, and specifically the acceptor deck 110 that is protected, includes the following elements, each of which may require protection from the dynamic pressurisation event generated by the initiation of the donor deck: a bulk explosive material, e.g., a commercially available ammonium nitrate based emulsion, e.g., from ORICA; and one or more devices, including electronic devices, such as: o an initiating system, e.g., at least one detonator, initiator and / or primer; o optionally a booster, depending on the application, e.g., a commercially available booster; and o optionally, monitoring equipment, e.g., a commercially available pressure gauge, a movement monitor or ore marker, or a sensor device.

[0042] To reiterate, the compressible deck 106 is configured and located to protect at least the subsequent deck from the blast effects of earlier decks, including protecting the bulk explosive material, and the (electronic) devices.

[0043] The compressible deck 106 may be designed according to the following method, as shown in FIG. 4: determining whether interdeck pressure protection is required for the elements (bulk explosive material and devices) of the second and subsequent decks (step 402); if so, determining whether there are any additional risk factors associated with the blast-hole, e.g., whether it is a water-filled hole, whether there is hard rock / competent rock mass, if the aggregate stemming length is short (e.g., less than 30 hole diameters), and if the devices include sensitive electronics (step 404); if there are no additional risk factors, proceeding with the shot (step 406); if there are additional risk factors, determining the pressure expected from initiating at least the first deck of the blast-hole, which can include making experimental measurements of an instrumented blast-hole (with the same decks as required) and / or making calculations, e.g., using a finite element analysis system (e.g., ELFEN, using a mechanistic blasting model) — step 408; if the pressure resistance is sufficient, then determining that pressure levels are not a concern for the object(s) being protected (step 410), and proceeding with the shot (step 412);- if the pressure resistance is insufficient, determining that additional pressure mitigation is required (step 414);- if the stemming portion is determined to be not suitable, e.g., the material type, and / or the length (step 416), then adjusting the stemming portion (step 418), and again determining the pressure expected from the initiating in step 408,if the pressure resistance is insufficient, and if the stemming portion is suitable (determined in step 416), then determining a number / length / volume / properties of the compressible deck 106 sufficient to reduce the pressure expected from the initiating to below the threshold for the subsequent decks, e g., by adjusting the model or experiment (step 420); adding the compressible deck 106 with the determined properties (step 422); then proceeding with the shot (step 424), and measuring the blast outcomes after the shot and adjusting future designs if there was a failure of a subsequent deck (step 426).

[0044] Also disclosed herein is an arrangement (also referred to as an “apparatus” or “system”) including: the water-excluding compressible deck 106 (including the water-proof compressible material); coupled to and combined with the stemming 108, arranged / held adjacent to the water-excluding compressible deck 106, such that the arrangement can be provided between a first deck (the donor deck 104) and a second deck (the acceptor deck 110) of bulk explosive material in the blast-hole 102 in order to protect the acceptor deck 1 10 from: blast effects generated by initiation of the donor deck 104; and a dynamic pressurisation event generated by initiation of the donor deck 104

[0045] The arrangement may include the weight arranged hold the water-excluding compressible deck 106 under water 202 if the blast-hole 102 has water 202 between the stemming 108 and the donor deck 104. In other words, the water-excluding compressible deck 106 and the weight (which may be rock or stemming) have together a density greater than the water 202 in the blast-hole 102.

[0046] The water-excluding compressible deck 106 may be sized to substantially extend across a cross-sectional area of the blast-hole 102 to mitigate portions of the dynamic pressure pulse travelling around the water-excluding compressible material.

[0047] The water-excluding compressible deck 106 includes at least an outer material that withstands degradation due to water and / or due to the bulk explosive material in the blasthole 102.

[0048] The water-excluding compressible material resists compression by other matter placed thereon in the blast-hole 102 before the explosion of the donor deck 104 — partial compression may acceptable but not complete compression, otherwise the water-excluding compressible deck 106 would not then be able to compress when the dynamic pressure event impinges thereon. The other matter may include the explosive material and / or the stemming 108, depending on the loading and orientation of the blast-hole 102. In other words, the compressible deck 106 is configured to withstand hydraulic pressure of anything placed upon the compressible deck 106 within the blast-hole 102 before the explosion of the donor deck 104.

[0049] The water-excluding compressible deck 106 (by way of properties of the waterexcluding compressible material) may be configured to withstand multiple dynamic pressure events (or shocks) within the blast-hole 102 when there are more than two donor explosive decks 104 loaded and exploded prior to the acceptor deck 110 associated with that waterexcluding compressible deck 106, e.g., the water-excluding compressible material may be an elastic water-excluding compressible material.

[0050] The water-excluding compressible material may include a water-proof material containing a gas (which is reversibly compressible, e.g., air). The water-excluding compressible material may include a foam (e.g., gas bubbles or material beads (for instance, glass spheres) (trapped) in a matrix, e.g., a polymer matrix), e.g., polyurethane, polyethylene, polystyrene, EVA, PVC. The foam may include a syntactic foam or an integral skin foam. The foam may include a metal foam, e.g., an aluminium foams. The water-excluding compressible material may include one or more gas-filled water-proof balls, e.g., tennis balls(e g., pressurised to over 1 atmosphere, e.g., to substantially 2 atmospheres). The waterexcluding compressible material may include one or more gas-filled bags, e.g., BLASTBAGS or BLASTBALLS from MT1 GROUP. In some examples, the waterexcluding compressible deck 106 is a non-explosive deck, thus excluding explosives like bulk explosive material. In other examples, the water-excluding compressible deck 106 may include some explosive material, e g., the water-excluding compressible material may include an explosive emulsion with a high voidage and low density, e.g., an explosive emulsion with at least 30% voidage, including loaded from a bulk truck, e.g., a Mobile Manufacturing Units (MMU), that is also configured for loading the bulk explosive materials into the blast-holes (albeit with different voidage percentages), e.g., as described in International Patent Application No. PCT / SG2022 / 050636, "Systems and methods for loading explosive compositions having programmably / selectively defined density profiles into boreholes", or in International Patent Application No. PCT / SG2024 / 050177, "Systems, apparatuses, and methods for delivering explosive compositions into boreholes".

[0051] The water-excluding compressible deck 106 inhibits / limits / reduces the displacement wave, including if there is water 202 in the blast-hole 102. The compressible deck 106 may effectively provide time and space for pressures from the donor explosive to attenuate, e g., by slowing the pressure wave(s). The compressible deck 106 may attenuate some portion of the energy of the dynamic pressure event, e.g., converting it to heat and / or sound. The compressible deck 106 may reflect some portion of the energy of the dynamic pressure event away from the acceptor desk 110, e.g., due to reflective structures / interfaces in the compressible deck 106: due to the change in density and speed of sound in the material of the compressible deck 106, it can act as a reflector for a primary wave (of the dynamic pressure event), then it can deliver energy back as it expands after the compression of the primary wave. The substantial compressibility of the compressible deck 106 means it acts as an energy absorber / reflector for the energy of the dynamic pressure event: in contrast, an incompressible plug would function in the same manner as existing stemming products, with a risk that it would act as a slug that shot though the borehole / blast-hole if it were to yield. The compressible deck 106 may broaden a pressure pulse of the dynamic pressurisation event: broadening the pulse tends to reduce the peak pressure, which can have the benefit ofprotecting in-hole components (such as a detonator) by potentially lowering the peak pressure below the yield point of the system. The compressible deck 106 may delay an arrival time of a pressure pulse of the dynamic pressurisation event: delaying the arrival of the pressure pulse increases the likelihood the blast may be timed to initiate prior to this pulse, at least in some application instances. The inhibition / limitation / reduction of the displacement wave minimizes acceleration of the stemming 108 and the water 202 (which is an "accelerateable" mass) into the acceptor deck 110, thus lowering compressive forces experienced by the acceptor bulk explosive material and any objects in the acceptor bulk explosive material, e.g., primers.

[0052] The compressible deck 106 may be designed to have one or more of the following properties: a. yield at a force less than a damage point of the obj ects in the acceptor bulk explosive material (e.g., approximately 50 bar to 250 bar, for instance approximately 100 bar)-in other words, for the compressible deck 106 to protect a certain object, it needs to yield before the object does; however, the compressible deck 106 does not collapse due to static pressure in the blasthole before blasting, accordingly resists pressure of up to 10 bar when in the blast-hole, including (i) at temperatures above 0 degrees Celsius and below 100 degrees Celsius, typically between around 40 degrees and around 55 degrees, and (ii) for up to 90 days or 3 months, up to 60 days or 2 months, up to 30 days or 1 month, up to 15 days or 2 weeks, up to 7 days or 1 week; b. remaining substantially compressible in the typical loaded blast-hole temperatures, pressures and in-hole durations described hereinbefore in order to absorb / reflect a substantial fraction of the energy in the dynamic pressure event, e.g., at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95%; and the compressibility of the compressible deck 106 may be due to the compressible deck 106 having a Poisson's ratio of less than 0.3, e.g., substantially 0.2, or less than 0.2, e.g., close to zero, whilst remaining nonnegative;c. substantially water-excluding by being water proof or sealed to substantially resist water at the typical loaded blast-hole temperatures, pressures and in-hole durations described hereinbefore; d. physically and chemically inert to resist degradation by the water or soil or stemming or bulk explosive material at typical pressures / temperatures in a loaded blast-hole before initiation, including when exposed to the typical loaded blast-hole temperatures, pressures and in-hole durations described hereinbefore; and e. a grip / mass to maintain its selected position within the column, e.g., via weight (if placed above the stemming portion) and / or via friction with the blast-hole wall.

[0053] The compressible deck 106 may be arranged in the blast-hole 102 using a deployment mechanism, e.g., as shown in FIG. 2 and FIG. 3. The compressible deck 106 may be weighted, including by the deployment mechanism, e.g., the pole or loading hose, e.g., of an MMU.

[0054] More than one compressible deck 106 may be provided and used in the blast-hole 102, and the acceptor deck 1 10 for the first compressible deck may become the donor deck 104 for the second compressible deck.

[0055] Example hole types and corresponding sizes / properties of the compressible deck 106 may include: a. for through-seam blast-holes, the blast-hole 102 may have a diameter of 229 mm and a length of 15-50 m, the blast-hole 102 may include up to 10 decks, there may be water 202 in the blast-hole 102, and the compressible deck 106 may have a length that is substantially 1 to 3 times the blast-hole diameter when loaded;b. for a quarry deck, the blast-hole 102 may have a diameter of 102 mm and a length of 15 m, the blast-hole 102 may include 2 to 3 decks, and the compressible deck 106 may have a length that is substantially 1 to 3 times the blast-hole diameter when loaded; and c. for a construction shaft, the blast-hole 102 may have a diameter of 76 mm, the blast-hole may include 2 decks, each 2-m long, the inter-deck stemming may be 2-m long (comprising aggregate), the stemming to the collar may be 1.5 m long, and the compressible deck 106 may have a length that is substantially 1 times the blast-hole diameter when loaded (i.e., when under compression, with the weight of the material compressing the compressible deck).Experimental Examples

[0056] Finite element (FE) modelling was used to determine transmitted pressure reduction with the use of an example compressible deck.

[0057] Two experimental blast-holes were tested: the first had a compressible deck and the second did not. The two blast-holes were cast in a concrete cylinder with embedded pressure sensors in the acceptor deck, specifically 80 mm from the bottom of the acceptor deck ("lower sensor"), 280 mm from the bottom of the acceptor deck ("mid sensor"), and 4 5 mm from the bottom of the acceptor deck ("upper sensor"). The first blast-hole had an example compressible deck in the form of a tennis ball pressurised to 2 atmospheres, having a substantially 7-cm diameter. The second blast-hole was a “control” that had, instead of the example compressible deck, an equivalent volume of 10-mm aggregate stemming. Each experimental blast-hole was substantially 1.8 m deep in a 2.0 m deep concrete block. Each experimental blast-hole had a diameter of substantially 70 mm centred within the 750-mm diameter of the concrete block The donor deck was 0.4-m deep and included Pyromex with an IKON electronic detonator. The stemming was substantially 0.8-m deep (around 0.73 m), and included mostly wet (or water-saturated) 10-mm aggregate. The acceptor deck was substantially 0.6-m deep. Blasts from the donor decks of the two experimental blast-holes were measured at the pressure sensors to determine whether the forces were different. Theexperimental implementation showed a reduction in both peak pressure and transmitted energy ("energy fluence") of up to 80%.

[0058] An FE model corresponding to the experimental blast-holes showed a peak pressure (or effective stress) reduction due to a simulated compressible deck of: 30% at an upper sensor, 39% at a mid sensor (also referred to as an “intermediate sensor”), and 37% at a lower sensor. The experimental blasts showed a peak pressure (or effective stress) reduction due to the example compressible deck of: 82% at the upper sensor, 54% at the mid sensor, and -10% (i.e., an increase) at the lower sensor The FE model showed a total energy fluence (kJ / mA2) reduction due to the simulated compressible deck of: 43% at the upper sensor, 44% at the mid sensor, and 48% at the lower sensor. The experimental blasts showed a total energy fluence (kJ / mA2) reduction due to the example compressible deck of: 90% at the upper sensor, 88% at the mid sensor, and 19% at the lower sensor.Interpretation

[0059] Herein, reference to one or more embodiments, e.g., as various embodiments, many embodiments, several embodiments, multiple embodiments, some embodiments, certain embodiments, particular embodiments, specific embodiments, or a number of embodiments, need not or does not mean or imply all embodiments

[0060] As used herein, the term “set” corresponds to or is defined as a non-empty finite organization of elements that mathematically exhibits a cardinality of at least 1 (i.e., a set as defined herein can correspond to a unit, singlet, or single element set, or a multiple element set), in accordance with known mathematical definitions (for instance, in a manner corresponding to that described in An Introduction to Mathematical Reasoning:Numbers, Sets, and Functions , “Chapter 11 : Properties of Finite Sets” (e.g., as indicated on p. 140), by Peter J. Eccles, Cambridge University Press (1998)). Thus, a set includes at least one element. In general, an element of a set can include or be one or more portions of a system, an apparatus, a device, a structure, an object, a process, a procedure, physical parameter, or a value depending upon the type of set under consideration.

[0061] The FTGs. included herewith show aspects of non-limiting representative embodiments in accordance with the present disclosure, and particular structural elements shown in the FIGs. may not be shown to scale or precisely to scale relative to each other. The depiction of a given element or consideration or use of a particular element number in a particular FIG. or a reference thereto in corresponding descriptive material can encompass the same, an equivalent, an analogous, categorically analogous, or similar element or element number identified in another FIG. or descriptive material associated therewith. The presence of “ / ” in a FIG. or text herein is understood to mean “and / or”, i.e , “X / Y” is to mean “X” or “Y” or “both X and Y”, unless otherwise indicated. The recitation of a particular numerical value or value range herein is understood to include or be a recitation of an approximate numerical value or value range, for instance, within + / - 20%, + / - 15%, + / - 10%, + / - 5%, + / - 2.5%, + / - 2%, + / - 1%, + / - 0.5%, or + / - 0%. The term “essentially all” or “substantially” can indicate a percentage greater than or equal to 50%, 60%, 70%, 80%, or 90%, for instance, 92.5%, 95%, 97.5%, 99%, or 100%.

[0062] Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

[0063] Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0064] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

CLAIMS1. A blast-hole loading method for commercial blasting applications, the method including: providing a first explosive deck of bulk explosive material in a blast-hole; providing at least one explosive second deck of bulk explosive material in the blasthole; providing stemming between the first explosive deck and the or each second explosive deck to protect the or each second explosive deck from blast effects generated by initiation of the first explosive deck; and providing a water-excluding compressible deck between the stemming and the first explosive deck to protect the or each second explosive deck from a dynamic pressurisation event generated by the initiation of the first explosive deck, wherein the water-excluding compressible deck absorbs and / or reflects at least a portion of energy of the dynamic pressurisation event when it is compressed by the dynamic pressurisation event.

2. The blast-hole loading method of claim 1, wherein each explosive deck includes: the bulk explosive material and at least one device to be protected from the dynamic pressurisation event.

3. The blast-hole loading method of claim 1 or 2, wherein the or each water-excluding compressible deck is arranged / held adjacent to the or each corresponding stemming when in the blast-hole, optionally by a weight.

4. The blast-hole loading method of any one of the preceding claims, wherein the waterexcluding compressible deck is non-explosive.

5. The blast-hole loading method of any one of the preceding claims, including:providing more than two explosive decks in the blast-hole, including at least two second decks; providing further stemming between each sequential pair of the second decks to protect one of the second decks in each pair from blast effects generated by the other second deck in the pair; and providing further one or more water-excluding compressible decks between the further stemming portion and the other second deck in each pair to protect the one of the second decks in each pair from a dynamic pressurisation event generated by the initiation of the other second deck in each pair.

6. The blast-hole loading method of any one of the preceding claims, wherein the dynamic pressurisation event includes a pressurizing effect that is caused by the initiation of the first deck, including one or more of: a p-wave, a compression wave, a pressure wave, a displacement wave, a water hammer through a column in the blast-hole, a blast-hole collapse, and / or pressurization of existing water channels / soil / clay.

7. The blast-hole loading method of any one of the preceding claims, wherein the dynamic pressurisation event has a time duration of less than 1 second, optionally substantially 100s of milliseconds.

8. The blast-hole loading method of any one of the preceding claims, wherein the dynamic pressurisation event has a speed between 80 m / s and 500 m / s, optionally substantially 500 m / s.

9. The blast-hole loading method of any one of the preceding claims, further including providing weight, optionally rocks or stemming, to hold the compressible deck from floating in water in the hole, wherein the weight is of lower mass than the stemming portion.

10. An arrangement in a blast-hole, the arrangement including: a water-excluding compressible deck; anda stemming portion, arranged / held adjacent to the water-excluding compressible deck, such that the arrangement, when provided between a first deck and a second deck of bulk explosive material in the blast-hole, protects the second deck from: blast effects generated by initiation of the first deck; and a dynamic pressurisation event generated by initiation of the first deck.

11. The arrangement of claim 10, including a weight arranged hold the water-proof compressible deck under water if the blast-hole has water between the stemming and the first deck.

12. The arrangement of claim 10 or 11, wherein the water-excluding compressible deck is sized to substantially extend across a cross-sectional area of the blast-hole to mitigate portions of the pressure pulse travelling around the water-excluding compressible deck.

13. The arrangement of any one of claims 10 to 12, wherein the water-excluding compressible deck includes at least an outer material that withstands degradation due to the bulk explosive material in the first deck and / or due to water in the blast-hole.

14. The arrangement of any one of claims 10 to 13, wherein the water-excluding compressible deck resists compression by other matter placed thereon in the blast-hole before the explosion of the first deck.

15. The arrangement of any one of claims 10 to 14, wherein the water-excluding compressible deck is configured to withstand multiple shocks within the blast-hole when there are more than two decks of bulk explosive material in the blast-hole, wherein the waterexcluding compressible deck includes an elastic water-proof compressible material.

16. The method of any one of claims 1 to 9 or the arrangement of any one of claims 10 to 15, wherein the water-excluding compressible deck includes one or more of: a water-proof material containing a gas; a foam with gas bubbles or material beads in a matrix, optionally a polymer matrix,polyurethane, polyethylene, polystyrene, ethylene vinyl acetate (EVA), and / or polyvinyl chloride (PVC); and an explosive emulsion with at least 30% voidage.

17. The method or arrangement of claim 16, wherein the foam includes a syntactic foam or an integral skin foam.

18. The method or arrangement of claim 16 or 17, wherein the water-proof material containing a gas includes: at least one gas-filled water-proof ball; and / or at least one gas- filled bag.

19. The method of any one of claims 1 to 9 and 16 to 18, or the arrangement of any one of claims 10 to 18, wherein the water-excluding compressible deck resists a pressure of at least 10 bar for at least 7 days when in the blast-hole.

20. The method of any one of claims 1 to 9 and 16 to 1 , or the arrangement of any one of claims 10 to 19, wherein the water-excluding compressible deck is substantially compressible when in the blast-hole in order to absorb and / or reflect a substantial fraction of energy from the dynamic pressurisation event, wherein the substantial fraction is at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95%.

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