Patent Application
20240190788
This application claims priority to Australian Provisional Patent Application No. AU2022903767, filed Dec. 9, 2022, which is incorporated by reference in its entirety.
The present invention relates to the field of explosives. In particular, the present invention relates to explosive formulations for use or when used in reactive ground. However, it will be appreciated that the invention is not limited to this particular field of use.
The following discussion of the prior art is provided to place the invention in an appropriate technical context and enable the advantages of it to be more fully understood. It should be appreciated, however, that any discussion of the prior art throughout the specification should not be considered as an express or implied admission that such prior art is widely known or forms part of the common general knowledge in the field.
The presence of sulphides in reactive ground, such as metal sulphides, that release heat (i.e. are exothermic) upon reaction with explosives, such as ammonium nitrate (AN) compositions, can result in premature detonation of the explosive, with potentially catastrophic consequences. Further, the products of the reaction, including metal ions and/or nitrous acid, destabilise AN and/or facilitate the decomposition of AN. Accordingly, the formulation of explosive products, particularly for use in reactive ground or high temperature reactive ground that can be reactive with such products can be challenging.
Further, explosives per se generally can be more sensitive to initiation at higher temperatures, and as such can intrinsically be prone to premature detonation if used at high temperatures. For example, AN, when pure, intrinsically decomposes (and can detonate) at around its melting point (169.6° C.).
There have been a number of premature detonation events at mine sites throughout the world in which explosives have reacted with reactive ground. For example, in the 1960s at a mine in Mount Isa in Australia, holes in the ore body (a reactive ground) became incandescent on contact with ammonium nitrate explosive compositions, resulting in premature detonations. Similarly, at a mine in Collinsville, Australia, in 1998, a hole in reactive ground that had been loaded with an ammonium nitrate-containing explosive detonated prematurely. Further, at the Black Star mine in Mount Isa in Australia in 2005, there was a premature detonation event caused by the reaction of an explosive with a high temperature reactive ground.
Standard inhibitors known in the art to prevent premature detonation of explosive compositions can generally be less effective at higher temperatures, or may be required in such high quantities to be effective in preventing premature detonation in reactive and/or high temperature ground, that they can render the explosive unable to be detonated using standard detonation means.
Accordingly, there is a need for new explosive formulations for use in reactive and/or high temperature ground.
It is an object of the present invention to overcome or ameliorate one or more the disadvantages of the prior art, or at least to provide a useful alternative.
It is an object of at least one preferred embodiment of the present invention to provide an explosive formulation for safe blasting of reactive and/or high temperature sulphidic ground.
According to a first aspect of the present invention there is provided an explosive formulation for use or when used in reactive ground comprising metal sulphide, the formulation comprising:
The inventors of the present invention have surprisingly found an explosive formulation that improves the stability of nitrate-based explosives in reactive ground. Without wishing to be being bound by any theory, it is believed that the metal-ion binding agent disrupts the availability of metal ions (an explosive destabiliser) formed in the reaction of explosives and reactive ground in a surprisingly effective way, and therefore improves the stability of the explosives in reactive ground. Further, the pH buffering agent reduces the likelihood of a thermal runaway and slows down the rate of the reaction between explosives and reactive ground, by reducing the amount of acid present. Yet further still, the inventors have surprisingly found a combination of the metal-ion binding agent and the pH buffering agent provides synergistic effects.
In an embodiment of the invention, the nitrate comprises ammonium nitrate, calcium ammonium nitrate, calcium nitrate and/or sodium nitrate.
In an embodiment of the invention, the nitrate comprises ammonium nitrate, calcium ammonium nitrate, calcium nitrate, sodium nitrate, potassium nitrate, barium nitrate and/or magnesium nitrate.
In an embodiment of the invention, the metal sulphide comprises iron sulphide, iron disulphide, iron copper sulphide, copper (II) sulphide, lead sulphide, molybdenum disulphide, zinc sulphide, and/or copper (I) sulphide. However, the person skilled in the art will appreciate that other metal sulphides may be present in the reactive ground.
In an embodiment of the invention, the metal-ion binding agent comprises phosphate, phospholipids, amino acid, xanthate salt, silicate, and/or acid. However, the person skilled in the art will appreciate that other chemical species are suitable in binding the metal ion.
In an embodiment of the invention, the phosphate comprises melamine phosphate, melamine polyphosphate, sodium hexametaphosphate (NaHMP, or SHMP), sodium polyphosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, monoammonium phosphate (MAP), diammonium phosphate (DAP), urea phosphate, monoethanolamine phosphate, hydroxy ammonium phosphate, bone meal and/or calcium hydroxyapatite (CaHAP).
In an embodiment of the invention, the amino acid comprises glycine, asparagine, and/or arginine.
In an embodiment of the invention, the xanthate salt comprises potassium ethyl xanthate, sodium ethyl xanthate, lithium ethyl xanthate, sodium isopropyl xanthate, potassium isopropyl xanthate, lithium isopropyl xanthate, sodium isobutyl xanthate, potassium isobutyl xanthate, lithium isobutyl xanthate, potassium amyl xanthate, sodium amyl xanthate, and/or lithium amyl xanthate.
In an embodiment of the invention, the acid comprises tannic acid, humic acid, fulvic acid, gallic acid, citric acid, ascorbic acid, glyoxylic acid and/or potassium hydrogen phthalate.
In an embodiment of the invention, the silicate is tetraethyl orthosilicate.
In an embodiment of the invention, the metal-ion comprises iron (I), iron (II), iron (III), iron (IV), iron (V), iron (VI), iron (VII), copper (I), copper (II), copper (III), copper (IV), lead (II), lead (IV), zinc (II), molybdenum (I), molybdenum (II), molybdenum (III), molybdenum (IV), molybdenum (V), and/or molybdenum (VI). However, the person skilled in the art will appreciate that the metal-ion binding agent may bind to other suitable metal ions.
In a specific embodiment of the invention, the metal-ion is iron (III).
In an embodiment of the invention, the metal-ion binding agent forms a precipitate with the metal-ion. In other embodiments of the invention, the metal-ion binding agent forms a complex with the metal-ion, preferably a stable complex.
In an embodiment of the invention, the metal-ion binding agent is more effective than the pH buffering agent in stabilising explosives in reactive ground. For example, the metal-ion binding agent is 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10 times more effective.
In an embodiment of the invention, the pH buffering agent comprises base, acid, and/or amino acid. However, the person skilled in the art will appreciate that other chemical species are suitable pH buffering agent.
In an embodiment of the invention, the pH buffering agent has a pH between about 1 to 10, about 1 to 7, about 2 to 7, about 7 to 10, or about 8 to 10. For example, the pH buffering agent has a pH of 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10.
In an embodiment of the invention, the base comprises 2-amino-2-(hydroxymethyl)-1,3-propanediol (Tris), sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium carbonate, calcium bicarbonate, magnesium carbonate, magnesium bicarbonate, piperazine, and/or pyrrole.
In an embodiment of the invention, the acid comprises N-(2-acetamido)-2-aminoethanesulfonic acid (Aces), tannic acid, humic acid, fulvic acid, gallic acid, citric acid, ascorbic acid, glyoxylic acid and/or potassium hydrogen phthalate.
In an embodiment of the invention, the amino acid comprises arginine, glycine and/or asparagine.
In an embodiment of the invention, the pH buffering agent does not react with ammonium ion.
In an embodiment of the invention, the pH buffering agent does not lead to breakdown of the explosive.
In an embodiment of the invention, the metal-ion binding agent and/or the pH buffering agent are stable at a temperature of between about 50° C. and 500° ° C. For example, the metal-ion binding agent and/or the pH buffering agent are stable at between about 50° C. and about 60° C., or between 60° C. and about 70° C., or between 70° C. and about 80° C., or between 80° C. and about 90° C., or between 90° C. and about 100° C., or between 100° C. and about 110° C., or between 110° C. and about 120° C., or between 120° C. and about 130° C., or between 130° C. and about 140° ° C., or between 140° C. and about 150° C., or between 150° C. and about 160° C., or between 160° C. and about 170° C., or between 170° C. and about 180° C., or between 180° C. and about 190° C., or between 190° C. and about 200° C., or between 200° C. and about 210° C., or between 210° C. and about 220° C., or between 220° C. and about 230° C., or between 230° ° C. and about 240° C., or between 240° C. and about 250° C., or between 250° C. and about 260° C., or between 260° C. and about 270° C., or between 270° C. and about 280° C., or between 280° C. and about 290° ° C., or between 290° C. and about 300 ºC, or between 300° ° C. and about 310° C., or between 310° C. and about 320° C., or between 320° C. and about 330° ° C., or between 330° C. and about 340° C., or between 340° C. and about 350° C., or between 350° C. and about 360° C., or between 360° C. and about 370° C., or between 370° C. and about 380° ° C., or between 380° C. and about 390° C., or between 390° C. and about 400° C., or between 400° C. and about 410° C., or between 410° C. and about 420° C., or between 420° C. and about 430° C., or between 430° C. and about 440° C., or between 440° C. and about 450° C., or between 450° C. and about 460° C., or between 460° C. and about 470° C., or between 470° C. and about 480° ° C., or between 480° C. and about 490° C., or between 490° C. and about 500° C.
In an embodiment of the invention, the metal-ion binding agent and/or the pH buffering agent are stable at a temperature of between about 130° C. and 250° C.
In an embodiment of the invention, the metal-ion binding agent and/or the pH buffering agent are stable at a temperature of between about 150° C. and 200° C.
Advantageously, the metal-ion binding agent and/or the pH buffering agent can withstand high temperature such that they are effective in preventing premature detonation when explosives are used in high temperature reactive ground.
In an embodiment of the invention, the formulation comprises between about 0.1 wt % and about 30 wt % of the metal-ion binding agent. For example, the formulation comprises between about 0.1 wt % and 1 wt %, or between about 1 wt % to about 5 wt %, or between about 5 wt % to about 10 wt %, or between about 10 wt % to about 15 wt %, or between about 15 wt % to about 20 wt %, or between about 20 wt % to about 25 wt %, or between about 25 wt % to about 30 wt % of the metal-ion binding agent.
In an embodiment of the invention, the formulation comprises between about 0.1 wt % and about 30 wt % of the pH buffering agent. For example, the formulation comprises about about 0.1 wt % and 1 wt %, or between about 1 wt % to about 5 wt %, or between about 5 wt % to about 10 wt %, or between about 10 wt % to about 15 wt %, or between about 15 wt % to about 20 wt %, or between about 20 wt % to about 25 wt %, or between about 25 wt % to about 30 wt % of the pH buffering agent.
In an embodiment of the invention, the blasting agent is in the form of an emulsion with fuel oil, whereby the fuel oil is a continuous organic phase and the blasting agent is a discontinuous oxidiser phase
In an embodiment of the invention, the discontinuous oxidiser phase comprises the metal-ion binding agent, and/or the pH buffering agent.
In an embodiment of the invention, the metal-ion binding agent and/or the pH buffering agent are in the form of crystals, granules, and/or powders.
The skilled person would appreciate that the metal-ion binding agent and/or the pH buffering agent may be included in the oxidiser phase of the explosive emulsion during manufacture, or added to the formed explosive products (“post-add”), or both.
In an embodiment of the invention, the formulation further comprises a nitrous acid neutralising agent.
Advantageously, the nitrous acid neutralising agent neutralises at least a portion of the nitrous acid (an explosive destabiliser) formed in the reaction of explosives and reactive ground and therefore improves the stability of the explosives in reactive ground.
In an embodiment of the invention, the nitrous acid neutralising agent comprises urea, allantoin, arginine, glycine, asparagine, hydroxy ammonium salts and/or biuret.
In an embodiment of the invention, the nitrous acid neutralising agent is stable at a temperature of between about 50° C. and 500° C. For example, the nitrous acid neutralising agent is stable at between about 50° C. and about 60° C., or between 60° C. and about 70° C., or between 70° C. and about 80° C., or between 80° C. and about 90° C., or between 90° C. and about 100° C., or between 100° C. and about 110° C., or between 110° C. and about 120° C., or between 120° C. and about 130° ° C., or between 130° C. and about 140° C., or between 140° C. and about 150° C., or between 150° C. and about 160° C., or between 160° C. and about 170° C., or between 170° C. and about 180° C., or between 180° C. and about 190° C., or between 190° C. and about 200° ° C., or between 200° C. and about 210° C., or between 210° C. and about 220° ° C., or between 220° C. and about 230° C., or between 230° C. and about 240° C., or between 240° C. and about 250° C., or between 250° C. and about 260° C., or between 260° C. and about 270° C., or between 270° C. and about 280° C., or between 280° C. and about 290° C., or between 290° ° C. and about 300° C., or between 300° C. and about 310° C., or between 310° C. and about 320° ° C., or between 320° C. and about 330° C., or between 330° C. and about 340° C., or between 340° ° C. and about 350° C., or between 350° C. and about 360° C., or between 360° C. and about 370° C., or between 370° C. and about 380° C., or between 380° C. and about 390° C., or between 390° ° C. and about 400° ° C., or between 400° C. and about 410° C., or between 410° C. and about 420° C., or between 420° C. and about 430° C., or between 430° C. and about 440° ° C., or between 440° C. and about 450° C., or between 450° C. and about 460° C., or between 460° C. and about 470° C., or between 470° C. and about 480° C., or between 480° C. and about 490° C., or between 490° C. and about 500° C.
In an embodiment of the invention, the nitrous acid neutralising agent is stable at a temperature of between about 130° C. and 250° C.
In an embodiment of the invention, the nitrous acid neutralising agent is stable at a temperature of between about 150° C. and 200° C.
In an embodiment of the invention, the formulation comprises between about 0.1 wt % and about 30 wt % of the nitrous acid neutralising agent. For example, the formulation comprises between about 0.1 wt % and 1 wt %, or between about 1 wt % to about 5 wt %, or between about 5 wt % to about 10 wt %, or between about 10 wt % to about 15 wt %, or between about 15 wt % to about 20 wt %, or between about 20 wt % to about 25 wt %, or between about 25 wt % to about 30 wt % of the nitrous acid neutralising agent.
The skilled person would appreciate that the nitrous acid neutralising agent may be included in the oxidiser phase of the explosive emulsion during manufacture, or added to the formed explosive products, or both.
In some embodiments of the invention, the metal-ion binding agent, the pH buffering agent, and/or the nitrous acid neutralising agent comprises magnesium oxide, zinc oxide, aluminium oxide, melamine, hexamine, N-(n-butyl)thiophosphoric triamide, sodium acetate, sodium tetraborate, imidazole, hydroxyethylethylenediaminetriacetic acid (Dissolvine H-40), diethylenetriaminepentaacetic acid (Dissolvine D-50), sodium thiocyanate, oxamide, taurine, and/or ethylenediaminetetraacetic acid (EDTA).
In some embodiments of the invention, the explosive formulation has a sleep time of between about 1 hour and about 100 days at a temperature of between about 100° C. and about 110° ° C., or between 110° C. and about 120° C., or between 120° C. and about 130° C., or between 130° C. and about 140° C., or between 140° C. and about 150° C., or between 150° C. and about 160° C., or between 160° C. and about 170° C., or between 170° C. and about 180 ºC, or between 180° C. and about 190° C., or between 190° C. and about 200° C., or between 200° C. and about 210° C., or between 210° C. and about 220° C., or between 220° C. and about 230° C., or between 230° C. and about 240° C., or between 240° C. and about 250° C., or between 250° C. and about 260° C., or between 260° C. and about 270° C., or between 270° C. and about 280° C., or between 280° ° C. and about 290° C., or between 290° C. and about 300° C. For example, the sleep time is between about 1 hour and about 5 hours, or between about 5 hours and about 10 hours, or between about 10 hours and about 20 hours, or between about 20 hours to about 2 days, or between about 2 days and about 3 days, or between about 3 days and about 4 days, or between about 4 days and about 5 days, or between about 5 days and about 6 days, or between about 6 days and about 7 days, or between about 7 days and about 8 days, or between about 8 days and about 9 days, or between about 9 days and about 10 days, or between about 10 days and about 20 days, or between about 20 days and about 30 days, or between about 30 days and about 40 days, or between about 40 days and about 50 days, or between about 50 days and about 60 days, or between about 60 days and about 70 days, or between about 70 days and about 80 days, or between about 80 days and about 90 days, or between about 90 days and about 100 days.
In an embodiment of the invention, the explosive formulation is stable at a temperature of between about 50° C. and 500° C. For example, the explosive formulation is stable at between about 50° C. and about 60° ° C., or between 60° C. and about 70° C., or between 70° C. and about 80° C., or between 80° C. and about 90° C., or between 90° C. and about 100° C., or between 100° C. and about 110° C., or between 110° C. and about 120° C., or between 120° C. and about 130° ° C., or between 130° C. and about 140° C., or between 140° C. and about 150° C., or between 150° C. and about 160° C., or between 160° C. and about 170° C., or between 170° C. and about 180° C., or between 180° C. and about 190° C., or between 190° C. and about 200° ° C., or between 200° C. and about 210° C., or between 210° C. and about 220° C., or between 220° C. and about 230° C., or between 230° C. and about 240° C., or between 240° C. and about 250° C., or between 250° C. and about 260° C., or between 260° C. and about 270° C., or between 270° C. and about 280° C., or between 280° C. and about 290° C., or between 290° C. and about 300° ° C., or between 300° C. and about 310° C., or between 310° C. and about 320° C., or between 320° C. and about 330° C., or between 330° C. and about 340° C., or between 340° ° C. and about 350° C., or between 350° C. and about 360° C., or between 360° C. and about 370° C., or between 370° C. and about 380° C., or between 380° C. and about 390° C., or between 390° C. and about 400° C., or between 400° C. and about 410° C., or between 410° C. and about 420° C., or between 420° C. and about 430° C., or between 430° ° C. and about 440° ° C., or between 440° C. and about 450° C., or between 450° C. and about 460° C., or between 460° C. and about 470° C., or between 470° C. and about 480° C., or between 480° C. and about 490° C., or between 490° C. and about 500° C.
According to a second aspect of the present invention there is provided use of the explosive formulation according to the first aspect of the invention in blasting reactive ground.
According to a third aspect of the present invention there is provided use of the explosive formulation according to the first aspect of the invention for the manufacture of a product for blasting reactive ground.
According to a fourth aspect of the present invention there is provided a method of blasting in reactive ground, the method comprising loading a blasthole with the explosive formulation according to the first aspect of the invention.
In an embodiment of the invention, the reactive ground is high temperature reactive ground.
In a preferred embodiment of the invention, the explosive formation comprises a blasting agent comprising a nitrate, urea, preferably 10-20% urea, and SHMP, and optionally up to 10% CaHAP.
In a preferred embodiment of the invention, the explosive formation comprises a blasting agent comprising a nitrate, urea, preferably 10% urea, arginine, preferably 5% arginine, and citric acid, preferably 5% citric acid, and optionally up to 10% CaHAP.
In a preferred embodiment of the invention, the explosive formation comprises a blasting agent comprising a nitrate, urea, preferably 10% urea, and allantoin, preferably 10% allantoin, and optionally up to 10% CaHAP.
In a preferred embodiment of the invention, the explosive formation comprises a blasting agent comprising a nitrate, urea, preferably 10% urea, glyoxylic acid, preferably 5% glyoxylic acid, and arginine, preferably 5% arginine, and optionally up to 10% CaHAP.
In a preferred embodiment of the invention, the explosive formation comprises:
In a preferred embodiment of the invention, the explosive formation comprises:
In a preferred embodiment of the invention, the explosive formation comprises:
Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to be limiting.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which the invention pertains.
Unless the context clearly requires otherwise, throughout the description and the claims, the terms “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”. For example, a composition, mixture, process or method that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, mixture, process or method.
Where applicants have defined an invention or a portion thereof with an open-ended term such as “comprising”, it should be readily understood that (unless otherwise stated) the description should be interpreted to also describe such an invention using the terms “consisting essentially of” or “consisting of.” In other words, with respect to the terms “comprising”, “consisting of”, and “consisting essentially of”, where one of these three terms is used herein, the presently disclosed and claimed subject matter may include the use of either of the other two terms. Thus, in some embodiments not otherwise explicitly recited, any instance of “comprising” may be replaced by “consisting of” or, alternatively, by “consisting essentially of”.
Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
Also, the indefinite articles “a” and “an” preceding an element or component of the invention are intended to be non-restrictive regarding the number of instances (i.e., occurrences) of the element or component. Therefore “a” or “an” should be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is obviously meant to be singular.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term “about”. The examples are not intended to limit the scope of the invention. In what follows, or where otherwise indicated, “%” will mean “weight %”, “ratio” will mean “weight ratio” and “parts” will mean “weight parts”.
The terms “predominantly” and “substantially” as used herein shall mean comprising more than 50% by weight, unless otherwise indicated.
As used herein, with reference to numbers in a range of numerals, the terms “about,” “approximately” and “substantially” are understood to refer to the range of −10% to +10% of the referenced number, preferably −5% to +5% of the referenced number, more preferably −1% to +1% of the referenced number, most preferably −0.1% to +0.1% of the referenced number. Moreover, with reference to numerical ranges, these terms should be construed as providing support for a claim directed to any number or subset of numbers in that range. For example, a disclosure of from 1 to 10 should be construed as supporting a range of from 1 to 8, from 3 to 7, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, from 8 to 10, and so forth.
As used herein, wt. % refers to the weight of a particular component relative to total weight of the referenced composition.
The term “and/or” used in the context of “X and/or Y” should be interpreted as “X,” or “Y,” or “X and Y.” Similarly, “at least one of X or Y” should be interpreted as “X,” or “Y,” or “both X and Y.”
The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.
Terms like “preferably”, “commonly”, “significantly”, “typically”, and the like, when utilised, are not utilised to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to identify particular aspects of an embodiment of the present disclosure or to emphasise alternative or additional features that may or may not be utilised in a particular embodiment of the present disclosure.
The term “reactive ground” refers to ground that undergoes a spontaneous exothermic reaction when it comes in contact with nitrates, such as ammonium nitrate. The reaction of concern typically involves the chemical oxidation of sulphides (usually of iron or copper) by nitrates and the liberation of potentially large amounts of heat. The process can be unpredictable and so violent that it results in mass explosions.
In certain embodiments, the term “reactive ground” means a ground which contains an average metal sulfide concentration of at least about 0.5 wt. %, 1 wt. %, 2 wt. %, or 5 wt. % in the region where a blast hole is drilled, or is to be drilled. In other words, the material excavated when drilling a blast hole in reactive ground contains an average metal sulfide concentration of at least about 0.5 wt. %, 1 wt. %, 2 wt. %, or 5 wt. %. Alternatively, in the case where a blast hole has already been drilled, the ground will be a reactive ground if ground samples taken from the inner surface of said blast hole contain an average metal sulfide concentration of at least about 0.5 wt. %, 1 wt. %, 2 wt. %, or 5 wt. %.
The term “blast hole” should be construed broadly to include a hole which has been drilled into a ground which is to be loaded with one or more explosives, as well as a natural hole or fissure in ground which is to be loaded with one or more explosives.
The term “high temperature reactive ground” refers to reactive ground that has a temperature of over 50° C., 100° C., 150° C. or 200° C.
The terms “metal-ion binding agent”, “pH buffering agent” and “nitrous acid neutralising agent” are not used mutually exclusively. That is, a metal-ion binding agent can also be a pH buffering agent and/or a nitrous acid neutralising agent, a pH buffering agent can also be a metal-ion binding agent and/or a nitrous acid neutralising agent, a nitrous acid neutralising agent can also be a pH buffering agent and/or a metal-ion binding agent.
In some embodiments, a metal-ion binding agent, pH buffering agent, and/or nitrous acid neutralising agent are referred to as an inhibitor, suitable for inhibiting premature detonation of an explosive. However, the skilled person would appreciate that these agents are not limited to be used as inhibitors.
The term “sleep time” refers to the length of time an explosive can remain in the ground after charging and still detonate reliably.
The term “stable” means the chemical does not decompose or undergoes a reaction at a particular temperature.
In certain embodiments, a stable explosive formulation refers to a formulation that does not experience a significant change of temperature due to an exothermic reaction with the reactive ground. In some embodiments, no (or substantially no) exotherm is produced.
The skilled addressee will understand that the invention comprises the embodiments and features disclosed herein as well as all combinations and/or permutations of the disclosed embodiments and features.
An isothermal test is a primary method of determining if rock/ground samples are reactive with nitrate-based explosives, and a primary method of determining if the available sleep time of an explosive with reactive ground meets the requirements. It involves mixing reactive ground samples with an explosive formulation and heating the mixture to a desired testing temperature. The mixture is monitored for any visual reactions (such as colour change or signs of chemical reactions such as gas liberation) and reactivity is identified by a change in temperature, detected using thermocouples with continuous temperature logging. A reactive response is identified by an increase in temperature from the base line test temperature.
Table 1 shows the references of reactive ground samples used in the isothermal tests, and Table 2 the compositions of different explosive formulations used in the isothermal tests.
Table 3 shows isothermal test results performed at 100° C. with RG sample 2. In these tests. 10% of AN was replaced by an inhibitor.
Incorporation of sodium carbonate at 10 wt % of the AN component inhibited the isothermal test for its duration of 5.7 days. This result is consistent with keeping the amount of available acid in the mixture to a sufficiently low level.
Incorporation of sodium thiocyanate was found to provide significant inhibition and reduction in the exotherm generated. Mechanistically, it was believed that any Fe (III) ion formed may have reacted to form any of the ferrothiocyanato complexes [Fe(SCN)x(H2O)6-x]3-x+; or the thiocyanate may be been oxidized by any nitrous acid formed.
Iron complexing compounds hydroxyethylethylenediaminetriacetic acid and diethylenetriaminepentaacetic acid and salts provided only minor levels of inhibition.
Glycine provided some benefit, consistent with the level of ammonium on the molecule reacting with formed NOx and/or nitrous acid.
MAP provided some inhibition, suggesting that complexation with Fe (III) may be occurring, while DAP provided only marginal benefit.
Table 4 shows isothermal tests results performed at above 150° C. with the inhibitors added to AN with urea (the standard inhibitor) or the existing inhibited product (DX5030) that contains both AN and urea.
In Example 2, the higher temperature was used to better mimic the higher temperatures in the ground, and to allow for quicker results to be obtained.
Inhibition was achieved for over 10 days at 150° C. for a blend of DX5030 with 10% post added MAP. In comparison, standard DX5030 allowed a sleep time of 5.10 days with an exotherm of 129° C. 4867-0972-482211
Incorporation of sodium thiocyanate provided minor (2° C.-3° C.), broad exotherms that occurred relatively early in the test (after 10-12 hours).
Incorporation of EDTA allowed a similar time to exotherm to be achieved compared to standard, and significantly reduced the size of the exotherm to around 12-13° C. In comparison, the AN/urea exotherm was 183° C.
Incorporation of 10% sodium carbonate to DX5030 reduced the size of the exotherm to 2-6° C., but the time to exotherm was reduced to 47-59 hours. In comparison, the time to exotherm for DX5030 was 122 hours.
Table 5 shows isothermal tests results performed at above 170° C. with the inhibitors added to the existing inhibited product (DX5030) that contains both AN and urea.
Example 3 investigated optimizing the use of post added MAP to DX5030 in a blend when the isothermal testing was performed with the highest reactivity rock sample from the high temperature mine, at the maximum proposed temperature of use (including in-ground and instrumental measurement uncertainties). Hence testing was performed with the sample at a nominal block temperature of 173° C., with a range of MAP addition rates and physical forms. The following observations were made:
An addition of 15% post added crushed MAP to DX5030 provided the best results, with no exotherm being recorded over the test time of 1.725 days (41.4 hours). With the standard safety factor used of 4:1 for time to reaction, a sleep time in the most reactive ground tested to date of 10 hours is available.
An addition of 20% post added uncrushed MAP provided minor exotherms of approximately 2° C. after 50-53 hours. With the standard safety factor used of 4:1 for time to reaction, a sleep time in the most reactive ground tested to date of 12 hours is available.
Table 6 shows the control tests performed with three different RG samples. In these tests explosive sample 1 with 10% urea is tested at 150° C. Table 6 shows that sleep times are different for different RG samples.
Table 7 shows explosive sample 1 with 10% of different inhibitors showing improved results at 150° C.
Table 8 shows explosive sample 1 with 20% urea or 10% of different inhibitors showing improved results than 10% urea at 150° C.
Detailed isothermal test temperature curves are illustrated in
Table 9 shows explosive sample 1 with mixed inhibitors showing improved results at 150° C.
An example of the results can be found in
Table 10 shows explosive sample 1 with mixed inhibitors showing improved results at 150° C.
It is worth noting that 10% of biuret, allantoin and arginine outperform formulations with an additional 10% of urea (that is, 20% urea in total). Examples can be seen in
The isothermal rests were also performed at an elevated temperature of 173° C. for different inhibitors. The results are shown in Table 11 and
Selected experiment results can be seen in
Further isothermal tests were performed for different inhibitors and illustrated suppression of reaction and/or extension of reaction time. These include MAP (
Table 12 shows mixed inhibitor tests results with explosive sample 1 with reactive ground.
Selected experiment results can be seen in
DX5128 base emulsion was mixed with NaHMP on August 4th and then blended at a mine with 2.82 wt % glass microsphere (GMB) to produce DX5128. Two 10.7 kg batches were prepared and transferred to 2 PVC pipes of 1000 mm length and 104 mm internal diameter. The pipes were detonated on August 5th at 16:18 PM as part of shot 1004-010 using a 400 g cast booster initiated with a DSP.4G electronic detonator for each pipe. Temperature logging and Velocity of Detonation (VoD) measurements were completed for both pipes. The blast results presented in Table 13 conclude full order detonation with high VoD values slightly above 5 km/s for both pipes.
Two batches of 9.2 kg DX5128 base emulsion manufactured were blended in a plastic bucket with 1.25 kg NaHMP each using a battery powered drill with curved stirrer blade as shown in
Product sensitisation with GMB's was conducted at the shot by mixing 10.45 kg DX5128/NaHMP emulsion with 254 g GMB's (2.43%) in 6 mins moving the blender up and down the emulsion. After this the density measured 1.245 g/cc. Another 41 g of GMB's was added followed by 5 mins of blending. This resulted in a final DX5128 density of 1.224 g/cc which is within specification of 1.22±0.02 g/cc. A second batch was prepared by mixing 10.45 kg DX5128/NaHMP emulsion with 295 g GMB's resulting in DX5128 of 1.231 g/cc density. The GMB loading for both batches is 2.82 wt %. It is expected that a lower loading is needed on larger scale on the MPU. For example, the loading on the MPU for DX5030 is 1.50% and for DX5112 is 1.75 wt %.
For the testing, temperature registration was conducted using a four channel data logger with K-Type sensors inserted 10 cm into the DX5128 at the booster end of the pipes. The temperature logger was rescued approx. 40 mins before firing. There was a small temperature rise for the pipes recorded; from 36.0 to 36.4° C. for pipe 1 and from 35.2 to 37.0° C. for pipe 2 over 2 hours. VoD measurements were conducted by Time Domain Reflectometry with a ShotTrack. A length of quad shield coaxial cable was attached to the pipes to detect the VoD. The VoD monitor was checked once more 15 mins before firing and it appeared that the ShotTrack had triggered and shut down. The instrument was reset, and the shot was abandoned. After the firing the test area was inspected for the presence of remnants, and none could be found. The pipes produced impressive sound levels (much louder than the in-ground explosives) and left relatively large craters of 40-50 cm depth. The results are summarised in Table 14.
DX5128 base emulsion was blended with NaHMP on August 6th-7th and transferred to a Safe Loading MPU. A total amount of 1278 kg blend was produced. The product was solid sensitised on the MPU and loaded on 11 Aug. 2023 at Phase 16, Bench 860 in hole #A with neighbouring hole #B loaded with DX5030G from a standard MPU. Column rise measurement, temperature logging and VoD measurement was conducted for both holes.
As the IP hole (#C) and 2nd initiated hole (#D) were above 105° ° C. they exceeded the maximum allowable temperature for this trial and could not be selected. Consequently, the first available lower temperature holes which were the 5th (#A, 100° C.) and 9th (#B, 100° C.) initiated holes had to be selected. It was expected that this reduced the chance of obtaining a successful VOD measurement and this was indeed the case. The VoD trace recording registered cable cut-offs at the collar for both holes, rendering the VoD measurement impossible.
The DX5128 emulsion blend was sensitised to a density of 1.223 g/cc (specification=1.22±0.02) and loaded into the hole using conservative pumping flow rates of 150 kg/min for the emulsion and 4.2 kg/min (2.8 wt %) for the GMB's. The monopump pressure on the MPU was only 2.6 bar which indicates that there is sufficient room for flow rate increase (a maximum pressure of 6-7 bar is acceptable) hence, it is expected that flow rates similar to DX5030G will be available. Determining the maximum flow rate is part of another trial which involves loading of 10-15 holes. Column rise for the DX5128 product without stemming was only 0.5 m after heating for 225 mins in the unstemmed hole which is expected to cause no operational issues. For the DX5030G loaded hole a similar column rise was measured. The holes were then stemmed as per normal procedure.
It is concluded that this trial has been successful with product manufactured within density specification and of good pumpability on Safe Loading MPU. The column rises from 6.5 to 7.0 m for DX5128 measured 225 minutes after loading is minimal. It is recommended to repeat column rise measurements once higher temperature holes are available in a next stage trial. VoD measurements were unsuccessful due to no IP hole being available for the measurement and the first acceptable (below 105° C.) holes being further away from the IP hole.
Test Results—Blending of Base Emulsion with NaHMP
The blending of DX5128 base emulsion with NaHMP was performed using a 180-litre cement mixer placed on pallet scales, an IBC that was prepared for the trial and a timber funnel that was made for easy transfer of product from the cement mixer to the IBC.
Emulsion was introduced into the cement mixer by gravity from an IBC positioned above the cement mixer using a forklift. To determine the weight accurately the timber funnel was temporarily removed during weighing. After some optimization batch sizes of 75 kg emulsion (88 wt %)+10.2 kg NaHMP (12 wt %) could be manufactured in approx. 10 mins provided NaHMP was filtered at the same time the emulsion was poured into the cement mixer. The blending process in the mixer requires 3 minutes. After blending the mixer contents were transferred by gravity into the cut open IBC using the timber funnel. The product was then pumped into an MPU in circa 500 kg batches by means of a Wilden pump. The MPU tank was visually inspected prior the transfer and found to be sufficiently clean.
A total of 1278 kg product was produced in 3 batches of 56.8 kg and 13 batches of 85.2 kg. The open cup density of the blend measured 1.432 g/cc after 500 kg production and 1.428 g/cc after 1000 kg. The average density at ambient temperature (ca. 30° ° C.) is 1.43 g/cc.
Test Results—In-Hole Trial at the Mine with Safe Loading MPU
The DX5128 emulsion blend was sensitised to a density of 1.223 g/cc (specification=1.22±0.02) and loaded into the hole using conservative pumping flow rates of 150 kg/min for the emulsion and 4.2 kg/min (2.8 wt %) for the GMB's (DX5030S is normally loaded at 320 kg/min flow rate with 1.5 wt % GMB addition). The monopump pressure on the MPU was only 2.6 bar which indicates that there is sufficient room for flow rate increase (a maximum pressure of 6-7 bar is acceptable). Therefore it is expected that flow rates similar to DX5030S are available. Determining the maximum flow rate is part of the stage trial which involves loading of 10-15 holes.
Prior to loading the sensitised product, the two selected holes (#A and #B) were fitted with VoD cable and three temperature sensors in each column: at 11 m depth near the toe, at 9 m depth near the middle of the column and at 7 m depth near the top of the column. The results are presented in
A similar temperature increase is measured for DX5030G but the rate is slightly faster. One of the reasons for the difference could be a lower thermal conductivity of GMB based product compared to chemically gassed product. The sensor near the bottom of the toe is most likely positioned onto or near the rock material and not fully emersed in emulsion as the start temperature is significantly higher.
After loading emulsion, the DX5128 hole was dipped over a time period of 225 minutes to determine column rise. The hole was then stemmed. The results are tabled below.
Hole #A and #B were stemmed 225 mins after hole #A was loaded. Hole #B was loaded 85 minutes after hole #A with DX5030G of 1.20 g/cc density and measured 0.5 m column length increase to 7.0 m before stemming.
Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms in particular features of any one of the various described examples may be provided in any combination in any of the other described examples. Various modifications and alterations to this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention. It should be understood that this invention is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and that such examples and embodiments are presented by way of example only with the scope of the invention intended to be limited only by the claims set forth herein as follows.
Other embodiments of the present invention as described herein are defined in the following paragraphs:
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022903767 | Dec 2022 | AU | national |
