Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
  • C06B21/0091—Elimination of undesirable or temporary components of an intermediate or finished product, e.g. making porous or low density products, purifying, stabilising, drying; Deactivating; Reclaiming
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
  • C06B23/001—Fillers, gelling and thickening agents (e.g. fibres), absorbents for nitroglycerine
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
  • C06B47/14—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase comprising a solid component and an aqueous phase

Definitions

• the present invention relates to a process for the phlegmatization of explosives as well as phlegmatized explosives obtainable by this process.
• the invention further relates to a method which enables sensitization of the phlegmatized explosives.
• the invention comprises a method for transporting explosives, which is based on the phlegmatization method according to the invention.
• the term “phlegmatization” (or “desensitization”) is used for processes by which the sensitivity of explosives to shock and friction can be reduced, making them (temporarily or permanently) non-explosive.
• phlegmatization is used for processes by which the sensitivity of explosives to shock and friction can be reduced, making them (temporarily or permanently) non-explosive.
• known phlegmatization methods is in particular the embedding or granulation by means of wax or other binders or carriers to call (eg. EP 217 770 B1 . DE 28 20 704 A1 . DE 39 34 368 C1 ).
• the object of the present invention is to provide a phlegmatization process for explosives which avoids the disadvantages of known processes and makes it possible to suppress or reduce the danger of explosives.
• the explosives treated by the method according to the invention no longer have to be classified in the dangerous goods class 1, but can be classified in another dangerous goods class for which apply less stringent safety requirements.
• a classification of the treated explosives in Class 4 should be made possible.
• Another object of the invention is to provide a method for the phlegmatization of explosives which is reversible, d. H. which allows a renewed sensitization of the explosive and its recovery.
• a phlegmatization of explosives which fulfills the above-mentioned objectives, can be effected by a method according to claim 1.
• the explosive is dispersed in the form of particles in a fluid having a yield point, wherein the yield point of the fluid is not exceeded by the explosive particles dispersed therein.
• the dispersed explosive particles are thereby kept suspended in the fluid, which reduces the explosiveness and the desired phlegmatization is brought about.
• yield point in rheology refers to the shear stress to be applied, above which a substance passes to flow. Fluids, in particular liquids, which have such a flow limit, are basically known to the person skilled in the art. Above the shear stress, which defines the yield point, the fluid behaves like a liquid; in the underlying shear stress range, the fluid behaves like an elastic or viscoelastic solid. The yield point is thus the shear stress at which the transition between flow behavior and (visco) elastic behavior - or vice versa - takes place.
• the term “fluid” is also used for the state after falling below the yield point, ie for the plastic (elastic or viscoelastic) state.
• an explosive in particulate form i. H. as a plurality of particles, dispersed in a fluid having a yield point as defined above.
• the yield stress ⁇ of a fluid is the minimum shear stress that must act on the fluid to allow it to flow.
• a particle contained in the fluid exerts a force F on the surface A below it, wherein F corresponds to the weight force minus the buoyancy force. If ⁇ ⁇ F / A, then the particle in question sinks to the ground; otherwise it will remain in suspension if ⁇ > F / A; because in this case, the thrust force exerted by the particle is not sufficient to make the previously non-flowable fluid to flow.
• whether the particle sinks depends on whether the flow limit of the fluid is smaller than the product of the density difference (p - pw), the height h of the particle in the fluid and the gravitational acceleration.
• the density p is predetermined by the nature of the particular explosive, with respect to the desired floating state of the particles in the fluid, it essentially depends on the particle size (that is to say the height of the particles in the fluid) in relation to the yield point of the respective fluid used.
• the height of the particles in the fluid can generally be determined by measuring the longitudinal extent of the particles in the vertical direction by means of a length measuring device (eg ruler).
• the particle size of the dispersed explosive particles is selected or adjusted so that the shear stress exerted by the particles is smaller than the yield point of the fluid.
• the above-mentioned "height of the particle in the fluid” does not necessarily correspond to the particle size, since a (non-spherical) particle may have different length expansions depending on the measuring direction. Depending on the spatial orientation of a particle within the fluid, its “height in the fluid” may vary. In extreme cases, the longest side (or the largest diameter) of a particle can form the "height h” in the above formula, depending on the orientation of the particle in the fluid. In the context of the present invention, therefore, "particle size” is understood to mean the "height of the particle in the fluid".
• the maximum height of a particle in the fluid essentially corresponds to the greatest length extension or the largest diameter of a particle.
• the yield strength of a fluid can be determined by the following method:
• Test particles of a previously determined or known density are dispersed in a transparent vessel in the fluid whose flow limit is to be determined. After a waiting period of 1 month, one part of the particles has sedimented, while another part has remained in suspension. For the latter particles, the average value for the "height in the fluid" (see above) is determined. By substituting this value in formula (I) above, the yield stress ⁇ can be calculated. The determination of the yield point is generally carried out at a temperature range of 10 to 25 ° C, in particular at 20 ° C.
• the yield value is generally in the range of 5 to 10 N / m 2 , especially 10 to 50 N / m 2 .
• the size of the particles to be dispersed, etc. it is also possible to deviate from the stated ranges.
• the dispersed explosive particles in the fluid which shows an elastic or viscoelastic behavior, are kept floating.
• a substantially stable state is produced, which is characterized in that the explosive particles are spaced apart from each other and are immobilized in the elastic or viscoelastic matrix formed by the fluid. It is believed that this is the cause of the observed phlegmatization of the explosive.
• the phlegmatization according to the invention causes an explosion even when exposed to sparks or heat, or mechanical impact (eg, shocks, shocks, shocks).
• the dispersing operation may be carried out by exposing the fluid to such shear or shear stress, for example by rotation or agitation by means of a mixer, that the flow limit is thereby exceeded and the fluid begins to flow. If explosive particles are added, they can move through the viscous fluid and be dispersed therein with continued stirring or mixing. As soon as sufficient dispersion of the particles has been achieved, the stirring or rotation speed can be gradually slowed down until the yield point is no longer exceeded by the rotation or agitation and the explosive particles are kept in the abovementioned state of suspension.
• Example Another possibility for carrying out the dispersing z. Example, in that the fluid is heated and in this way the yield point is lowered, so that explosive particles can be introduced by means of stirring in the fluid and dispersed therein. To generate the mentioned floating state, the fluid is then cooled, whereby the yield point is raised again.
• all explosive substances or mixtures of substances are considered explosives, provided that they can be processed into particles or in the form of particles.
• the explosives used in the present invention are solids or mixtures of substances.
• the present invention relates in particular to explosives made from ammunition, ie from military articles or components Purposes consisting of or containing explosives (eg cartridge and cartridge ammunition, torpedoes, grenades, bombs, missiles), but also explosives used in technical or civilian use.
• a preferred field of application relates to the phlegmatization of explosives from ammunition contaminated sites (eg bomb duds) or ordnance that are stored in waters, on the seabed or in the ground, and which must be salvaged and transported away for the purpose of rendering them harmless.
• explosives which can be phlegmatized by the process according to the invention, there are basically no particular restrictions. Nor is it necessary for the performance of the method to know the nature of the explosive or its composition.
• explosives include trinitrotoluene (TNT), trinitrobenzene (TNB), hexogen (RDX), octogen (HMX), nitropenta (PETN).
• the explosive which may also be an explosive-containing substance mixture, is dispersed in the form of particles in said fluid.
• the explosive is comminuted by known methods and, if necessary, subjected to mechanical separation processes to obtain particles with the required particle size, in which an exceeding of the yield point is avoided.
• the particle size of the explosive particles can be determined in a known manner by sieve analysis. However, a preceding sieve analysis is not absolutely necessary since it is also possible (and preferred) according to the invention to use the fluid itself as a means for size classification. After introducing and dispersing explosive particles of different sizes, sink into the fluid those particles whose size (ie their height in the fluid) exceeds the maximum permissible value, due to gravity down and accumulate as sediment. After separation of the sedimented particles, the fluid essentially contains only those particles which can remain suspended in the fluid; these particles satisfy the condition resulting from the above-mentioned formula (I) with regard to the height of the particles in the fluid ( ⁇ > (p-pw) xhxa).
• the separated sedimented particles can be subjected to comminution again and then dispersed in a fluid according to the invention.
• the procedure described above can be repeated to further increase the proportion of suspended explosive particles. In this way it can be achieved that the explosive particles are substantially completely suspended in the fluid, or that at least 90 wt .-%, preferably at least 95 wt .-% of the particles are in this state.
• the maximum particle size of the explosive particles depends essentially on the density of the respective explosive (see formula (I) above). Since this parameter is known or easily determinable, the appropriate maximum particle size can be calculated. Alternatively, the maximum permissible particle size can also be determined experimentally by preliminary experiments.
• the explosive may be incorporated into the fluid in an amount up to 80% by weight (based on the total mass of the phlegmatized explosive, ie including the bulk of the fluid and additives contained therein); Under certain circumstances, this value can also be exceeded.
• the explosive content is 10 to 80 wt .-%, in particular 20-50 wt .-%.
• the proportion can be limited. For example, according to ADR 4.1 UN 1356, a maximum mass fraction of 70% TNT particles in water is permissible.
• fluids which can be used in the process according to the invention basically all fluids are considered which have a flow limit, as explained above.
• aqueous fluids are used for this purpose.
• the property of a yield point is generally due to the fact that the respective fluid contains at least one rheology additive, or that at least one such additive is added.
• an aqueous solution of xanthan or carboxymethylcellulose (CMC) is used as said fluid having a yield point; Mixtures of xanthan and CMC can also be used.
• CMC is preferably used in the form of the sodium salt (Na-carboxymethylcellulose).
• a preferred concentration range of CMC is 0.5 to 5 wt .-%, in particular 0.5 to 2 wt .-%.
• hydrocolloids can also be used to prepare a fluid which can be used in the process according to the invention.
• Various rheology additives may be suitable for different temperature ranges; depending on the particular application, this can be taken into account when selecting the rheology additive (s).
• a rheology additive is used which is selected from the group consisting of polysaccharides, preferably xanthan, pectins, alginates, chitosan, dextran and pullulan, and cellulose ethers, Preferably, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose and hydroxypropylmethylcellulose, and combinations of the aforementioned substances.
• the yield strength of the fluid is adjusted accordingly, depending on the type of explosive used in each case and / or the particle size by adding one or more rheology additives, preferably hydrocolloids.
• rheology additives eg xanthan, CMC or other hydrocolloids
• increasing the concentration of the rheology additive can increase the flow limit. This allows explosive particles of larger particle size to be kept suspended in the fluid, i. H. without exceeding the yield point. There is an approximately linear relationship between the flow limit and the particle size (see Example 2).
• the proportion of said rheology additive is usually in the range of 0.01 to 10 wt .-%, preferably in the range of 0.1 to 5 wt .-% (based on the total mass of the fluid, without explosive particles). The amount of this fraction depends mainly on the type of additive used and on the desired yield value.
• the explosive initially is not present in particulate form, it can be processed by known methods to particles of suitable size.
• it is provided that it has an upstream process step in which said particles are produced from an explosive. This can be done in particular by cutting the explosive by means of water jet.
• the explosive (eg TNT) phlegmatized in accordance with the above method can be transported according to ADR 4.1 UN 1536, for example.
• the phlegmatized explosive can be sensitized again, e.g. by introducing liquid (in particular water) into the fluid and / or by suitable filtering methods or other separation methods.
• the processes of the invention are generally applicable at a temperature range of 10 to 25 ° C; This is especially true when using CMC as a rheology additive. However, an application outside this temperature range is not excluded.
• the present invention further extends to a phlegmatized explosive, in particular a phlegmatized explosive, which has been prepared by a process of the invention as defined above or defined in the claims, or obtainable by such a process.
• the phlegmatized explosive of the present invention comprises a yield point-containing fluid in which a plurality of explosive particles are suspended in suspension, as discussed above. Sedimentation of the particles in the fluid does not take place since the shear stress of the particles dispersed in the fluid due to gravity is smaller than the yield stress of the fluid. Since the yield point is not exceeded, the fluid (with the particles dispersed therein) has the properties of a deformable, elastic or viscoelastic body.
• the fluid when using the mentioned hydrocolloids, may be in the form of a preferably aqueous gel matrix within which the explosive particles are dispersed and immobilized.
• the explosive content is preferably 10 to 80 wt .-%, in particular 20-50 wt .-%, each based on the total mass of the patented explosive (i.e., including the mass of the fluid and additives contained therein).
• the explosive particles are suspended in the phlegmatized explosives according to the invention.
• this condition is stably maintained over a period of at least 1 week to several weeks or at least two months, ie, during this time, no visible change in the suspended state of the particles occurs.
• Such stability of the floating state can be achieved, for example, by using 1% CMC.
• the stability of the suspended state and the durability of the fluid can be increased if necessary.
• An advantage of the phlegmatization process according to the invention is that the phlegmatization is reversible.
• the process can be reversed or reversed, so that it is subsequently possible to sensitize the phlegmatized explosive again, d. H. to restore the explosiveness.
• this can be achieved by lowering the yield point of the fluid in which explosive particles are dispersed in such a way that the shear stress exerted by the explosive particles is greater than the yield point, as a result of which the particles sink gravitationally to the bottom.
• the present invention further comprises a method for sensitizing an explosive stabilized according to the invention, this method being based on the principle that the yield point of the fluid containing the explosive particles is lowered such that the particles floating in the fluid sediment.
• a lowering of the yield point can preferably be achieved by increasing the liquid fraction of the fluid in which the rheology additive (s) is / are dissolved by adding liquid (dispersion medium).
• liquid dispersion medium
• aqueous fluids eg containing hydrocolloids such as xanthan and / or CMC
• the sedimented explosive particles can be separated from the fluid in a further step by means of known mechanical separation processes, preferably sieving or filtration and be recovered with it. Since the explosive particles are no longer immobilized in the fluid, the phlegmatization is removed and the explosive capacity is restored.
• the fluid after separation of the explosive particles again for phlegmatization of explosives can be used.
• the process can be very cost-effective.
• rheology additives as described above may be re-added to the fluid prior to reuse to adjust the desired yield value.
• the inventive method for the desensitization of explosives is particularly suitable to facilitate the transport of explosives, such as those contained in ammunition contaminated sites or other warfare agents, and to make cheaper.
• the classification into hazardous substance class 1 (according to ADR, RID or IMDG) is omitted; instead it is possible to assign the phlegmatized substances to class 4.
• transport and subsequent treatment or destruction can be carried out under less stringent safety conditions and correspondingly larger existing transport and plant capacities can be used.
• the reduced danger also makes it possible to develop existing industrial-scale treatment and disposal capacities for explosives.
• Red-colored test particles having a previously determined density were placed in a transparent vessel filled with a fluid.
• the fluid used was water with one or more stirred rheology additives (preferably CMC). Of those particles which remained in suspension after 1 month, their average height in the fluid was determined. The average height of the largest of these particles was set in the above-mentioned formula (I) and thus calculated a value ⁇ ; this corresponds to the yield point, which is at least achieved by the fluid under investigation. The yield point was determined using CMC as an additive at 20 ° C.
• the measurement of the height of the particles in the fluid takes place in such a way that the longitudinal expansion of the particles in the vertical direction is determined by means of a ruler or another length measuring device.
• a ruler or another length measuring device For the practice of the method according to the invention, it is generally quite sufficient if the average height of the largest particles is determined. In this way, the yield point can be approximated to estimate down.

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Citations (12)

• 2016
  • 2016-06-08 EP EP16173455.3A patent/EP3255028A1/fr not_active Withdrawn

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