EP3255028A1 - Method for the phlegmatisation of explosives and phlegmatised explosives obtainable using this method - Google Patents

Abstract

The invention relates to a method for the desensitization of an explosive, wherein the explosive is dispersed in the form of particles in a fluid having a yield point, and wherein the yield strength of the fluid is not exceeded by the explosive particles dispersed therein.

Description

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. Furthermore, the invention comprises a method for transporting explosives, which is based on the phlegmatization method according to the invention.

The handling, in particular the transport of explosives, explosive ordnance or explosives is associated with considerable risks and requires appropriate safety precautions. Therefore, at both national and EU level and at international level, there are appropriate regulations containing specific rules for transport in terms of packaging, load securing and marking (eg "European Convention on the International Carriage of Dangerous Goods by Road" (ADR "Regulation on the International Carriage of Dangerous Goods by Rail" (RID), "Dangerous Goods Labeling of Dangerous Goods by Sea" (IMDG).

In general, a classification of dangerous goods according to various hazards characteristics is provided in these regulations. The classification system of all regulations is numerically represented and comprises nine dangerous goods classes. Explosives are after this Classification classified as class 1; the same applies to items containing explosives.

Particularly problematic proves the transport and removal of old ammunition from the past wars. The transport of these explosive ordnance, each of which requires a separate classification, requires a derogation from the competent authority.

It is estimated that the amount of conventional ordnance stored in German marine waters is up to 1,600,000 tonnes, which includes several hundred thousand tonnes of TNT and other explosives.

Due to the large amount of explosives and the resulting risks during transport and the further treatment to neutralize such ammunition, it has previously been assumed that the best solution is to leave the ammunition on the seabed. However, these ammunition contaminated sites pose a problem when the seabed is to be used as a subsoil, for example in the construction of wind farms.

With regard to the quantities of conventional ordnance stored in the ground ashore (ammunition, especially bomb duds), there are no reliable figures. However, even in this case, particularly high risks during transport and subsequent disposal are to be obtained.

In addition, in Germany the installed and approved treatment capacity for the destruction of ammunition is only a few 1000 t per year. These capacities are already largely due the destruction of camp ammunition of the armed forces is utilized. In addition, for the storage and destruction of substances that have been classified in the "Class 1" according to ADR (or RID, IMDG, see above), a special plant approval according to the German Federal Immission Control Act is required. This additionally limits the possibilities for the removal of explosives.

On the other hand, for substances classified as "Class 4" according to ADR (or RID, IMDG), which are to be disposed of, there is an installed and officially approved treatment capacity of several million tonnes per year.

Class 4 according to ADR / RID / IDMG generally includes "flammable solids", and in particular desensitized (= phlegmatized) explosives, i. H. explosive substances that have been treated in such a way that their explosive properties are suppressed.

Generally, 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. Among the 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 ).

However, these known methods are disadvantageous for various reasons. Due to the aids used (waxes, binders) and the elaborate procedures, the costs are too high, especially in the treatment of larger quantities of explosives. For the removal of ammunition contaminated sites on an industrial scale such methods are therefore out of the question. There are also some the method known in the art only suitable for the phlegmatization of certain selected types of explosives. In addition, the phlegmatization caused by known techniques is in many cases not reversible, ie a subsequent sensitization of the phlegmatized explosives is not or only to a limited extent possible.

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.

In particular, it should be achieved that 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. In particular, 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.

The above objects are achieved by a method for phlegmatization according to claim 1, by a phlegmatized explosive according to claim 13, by a method for sensitizing according to claim 17 and by a transport method according to claim 20, and by the embodiments specified in the subclaims.

Surprisingly, it has been found that a phlegmatization of explosives, which fulfills the above-mentioned objectives, can be effected by a method according to claim 1. Here, 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.

Due to the reduced danger of the phlegmatized explosives, the transport in road, rail or maritime transport is simplified, less risky and cheaper. In addition, there are usually no exemptions required, and greater transport and treatment capacities are available than for Class 1 dangerous goods.

In general, the term "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. In the context of the present invention, the term "fluid" is also used for the state after falling below the yield point, ie for the plastic (elastic or viscoelastic) state.

In the phlegmatization process of the present invention, an explosive in particulate form, i. H. as a plurality of particles, dispersed in a fluid having a yield point as defined above.

According to the invention, the flow limit of the fluid is not exceeded by the explosive particles dispersed in the fluid. This is achieved by the shear stress generated by the dispersed particles due to gravity in the fluid being lower than the minimum shear stress required to effect a transition from the elastic state to the flow state (= flow limit).

Generally, the yield stress σ 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 σ <F / A, then the particle in question sinks to the ground; otherwise it will remain in suspension if σ> 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.

wobei

• σ : Fließgrenze des Fluids;
• F : Gewichtskraft (abzüglich Auftriebskraft des Partikels im Fluid);
• A: Fläche unter dem Partikel, auf welche dessen Gewichtskraft wirkt;
• m: Masse des Partikels;
• mw: Masse des durch das Partikel verdrängten Fluids;
• a: Erdbeschleunigung;
• ρ : Dichte des Partikels;
• pw: Dichte des durch das Partikel verdrängten Fluids;
• h: Höhe des Partikels bezüglich der Fläche A.

The above-mentioned relationships can be represented by the following formula (I): $$\mathrm{\sigma }=\mathrm{F}/\mathrm{A}=\left(\left(\mathrm{m}-\mathrm{mw}\right)\times \mathrm{a}\right)/\mathrm{A}=\left(\left(\mathrm{\rho }-\mathrm{pw}\right)\times \mathrm{A}\times \mathrm{H}\times \mathrm{a}\right)/\mathrm{A}=\left(\mathrm{\rho }-\mathrm{pw}\right)\times \mathrm{H}\times \mathrm{a}$$

in which

• σ: yield point of the fluid;
• F: weight (minus buoyancy of the particle in the fluid);
• A: area under the particle on which its weight acts;
• m: mass of the particle;
• mw: mass of the fluid displaced by the particle;
• a: gravitational acceleration;
• ρ: density of the particle;
• pw: density of the fluid displaced by the particle;
• h: height of the particle with respect to the area A.

According to the above formula, 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. Since 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).

According to a preferred embodiment of the method according to the invention is therefore carried out in such a way that 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 flow limits of different fluids can be found in the literature. If necessary, 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 σ 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.

In the fluids contemplated by the present invention, the yield value is generally in the range of 5 to 10 N / m ² , especially 10 to 50 N / m ² . Depending on the type of explosive used in each case, the size of the particles to be dispersed, etc., it is also possible to deviate from the stated ranges.

Since exceeding the yield point is avoided according to the invention, this has the consequence that the dispersed explosive particles in the fluid, which shows an elastic or viscoelastic behavior, are kept floating. In this case, 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.

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.

In principle, all explosive substances or mixtures of substances are considered explosives, provided that they can be processed into particles or in the form of particles. In general, 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.

With regard to the chemical composition of the 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. Examples of 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. To produce these particles, 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 (σ> (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, in which they can be dispersed in the fluid without exceeding the yield point, 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. Preferably, the explosive content is 10 to 80 wt .-%, in particular 20-50 wt .-%. To get a sufficient To achieve phlegmatization, depending on the type of explosive used, 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.

As 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. Preferably, 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.

According to a preferred embodiment of the phlegmatization process according to the invention, 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 .-%.

In addition to xanthan and CMC, other 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).

Preferably, 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.

According to a further embodiment of the method according to the invention, it is provided that 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. In particular, increasing the concentration of the rheology additive (eg xanthan, CMC or other hydrocolloids) 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.

If the explosive initially is not present in particulate form, it can be processed by known methods to particles of suitable size. In a further embodiment of the method according to the invention, 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.

1. a) Herstellen oder Bereitstellen eines Fluids, welches eine Fließgrenze aufweist. Als Fluid wird vorzugsweise eine wässrige Lösung von Carboxymethylcellulose verwendet, insbesondere mit einer Konzentration im Bereich von 0,5 bis 2 Gew.-%.
2. b) Durchmischen des Fluids, vorzugsweise mittels einer rotierenden Mischvorrichtung (z. B. Laborrührer), so dass aufgrund der erzeugten Schubspannung die Fließgrenze des Fluids überschritten wird. Infolgedessen beginnt das Fluid beginnt zu fließen und verhält sich nun wie eine Flüssigkeit. Dieser Schritt, wie auch die anderen Verfahrensschritte, wird vorzugsweise bei Raumtemperatur (20 °C) durchgeführt.
3. c) Hinzufügen und Dispergieren der Explosivstoff-Partikel (insbesondere TNT) im Fluid unter fortgesetztem Mischen.
4. d) Nachdem die Explosivstoffpartikel im Fluid dispergiert worden sind, wird der Rühr- oder Mischvorgang beendet. Dies geschieht vorzugsweise durch allmähliches Verringern der Rührgeschwindigkeit bis zum völligen Stillstand des Rührwerkzeugs.
5. e) Anschließend werden diejenigen Partikel, welche nach Beendigung des Mischvorgangs, insbesondere innerhalb von 0,5 bis 2 h nach Beendigung des Mischvorgangs, einen Bodensatz bilden (d. h. sedimentieren), aus dem Fluid abgetrennt. Dieser Schritt kann auch entfallen, falls der Anteil von sedimentierenden Partikeln gering ist und/oder eine Abtrennung nicht für erforderlich gehalten wird.
   Abhängig von der Art des Explosivstoffs und je nach Art und Konzentration des gewählten Rheologie-Additivs werden dabei bevorzugt Partikel einer bestimmten Größenklasse in dem Fluid in der Schwebe gehalten, d. h. die Fließgrenze wird nicht überschritten. Beispielsweise können die bei Verwendung einer wässrigen CMC-Lösung mit einem CMC-Gehalt mindestens 1 Gew.-% in der Schwebe gehaltenen TNT-Partikel eine durchschnittliche Höhe im Fluid von bis zu 5 mm haben.
6. f) Die in Schritt (e) abgetrennten Explosivstoffpartikel können erneut oder weiter zerkleinert werden und gemäß den vorstehend beschriebenen Verfahrensschritten (b) und (c) in dem Fluid dispergiert werden. Falls erforderlich oder gewünscht, kann eine erneute Abtrennung von sedimentierten Partikeln gemäß den Schritten d) und e) vorgenommen werden. Die Schritte (b) bis (f) können nach Bedarf wiederholt werden.

According to a preferred embodiment, the method for phlegmatizing an explosive comprises the following steps:

1. a) producing or providing a fluid having a yield point. The fluid used is preferably an aqueous solution of carboxymethylcellulose, in particular having a concentration in the range from 0.5 to 2% by weight.
2. b) Mixing of the fluid, preferably by means of a rotating mixing device (eg laboratory stirrer), so that due to the generated shear stress, the yield point of the fluid is exceeded. As a result, the fluid begins to flow and now behaves like a liquid. This step, as well as the other process steps, is preferably carried out at room temperature (20 ° C).
3. c) Adding and dispersing the explosive particles (especially TNT) in the fluid with continued mixing.
4. d) After the explosive particles have been dispersed in the fluid, the stirring or mixing process is stopped. This is preferably done by gradually reducing the stirring speed until the stirrer is completely stopped.
5. e) Subsequently, those particles which after the completion of the mixing process, in particular within 0.5 to 2 hours after completion of the mixing process, form a sediment (ie sediment), separated from the fluid. This step can also be omitted if the proportion of sedimenting particles is low and / or a separation is not considered necessary.
   Depending on the type of explosive and depending on the type and concentration of the chosen rheology additive particles of a particular size class are held in suspension in the fluid preferably, ie the yield point is not exceeded. For example, the TNT particles held in suspension when using an aqueous CMC solution having a CMC content of at least 1 wt.% May have an average height in the fluid of up to 5 mm.
6. f) The explosive particles separated off in step (e) can be re-comminuted or further dispersed and dispersed in the fluid according to the process steps (b) and (c) described above. If necessary or desired, a new separation of sedimented particles according to steps d) and e) can be carried out. The steps (b) to (f) may be repeated as needed.

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.

In particular, when using the mentioned hydrocolloids, the fluid 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. In general, 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. Depending on the selection and concentration of the rheology additives used, 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. In general, 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.

Accordingly, 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). In the case of aqueous fluids (eg containing hydrocolloids such as xanthan and / or CMC), it is preferred to bring about a drop in the flow limit by adding water.

After sedimentation, 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.

In the process variant described above, the fluid after separation of the explosive particles again for phlegmatization of explosives, as described above, can be used. In this way, the process can be very cost-effective. If necessary, 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.

• Phlegmatisieren eines Explosivstoffs durch ein Verfahren wie oben beschrieben und wie in den Ansprüchen angegeben;
• Transport des phlegmatisierten Explosivstoffs zu einem anderen Ort zum Zwecke der Lagerung, Beseitigung oder Verwertung.

The present invention therefore relates to a method for transporting explosives, which comprises the following steps:

• Phlegmatizing an explosive by a method as described above and as recited in the claims;
• Transport of the phlegmatized explosive to another location for storage, disposal or recovery.

Due to the phlegmatization according to the invention, 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. As a result, 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.

Examples A. Phlegmatization of TNT by CMC solution

1. (1) TNT wird z. B. mit einem Hochdruckwasserstrahl in Partikel geeigneter Korngröße zerkleinert.
2. (2) Das Fluid (wässrige CMC-Lösung, siehe oben) wird bei 20 °C in einem Labormischer derart in Rotation versetzt, dass es zu fließen beginnt.
3. (3) Die in Schritt (1) erzeugten TNT-Partikel werden in die CMC-Lösung gegeben, wobei der TNT-Anteil 30 Gew.-% beträgt. Bei der angegebenen CMC-Konzentration (1 Gew.-% oder höher) bleiben erwartungsgemäß sämtliche TNT-Partikel, die eine durchschnittliche Höhe im Fluid von weniger als 5 mm haben, in der Schwebe (bei 20 °C).
4. (4) Die Rotationsgeschwindigkeit des Labormischers wird nach und nach verlangsamt, bis dieser zu Stillstand kommt.
5. (5) Eine Stunde nach Stillstand des Labormischers werden diejenigen Sprengstoffpartikel, die sich als Bodensatz angesammelt haben, dem Fluid entnommen und weiter zerkleinert. Die zerkleinerten Partikel werden der Lösung wieder zugeführt. Die Schritte (2) bis (5) können je nach Bedarf wiederholt werden.
6. (6) Der so phlegmatisierte Explosivstoff TNT kann nun nach ADR 4.1 UN 1356 befördert werden.
7. (7) Der phlegmatisierte Explosivstoff kann wieder sensibilisiert werden, z. B. durch Verdünnen des Fluids mit Wasser und/oder durch Filtration (zum Abtrennen der TNT-Partikel aus dem Fluid).

The principle of the method according to the invention is illustrated by the following embodiment, in which TNT was used as explosive. As the fluid (dispersion medium), an aqueous solution of carboxymethyl cellulose (CMC) having a CMC content of 1 wt% (or higher) was used.

1. (1) TNT is z. B. crushed with a high pressure water jet into particles of suitable particle size.
2. (2) The fluid (aqueous CMC solution, see above) is rotated at 20 ° C in a laboratory mixer so that it begins to flow.
3. (3) The TNT particles produced in step (1) are added to the CMC solution, the TNT content being 30% by weight. At the indicated CMC concentration (1% by weight or higher), as expected, all TNT particles having an average height in the fluid of less than 5 mm are suspended (at 20 ° C).
4. (4) The rotational speed of the laboratory mixer is gradually slowed until it comes to a standstill.
5. (5) One hour after the laboratory mixer comes to a standstill Explosive particles that have accumulated as sediment, taken from the fluid and further crushed. The crushed particles are returned to the solution. The steps (2) to (5) may be repeated as needed.
6. (6) The phlegmatized explosive TNT can now be transported in accordance with ADR 4.1 UN 1356.
7. (7) The phlegmatized explosive may be sensitized again, e.g. By diluting the fluid with water and / or by filtration (to separate the TNT particles from the fluid).

B. Determination of the yield point

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 σ; 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. 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.

When using aqueous solutions of CMC (in various concentrations) and test particles with a density of 1.75 g / cm ³ , the following values were respectively determined for the yield point: CMC concentration h average height of the particles in the fluid σ yield point 0.7% 2.0 mm 14.7 n / m ² 0.8% 2.5 mm 18.4 n / m ² 1.0% 3.5 mm 25.8 n / m ² 1.1% 4.0 mm 29.4 n / m ² 1.2% 5.5 mm 40.5 n / m ² These results demonstrate the general principle that the yield point increases approximately linearly with increasing concentration of the rheology additive (CMC). In addition, the results demonstrate the basic rule that the higher the yield point, the greater the average height of the particles still floating in the fluid.

Claims (20)

A method for desensitizing an explosive, characterized in that 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. A method according to claim 1, characterized in that 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. A method according to claim 1 or 2, characterized in that an aqueous fluid is used as the fluid. Method according to one of the preceding claims, characterized in that the fluid contains at least one rheology additive, preferably from the group of hydrocolloids. Method according to one of the preceding claims, characterized in that the rheology additive 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, as well as combinations of the aforementioned substances. Method according to one of the preceding claims, characterized in that the fluid used is an aqueous solution of xanthan or / and Na-carboxymethylcellulose. Method according to one of the preceding claims, characterized in that the yield point is increased by adding one or more rheology additives, preferably hydrocolloids, or adjusted to a desired value. Method according to one of the preceding claims, characterized in that the yield point is adjusted by adding one or more rheology additives, preferably hydrocolloids, depending on the type of explosive used in each case and / or the particle size. Method according to one of the preceding claims, characterized in that it comprises an upstream process step in which said particles are prepared from an explosive, preferably by cutting the explosive by means of a water jet. Method according to one of the preceding claims, characterized in that it comprises the following steps: a) producing or providing a fluid having a yield point; b) mixing the fluid, preferably by means of a rotating mixing device, so that the yield point is exceeded and the fluid behaves like a liquid; c) Adding and dispersing the explosive particles in the fluid with continued mixing. A method according to claim 10, characterized in that it further comprises the following steps: d) termination of the mixing process; e) separating the particles which sediment after completion of the mixing operation, preferably within 0.5 to 2 hours, in particular within 1 hour after completion of the mixing operation. Method according to claim 11, characterized in that it further comprises the following steps: f) crushing the sedimented explosive particles separated in step e); g) dispersing these comminuted particles in the fluid according to process steps b) and c). A phlegmatized explosive, in particular a phlegmatized explosive prepared or obtainable by a process according to any one of the preceding claims, characterized in that the explosive is dispersed in the form of particles in a fluid having a yield point and the particles float in the fluid are. A phlegmatized explosive according to claim 13, characterized in that the shear stress caused by gravity of the particles dispersed in the fluid is smaller than the yield stress of the fluid. A phlegmatized explosive according to claim 13 or 14, characterized in that the explosive content is 10 to 80 wt .-%, in particular 20-50 wt .-%, is. A phlegmatized explosive according to any one of claims 13 to 15, characterized in that the fluid used is an aqueous fluid which contains at least one rheology additive, preferably from the group of hydrocolloids, with aqueous solutions of xanthan and / or Na-carboxymethylcellulose being particularly preferred are preferred. A method of sensitizing an explosive stabilized according to any one of claims 1 to 12 or a phlegmatized explosive according to any one of claims 13 to 16, characterized in that the yield point of the fluid containing the explosive particles is lowered such that the particles dispersed in the fluid sediment. A method according to claim 17, characterized in that the lowering of the yield point is effected by adding dispersion medium, in the case of aqueous fluids by adding water. A method according to claim 17 or 18, characterized in that the sedimented explosive particles are separated by mechanical separation processes, preferably screening or filtration, from the fluid. Method for transporting explosives, characterized by : - phlegmatizing an explosive by a method according to any one of claims 1-12; - Transport of the phlegmatized explosive to another location for storage, disposal or recovery.