CS252972B1 - A method of modifying inorganic nitrates - Google Patents

Abstract

The solution deals with a method of modifying inorganic nitrates for the production of explosive mixtures and/or explosive mixtures of additives to them before, or in the process of producing explosive mixtures of zeolites with a specific surface area of 20 to 200 m2. g_1 in an amount of 1.0 to 10.0 wt. % per weight of the resulting mixture. The procedure according to the solution is useful especially in the production of industrial explosives.

Description

The invention relates to the modification of inorganic nitrates for the production of explosive mixtures and/or explosive mixtures themselves by adding zeolites thereto.

Mixed explosives are becoming increasingly important in both civil and military applications. The most common oxygen donor in them is ammonium nitrate, but sodium nitrate and calcium nitrate are also widely used. These explosives can be divided into two main groups:

I. mixtures of ammonium nitrate with fuel;

II. mixtures of ammonium nitrate, or sodium or calcium nitrate, water with the addition of a plasticizer and/or emulsifier and an explosive compound or sensitizer.

Explosives of the first group can be produced by stable technological equipment, but more often they are produced directly at the place of use (i.e. in mobile mixing equipment or directly in wells). Ammonium nitrate is mixed with fuel, which can be a wide variety of organic compounds - however, paraffins, fuel oils or diesel are most often used. These mixtures have an approximately zero oxygen balance, which corresponds to a content of 94% by mass of ammonium nitrate and 6% by mass of diesel or fuel oil in the explosive; the specified fuel content will increase the value of the heat of explosion from 1,470 kj . kg ^-1 for ammonium nitrate up to 3,738 kj . kg ¹ , which is proportional to the increase in the working capacity of the explosive compared to ammonium nitrate alone. Explosives of this type are known in our country under the code name DAP, while abroad similar mixtures are called ANDK (in the GDR), ANC (in the FRG), Igdanit (in the USSR, ANFO or ANBA (in the USA and Great Britain). When the fuel is coal dust, metal powder, etc., these mixtures are also called nitrocarbonitrates and are designated by the code NCN.

Explosives of the second group are characterized by a relatively simple and undemanding production technology. In our country they are known under the designation TPV (water plasticized explosives); in the USA and Canada they are called "Slurry Explosives" due to their mushy consistency. Currently, the most common division of explosives of this type is according to the method of sensitization, namely:

a] "Slurry Explosives" (SE), which are sensitized with an additive of explosive nature (trinitrotoluene, hexogen, nitroesters, alkanol or alkylamine nitrates, hydroxyalkyl nitrates, etc.);

b) "Slurry Blasting Agents" (SBAj, which do not contain additives of an explosive nature and are sensitized with non-explosive components, most often aluminum dust (e.g. Soviet Akvanaly) and/or another substance (fuel oil, fibrous cellulose, polyvinyl chloride dust, sulfur, paraffin, hexamethylenetetramine, polyols, sugars and others), respectively aerating additives (expanded perlite, glass crumb or hollow beads, cork, polystyrene, prilled ammonium nitrate and the like), or gas-releasing substances (peroxides, nitrites, carbonates, 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetraazacyclooctane and others).

The constancy of physical stability, i.e. prevention of separation of the components of these subgroups of "Slurry" explosives while maintaining the fluidity or plasticity of the composition, is ensured by the addition of a gel-forming substance (plasticizer), such as guar gum and its alkyl derivatives, polyvinyl alcohol, sodium or ammonium salts of carboxymethylcellulose, oxyethylcellulose, polyacrylamide and others.

The youngest type of "Slurry" explosives are water-in-oil emulsion compositions, code-named W/O, or oil-in-water emulsion compositions, code-named O/W. The production of W/O compositions consists of introducing aqueous solutions of explosive components into a hydrophobic liquid (fuel oil, diesel, etc.), and the opposite procedure is used to produce O/W compositions. These emulsions are stabilized by dispersants, such as salts of fatty acids (especially stearic or oleic), fatty acid esters (e.g. decaglycerin decaoleate, decaglycerin decastearate), partially esterified polyols with fatty acids (e.g. sorbitol monostearate, monooleate, monopalmitate or tristearate, mono- or diglycerides of fat-forming fatty acids), alkylphenylsulfonates, soybean lecithin, copolymers of ethylene oxide with propylene oxide and others. Emulsion explosives can be sensitized with nitro compounds, most often nitromethane, or other nitroparaffins, but in technical practice their sensitization with aerators or gas-releasing additives is the most common.

Low production costs, high safety of handling and own production and possibility of mechanization of blasting machines are characterized mainly by mixtures based on ammonium nitrate. This is the main reason why in technical practice the exploitation of explosives of the DAP, TPV, W/O and O/W type significantly prevails over the exploitation of other types of industrial explosives. An analogous trend can also be observed in the field of explosives for military purposes (aluminized aqueous ammonium nitrate gels are, for example, used in some types of air bombs, trinitrotoluene is replaced by liquid compositions based on aqueous solutions of hydrazine nitrate, etc.).

If solid inorganic nitrates are used for the production of mixed explosives, it is important that they are in a loose form; this is achieved by eliminating or suppressing their caking by adding anti-caking additives to them in the production process, such as iron salts of fatty acids, paraffins, powdered urea-formaldehyde condensates, etc., i.e. products of chemical technologies, the implementation of which is associated with considerable demands on energy, equipment, human labor and land, including the corresponding environmental pollution. In the event that nitrates are not treated against caking, their agglomeration occurs during their transport to the production of mixed explosives; in this case, grinding of nitrates must be included in the explosives production process, which in turn is associated with demands on energy, equipment and human labor. Caking is an undesirable phenomenon even in manufactured mixed explosives, where it causes difficulties, especially in the area of functionality of these products. All sensitizers used so far are products of chemical technologies with considerable demands on energy, equipment, human labor and land resources, many of which are finding increasingly significant and economically attractive use in various sectors of the national economy. Therefore, research and development efforts should be focused on finding technically, economically and ecologically more accessible anti-caking and sensitizing additives for mixed explosives, or rather starting inorganic nitrates.

According to the present invention, the method of modifying nitrates for the production of explosive mixtures consists in adding to them before, or in the process of producing explosive mixtures, zeolites with a specific surface area of 20 to 200 m ² . g ^-1 in an amount of 1 to 10 wt. % per weight of the resulting mixture.

The advantage of the process of the present invention is the increase in the physical stability of the starting nitrates and/or explosive mixtures with their content, or sensitization of this mixture, by adding technically and economically available additives, i.e. zeolites. These sensitizers-aerators of explosive mixtures are formed due to the physicochemical properties of zeolites; the application of zeolites in the sense of the present invention thus enables the implementation of even small-diameter charges and suppresses the occurrence of "failures" during their application, which ultimately has a positive effect on the safety and economy of blasting machines.

The higher effect achieved by the method of this invention has not been described in the literature so far, and is documented in the following by examples, which, however, in no way limit the scope or variability of the method according to this invention.

Example 1

Zeolite is available, mined in the Nižný Hravoce locality in eastern Slovakia, characterized by the following parameters:

— in terms of chemical composition, it contains (% by weight): up to 71.76% silicon dioxide, up to 12.85% aluminium oxide, up to 0.33% titanium dioxide, up to 1.72% iron oxide, up to 4.36% calcium oxide, up to 1.26% magnesium oxide, up to 0.01% manganese oxide, up to 0.7% sodium oxide, up to 3.02% potassium oxide, up to 0.05% phosphorus pentoxide and up to 0.09% sulphur trioxide;

— spectral analysis of ύο'ο in a sample of zeolite rock, ground to a fineness below 0.09 mm and containing approximately 53% by weight of clinoptiolite, demonstrated the presence of 400 ppm barium, 350 ppm strontium, 13 ppm lead, 3 ppm copper and traces of arsenic, mercury, cadmium, fluorine, chromium, tin, bismuth, gallium, nickel, lithium, vanadium, yttrium and ytterbium;

— the specific gravity of zeolite rock generally ranges from 2,222 to 2,440 kg. m ^-3 , the bulk density from 1,850 to 1,950 kg. m ^-3 , its hardness from 1.5 to 2.0 degrees according to Mohs, the compressive strength (cat 50 X 50 X 50) is 20.3 to 49.7 MPa, the specific surface area from 30 to 50 m ² . g" ¹ (it can be increased up to fourfold by activation), the effective surface area (from water vapor adsorption) is 120.33 to 140.66 m ² . g~ ³ and the grindability according to VTI is 1.205 (i.e. medium to good grindability);

— bulk weight of zeolite rock s

content 4 to 7% mass of moisture is next- blowing: fraction — ground (up to 0.2 mm) 670 kg . no. ³ up to 1 mm 945 kg . m- ³ up to 4 mm 1090 kg . m ^-3 0.2 to 2 mm 830 to 950 kg . m ^-3 0.5 to 1 mm 845 kg . m~ ³ 2.5 to 3.15 mm 905 kg . m~ ³ 2 to 5 mm 760 to 850 kg . m ^-3 8 to 16 mm 780 kg. . m~ ³ — granulometry samples of zeolite, used in this example it is 22.9% by weight grains above

microns and 77.1% by weight of grains below 20 microns;

Furthermore, technical ammonium nitrate is available with a content of 96.9% by weight of granules with a diameter of 1 to 3 mm and the rest are particles with a diameter of less than 1 mm.

Ammonium nitrate is fed from the drying line of its production into a homogenizing drum, where zeolite is added to it, resulting in a mixture containing 97% by weight of ammonium nitrate, 2% by weight of zeolite and up to 1% by weight of water. This nitrate, after 3 months of storage at a temperature of 20 to 26 °C in polyethylene self-supporting bags, stacked on top of each other in four layers, had a tendency to form agglomerates, which, however, could be very easily broken up by manipulating the bag.

Using differential thermal analysis (DTA), operating with a linear temperature rise rate of 5 °C/min, a measurement range of 1 mV per scale scale and weighing 40—60 mg of sample, it was found:

Ammonium nitrate starting material with 2% zeolite content

Story

Polymorphic transition II—I (°C)

beginning 128.5 128.8 Peak 133.2 132.9 Heating (°C) beginning 168.4 168.4 peak 172.9 172.3 The beginning of the exothermic decomposition (°C) 210.6 210.5

Example 2

A mixed explosive of the Amatol 80/20 type with a content of 77.5% by weight of ammonium nitrate is produced in the usual way from technical 2,4,6-trinitrotoluene (TNT) and ammonium nitrate, prepared according to Example 1,

Parameters

Volume of post-explosion products (dm ³ . kg ^-1 }

Max. explosion heat (kj. kg ¹ )

Complete ideal work of explosion (kJ. kg- ¹ )

Detonation transmission from a 200 g TNT charge over distance (cm)

Detonation velocity (km . s' ¹ ) for a charge density of 1,100—1,300 kg . m~ ³

Bulk density (kg . m~ ³ )

The presence of zeolite sensitizes Amatol to the transmission of detonation by a shock wave while practically preserving the working capacity of this explosive mixture.

Example 3

The zeolite from Example 1 is available, which is subjected to activation by two-hour exposure at 300 °C, which increases its specific surface area to 194 m ² . g ^-1 . Furthermore, technical ammonium nitrate as in Example 1 and aluminum powder with a specific surface area of about 0.7 m ² . g ^_1 are available.

A mixture consisting of (% by weight): 90.6% ammonium nitrate, 4.6% aluminum and 4.8% activated zeolite is prepared by the procedure of Example 1. This mixture, stored as the treated ammonium nitrate of Example 1, shows no signs of agglomeration.

Example 4

From the modified ammonium nitrate according to Example 3 and diesel fuel with a cetane number of 45 and a viscosity of 2.4 . 10“ ⁶ m ² . . s ¹ , a mixture with the composition (% wt. ]: 87.1% ammonium nitrate,

4.6% zeolite, 4.4% aluminum and 3.9% diesel fuel. This mixture is for the charge measure20.9% by weight TNT and 1.6% by weight zeolite. For comparison, standard Aniatol 80/20 is prepared with a content of 79% by weight technical ammonium nitrate and 21% by weight TNT. These mixtures with an approximately zero oxygen balance are characterized by the following parameters:

Amatol 80/20 standard with zeolite

890 880 4,350 4,310 3,600 3,600 25—30 32—36 4.2-4.8 4.5-5.0 800—850 810—860 weight 1,100 kg . with parameters: m- ³ characterized- oxygen balance (% mass} ca 0

volume of explosion products (dm ³ . kg ^_1 j 860 max. heat of explosion (kj . kg- ¹ } 4,460 total ideal work of explosion (kj . kg ^-1 } 3,600 detonation velocity (km . s-'] 4.1

Unlike classic DAP explosives, the mixture according to this example does not show any clear signs of diesel fuel segregation (i.e., flowing to the bottom of the charge) after 24 hours of standing.

Example 5

From the zeolite from example 1, an 87% aqueous solution of ammonium nitrate warmed to 80 °C, technical sodium nitrate, diesel fuel as in example 4, technical 1,5-endomethylene-3,7-dinitroso-1,3,5,7-teraaza-cyclooctane (DNPT) and an emulsifier based on a copolymer of ethylene oxide with propylene oxide with an average molecular weight of 6,000 containing 80% by weight of polypropylene oxide, an oil-in-water emulsion type mixture is produced in a conventional manner in a kneader with the composition (% by weight): 60% ammonium nitrate, 15% sodium nitrate, 9% zeolite, 3% diesel fuel, 3% emulsifier and 1% DNPT. This semi-loose mixture, with not too much pressure, is easily pressed to a specific weight of 1110 kg. m~ ³ , is characterized by the parameters:

oxygen balance (% mass) ca 0 volume of post-explosion products (dm ³ . kg- ¹ ) 810 maximum explosion heat (kj . kg- ¹ ) 3,300 complete ideal work of explosion (kj.kg- ¹ ) 2,740 detonation velocity (km . s ^_1 ) 3.9 detonation transfer from a 200 g TNT charge at a distance (cm) up to 2 detonates with detonator No. 8

Replacing zeolite in this mixture with glass beads with a diameter of 30 to 150 microns (i.e., a Kasia explosive mixture) will reduce the sensitivity to the transfer of detonation by the shock wave of a 200 g TNT charge, thus reducing the transfer distance to the point of contact.

SUBJECT

Claims (1)

% Of composition (% by weight): 60% ammonium nitrate, 15% sodium nitrate, 9% zeolite, 3% by weight naphtha, 3% emulsifier and 1% DNPT. This semi-dense mixture easily compresses to a specific gravity of 1110 kg, not too much pressure. m ~ 3 is characterized by parameters: oxygen balance (% by weight) ca 0 volume of post-explosion fumes (dm3. kg-1) 810 maximum explosion heat (kj. kg-1) 3 300 full ideal explosion work (kj.kg -1) 2740 detonation velocity (km. S_1) 3.9 transfer of detonation from 200 g TNT cartridge to distance (cm) to 2 detonates by detonator # 8 Replacement of zeolite in this mixture by glass beads of diameter 30 to 150 microns (hence in the case of a classic explosive mixture, the reduction in sensitivity to transmission by the detonation-wave wave of the 200 g TNT cartridge, thus reducing the transmission distance to the touch. SUBJECT MATERIAL Modification of inorganic nitrates for the production of explosive mixtures and / or explosive mixtures themselves, characterized in that the modification is effected by addition to inorganic nitrates prior to or in the process of producing explosive mixtures, zeolites YLAZEZ with a specific surface area of 20 to 200 m2 . g-1, preferably with a surface area of 30 to 194 m 2 / g, in an amount of 1 to 10% by weight, preferably 1.6 to 9% by weight. to the weight of the resulting mixture.