RU2670851C9 - Heat-resistant inflammatory environmentally friendly composition and method of preparation thereof - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to the production of means of initiation, namely to pyrotechnic compositions for electric igniters. Heat-resistant igniter environmentally friendly composition contains fuel – a double salt of potassium magnesium or potassium calcium ferrocyanide, and the oxidizer is perchlorate, chlorate, bromate or potassium nitrate. Composition is obtained by chemical co-precipitation of the components in aqueous solutions in one stage.EFFECT: igniter composition is characterized by non-toxic products of combustion and a safe way of its production and can be used for manufacture of electric igniters with less sensitivity to static electricity, mechanical effect and greater energy of operation, and is also safer during handling and operation.2 cl, 1 dwg, 4 tbl

Description

The invention relates to the production of initiating means, namely to pyrotechnic compositions for electric igniters (EV).

The electric igniter is two electrodes 4 mounted in a sleeve with a detonator capsule 1, interconnected by a thin conductor - an incandescent bridge 2, surrounded by a flammable composition - an ignition head 3, fixed in the sleeve with mastic 5 (Fig. 1).

There are a number of specific requirements for electric igniters:

- an electric igniter should be sufficient, but not overly sensitive to electric current, to ensure reliable operation and safety of use in conditions of relatively high stray currents and electromagnetic fields;

- the electric igniter must be stable during storage and have high heat resistance and moisture resistance;

- the beam of fire from the electric igniter must be of sufficient strength in order to cause reliable operation of the next element of the initiating fire chain (detonator capsule, moderator, etc.).

From the requirements for electric igniters it is clear that igniter compositions play a large role in their implementation.

Of the compositions used for electric igniters (elektrozapalov), the composition [1] (wt.%) Deserves attention:

pyroxylin wool - 40

ferruginous-synergy lead - 30

Bertoletova salt - 30.

The disadvantages of this composition are the high explosiveness of its manufacture and low reliability.

At present, in Russia for igniters the igniter composition is widely used [2] (wt.%):

bertoletova salt - 49.5

lead thiocyanate - 49.5

lead oxide Pb ₃ O ₄ - 1.

The disadvantages of this composition is also a high explosiveness and sensitivity to mechanical stress and an electric spark. Therefore, the stages of preparation of the initial components of igniter compositions, and especially the stages of their mixing, are extremely explosive, which is why explosions that destroy equipment often occur at manufacturers of electric igniters.

Deficiencies in the composition lead to a dangerously low minimum operating current and electrostatic sensitivity of the finished product compared to the global level of manufacture of EV.

As another analogue, the composition [3] can be given, which is less sensitive to external influences and has a safer way to obtain chemical coprecipitation (wt.%):

lead thiocyanate - 44-50

potassium perchlorate - 49-50

lead chromate - 1-6.

A common disadvantage of the known analogues is the presence of highly toxic lead compounds (MPC = 0.005 mg / m ³ ). Recently, environmental requirements have made this drawback very significant.

From the patent [4] known igniter composition, (wt.%):

potassium perchlorate - 61

potassium ferricyanide or potassium hexacyanocobaltate - 31.

It has good performance properties and can be used as a pyrotechnic igniter composition. However, it also has drawbacks: potassium ferricyanide and potassium hexacyanocobaltate are readily soluble in water and hygroscopic.

These disadvantages are eliminated in the proposed igniter composition and non-explosive method for its preparation. Explosion safety, improved performance, as well as the current environmental cleanliness of the electric igniter are achieved using the proposed heat-resistant electric igniter composition. It contains double salts as fuel: sparingly soluble ferrocyanides with two cations from the first and second groups of the periodic table, for example, potassium-magnesium ferrocyanide or potassium-calcium ferrocyanide. As oxidizing agents, perchlorate, chlorate, bromate and potassium nitrate can be used.

An example is a composition consisting of components taken in the following percentage (wt.%):

potassium magnesium ferrocyanide - 40 ± 5

potassium perchlorate - 60 ± 5.

This igniter composition is more heat-resistant than analogues, as it contains a double salt of potassium magnesium ferrocyanide and potassium perchlorate.

The method of obtaining the composition consists in the process of chemical coprecipitation from aqueous solutions of the starting reagents in one stage.

The invention is directed to the creation of a new heat-resistant igniter composition with non-toxic combustion products, a safe way to obtain it and its use for the manufacture of electric igniters with less sensitivity to static electricity, mechanical stress, higher response energy, and, therefore, safer during handling and operation.

The proposed heat-resistant igniter composition, depending on the route of preparation, can be obtained in two versions:

1) Co-precipitation from aqueous solutions;

2) Co-precipitation upon dilution of hot saturated aqueous solutions with a large excess of isopropyl or ethyl alcohol.

Obtaining composition 1:

To mixed solutions of anhydrous K ₄ Fe (CN) ₆ in water and KNO ₃ in water, a solution of Mg (ClO ₄ ) ₂ in water is added. The reaction mass is stirred until a white suspension is formed. The precipitate was filtered and washed successively with water and alcohol.

Reaction equation:

K ₄ Fe (CN) ₆ + 2Mg (ClO ₄ ) ₂ + 2KNO ₃ = K ₂ Mg [Fe (CN) ₆ ] ↓ + 4KClO ₄ ↓ + Mg (NO ₃ ) ₂

This method of manufacturing a new igniter composition is simple, safe and cheap.

Obtaining composition 2:

a) Fuel fabrication:

To obtain composition 2, you must first prepare a complex salt of potassium magnesium ferrocyanide.

The synthesis is carried out according to the scheme:

K ₄ Fe (CN) ₆ + MgCl ₂ = K ₂ Mg [Fe (CN) ₆ ] ↓ + 2KCl

Yellow blood salt and magnesium chloride dissolve in water. While stirring, a solution of magnesium chloride is poured into a solution of yellow blood salt. A fine white precipitate is formed. The suspension is filtered and washed with water and alcohol.

b) Production of the composition:

The resulting product K ₂ Mg [Fe (CN) ₆ ] - a double salt of potassium ferrocyanide - magnesium, is stirred to a homogeneous suspension in alcohol with stirring using a turbine stirrer and potassium perchlorate dissolved in water is added to it in one go. The precipitate formed is filtered and washed with alcohol.

This method of manufacturing a new igniter composition is not as simple and cheap as the first, but safer than the applied method of mechanical mixing.

To confirm the above advantages, comparative tests of the proposed compositions were carried out with analogues and standard initiating explosives (TRS).

A comparison of the sensitivity to external influences (heat, shock, friction, and electric spark) of the ignition compositions we offer with analogues and such TRSs as TNRS and tetrazene is shown in Table 1. Note that TNRS is also used in electric igniters mainly for military and space purposes, especially for extreme temperatures and pressures.

From table 1 it can be seen that, in terms of sensitivity to mechanical influences, composition 1 and composition 2 are at the level of highly sensitive initiating explosives. However, the proposed technology for their production and equipment reduces the danger in the production and operation of EV with them.

The burning rate of compositions 1 and 2 is slightly higher than that of the currently used igniter composition - analogue [1], but significantly lower than that of analogue [2] and TNRS [5]. High burning rates of the analogue [2] and TNRS [5] lead to the destruction of the EV bodies, which is not always acceptable. Therefore, close to analogue [1], the burning rates of the proposed compositions allow for a more “soft” operation of the electric igniters equipped with them without breaking the bodies.

From table 3 it can be seen that the minimum response energies (E ₀ ) of electric igniters with a nichrome filament 25 microns thick and with compositions 1 and 2 are close to each other and are 1.5–2 times greater than the minimum response energy of electromagnets with TNRS and an analog [ one]. The difference between EV with the proposed compositions from EV with an analogue [2] lies in the nature of the work, namely, electric igniters with compositions 1 and 2 work much more “softer”. Such energies are sufficient to use the compositions in the manufacture of electric igniters, both civilian and military purposes. Also, EVs with compositions 1 and 2 operate in a vacuum stably and gently, which allows them to be used at low pressures.

An additional advantage of the proposed composition is that it does not cause corrosion of brass (the main material of the EV housings), unlike analogues [1] and [2], and therefore does not require preliminary varnishing.

Characteristics of an igniter composition based on a double salt of potassium ferrocyanide - calcium and potassium perchlorate.

Production Method:

To mixed solutions of anhydrous K ₄ Fe (CN) ₆ in water and KNO ₃ in water, a solution of Ca (ClO ₄ ) ₂ in water is added. The reaction mass is stirred until a white suspension is formed. The precipitate was filtered and washed successively with water and alcohol.

Reaction equation:

K ₄ Fe (CN) ₆ + 2Ca (ClO ₄ ) ₂ + 2KNO ₃ = K ₂ Ca [Fe (CN) ₆ ] ↓ + 4KClO ₄ ↓ + Ca (NO ₃ ) ₂

The main properties of the proposed igniter composition and EV with it are shown in table 4.

This igniter composition is also heat resistant ( _Tsp = 400 ° C), as it contains a double salt of potassium-calcium ferrocyanide.

EVs with the proposed composition work “softly”, without breaking the case, both under normal conditions and in vacuum. The ignition energies of the electrons are sufficient to use the compositions in the manufacture of electric igniters, both civilian and military.

Thus, the proposed igniter composition and methods for its preparation are justified and meet the new increased requirements for igniter compositions for modern electric igniters.

At present, electric igniters with new compositions that are simple and cheap to manufacture, and also have lower sensitivity than regular explosives and do not contain toxic and heavy metals (Pb, Hg), and the method of their production are in the process of industrial development.

Bibliographic data:

1. Bubnov P.F., Sukhov I.P. Means of initiation. - M .: NKAP, Oborongiz, 1945 - 162 p.

2. Schukin Yu.G., Lyutikov G.G., Pozdnyakov Z.G. Means of initiation of industrial explosives. - M: Nedra, 1996 - 23 p.

3. Pat. 2179544 RF. Heat-resistant igniter compositions for electric igniters and a method for their manufacture / Baskakov Yu.M., Korolev V.P., Bibnev N.M., Kolesov V.I. and other publ. 02/20/2000.

4. Pat 3793100 United States. Ignitercompositioncomprising a perchlorate and potassiumhexacyanocobaltate III / Fronabarger J. Publ. 02/19/1974.

5. Bagal L.I. Chemistry and technology of initiating explosives. - Moscow: Engineering, 1975

Claims (3)

1. Heat-resistant igniter environmentally friendly composition for electric igniters, containing an oxidizing agent and fuel, characterized in that the fuel contains a double salt of potassium magnesium ferrocyanide or potassium calcium ferrocyanide, and the oxidizing agent contains perchlorate, chlorate, bromate or potassium nitrate in the following ratio of components (wt.%): potassium magnesium ferrocyanide or potassium calcium ferrocyanide 40 ± 5 perchlorate, chlorate, bromate or potassium nitrate 60 ± 5 2. A method of obtaining a heat-resistant igniter environmentally friendly composition for electric igniters according to claim 1, characterized in that the composition is obtained by chemical coprecipitation of the components in aqueous solutions in one stage.

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