RU2379271C2 - Method for production of spherical powder - Google Patents

Abstract

FIELD: explosives.

SUBSTANCE: method for production of spherical powder includes preparation of powder varnish in process of mixing of ethyl acetate in water medium with pyroxylin or its mixture with return technological waste, introduction of emulsifier, dispersion of powder varnish into spherical particles. Preparation of powder varnish is carried out with application of pyroxylin having viscosity of not more than 4°E and ethyl acetate in amount of 1.8-2.5 wt parts versus 1 wt part of pyroxylin or its mixture with return technological wastes at the temperature of 68°C. After powder varnish is dispersed into spherical particles, 50 wt % of sodium sulfate is introduced out of its overall amount, which makes 2.5 - 6.0 wt % versus water. Then it is mixed and heated up to temperature of 75°C. Distillation is applied to remove 15 vol. % of ethyl acetate from its overall amount, remaining 50 wt % of sodium sulfate are introduced, and remaining amount of ethyl acetate is removed by distillation.

EFFECT: invention makes it possible to produce dense powder granules.

1 tbl, 1 ex

Description

The invention relates to the field of production of spherical powders (TFP) for small arms and small-caliber artillery.

Known methods for producing spherical powders, which include obtaining a powder varnish in an aqueous medium in the presence of a solvent (for example, ethyl acetate), dispersing it onto spherical particles of a given size under the action of an emulsifier (glue, gelatin or other surfactants), dehydrating the dispersed particles (when obtaining dense particles granules) followed by distillation of the solvent [1-3]. The gunpowder obtained by this method is highly and medium dispersed (fraction of not more than 0.7-0.8 mm) and does not provide ballistic characteristics of the propellant charges of small-caliber artillery.

The closest technical solution (prototype) is a method for producing TFP [4], including the preparation of powder varnish with stirring in an aqueous medium of pyroxylin or its mixture with recycling waste (WTO) together with diphenylamine, an aqueous suspension of carbon black and ethyl acetate (EA), dispersing varnish onto spherical particles and removing ethyl acetate when the mixture is heated to 92-94 ° C, characterized in that in order to increase efficiency by reducing the intensity of gas production of gunpowder in the initial period d combustion, slurry concentration is 1 part by weight soot for 8-10 parts by weight water, and the initial removal of ethyl acetate in an amount of 70-75% is carried out at a rate of 0.4-1.2 l / s per cubic meter of mixture.

The powder thus obtained has a density of 0.7-0.85 g / cm ³ and a fractional composition of not more than 0.7-0.8 mm. The disadvantage of this method is the impossibility of obtaining coarse-grained powder with a diameter of granules of 1.0-3.0 mm, providing ballistic characteristics, for example, in a hunting cartridge "Magnum" with a shotgun mass of up to 50 g.

The objective of the invention is to obtain dense gunpowder with a diameter of a granule of 1.0-3.0 mm, providing ballistic characteristics in hunting shotgun cartridge "Magnum".

The technical result is achieved in that in a method for producing spherical powder, including the preparation of powder varnish with stirring in an aqueous medium of ethyl acetate and pyroxylin or its mixture with recycling waste, the dispersion of powder varnish on spherical particles, the preparation of varnish is carried out using pyroxylin with a viscosity of not more than 4 ° E and ethyl acetate in an amount of 1.8-2.5 parts by weight in relation to 1 wt.h. pyroxylin or its mixture with process waste at a temperature of 68 ° C, an emulsifier is introduced into the prepared powder varnish, after dispersing the powder varnish onto spherical particles, 50 wt.% sodium sulfate from the total amount of 2.5-6.0 wt. % with respect to water, stirred for 10-15 minutes, heated to a temperature of 75 ° C, removed by distillation of 15 vol.% ethyl acetate from its total amount, the remaining 50 wt.% sodium sulfate from its total amount was introduced and the remaining amount of ethyl acetate was removed by distillation.

Controlling the size of spherical particles, in particular, achieving a diameter of up to 3 mm as part of a regular distribution process, is a new and rather complicated task. Obtaining a dense large granule compared to a porous one is complicated by the multifactorial effect of sodium sulfate, which is introduced as a dehydrator after the dispersion operation. The introduction of salt causes not only a decrease in the viscosity of the dispersed particles, but also under certain formation conditions, either a loss in the size and shape of the particles or their coagulation can occur. These effects are explained by the fact that when salt is introduced into the EA-water system, the solubility of EA in water decreases from 4.7 to 2.8% (at a temperature of 65 ° C) with an increase in the concentration of sodium sulfate from 2.0 to 6.0%. EA separated into a separate phase enters the surface of the formed dispersed particles, causing the destruction of the boundary layer of varnish droplets, a decrease in their thixotropy and aggregative stability. This moment of volley release of EA on the surface of the varnish particles with a single injection of a large amount of dehydrator (2.5-6.0 wt.%) Becomes decisive when obtaining coarse-grained TFP. A decrease in the amount of introduced dehydrator less than 2.5 wt.% Leads to an increase in the porosity of the TFP. Therefore, in order to exclude the destruction of droplets, salt input must be carried out in 2 doses: 50% of the total amount of salt before the start of EA distillation, with stirring for 10-15 minutes, because a decrease in time of less than 10 minutes leads to a porous product, 50% after distillation of 15 vol.% EA. Obtaining dense granules is provided for a fraction of 1.0 ... 1.5 mm with a salt concentration of 2.5 ... 3.0% and for a fraction of 1.5 ... 3.0 mm - 3.0 ... 4.0%. Salt input is consistent with EA stripping. Increasing the dosage ratio of sodium sulfate by more than 2% does not give the desired effect, since with a larger amount of distilled EA, curing of the emulsified particle begins, which reduces the effect of osmosis.

To obtain large dense granules, it is necessary to use pyroxylin with a minimum conditional viscosity of not more than 4 ° O, since varnish particles of equivalent volume in this case contain the maximum mass of dry residue. The lower viscosity limit of pyroxylin is limited by the production method and practically does not happen below 0.5 ° Oe.

A decrease in EA module of less than 1.8 with respect to pyroxylin or its mixture with WTO leads to an increase in the viscosity of powder varnish, at which a high-quality dispersion operation is impossible, i.e. or the required form of the powder elements is missing, or dispersion is formed due to the high adhesive interaction in the lacquer phase. An increase in the module of more than 2.5 leads to the formation of a low-viscosity varnish and to instability of a large drop of emulsion, as a result of which they are subjected to subsequent dispersion.

The table shows examples of the implementation of the method of producing gunpowder according to the standard version, within the boundary conditions and beyond.

Table 1 Technological parameters of the method Name of indicator Example 1 Example 2 Example 3 Example 4 Example 5 Prototype The viscosity of pyroxylin, ° E 0.5 2 four 0.5 5 6 EA module 1.8 2.0 2.5 1,5 3.0 3,5 Multiplicity of input Na ₂ SO ₄ 2 2 2 one 3 - Dosage of Na ₂ SO ₄ , wt.% To water:
- primary (after dispersion), 2.0 1,5 1.25 2.0 7.0 - - secondary (after distillation of 15% EA) 2.0 1,5 1.25 - - - Mixing with Na ₂ SO ₄ until distillation of the solvent, min 10-15 10-15 10-15 10-15 10-15 10-15 The first stage of EA distillation, ° С 75 75 75 75 75 75 The second stage of distillation EA, ° C 94-96 94-96 94-96 94-96 94-96 94-96 Gunpowder characteristics Grain Diameter (D ₃ ), mm 2.5-3.0 1.5-2.5 1.0-1.5 0.7 0.4-0.5 0.4-0.6 Density, g / cm ³ 1,58 1,59 1,60 1.43 1,60 1.40 Bulk density, g / cm ³ 0.94 0.95 0.97 0.83 0.97 0.80 Ballistic characteristics in the hunting cartridge "Magnum" with a shotgun mass of 50 g Mass propellant charge, g 2.90 2.89 2.87 2.70 2.54 2.60 Shot shell velocity, V ₁₀ , m / s 326 327 325 321 319 321 The average maximum pressure of the powder gases, MPa 64.9 65,2 63,4 90.7 91.2 94.3 Requirements of TU for the cartridge "Magnum" with a sleeve length of 76 mm: the velocity of the shot projectile is not less than 315 m / s, the average maximum pressure of the powder gases is not more than 90.0 MPa

Example 1. In a volumetric type reactor equipped with a stirrer and a heating jacket, 12 L of water is poured, 3 kg of pyroxylin or its mixture with process waste and 5.4 L of ethyl acetate are loaded. The mixture is heated to 68 ° C and mixed for 15 minutes. Then 0.09 kg of emulsifier is loaded and dispersion is carried out, at the end of which 0.06 kg (2%) of sodium sulfate is introduced, and the emulsion is mixed for 10-15 minutes. The temperature rises to 75 ° C and 15% EA is distilled off, then 0.06 kg (2%) of sodium sulfate is additionally charged and the residual EA is distilled off (temperature rises to 94-96 ° C). Subsequently, the gunpowder is washed, fractionated, graphitized and dried.

The remaining samples are made in the same way.

From the data of the table it can be seen that the TFP made according to the declared modes have a grain diameter of 1.0-3.0 mm with a bulk density of 0.94-0.97 g / cm ³ , which provides ballistic characteristics in the hunting cartridge "Magnum". The manufacture of gunpowder outside the boundary conditions leads to the production of finely dispersed and porous granules, which burn more degradedly, which causes an increase in the pressure of the powder gases above the indicated norms (Example 4.5, Table 1).

Thus, the developed production modes of TFPs ensure the production of dense large granules with a grain diameter of 1.0-3.0 mm and a bulk density of at least 0.94 g / cm ³ using water dispersion technology.

LITERATURE

1. US patent No. 3824108, 1974, Cl. C08B 21/12.

2. Auth. St. USSR No. 1727375, MKI C06B 21/00.

3. US Patent No. 2915519, 1959, Cl. C08B 21/12.

4. RF patent No. 1806462, MKI C06B 21/00 (prototype).

Claims (1)

A method of producing spherical powder, including the preparation of powder varnish with stirring in an aqueous medium of ethyl acetate and pyroxylin or its mixture with process waste, dispersing the powder varnish on spherical particles, characterized in that the preparation of powder varnish is carried out using pyroxylin with a viscosity of not more than 4 ° E and ethyl acetate in an amount of 1.8-2.5 wt.h. in relation to 1 wt.h. pyroxylin or its mixture with process waste at a temperature of 68 ° C, an emulsifier is introduced into the prepared powder varnish, after dispersing the powder varnish onto spherical particles, 50 wt.% sodium sulfate from its total amount of 2.5-6 are added, 0 wt.% With respect to water, stirred for 10-15 minutes, heated to a temperature of 75 ° C, removed by distillation of 15 vol.% Ethyl acetate from the total amount, the remaining 50 wt.% Sodium sulfate from the total amount was added and removed distillation of the remaining amount of ethyl acetate.