RU2201913C2 - Method and plant for producing commercial explosives - Google Patents

Abstract

FIELD: production of commercial explosives. SUBSTANCE: method for producing commercial explosives including those having in their composition granular ammonium nitrate, trinitrotoluene, and sodium chloride or aluminum involves preparation of ingredients, that is ammonium nitrate, trinitrotoluene, and sodium chloride or aluminum, and double-stage mixing of explosive ingredients; during first stage ammonium nitrate and trinitrotoluene are mixed up and milled in two three-compartment mill/mixers to particle size of 100-270 mcm; during second stage mixture obtained is mixed up with sodium chloride or aluminum in three-compartment ball mill and milled to particle size of about 60-620 mcm; after that mixture is conveyed for packaging by pneumatic transport facilities at 27±3^°C. Plant for producing commercial explosives has ingredients preparation unit; ammonium nitrate and trinitrotoluene mixture preparation unit incorporating weight batcher, mixer, and two three-compartment ball mill/mixers; ammonium nitrate, trinitrotoluene, and sodium chloride or aluminum mixture preparation unit incorporating three-compartment ball mill/mixer; and pneumatic transport facility used to convey mixture for packaging; three- compartment ball mills are inclined towards mixture outlet through 1 deg.; mass of plastic balls amounts to 900 kg per compartment, ball diameter is 40-60 mm; pneumatic transport facility designed to convey mixture for packaging is provided in addition with jacket heating system and jacket solution blow-out system. EFFECT: enhanced stability and power characteristics of explosive; optimal packaging conditions in all seasons. 2 cl, 2 dwg, 1 tbl

Description

 The invention relates to the field of manufacturing industrial explosives (PVV), in particular, to the industrial manufacture of safety explosives based on granular ammonium nitrate, flaky trotyl and as a flame arrester - table salt used for blasting in mines and mines hazardous to methane air mixture and coal dust.

 Mixed explosives based on ammonium nitrate and TNT in various proportions are widely used both abroad and in Russia.

 The detonation ability and energy characteristics of explosive mixtures are greatly influenced not only by the chemical composition of their constituent components, but also by the absolute particle size, the ratio between the sizes of various components, and the uniformity of their mixing. The smaller the particles of heterogeneous components and the more uniform their distribution in the volume, the faster the reactions in the detonation wave, and, consequently, the higher the detonation ability of the explosive. However, excessive regrinding of particles negatively affects the explosive characteristics of the compositions, which is associated with an increase in density and a decrease in the free combustion surface of particles. In addition, the regrinding of the flame arrester in the composition of the safety PVV leads to a decrease in their performance and safety properties, i.e. grinding compositions should be in a certain range. Therefore, for mixed PVV an important factor is the degree of grinding (dispersion) of the components.

 There are various methods for producing PVV by mixing the individual components (periodic, semi-continuous, continuous mixing) with their inherent positive and negative factors.

 Known, for example, is a method of manufacturing industrial explosives (PVV) according to the patent RU 2107056 from 08.25.95, in which, along with the ease of use of the equipment, a significant drawback is the low quality of the dosage of the components.

There is also a known method of manufacturing ammonium nitrate explosives according to the copyright certificate RU 221550 of 08.08.67, in which the components are mixed in a hot state, namely, before mixing, ammonium nitrate is heated to a temperature of 70 ÷ 80 ^o C, and TNT is fed to the mixing apparatus in the molten state. The coolant is supplied to the mixer jacket, and before packaging, the mixture made is cooled with cold air.

The disadvantages of this method
1. When ammonium nitrate is heated above 32 ^° C, its crystals recrystallize, which negatively affects the caking of finished products, i.e. caking increases.

 2. In the process of cooling the molten TNT after the mixing phase, coarsening of TNT particles occurs, which negatively affects the explosive and energy characteristics of the explosives.

 Closest to the technical nature of the present invention is the "Method and installation for the production of ammonites or ammonals by low-load technology" according to patent RU 2096397 from 09/13/95, which is accepted by the authors as a prototype.

 The method consists in the following: the preparation of ammonites and ammonals is carried out in two stages - first a double mixture is prepared (ammonium nitrate - trotyl) in a disc-type frame-paddle mixer and a three-chamber ball mill with preliminary weighing of components. The supply of all components and the finished PVV is carried out by pneumatic conveying with simultaneous cooling, then salt or aluminum is introduced into the double mixture and the three-component mixture is mixed in a disc-type frame-paddle mixer. Pneumatic transport is equipped with a detonation chopper, means of flame detection and interruption of the combustion process.

The disadvantages of this method of manufacturing PVV are:
1) the absence of requirements for the degree of grinding of the components, which significantly affects the density of cartridges during patronage, on energy and explosive characteristics, on the catalytic reactions of the products of the explosion (PW) with a combustible (explosive) mine environment;
2) the use of pneumatic transport for interphase supply of components requires the consumption of a large amount of compressed air, which in turn requires the installation of additional equipment (compressor installation);
3) the existing dust removal plants do not provide for the complete purification of polluted air, which worsens the ecological situation of the environment;
4) the specified method for the manufacture of PVV does not provide the possibility of heating the powder before patronage in the winter, which significantly affects the quality of the cartridge, in particular on the bucking and density of cartridges.

 The proposed method of manufacturing a safety PVV eliminates or significantly reduces the above disadvantages.

 The objective of the invention is the manufacture of industrial explosives (PVV) based on granular ammonium nitrate, flaked TNT and salt (ammonites) with stable explosive and energy characteristics and optimal conditions for patronage at any time of the year.

The problem is solved due to the fact that in the known method for producing industrial explosives, which includes the preparation of the starting components (ammonium nitrate, TNT and table salt) and a two-stage process for producing a three-component mixture, while in the first stage a two-component mixture is prepared (ammonium nitrate and TNT) , at the second stage, table salt is introduced into the double mixture, the finished product is discharged by pneumatic conveying for patronage, the two-component mixture is ground in two ball three-chamber mills to dispersion D _dd ≈100 ÷ 270 microns, and the ternary mixture is ground in a ball mill, a three-chamber mixer to dispersion D _mp ≈60 ÷ 620 microns and the finished product during pneumatic transport in winter is heated to a temperature of 27 ± 3 ^o C.

In addition, the problem is solved due to the fact that in the known installation for the production of PVV, containing units for preparing components, a unit for preparing a two-component mixture (ammonium nitrate and trotyl), including a weighing batcher and a three-chamber ball mill-mixer, a unit for preparing a three-component mixture (ammonia nitrate, trotyl, table salt or aluminum powder) and a pneumatic vehicle for removing the finished explosive and feeding it for patronage, and the unit for preparing a two-component mixture includes two ball three molecular weight of the mill-mixers, ternary mixture preparation unit comprises also a spherical three-chamber mill-mixer, wherein the mixers of the mill have the angle of inclination in the downstream direction of the mixture to 1 ^o, the mass of plastic balls is 900 kg in each chamber, the diameter of balls 40 ÷ 60 mm, and the pneumatic vehicle for supplying the finished PVV for patronage is additionally equipped with a powder heating system and a solution purge system from the pneumatic transport jacket.

 Figure 1 shows the installation for the preparation of industrial explosives based on granular ammonium nitrate, flaked TNT and sodium chloride.

 The installation contains components preparation units, a hopper-agitator 1, unloaders 2, twin screw feeders 3, weight batchers 4, twin-shaft mixers 5, screw conveyors 6, three-chamber mill mixers 7, screw conveyors 8, cascade conveyor 9, twin screw feeders 10 and 11, metering screws 12, metering belt conveyor 13, screw conveyor 14, three-chamber mill 15, cascade screw conveyor 16, screw feeder 17, metering screws 18, feeders with vibration exciters 19, pneumatic conveying main pipe 20, cutters 21 and 22, discharge knot 23, detonation choppers 24, blockage elimination unit 25, piston passage sensor 26.

 The installation is unified and can be used for the manufacture of both safety and non-safety air-blowers with different content of components.

The essence of the proposed method and installation for its implementation is as follows:
ammonium nitrate and salt undergo preliminary preparation (sifting, drying, preliminary grinding) in separate preparation buildings and are conveyed by conveyor belts for dosage to the mixing building, trotyl is crushed and sifted also in a separate building and pneumatically transported to the storage hopper of the mixing building.

 The components are mixed in two stages, first a double mixture is prepared (ammonium nitrate-trotyl): ammonium nitrate from the hopper with agitator 1 and TNT from the unloader 2 with a twin-screw feeder 3 are fed into the weight batcher 4, from the weight batcher weighed ammonia nitrate and TNT in a given ratio dumped into the twin-shaft mixer 5, where they are pre-mixed.

After the double-shaft mixer the mixture by means of screw conveyers 6 is fed in three-compartment mill mixers 7, which produces a double grinding the mixture to dispersion D _dd ≈100 ÷ 270 microns. The specified dispersion is achieved by an angle of inclination of the mill chamber of 1 ^o in the direction of the product outlet, the mass of plastic balls (900 kg in each section), the diameter of the balls (40 ÷ 60 mm) and mill productivity (1.5 ÷ 4.0 t / h) .

The second stage is to prepare a triple mixture (ammonium nitrate - TNT - sodium chloride):
when leaving the mills 7, the double mixture is fed by screw conveyors 8 and cascade 9 to the twin-screw feeder 10 for the phase of preparation of the triple mixture, the double mixture and salt from the feeders 10 and 11 with the help of metering screws 12 are continuously fed to the conveyors of the metering belt conveyor 13 in the ratio of 4: 1. From the dosing conveyor belt, the double mixture with salt is fed through a screw conveyor 14 into a three-chamber mill 15, the angle of inclination of which is 1 ^o , towards the outlet of the mixture, the mass of balls in each chamber is 900 kg, the diameter of the balls is 40 ÷ 60 mm, productivity 2 ÷ 5 t / h, where the final mixing and grinding of the ternary mixture to a dispersion of D _tr ≈60 ÷ 620 microns is performed. The fractional composition of double and triple mixtures is determined by their sifting on sieves GOST 4403-91:
double mixture - on screens 29, 46,
ternary mixture - on sieves 15, 29, 46.

 The most optimal grinding parameters of the components are presented in the table.

 The table shows that the enlargement of the ternary mixture occurs due to the introduction of a larger salt fraction with simultaneous regrinding of the double mixture, which increases the detonation ability and increases the protective properties of the PVV.

 The triple mixture thus prepared by cascade screw conveyor 16 is fed into the screw feeder 17 of the pneumatic conveying line, from where the powder weighing 150 ÷ 180 kg is dispensed by the metering screws 18 into the feeders 19 with vibro-exciters, the powder is transferred to the main pipe 20 of pneumatic conveying under the influence of compressed air and vibration of the vibro-exciter for the first shutter 21. The thus formed ammonite piston stops in front of the second shutter 22, after which the first shutter closes, the second and second simultaneously in pneumatic main pipe from the "tail" of the piston is supplied with compressed air, which transports the powder discharger 23 in patterning the building. After sifting in a sieve-Burat, the powder is fed for patronage using standard technology.

 The main pipeline of pneumatic transport is equipped with two detonation breakers 24, a blocking unit 25, a piston passage sensor 26.

At the same time, during transportation of the powder in the summer, a brine is supplied to the pneumatic conveying jacket in a known manner to cool the powder to a temperature of 27 ± 3 ^° C.

However, in the winter, when transporting the powder with cold compressed air, the powder manages to cool down in pneumatic conveying and in the unloader to 10 ÷ 15 ^o C, which negatively affects the conditions of the cartridge, and there is a need for heating the powder.

 In FIG. 2 shows a powder heating system in pneumatic conveying, containing a storage tank 1, mixer 2, tubular heaters 3, level sensors 4 and 5, temperature sensor 6, solution supply pumps 7, solution supply and return pipes 9, compressed air 10, flexible connecting hoses 11 between sections of pneumatic transport 12.

The proposed installation (system) works as follows: in a separate storage tank 1, a solution of sodium chloride or potassium is prepared. Sodium or potassium chloride is poured into the storage tank 1 with warm water, mixed with a stirrer 2, the brine density is adjusted to 1.19 ÷ 1.20 kg / m ³ , the prepared solution is heated using tubular electric heaters (TENs) 3 to a temperature not exceeding 70 ^o With and pumps 7 through the pipeline 8 is fed into the jacket of pneumatic transport according to the principle of counterflow and through the pipe 9 is returned to the storage tank 1.

The storage tank contains
- a stirrer 2 for mixing the solution during its preparation;
- electric heaters (TENy) 3 for heating the solution;
- level sensors (upper 4 and lower 5) of the solution in the tank;
- temperature sensor 6 for measuring temperature.

 The temperature of the solution in the storage tank is controlled by a temperature controller.

The amount of solution supplied to the pneumatic conveying jacket is regulated in order to ensure the optimal mode of patronage in terms of maintaining a stable powder temperature of 27 ± 3 ^o C.

 Pneumatic transport is additionally equipped with a purge system to drain the solution and prevent the system from thawing.

 The pneumatic transport purge system works as follows: the supply valves 13 and drain 14 of the solution are opened, the compressed air inlet valve 10, the air passing sequentially through the pneumatic transport sections 12 and the flexible connecting hoses 11 displaces the solution of sodium chloride (potassium) from the pneumatic transport jacket and the solution through pipelines supply 8 and return 9 is discharged into the storage tank, and the input of compressed air is mounted at the highest point of pneumatic transport, and the supply and return pipelines are mounted at the lowest.

The advantages of the proposed method for producing PVV and installation for its implementation
1. Creation of favorable conditions for patronage at a powder temperature of 27 ± 3 ^o C at any time of the year.

 2. Exclusion from the process stream of bulky equipment in the form of a shelf refrigeration unit.

 3. Decrease in dust content in the building of patronage due to exclusion from the process stream of the shelf refrigerating apparatus - the main source of dust in the standard manufacturing technology of air-blast guns.

 4. Reducing the dust content in the mixing building by eliminating pneumatic transport for supplying the starting components (ammonium nitrate and salt) during interphase transportation, as dust collectors used in pneumatic conveying do not provide complete cleaning of polluted air.

 5. Reducing the consumption of compressed air as a whole by eliminating pneumatic transport during interfacial transportation of components.

 The method and installation are used in the industrial manufacture of safety and non-safety industrial explosives. Explosive and energy characteristics of the finished product are stable.

Claims (2)

1. A method of obtaining an industrial explosive, including the preparation of components - ammonium nitrate, TNT and sodium chloride or aluminum, two-stage mixing of the components of the explosive, in the first stage, ammonium nitrate and TNT are mixed and ground in a ball three-chamber mill mixer, in the second stage, the resulting mixture mixed with sodium chloride or aluminum, after which the mixture is fed for patronage by pneumatic vehicles, characterized in that the grinding of a mixture of ammonium nitrate and TNT they are carried out in two ball three-chamber mixer mills to a dispersion of about 100-270 microns, a mixture of ammonium nitrate and TNT is mixed with sodium chloride or aluminum in a three-chamber ball mill-mixer with grinding to a dispersion of about 60-620 microns, and the mixture is fed to cartridges by pneumatic vehicles carried out at 27 ± 3 ^o C. 2. Installation for producing an industrial explosive containing a component preparation unit, a unit for preparing a mixture of ammonium nitrate and TNT, including a weighing batcher, a mixer and a ball three-chamber mill-mixer, a unit for preparing a mixture of ammonium nitrate, TNT and sodium or aluminum salt, and a pneumatic vehicle supplying the mixture for patronage, characterized in that the unit for preparing a mixture of ammonium nitrate and TNT includes two ball three-chamber mill-mixers, the unit for preparing B ammonium nitrate, TNT and aluminum salt or comprises a ball-mill of three-chamber mixer, wherein the angle of inclination of ball mills, three-chamber in the downstream direction the mixture is 1 ^o, plastic mass is 900 kg balls in each chamber, the diameter of the balls of 40-60 mm and pneumotransport means for supplying the mixture for patronage is additionally equipped with a shirt heating system and a solution purge system from the shirt.

Images