Method of producing granular ammonium nitrate. RU patent 2520130.

FIELD: chemistry.

SUBSTANCE: method of producing granular ammonium nitrate involves adding a stabilising additive to an obtained ammonium nitrate solution while simultaneously neutralising the obtained solution with ammonia, evaporating the obtained solution until a melt forms, granulating the melt, wherein to increase absorption capacity of granular ammonium nitrate, granules are treated with a stabilising emulsion, the continuous phase of which is diesel fuel and the dispersed phase is water, with a variable ratio of the water phase to the oil phase of 1:(1.5-9).

EFFECT: invention enables to obtain granular ammonium nitrate with high static strength, low caking capacity and residual moisture content, high absorption and retention capacity without using blowing agents.

1 tbl, 5 ex

The invention relates to the field of special types of raw materials and technologies for production of inorganic substances (salts)that is used in the production of industrial explosive materials, namely to the production of granulated ammonium nitrate, used for manufacture of industrial explosives type ASDT and industrial emulsion explosives. The invention can be used for the manufacture of a wide range of explosives mixed type.

A method of obtaining granulated porous ammonium nitrate [EN 2101228, C1, 25.07.1995] by introducing a highly concentrated water ammonium nitrate as a hardening additive aluminium-containing inorganic polymers in the amount of 0.40% to 1,45% of the mass. from the mass of nitrate and as modifying additives mixture of ammonium salts and surfactants in the amount of 0.04% to 0,5% of the mass of nitrate with subsequent cooling and drying.

The disadvantages of this method are high content of water in the porous ammonium nitrate from 0.5 to 2.5% of the mass, which sharply reduces static strength of granules, increases their slumping capacities, as if bringing a product to the standards required by consumers, leads to the necessity of organizing additional vacuum drying of the received granules. In addition, the content in the melt of ammonium nitrate solid phase in the amount of 0.40% to 1,45% of the mass. from the mass of nitrate leads to complications with the organization of the process of dispersion of such melt into drops of static and vibratations-granulators.

The closest to the essential features and quality of the finished product technical solution is the way to obtain porous granular ammonium nitrate [EN 2396239 10.08.2010]including neutralizing nitric acid with gaseous ammonia 80 - 85% aqueous solution of ammonium nitrate at a temperature of 120 C, the introduction of stabilizing additives in the form of a mixture of ammonium salt of phosphoric acid in the amount of 0,3-1,0% mass. and ammonium salts of sulphuric acid in the amount of 0.03-0.25% of mass. in relation to ammonium nitrate or mixture of phosphoric acid in the amount of 0,3-1,0% mass. and sulfuric acid in the amount of 0.03-0.25% of mass. in relation to ammonium nitrate (as well as stabilizing additives use a mixture of oxides of magnesium (or caustic magnesite) and iron (III) (or the magnetite) in the amount of 0.3% to 2,0% of the mass. and 0.03 to 0.2% of mass. accordingly, in relation to ammonium nitrate), then evaporation the obtained solution to the state of water with a water content of 0.2% of mass. The purpose of steam formation received in the melt is injected saturated aqueous solution of surface-active substances (PAVA) at a temperature of its boiling in the amount of 0,02 - 0,1% weight. in terms of dry substance (as Surfactants are used, in particular, the mixture lauryl or sodium stearate with dispenser of metilsulfonilmetan naphthalene (NF)). Then, in the resulting water is injected preobrazujushchij substance - saturated aqueous solution of a mixture of ammonium carbonate and ammonium nitrate in the ratio 1:1 in the amount of 0.03% of the mass. in terms of dry substance. The resulting water is dispersed on the drops crystallized them, cool received granules and their condition.

The main disadvantage of this method is the necessity stage of steam formation, i.e. the introduction of a pore-forming additives, which includes a water solution of PEAHENS (used to minimize the size of the gas bubbles, uniform distribution and exceptions coalescence) and the actual pore-forming substances. Moreover, with the purpose of creation of optimum conditions of gassing the separation in time and space the introduction of additive components that also complicates the process.

The technical result of the invention is the possibility of obtaining granulated ammonium nitrate with high static strength, reduced caking and residual moisture resistant to thermal cycles of heating & cooling -20 l 60 C to 60 cycles, with a high prevalence of absorbing and retaining skills without the use of a pore-forming additives. Technological methods that are declared in this invention, allow to use non-porous ammonium nitrate as explosives with the necessary balance of oxidizer-fuel or with "zero oxygen balance" while lowering the total cost of production.

The technical result is achieved by the method of obtaining granulated ammonium nitrate, which includes introduction into the solution of ammonium nitrate stabilizing additives with simultaneous neutralization of the resulting solution of ammonia evaporation resulting solution to education Plava, granulation melt, and to increase the absorption of granulated ammonium nitrate granules are treated stable emulsion, continuous phase which is diesel, and the discrete phase - water, variable ratio of water and oil phase 1:(1,5 to 9). Micron size range allows the components of emulsion to penetrate into the smallest pores of pellets, providing improved absorption and retention abilities diesel non-porous ammonium nitrate, is the absorption of the necessary quantity of diesel fuel, which determines obtaining explosives with the necessary balance of oxidizer-fuel or with "zero oxygen balance". Examples proving the claimed method

Example 1. In the apparatus suitable for evaporation of water solution of ammonium nitrate, pour 85% (mass.) aqueous solution of ammonium nitrate, the concentration of which is controlled by the hydrometer densities; at a temperature of 120 C enter into him stabilizing additive in the form of a mixture of ammonium salt of phosphoric acid and ammonium salt of sulphuric acid in the amount of 1,0% mass and 0.25%, accordingly, in relation to ammonium nitrate, or a mixture of 70%phosphoric acid and 95%sulfuric acid in the amount of 1,0% mass and 0.25%, accordingly, in relation to ammonium nitrate, at the same time neutralize the resulting solution of ammonia at continuous stirring; then evaporated (and finally dried) solution of ammonium nitrate to the state Plava; the resulting water is dispersed from pravilnika in ascending at a rate of 0.5 m/s at the temperature of 25 C air flow in a glass column of diameter 100 mm, consisting of 6 tsarg 1 m long, equipped in the upper part pneumatic atomizer in the lower part - rotating beaded plate laid on her glass wool bathed in legisprudence liquid. The mixture of polydisperse granules cool in the fluidized bed of atmospheric air to 50 C, then dispersed through the pneumatic injectors 3·10 -4 kg/reverse emulsii water in the diesel fuel, the ratio of phases 1:9, stable two types of surfactants trademark AlkamulsOR/36 and V, taken in equal ratio, in the amount of 25% of the mass. in relation to diesel fuel. The emulsion flow rate is determined by its loss of supply capacity, receive parokotelnye stream with an average size of drops 60 microns. Next, the resulting granules ammonium nitrate is subjected to the tests according to the standard methods for THE 21436350020902399, the results are shown in the table.

Example 2. Implementation of the method according to example 1. The difference is that as a stabilizing additives use a mixture of oxides of magnesium (or caustic magnesite) and iron(III) (or the magnetite) in the amount of 2.5 wt.% and 0.35%, respectively.

Example 3. Implementation of the method according to example 2. The difference is that as impregnation use emulsion water in the diesel fuel, the ratio of phases 1:4, stabilized by surfactants trademark AlkamulsOR/36 and V together in the amount of 20% of the mass. in relation to diesel fuel.

Example 4. Implementation of the method according to example 3. The difference is that as impregnation use emulsion water in the diesel fuel, the ratio of phases 1:4, stabilized by surfactants trademark EmulsogenEL 360 and Emulsogen SF 8 together in the amount of 20% of the mass. in relation to diesel fuel.

Example 5. Implementation of the method according to example 2. The difference is that as impregnation use emulsion water in the diesel fuel, the ratio of phases 2:3, stabilized by surfactants trademark AlkamulsOR/36 and V together in the amount of 17% of the mass. in relation to diesel fuel.

Required and received (the prototype and the proposed method) properties of granulated ammonium nitrate

Name of indicator

Prototype

The proposed method

Absorption ability in relation to diesel fuel, %, not less

Holding capacity in relation to diesel fuel, %, not less

Static strength of granules, n/granule, not less

The number of thermal cycles heating & cooling-20 l 60 with a reduction of static strength of granules in 2 times

The test results obtained granulated ammonium nitrate has shown that the best way to obtain the product is used as a stabilizing additives mixture of oxides of magnesium (or caustic magnesite) and iron (III) (or the magnetite) in the amount of 2.5 wt.% and 0.35% mass accordingly, as the impregnation - emulsii water in the diesel fuel, the ratio of phases 1:4, stabilized by surfactants trademark AlkamulsOR/36 and V together in the amount of 20% of the mass. in relation to diesel fuel.