RU2565283C1 - Method of production of porous granulated ammonium nitrate - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: method of production of the porous granulated ammonium nitrate comprises preparing the solution of ammonium nitrate, adding the structuring additive into it, evaporation of the resulting solution to melt state with a water content of not more than 0.2 wt %, adding into the melt of the water solution of surfactant, dispersing the resulting melt into droplets, their crystallization, cooling and conditioning the obtained granules, and the structuring additive is used as a mixture of magnesium oxide and iron oxide (III) in an amount 0.3÷2.0 wt % and 0.03÷0.2 wt %, respectively, and to the melt obtained after evaporation the saturated water solution of surfactant is sequentially added at its boiling temperature in an amount of 0.02÷0.1 wt %, based on dry substance, and then the saturated water solution of a mixture of commercial potash and soda in a ratio of 1:1 at its boiling temperature in an amount of 0.1÷0.5 wt %, based on dry substance.

EFFECT: invention provides granular porous ammonium nitrate with increased static strength, reduced caking.

4 cl, 1 tbl, 13 ex

Description

The invention relates to the field of creating special types of raw materials and technology for producing inorganic substances (salts) used in the production of industrial explosive materials, namely the production of porous granular ammonium nitrate. The invention can be used for the manufacture of a wide range of mixed explosives.

Technical field

A known method for producing porous granular ammonium nitrate described in the patent (RU 2101228 C1, 07.25.95) by introducing additives into a highly concentrated melt of ammonium nitrate (solutions of aluminum-containing inorganic polymers in an amount of 0.4 ÷ 1.45% by weight are used as a hardening additive) from the mass of nitrate, and as a modifying additive, use a solution of a mixture of ammonium salts and surfactants in an amount of 0.04 ÷ 0.5% wt. from the mass of nitrate), followed by cooling and drying.

The disadvantage of this method is the increased water content in the resulting granules of porous ammonium nitrate from 0.5 to 2.5% of the mass, which dramatically reduces the static strength of the granules and increases their caking.

A known method of producing porous granular ammonium nitrate, described in the patent (RU 2078065 C1, 02.01.94), including the introduction of concentrated ferrous ammonium nitrate sulfate of ferric iron in the form of its aqueous solution in the amount of 0.06 ÷ 0.08% of the mass. in terms of Fe + 3, then an aqueous suspension of a pore-forming additive is introduced, consisting of chalk, a dispersant NF (sodium or ammonium salt of methyldisulfonic acid naphthalene) and sodium stearate or potassium stearate in appropriate amounts of 0.1 ÷ 0.4 wt.%, 0, 01 ÷ 0.05% mass., 0.0002 ÷ 0.001% mass., Taken in relation to the mass of the final product.

The disadvantages of this method are:

- increased amount of water introduced with additives into the resulting granules of ammonium nitrate;

- the introduction of chalk (CaCO ₃ ), which is partially converted to calcium nitrate, reducing the quality of the granules, increasing their caking and reducing static strength;

- introducing into the melt of ammonium nitrate a pore-forming additive in the form of a mixture of surfactants (NF dispersant and sodium or potassium stearates) and a pore-forming component (chalk) leads to foaming of the prepared aqueous suspension, which complicates its preparation, pumping and dosing.

The closest technological solution is the method (RU 2230028 C1, 02.10.2003) for producing porous granular ammonium nitrate, including neutralizing nitric acid with ammonia, evaporating the solution to obtain concentrated melt, introducing hydrolyzed salts of trivalent metals into the melt, mixing with an aqueous suspension containing a pore-forming agent in the form of a carbonate salt of a metal, sodium or ammonium salt of methyldisulfonic acid naphthalene (dispersant NF) and sodium or potassium stearate, granulation of the mixture with the last processing granules with surface-active additives, characterized in that a combination of water-soluble sodium or potassium carbonate and calcium carbonate suspended in its solution is used as a pore-forming agent, the concentration of sodium or potassium carbonate being 5–15%, and the content of calcium carbonate 30–30 50% of the total weight of the suspension fed to the mixing. This method is selected as a prototype.

The disadvantages of this method are:

- increased amount of water introduced with additives into the resulting granules of ammonium nitrate;

- the introduction of chalk (CaCO ₃ ), which is partially converted to calcium nitrate, which leads to a decrease in the quality of the granules, increasing their caking and reducing static strength;

- introducing into the melt of ammonium nitrate a pore-forming additive in the form of a mixture of surfactants (NF dispersant and sodium and potassium stearates) and pore-forming components (a combination of water-soluble sodium or potassium carbonates and calcium carbonate suspended in their solution), which leads to foaming of the prepared aqueous suspension, which complicates its preparation, pumping and dosing into the melt.

SUMMARY OF THE INVENTION

The technical result of the present invention is to obtain granular porous ammonium nitrate with high static strength (up to 13 n / granule), reduced caking and residual moisture up to 0.35%, with an adjustable bulk density of granules (from 700 to 890 kg / m ³ ) and absorbing (from 9 to 25%) and holding (from 6.0 to 12.0%) diesel pellet ability, as well as with increased pellet resistance to thermal cycles, heating ↔ cooling (-20-60 ° С for 60 cycles) with a decrease in the static strength of the granules in 2 times, which both reduction ensures, reducing granule quality indicators during transportation and storage.

The technical result is achieved by the fact that:

- the required strength of the crystalline framework is ensured by the introduction of a structuring additive in ammonium nitrate in the form of a mixture of magnesium and iron (III) oxides, which in a certain ratio form stable double salts. The latter bind excess water to crystalline hydrates and significantly slow down the rate of nucleation and growth of centers of modification transformations;

- the most uniform distribution of the additive components in the melt volume of ammonium nitrate is ensured by the introduction of a modifying component of the additive into the initial solution of ammonium nitrate, followed by its evaporation to a melt state. Then, the most saturated at the boiling point is introduced into the melt, introducing a minimum of water into the melt, a solution of a surface-active substance (surfactant), in an amount of 0.02 ÷ 0.1% of the mass. It is evenly distributed in the melt, changing its surface tension;

- the creation of conditions for gas evolution, which ensures pore formation in the granule at the time of formation of the melt droplets and their crystallization, is ensured by introducing the additive component containing surfactant into the melt ahead and separated in space and time in comparison with the pore-forming component.

The process of obtaining granular porous ammonium nitrate according to the claimed method is as follows: by neutralizing nitric acid with gaseous ammonia, an 80-85% aqueous solution of ammonium nitrate is obtained, a stabilizing additive is introduced into it in the form of a mixture of magnesium and iron (III) oxides in an amount of 0.3- 2.0% of the mass. and 0.03-0.2% of the mass. respectively (the same additive can be introduced in the liquid state in the form of its nitric acid extract). Then the resulting solution is evaporated to a state of melt with a water content of not more than 0.2% of the mass. A saturated aqueous solution of a surfactant (surfactant) is introduced into the melt obtained at its boiling point in an amount of 0.02-0.1% by mass. in terms of dry matter (as surfactants use, in particular, a mixture of lauryl sulfate or sodium stearate with a dispersant NF (methyldisulfonic acid naphthalene) in a ratio of 1: 1). Then, a saturated aqueous solution of a mixture of technical potash and soda is introduced into the melt obtained in a ratio of 1: 1 at its boiling point in an amount of 0.1–0.5% of the mass. in terms of dry matter. The resulting melt is dispersed into droplets, crystallize them, cool the resulting granules and condition them.

The present invention is illustrated by the following examples.

Example 1

In an apparatus suitable for evaporation of an aqueous solution of ammonium nitrate:

(1) - flooded 80% of the mass. an aqueous solution of ammonium nitrate, the concentration of which was controlled by a hydrometer by its density, at a temperature of 120 ° C;

(2) - a structuring additive was introduced into it in the form of a mixture of magnesium oxide or caustic magnesites of the PMK-73, PMK-83, PMK-85 brand with a specified amount of magnesium oxide with an unchanged positive result and iron (III) oxide or magnetic iron concentrate ( natural mixture of iron oxides III and II) with a specified amount of iron oxide (III) in it and with a constant positive result in an amount of 0.3 and 0.03% of the mass. accordingly, with continuous stirring;

(3) - then the ammonium nitrate solution was evaporated (and dried) to a state of melt with a water content of not more than 0.2% of the mass. (according to Fisher);

(4) - then a saturated aqueous solution of a mixture of surface-active substances (SAS) was introduced into the melt obtained after evaporation: sodium stearate with an NF dispersant (grade A is the sodium salt of naphthalene methyldisulfonic acid that meets the requirements of GOST 6848-73) in a 1: 1 ratio in the amount of 0.02% of the mass. in terms of dry matter at its boiling point and continuous melt mixing;

(5) - then a saturated aqueous solution of a mixture of industrial potash and soda in a ratio of 1: 1 in an amount of 0.1% of the mass was gradually introduced into the obtained melt. in terms of dry matter at its boiling point with continuous stirring and dispersion of the melt with gas bubbles emitted from the smelter in the form of a polydisperse mixture of melt drops into an upward flow at a speed of 0.5 m / s at a temperature of 25 ° С in a glass column with a diameter of 100 mm , consisting of 6 tsars 1 m long and having a rotating flanged plate at the bottom with a glassy, poured on it, filled with easily evaporating liquid, the boiling point of which is lower than the Leidenfrost temperature on top pellet nostrils;

(6) - the resulting mixture of polydisperse granules was cooled on a rotating plate or in a fluidized bed with atmospheric air to 50 ° C, conditioned with various types of conditioning additives (see Section 4 of Table 1), as well as with NF dispersant, “lilamine” in an amount of 0 , 05% of the mass.

Example 2

The implementation of the method according to example 1 with differences in that in (2) the structural additive was introduced in the form of a mixture of magnesium oxides or caustic magnesites and iron (III) or magnetic iron ore in an amount of 1 and 0.1% of the mass. accordingly, with a constant positive effect; in (4), a saturated aqueous solution of a surfactant: lauryl sulfate with a dispersant NF (grade A) was introduced in a ratio of 1: 1 in an amount of 0.05% of the mass. in terms of dry matter; in (5), a saturated aqueous solution of a mixture of industrial potash and soda was introduced in a ratio of 1: 1 in an amount of 0.3% of the mass. in terms of dry matter.

Example 3

The implementation of the method according to example 1 with differences in that in (2) the structural additive was introduced in the form of a mixture of magnesium oxides or caustic magnesites and iron (III) or magnetic iron ore in an amount of 2 and 0.2% of the mass. accordingly, with a constant positive effect; in (4), a saturated aqueous solution of a surfactant was introduced: sodium stearate with a dispersant NF (grade A) in a ratio of 1: 1 in an amount of 0.1% of the mass. in terms of dry matter; in (5), a saturated aqueous solution of a mixture of industrial potash and soda was introduced in a ratio of 1: 1 in an amount of 0.5% of the mass, in terms of dry matter.

Example 4

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (2) the structuring additive was introduced in the form of 40% of the mass. nitric acid extracts from a mixture of magnesium oxides (or caustic magnesites) and iron (III) (or magnetic iron ore) in their amount of 1 and 0.1% of the mass. respectively.

Example 5

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (5) was introduced a saturated aqueous solution of technical soda in an amount of 0.3% of the mass. in terms of dry matter.

Example 6

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (5) a saturated aqueous solution of industrial potash and soda bicarbonates was introduced in a ratio of 1: 1 in an amount of 0.3% of the mass. in terms of dry calcined substances.

Example 7

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (5) was introduced a saturated aqueous solution of technical potash in the amount of 0.3% of the mass. in terms of dry matter.

Example 8

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (4) was introduced a saturated aqueous solution of surfactant - sodium stearate in an amount of 0.05% of the mass. in terms of dry matter.

Example 9

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (4) was introduced a saturated aqueous solution of surfactants in the form of a mixture of sodium stearate with a dispersant NF (grade A) in a ratio of 1: 1 in an amount of 0 , 05% of the mass. in terms of dry matter.

Example 10

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (4) was introduced a saturated aqueous solution of a surfactant - dispersant NF (grade A) in the amount of 0.05% of the mass. in terms of dry matter.

Example 11

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (4) was introduced a saturated aqueous solution of surfactant - lauryl sulfate in an amount of 0.05% of the mass. in terms of dry matter.

Example 12

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (4) was introduced a saturated aqueous solution of surfactants in the form of a mixture of: monoalkylphenolpolyglycol ether (OP-7) with a dispersant NF (grade A) in a ratio of 1: 1 in an amount of 0.05% of the mass. in terms of dry matter.

Example 13

The implementation of the method according to example 1 with the changes recorded in example 2, with the difference that in (4) a saturated aqueous solution of surfactant was introduced in the form of a mixture: dialkylphenolpolyglycol ether (OP-10) with a dispersant NF (grade A) in the ratio 1: 1 in an amount of 0.05% of the mass. in terms of dry matter.

Claims (4)

1. A method of obtaining a porous granular ammonium nitrate, including obtaining a solution of ammonium nitrate, introducing a structuring agent into it, evaporating the resulting solution to a state of melt with a water content of not more than 0.2% by weight, introducing a surface-active substance into the melt, dispersing the obtained melt into droplets, their crystallization, cooling and conditioning of the obtained granules, characterized in that a mixture of magnesium oxide and iron oxide (III) in coli is used as a structuring additive ETS 0.3 ÷ 2.0% by weight. and 0.03 ÷ 0.2% of the mass. respectively, and a saturated aqueous solution of a surfactant is successively introduced into the melt obtained after evaporation at a boiling point in the amount of 0.02–0.1% of the mass. in terms of dry matter, and then a saturated aqueous solution of a mixture of technical potash and soda in a ratio of 1: 1 at a boiling point in the amount of 0.1 ÷ 0.5% of the mass. in terms of dry matter. 2. The method according to claim 1, characterized in that the magnesium oxide is introduced in the form of caustic magnesite grades PMK-75, PMK-83, PMK-85, and iron oxide (III) in the form of a concentrate of magnetic iron ore. 3. The method according to any one of claims 1 to 2, characterized in that the mixture of magnesium oxide and iron oxide (III) in an amount of 0.3 ÷ 2.0% of the mass. and 0.03 ÷ 0.2% of the mass. respectively, they are added to the solution of ammonium nitrate, supplied to evaporation, in the form of its nitric acid extract. 4. The method according to claim 1, characterized in that as a surfactant using a mixture of lauryl sulfate or sodium stearate with a dispersant NF in a ratio of 1: 1.