RU2010023C1 - Method for porous granulated ammonium nitrate production - Google Patents

Abstract

FIELD: explosive production. SUBSTANCE: method involves nitric acid neutralization with the help of ammonia followed by evaporation to produce highly concentrated melt and by adding blowing additives into this melt. Carbamide, soda ash and disperser are used as mentioned above additives, their quantities, mass % are 0.1-0.5, 0.05-0.2 and 0.005-0.2 respectively. NH₄NO₃ solution containing calcium and phosphorous compounds is added before evaporation is carried out, quantities of these compounds being 0.015-0.04 and 0.005-0.03 mass % as calculated for CaO and P₂O₅. Thus prepared material has: absorbing capacity 16 g/100 g, bulk weight 0.71-0.85 g/cm³. EFFECT: increases strength of granules, decreases disperser quantity.

Description

 The invention relates to a technology for producing simple, cheap, affordable and at the same time explosion-proof explosives, igdanites and granulites M, used in the mining, mining, coal and water industries.

 However, as shown by experiments by consumers of porous granular amcelitra, it is also applicable to obtain, for example, a new type of combiser, where the percentage of TNT is almost halved.

 According to recent studies, the invention can be used for the manufacture of emulsions used in water-filled wells.

 There are several fundamentally different methods for producing porous amcelite. One of them is based on the introduction of various pore-forming additives into the melting amcellite. The bottom line is that, evenly distributed in the volume of the melt and reacting with it, the gases released will evaporate during granulation, forming pores that increase the sorption ability of the resulting product. The use of pore-forming additives allows to obtain nitrate with a high holding capacity of granules in relation to diesel fuel or other petroleum products up to 6 wt.% Instead of 0.9-1.5 wt.%. However, this reduces the strength of the granules.

A known method of producing porous nitrate by introducing into the melt NH ₄ NO ₃ infusoria, or infusoria and urea, or one urea. However, porous nitrate obtained with urea alone has very fragile granules and, therefore, is not very suitable as a commercial product. The proposed mixture contains from 0.5 to 3 wt.% Infusoria and from 0.1 to 0.3 wt.% Urea. The high content of ciliates significantly reduces the content of the main substance. This makes it impossible to use porous nitrate as a fertilizer. In addition, there are difficulties in the manufacture of pore-forming additives: special-grade infusorized soil with a low density should be used, urea should be ground before dosing [1].

There is also known a method of producing porous nitrate with increased strength of the granules by introducing NH ₄ NO ₃ into the melt before the granulation of chalk with a particle size dispersion of 5-20 mm in an amount of 0.25-3.0 wt.%. The strength of the granules of the finished porous product is 500-550 g / g [2].

The disadvantage of this method is the use of pore-forming additives in solid form and the inability to use it in liquid form due to the low solubility in water CaCO ₃ . This creates significant difficulties in the supply of solid additives to the height of the tower (more than 60 m). Moreover, a significant amount of manual labor is used.

 The strength of samples of porous granular nitrate of foreign companies is also in the range of 250-400 g / g.

There is also known a method of producing porous nitrate by introducing into the melt NH ₄ NO _{3 a} dispersant NF, used in the form of a 10-40% aqueous solution in an amount of 0.01-0.1 wt.% By weight of nitrate. With a relatively high absorption capacity of granules (up to 13 g per 100 g), the strength of the product is relatively low - approximately 350 g / g [3].

 This method is taken as a prototype.

 Currently, there is a need to provide consumers of porous nitrate with products with higher pellet strength. At the same time, the product must maintain its strength (with its minimum loss) during long-term mixed transport.

A method for producing porous granular ammonium nitrate by neutralizing NHO ₃ with ammonia, evaporating the solution to obtain a melt, introducing into the melt of ammonium nitrate a mixture of pore-forming additives: soda ash, urea and dispersant NF, preliminary introducing ammonium nitrate into the solution before the stage of evaporation of the NH ₄ NO ₃ solution containing calcium and phosphorus compounds in an amount on CaO - 0.015-0.04 wt.% and P ₂ O ₅ - 0.005-0.03 wt.%.

 The number of introduced pore-forming additives: urea, soda ash and NF dispersant is, respectively, wt.%: 0.1-0.5, 0.05-0.2 and 0.005-0.2.

 Dispersant NF is a scarce product, since it is produced in a relatively small amount only by the Novomoskovsk Organic Synthesis Plant.

Compounds CaO and P ₂ O ₅ , falling into the melt of amcelite containing a sulfate additive in an amount of 0.3-0.7 wt.%, Reacting with ammonium sulfate, form sulfate-phosphate and calcium sulfate compounds, which increase the strength of granules porous nitrate. The product has the following characteristics: absorbency of granules 9-16 g / 100 g; soda H ₂ O - 0.3-0.6 wt. % (according to Fisher); bulk density of 0.71-0.85 g / cm ³ ; granule strength 560-780 g / g.

The novelty of the method lies in the fact that before the evaporation stage, solutions of calcium and phosphorus compounds are introduced into the ammonium nitrate solution in terms of CaO 0.015-0.04 wt.% And P ₂ O ₅ 0.005-0.03 wt.%.

The novelty of the method also lies in the fact that the lower limit of the NF dispersant decreases significantly (by 6 times) (to 0.005 wt.%) With a simultaneous relatively insignificant (2 times) increase in the upper limit of soda ash content, which makes it possible to vary the limits of the change in bulk weight from 0.7 to 0.85 g / cm ³ .

The use of CaO and P ₂ O ₅ allows the use of conversion solutions of the azofoska workshop; it is possible to control the strength of the granules by the amount of supplied conversion solution.

Table 1 presents the results of the analysis of porous nitrate samples with the introduction of conversion solutions containing different amounts of calcium (CaO 0.015-0.04) and phosphorus (P ₂ O ₅ 0.005-0.03%) additives.

 For comparison, the analysis data of the porous product without additional additives.

 As follows from table 1, the porous product without additional introduction of additives is characterized by low strength granules compared with the porous product according to the proposed method.

 At the same time as the strength of the granules of the finished product increases, the percentage of dust removal of ammonium nitrate decreases, i.e. The ecology of the process is improving.

 The analysis data presented in Table 2 were obtained as average results for the production of pilot batches of porous granular ammonium nitrate.

 In the table. Figure 3 presents the results of the analysis of samples of porous granular ammonium nitrate obtained when amelite (as pore-forming additives) was introduced into the melt as a reduced amount of NF dispersant and an increased amount of soda ash, which makes it possible to vary widely with bulk density (at the request of consumers).

 The quantitative content of the NF dispersant and soda were experimentally selected taking into account the high strength of the granules of the obtained product.

 As follows from the table. 3, a decrease in the amount of dispersant NF less than 0.005 wt. % affects the decrease in the absorbency of granules lying outside the permissible (according to the Notice No. 3 on the change of TU to porous amcelite this indicator should be at least 9 g / 100 g).

As a result of physico-chemical studies have established that the stability of the granules of granulated porous ammonium nitrate samples with enhanced pellet strength when temperature fluctuations of 20-50 ^{° C} is significantly higher than the samples of porous ammonium nitrate with a lower strength granules (see. Table 4).

 As follows from Table 4, granules of porous nitrate of increased strength of granules under the influence of polymorphic transformations lose granule strength by 3.4 times after ten cycles, while granules of porous nitrate with a strength of ≈350 g / g - almost 3 times after five cycles.

Simultaneously, experiments were conducted to determine the stability of both samples granules of porous ammonium nitrate to negative temperature fluctuations (from - 35 to - 50 ^{° C)} compared with the stability of the pellets at t = - 50 ° ^C.

 The data are summarized in table 5.

 The basis of these experiments is a test to visually determine the number of whole granules (of 25 pcs.) Cooled in Dewar vessels at low temperatures (each cycle is 2 hours).

 As follows from Table 5, the heat resistance of the granules of the test samples is much higher (both at constant and at variable temperatures) in the case of testing granules of porous nitrate with increased granule strength.

 A study of the moisture absorption of both samples of porous nitrate by the static method at a relative humidity of 100% showed that a sample of porous nitrate with an increased granule strength absorbs less moisture than a sample with a lower granule strength. This gives hope for the transportation of porous nitrate with high strength granules in mineral carriers and hoppers, which is very important for consumers.

 The definition of physico-chemical characteristics that ensure the absorption of diesel fuel (5.5%) by the granules of the porous product are presented in table.6.

 For comparison, the analysis of a sample of ordinary granular ammonium nitrate is presented.

 As can be seen from table 6, the possibility of absorption of 5.5% of diesel fuel (compared with 2% in ordinary nitrate) is explained by an increase in the total pore volume (1.6 times); significantly greater strength of the granules, an increase in the specific surface of the pores. Moreover, ≈76% of the pore volume is accounted for by macropores, and only a smaller part (24%) is in transition pores. In the sample of ordinary granular amcelite, the same distribution pattern is observed.

In the examples, the change in the strength of the granules of the finished product after the introduction of an NH ₄ NO ₃ solution containing calcium and phosphorus compounds before the stage of evaporation is presented.

PRI me R 1. In one stripped off highly concentrated melt NH ₄ NO ₃ in the amount of 30 t / h before the granulation stage, the dispersant NF is introduced in the amount of 12 kg / h. In this case, a porous product is obtained having the following characteristic: absorbency 13 g / 100 g; retention capacity 5.5%; the content of H ₂ O according to Fischer 0.42%; bulk density of 0.78 g / cm ³ ; granulometric composition according to technical specifications for porous nitrate; granule strength 350 g / g.

Example 2. Before the evaporation stage, a solution of NH ₄ NO ₃ containing calcium and phosphorus compounds in terms of CaO in the amount of 4.5 kg / h (0.015 wt.%) And in terms of P is introduced into the ammonium nitrate solution ₂ O ₅ in an amount of 1.5 kg / h (0.005 wt.%). Next, the solution is evaporated to obtain a highly concentrated melt, and pore-forming additives are introduced into the melt in an amount of 30 t / h: urea 75 kg / h; soda ash 19 kg / h; NF dispersant 12 kg / h.

In this case, a product is obtained having the following characteristic: absorbency 12.8 g / 100 g; retention capacity 5.5%; pellet strength 760 g / g; bulk density of 0.82 g / cm ³ ; the content of H ₂ O (according to Fischer) 0.44%; particle size distribution according to technical specifications for porous nitrate. (56) 1. US patent N 3447982, CL. C 05 B 1/04, 1969.

 2. USSR author's certificate N 767025, cl. C 01 C 1/18, C 05 C 1/02, 1980.

 3. Copyright certificate of the USSR N 421627, cl. C 01 C 1/18, 1973.

Claims (1)

METHOD FOR PRODUCING POROUS GRANULATED AMMONIUM NITRITUDE, including the neutralization of nitric acid with ammonia, evaporation to obtain a highly concentrated melt, the introduction of a variety-forming additives, followed by the addition of a small amount of calcium CaO 0.015 - 0.04 wt.% And P ₂ O ₅ 0.005 - 0.03 wt.%, And carbamide, soda ash and NF dispersant in quantities of 0.1 - 0.5 m are used as rock-forming additives as.%, 0.05 - 0.2 wt.% and 0.005 - 0.2 wt.%, respectively.

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