A. A. Mamataliyeva, Sh. S. Namazov

Table 1
Crystallization temperature and composition of nitrogen-containing fertilizer

Mass ratio NH4NO3 : (NH4)2SO4	Crystallization temperature, ºС	Content in products, %
		Ntotal	Nammon.	Nnitrat.	S
Granulated NH4NO3 brand "B"	167.0	35.0	17.50	17.50	–
AN with 0.28% MgO	164.5	34.5	17.25	17.25	–
97 : 3.0	168.5	34.53	17.57	16.96	0.70
95 : 5.0	171.5	34.28	17.66	16.62	1.16
93 : 7.0	172.3	34.0	17.73	16.27	1.64
90 : 10	173.0	33.50	17.80	15.70	2.38
86 : 14	174.1	33.02	18.02	15.0	3.35
83 : 17	174.7	32.54	18.13	14.41	4.03
80 : 20	175.2	32.12	18.17	13.95	4.76
78 : 22	176.7	31.90	18.26	13.64	5.27
75 : 25	177.3	31.47	18.37	13.10	6.0
70 : 30	178.5	30.71	18.48	12.23	7.14
65 : 35	179.6	30.05	18.69	11.36	8.40
60 : 40	180.4	29.26	18.85	10.41	9.59

With an increase in the mass fraction of ammonium sulfate in the NH₄NO₃ melt, the amount of (NH₄)₂SO₄ from 97 : 3 to 60 : 40, the strength of the product granules increases from the initial 1.32 to 7.75 MPa in the final product (Fig. a).

From Fig., b it follows that the addition of any amount of (NH₄)₂SO₄ significantly reduces the caking of the AN (from 2.72 to 1.26 kg/cm²), which is 1.7-3.7 times less than the caking of standard nitrate with the addition of 0.28% MgO (4.67 kg/cm²).
Another indicator characterizing the quality of a thermostable speaker is the adsorption capacity of granules for liquid fuel. The lower the porosity of the granules, the lower their absorbency should be.
As the data in Fig. c in., this situation is really linked to each other. Depending on the weight ratio of the initial components, the absorbency of the nitrogen-sulfur-containing fertilizer granules ranges from 2.29-4.18 g of fuel per 100 g of the product. It is 4.82g for granulated NH₄NO₃. With an increase in the mass fraction of ammonium sulfate in the NH₄NO₃ melt from 97 : 3 to 60 : 40, the temperature of the beginning of decomposition increases from 210℃ for pure NH₄NO₃ to 241.8-246.3℃ in the finished product (Fig. d). Thus, the higher the strength of the granules, the lower their porosity and the inner specific surface of its granules, the less diesel fuel gets inside to granules, and as a result, the lower the detonation ability of AN. In this regard, (NH₄)₂SO₄ proved to be the most effective.



Fig. The influence of the weight ratio of NH₄NO₃: (NH₄)₂SO₄ on strength (a), caking (b), absorbency (c), temperature onset of decomposition (d), time of complete dissolution of granules of ammonium nitrate (e) and pH of a 10% solution of the product (f).
As the data in Fig. e, the presence of ammonium sulfate in the composition of nitrate affects the rate of dissolution of the granules of the latter. With an increase in the amount of (NH₄)₂SO₄ in the NH₄NO₃ melt, the time for complete dissolution of the finished product granules in water increases. The complete dissolution of granules of pure NH₄NO₃ and SA with a magnesian additive (0.28% MgO) in water is 44.6 sec on average. and 46.8 sec. accordingly, and with the addition of ammonium sulfate in an amount of 3 to 40 g, it slows down the dissolution rate of product granules from 70.32 to 116.24 sec.
This means that AN granules containing ammonium sulfate dissolve much more slowly in the soil solution. Therefore, the presence of ammonium sulfate in the nitrate promotes the gradual release of nitrogen from the pellet. In addition, the addition of ammonium sulfate to the NH₄NO₃ melt reduces the pH of a 10% solution of the latter from 5.17 to 4.12-3.03 (Fig. f), and this is the least effective in calcareous soils.
It can be seen from Table 2 that with an increase in the number of thermal cycles (2060℃), granules of pure NH₄NO₃ are completely destroyed after 90 thermal cycles, granules of nitrate with 0.28% magnesia additive - after 100 thermal cycles, and granules of nitrogen-sulfur fertilizers containing 3.0% (NH₄)₂SO₄ after 126 thermal cycles or with a content of 40% (NH₄)₂SO₄ - after 193 thermal cycles.