A. A. Mamataliyeva, Sh. S. Namazov

UTC 661.525:541.11
RESEARCHING SOME PHYSICO-CHEMICAL PROPERTIES OF NITROGEN AND SULFUR-CONTAINING FERTILIZERS BASED ON MELT OF AMMONIUM NITRATE AND AMMONIUM SULPHATE
A.A.Mamataliyev^a, Sh.S.Namazov^a
aInstitute of General and Inorganic Chemistry of the Academy of Sciences of the Republic of Uzbekistan, Tashkent, Uzbekistan;
Abstract. This work analyzes the methods of producing nitrogen and sulfur-containing fertilizer - ammonium sulfate-nitrate. Under laboratory conditions, samples of nitrogen and sulfur-containing fertilizers were obtained in which the mass ratios of ammonium nitrate (NH₄NO₃) to ammonium sulfate (NH₄)₂SO₄) varied from 97: 3 to 60: 40. In the samples, the pH values of a 10% solution, the beginning of temperature decomposition, strength, caking, absorbency and thermal stability of granules depending on the number of heating-cooling thermal cycles in the range of 2060℃. It is shown that the product obtained by introducing 40% ammonium sulfate into the ammonium nitrate melt contains 29.26% N (18.85% ammonia and 10.41% nitrate forms) and 9.59% S. Its granules are characterized by the following parameters: strength - 7.75 MPa, caking capacity - 1.26 kg/cm², absorption of diesel fuel - 2.29 g in relation to 100 g of product, dissolution time in water - 116 sec., pH - 3.03, thermal stability to repeated heating-cooling cycles (20 ↔60℃) - 193 thermal cycles and the temperature of the beginning of decomposition - 246.3℃. At the same time, for granules of pure NH₄NO₃ they are 1.32 MPa, 5.62 kg/cm², 4.82 g, 44.6 sec., 90 thermal cycles and 210℃. The results of the study are a decrease in caking and absorbency, an increase in the strength and stability of fertilizer granules to thermal cycles of heating-cooling, the time of dissolution of granules in water and the temperature of decomposition. Thus, mixing the ammonium nitrate melt with powdered ammonium sulfate, followed by granulation of the mixture, makes it possible to obtain high-quality nitrogen fertilizers with improved physicochemical and agrochemical properties.
Key words: ammonium nitrate melt, crystalline ammonium sulfate, nitrogen and sulfur-containing fertilizers, composition, onset of decomposition temperature, strength, caking, absorbency and thermal cycle.
Introduction. Ammonium nitrate (AN) is an affordable, ballastless, large-capacity and concentrated nitrogen fertilizer. It is used for all types of crops and on all types of soil.
Despite the universatility of this fertilizer, it is inherently flammable and explosive. Therefore, it can be used to create explosives. In Australia, China, Afghanistan, Ireland and some other countries, the free sale of ammonium nitrate, even in the form of fertilizers, is prohibited or restricted. After the terrorist attack in Oklahoma City, restrictions on the sale and possession of ammonium nitrate were introduced in some states of USA.