https://doi.org/10.15255/KUI.2016.041
Published: Kem. Ind. 66 (9-10) (2017) 457–466
Paper reference number: KUI-41/2016
Paper type: Original scientific paper
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Production of Straight Nitrogen Fertilizer as a Double Salt of Ammonium Sulphate Nitrate

N. Zečević, M. Ljubičić, J. Bjelić, H. Lisac and S. Valkov

Abstract

Fertilizer producers are facing the imperative imposed from agricultural production in the sense of using straight fertilizers which will ensure availability of more than one of the nutrients in different chemical forms. In order to meet these requirements, one of the potential solutions is the use of straight mineral fertilizers in the form of double salt. Double salts can be produced with direct neutralization reaction between different acids and alkalis. Double salt in the form of ammonium sulphate nitrate represents a straight nitrogenous fertilizer, which enables simultaneous application of nitrogen in nitrate and ammonia form, and the presence of sulphur in sulphate form. In addition, usage of a double salt of ammonium sulphate nitrate helps avoid the potential danger of misusing ammonium nitrate as an explosive agent, since the crystalline structure of the double salt and presence of ammonium sulphate like an inert compound completely stabilize the matrix of ammonium sulphate nitrate. The potential explosive properties of different mixtures of ammonium nitrate and ammonium sulphate are shown in Fig. 1. To satisfy all process conditions for proper production of double salt ammonium sulphate nitrate and to avoid potential explosive properties of the final material, used was the system of adapted pipe cross reactor shown in Fig. 2. The chemical reaction between Barrett's solution, liquid ammonia and sulphuric acid in the pipe cross reactor ensures the synthesis of double salt of ammonium sulphate nitrate whose saturated slurry serves in the granulation process for obtaining the straight nitrogen fertilizer. Planned and achieved consumptions of raw materials and utilities for production of granulated ammonium sulphate nitrate are shown in Table 1. Straight nitrogenous mineral fertilizers in the form of double salt of ammonium sulphate nitrate represents an ideal replacement for straight nitrogenous fertilizers based on ammonium nitrate, since it ensures the availability of nitrogen and sulphur as the main nutrients in all forms necessary for plant uptake, while avoiding potential abuse for explosive purposes. The aforementioned properties are shown in Table 2. To completely verify the chemical content of ammonium nitrate and double salt of the amount ratio 1 : 3, an X-ray diffraction survey of the powdered sample was conducted, the results of which are shown in Table 3 and Figs. 3 and 4. From the same it can be concluded that the final product possesses the ideal weight content of ammonium nitrate and minimum weight content of double salt with amount ratio 1 : 3 as potential explosive precursor. The appearance of the final product is shown in Fig. 3. The revamping procedure of the technological process and facility for the production of compound NPK fertilizers manages the production process of simple nitrogenous mineral fertilizer of double salt of ammonium sulphate nitrate with mass fraction of nitrogen 26 % and 15 % of sulphur, and subsequent nameplate capacity of 20 tons per hour. The final product in the shape of double salt of ammonium sulphate nitrate satisfies all requirements imposed from the agricultural side simultaneously ensuring prevention of misuse as an explosive agent.

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Keywords

ammonium sulphate nitrate, double salt, straight fertilizer, granulation, pipe cross reactor