Scholarly record

EXPERIMENTS WITH TROUGH TEST DETERMINATION OF THE SELF -SUSTAINING EXOTHERMIC DECOMPOSITION OF FERTILIZERS CONTAINING NITRATES

Andrei Szollosi-Moța, Maria Prodan, Irina Nălboc, Sonia Șuvar, Nicolae Ianc

Abstract

Under the effect of strong heat, chemical fertilizers tend to decompose. These decompositions can be followed by burns or explosions. The tendency to suffer self-sustaining decomposition is determined by the test method described in Test S.1 of the United Nation Manual of Tests and Criteria for the classification of ammonium nitrate fertilizers. The purpose of this work is to present the tests, experiments and interpretation of the experimental data necessary for the classification of chemical fertilizers based on ammonium nitrate. Decompositions are initiated, in the mass of chemical fertilizers measuring propagation in the horizontal direction. Chemical fertilizers may be able to maintain decompositions in the mass of fertilizer, in which the decomposition initiated in a localized area will spread throughout the mass of the chemical fertilizer based on nitrates. The propagation of decomposition continues throughout the mass of the substance, the fertilizer is considered capable of presenting and supporting self-supporting or self-sustaining decomposition. After removal of the heat source(s) the decomposition does not spread along the length of the test vessel the fertilizer shall be considered free from the risk of self-supporting decomposition. In the case of thermally initiated explosions, the theory of thermal explosion is valid, it is known that the self-ignition of a system occurs when the system temperature exceeds a certain value corresponding to the respective conditions (critical temperature). If the mass of the system is lower than the critical mass then there is no self-ignition of the system at that temperature. Complex fertilizers (NPK) due to the high content of active substance, have multiple benefits for both manufacturer and consumer. Research has shown at the thermal decomposition or burning of complex NPK fertilizers, that they almost always contained ammonium nitrate and potassium chloride. An important feature of the decomposition processes is that the fires are followed by a strong release of toxic gases that can have harmful effects to the population, with no decomposition of ammonium nitrate.

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DOI resolver: doi.org/10.5593/sgem2020v/4.2/s06.17

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