Экспериментальные исследования воспламенения нитрата аммония при взаимодействии с порошками магния и серы

Abstract

Выполнены экспериментальные исследования взрывоопасности взаимореагирующих веществ: нитрата аммония (аммиачной селитры), который является сильным окислителем, относится к пожароопасным соединениям, в смеси с магнием и серой. Исследования свидетельствуют о взрывоопасности металлов и серы при их взаимодействии с пожароопасным веществом - окислителем (нитратом аммония). Эти особенности аммиачной селитры должны учитываться в процессе ее обращения (производство, хранение, транспортирование, применение, утилизация), при предотвращении и тушении пожаров. Ammonium nitrate (ammonia nitrate) is widely used in industry and in agriculture. The use of ammonium nitrate as a fertilizer gives this strong oxidizer a reputation of harmless agricultural chemical. At the same time, many cases of fires and explosions were registered during the storage, transportation and processing of saltpeter. Saltpeter decomposes with the release of highly toxic nitrogen oxides, which actively maintain combustion, and in case of fire also with release of oxygen. The analysis of statistical data on fires and explosions during the circulation of ammonium nitrate indicates serious problems in ensuring fire and explosion safety of buildings and structures in particular facilities of its storage. Clean and dry saltpeter explodes at normal temperature only in the presence of large volumes of the substance under the influence of a strong initiator, for example, a detonator. However, in the presence of some substances of both organic and inorganic origin the decomposition temperature of saltpeter decreases and this process of chemical spontaneous combustion can lead to an explosion. There are conducted experimental investigations by the method of constant volume bomb to determine the excess explosion pressure (ΔР) at interaction of ammonium nitrate with magnesium and sulfur powders and to compare these data with the calculated data of the excess explosion pressure (ΔР). It is established that the explosion pressure increases continuously with an increase in the concentration of the oxidant for mutually reactive substances consisting of combustible chemical element (magnesium, sulfur) and ammonium nitrate. This feature of the explosion of metals with an oxidizer - ammonium nitrate is a consequence of metal oxidation as well as the direct influence of decomposition products of the oxidizer in explosion. The growth of the overpressure of the explosion is also determined in the experiments when changing the volume of the reaction vessel (bomb camera) At the same specific weight of the mixture of mutually reactive substances (magnesium - ammonium nitrate) the explosion pressure increases with the volume of the bomb (the camera). The performed studies show that the contact of ammonium nitrate (ammonia nitrate) with foreign inclusions (additives) and, in particular, with metals and sulfur can lead to an explosion.