The thesis is devoted to the study of possibility of reducing the technogenic load on the environment in the production of explosives by developing an environmentally safe technology for the starch nitrate production with a closed cycle of acids, which is based on starch nitration with nitrating media based on nitric acid. Using of this technology excludes the release of acidic drains into the environment and ensures high chemical stability of the obtained starch nitrate. Starch nitration with nitric acid occurs along with the dissolution of starch in two stages, which is associated with different rates of dissolution of amorphous and crystalline regions of starch grains in nitric acid. The nitrogen content in the obtained starch nitrate after a certain time of nitration becomes close to a constant value because of very slow dissolution of the most perfect fragments of crystalline regions (crystallites) in nitric acid. Among the regime parameters of this process, the water content in the acid that nitrating starch has the greatest influence on the nitrogen content in starch nitrate. The water content in the nitrating acid has the greatest influence on kinetics of starch nitration, and with its content increases, the rate of nitration decreases. These results became the basis for the development of a mathematical model of the kinetics of the process of starch nitration with nitrate acid, which allows, by setting its parameters, to calculate the nitrogen content in starch nitrate at different time of nitration and, accordingly, to justify the choice of rational modes of its production. It reduces the volume of acid production waste, energy consumption for their processing that reduce the technogenic load on the environment. In case of starch nitration with a mixture of nitric and sulfuric acids the nitrogen content in starch nitrate reaches its maximum value at the mass ratio of acids in the nitrating mixture H2SO4/HNO3 ≈ 3, the initial water content in the mixture 8-10%, its initial temperature 35-40°C, nitration time 30-35 minutes and nitration module 30-40. Starch nitrate obtained using a mixture of nitric and sulfuric acids, in contrast to the case of nitration with one nitric acid, preserves the granular structure of the original starch, but characteristic defects on the surface of the grains are formed due to a change in their internal structure. Precipitation of starch nitrate from nitric acid solutions occurs by spinodal mechanism. It occurs immediately upon contact with precipitating water with the formation of two phases: polymeric and low molecular. The temperature and concentration of solution have the most influence on the nature of interaction of starch nitrate solution with the precipitating water. The composition of precipitating medium and precipitating module don’t have a significant effect on the precipitation process and the state of the precipitated starch nitrate, which allows precipitation in dilute nitric acid, which concentration after precipitation becomes sufficient for regeneration. Starch nitrate obtained by nitration of starch with one nitric acid is much more chemically stable compared to starch nitrate obtained by using for nitration a mixture of nitric and sulfuric acids, under any stabilization option, because of absence unstable sulfate esters of starch, which catalyze its decomposition. It was established that to stabilize such starch nitrate, it is sufficient to wash with 90-95°С water for 10 minutes, the volume of which is 0,19 m3/kg of starch nitrate. This allows to limit the volume of acidic waste water to the minimum amount of water needed to ensure its chemical stability that reduce the technogenic load on the environment. An indicator for assessing the chemical stability of starch nitrate was also determined: starch nitrate is considered stable if the temperature of its active decomposition exceeds 168°С. It was proposed an environmentally safe version of the technological scheme for starch nitrate continuous production using a drum vacuum filter, in which combined all operations of its stabilization. The technology is based on the starch nitration with concentrated (at least 90%) nitric acid, subsequent precipitation of starch nitrate from the resulting solution in the 40-55% aqueous solution of nitric acid, the concentration of which after precipitation becomes ≈50%, which is sufficient for its effective regeneration. Stabilization of precipitated starch nitrate is carried out by washing with 90-95°C water, which, after adding concentrated nitric acid, is used to prepare the precipitation medium. Development of such technological process in laboratory conditions made it possible to establish its regimes which effective regeneration of the deposition medium and high chemical stability of the obtained starch nitrate are ensured. Using of the developed technology is the key to reducing the technogenic load on the environment in the field of explosives production.
