Preparation of sulfuric acid and its application.
Today, sulfuric acid is produced inmainly by two industrial methods: contact and nitrosic. The contact method is more progressive and in Russia it is applied more widely than the nitrous, that is, the tower.
The production of sulfuric acid begins with calcinationSulphurous raw materials, for example, iron pyrites. In special pyrite furnaces, the so-called calcined gas is produced, in which about 9% of sulfur dioxide is contained. This stage is the same for both the contact and nitrosic methods.
Next, it is necessary to oxidize the resulting sulfuranhydride in sulfuric acid. However, it must first be cleaned of a number of impurities that interfere with the further process. The calcined gas is cleaned of dust in electrostatic precipitators or in cyclone units, and then it is fed into a device containing solid contact masses, where SO2 SO22 is oxidized to sulfuric anhydride SO3.
This exothermic reaction is reversible-increasingtemperature leads to the decomposition of the sulfuric anhydride formed. On the other hand, when the temperature is lowered, the rate of the direct reaction is very small. Therefore, the temperature in the contactor is maintained within 480aboutC, adjusting its rate of passage of the gas mixture.
Later on, the contact method produces sulfuric acid when sulfuric anhydride is combined with water.
Nitric way is characterized by the fact thatSulfur dioxide is oxidized by nitrogen oxides. The production of sulfuric acid by this method is triggered by the formation of sulfuric acid by the interaction of sulfur dioxide from the calcined gas with water. Subsequently, the resulting sulfuric acid is oxidized with nitric acid, which leads to the formation of nitrogen monoxide and sulfuric acid.
This reaction mixture is fed into a specialtower. At the same time, by regulating the gas flow, it is achieved that in the gas mixture entering the absorption tower, dioxide and nitrogen monoxide is contained in a ratio of 1: 1, which is necessary for the production of nitrous anhydride.
Finally, upon the reaction of sulfuric acid and nitrous anhydride, NOHSO4 - Nitrosylsulfuric acid.
The resulting nitrosyl sulfuric acid is fed into the production tower, where it decomposes by water and releases nitrogenous anhydride:
2NOHSO4+ H2O = N2O3 + 2H2SO4,
which also oxidizes sulfurous acid formed in the tower.
Nitric oxide, released as a result of the reaction, again returns to the oxidation tower and enters a new cycle.
At present, in Russia, the production of sulfuric acid is mainly carried out by a contact method. Nitric method is rarely used.
The use of sulfuric acid is very wide and varied.
Most of it goes to the production of chemicalfibers and mineral fertilizers, it is necessary in the production of medicinal substances and dyes. With the help of sulfuric acid, ethyl and other alcohols, detergents and pesticides are produced.
Its solutions are used in textile, foodindustry, in the processes of nitration and for the production of explosives. Sulfuric sulfuric acid serves as an electrolyte for pouring into lead accumulators, which are widely used in transport.
