The TNT production process is based on the know reaction of toluene direct nitration with nitric acid in the presence of sulphuric acid. The process proceeds gradually in a series of reactors so that the same process and the same equipment are used for the manufacture of DNT as well.
The TNT plant is provided as a continuous line starting from the raw materials feeding up to the final drying, flaking and packing. It is highly automated, thus the process runs automatically.
The main process phases are: Raw Materials Feeding; Nitration; Purification; Drying; Flaking; Packing.
Toluene, acids and sulphite solution are fed by means of the metering pumps. Sulphite solution is previously prepared in the mixer.
The nitration of toluene to trinitrotoluene is carried out in the line of eight reactors. The process runs in counter-flow of the first two reactors the toluene is gradually nitrated, thus from the eights one comes out acid crude TNT. The nitric acid is added to some reactors, while the oleum is fed to the last one. Acid phase flows from the eighth towards the first reactor and, due to formation of reaction water, it is diluted so that the first reactor releases the waste acid with some nitric acid content.
The reactors for nitration are equipped with stirrers, coils and centrifugal separators enabling the organic and inorganic phase to be separated off at the outlet of the nitrators. During the nitration process nitrous gases are released which are led to the absorption unit.
Crude acid TNT is purified in the line of five washers in countercurrent flow with the water, sulphite solution respectively. In the first two washers is carried out washing with water, in the next two sulphitation, elimination of TNT isomers respectively, while in the fifth washer TNT washing is completed.
Purified TNT in emulsion with water is transferred to another building where it is separated from water by means of the centrifugal separator in the washer. TNT overflows from the washer to the drying unit where it is dried in the hot nitrogen stream.
The dried TNT flows from the drying unit to the drum crystallizer where the flakes are formed. Finally, TNT is weighed out and packed.
In the course of the purification process there appears the red waste water which is transferred for disposal by destruction. The destruction is made by incineration. The plant is flexible and operates with natural gas or fuel oil.
It is possible to produce DNT in the same equipment. Certain number of the apparatuses are excluded from the process in case of DNT production.
In order to ensure normal operation of the TNT plant and economical production, within the plant for the manufacture of TNT we can also supply or provide: