Both hexogen and penthrite are manufactured using the same equipment as in the nitrolytic process based on direct nitration of hexamine respectively pentaerythritol, with concentrated nitric acid.
Plants for hexogen and penthrite synthesis, hexogen phlegmatization and penthrite recrystallization are continuous ones and have a high automation level. The process is remote-controlled from the control house.
The process was developed in 1970, proved and tested in operation in several plants and is improved all the time.
The main process phases are: Raw Materials Storing and Feeding; Nitration; Decomposition; Filtration; Transport.
Hexamine prepared beforehand is hoisted by the conveyor from the raw materials daily store tank and by means of the feeding unit charged into the nitrators.
From the daily store tank, concentrated nitric acid is fed to the nitrators by means of metering pumps.
Reaction of hexamine nitration is carried out in three linked nitrators, followed by intensive stirring and cooling. In case of increase of temperature, feeding of hexamine is automatically stopped and, if the reaction does not calm down soon, the nitrators are automatically discharged into the tub for emergency draining.
Decomposition of reaction by-products takes place in four linked decomposers, followed by intensive stirring and cooling. If the temperature increases, feeding of the raw materials is stopped first and the decomposers are subsequently discharged into the tub for emergency draining. The process is followed by an intensive release of nitrous gases which are led to the absorption.
The cooled suspension of hexogen in weak nitric acid is separated on the continuous filter. Weak nitric acid is collected and transferred by pump to distillation or concentration.
After filtering, the separated hexogen is suspended in water and transferred by pump to further processing.
The PETN production process is the same as for hexogen, the only difference being that the decomposition process is not performed during the penthrite production.
Crude hexogen is received on the continuous filter wherefrom it is introduced as a water suspension in the injector battery where neutralization of acid resi¬dues and stabilization of hexogen crystals is accomplished.
Stabilized hexogen is fed from the injector battery to the first phlegmatizer. The previously prepared phlegmatizing agent is also charged in the same vessel. Phlegmatization is carried out in three phlegmatizers linked in a series by overflow.
Suspension overflows onto the mobile filter where the product is separated from water. The mobile filter is driven to the drying under vacuum and finally to the semi-automatic packing.
Penthrite recrystallization is carried out in the same equipment where hexogen phlegmatization occurs.
Crude penthrite is received on the continuous filter, wherefrom it is fed to the dissolver having been previously charged with acetone. Penthrite dissolving is performed in two dissolvers with stirring and heating.
Penthrite crystallization occurs in three linked crystallizers by diluting with the addition of the process water and heating.
Recrystallized penthrite is separated from weak acetone on the mobile filter and driven to packing or further processing. Weak acetone is collected and transferred by pump to the recovery.