urbaf2

354 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

Nitration of MNT and DNT to TNT. The mixture of nitrotoluenes was con-

verted into TNT in the following way:

The nitrator was charged with 4800-5000 kg of acids in the following pro-

portion :

H 2 SO 4 79.5%

HNO 3 17.8%

H 2 O 2.7%

Then crude DNT from the superdetoluator was added at a temperature of 66°C

(maintained by heating). The temperature was then raised to 100°C at a rate not

higher than 50°C per 10 min. Nitration ended at this temperature and the melting

point of a sample of TNT in the nitrator, after it had been acid washed, was 72.5°C

(this corresponded to the melting point 76°C of the dry product).

After nitration was completed, 550 1. of water were run into the nitrator to

reduce the solubility of the TNT in the acid, and the mixture was then transferred

to a separator, where TNT was separated from the spent acid.

After 30-45 mm the acid was drained off through the sight-glass to a detoluator,

and the molten TNT to a preliminary washing tank fitted with a mechanical stirrer

made of acid resistant material. 160 1. of boiling water were fed into the washing

tank prior to the TNT. The mixture was kept boiling by direct steam heating.

Stirring was discontinued after 5 min and after another few minutes the acidic

water (containing about 14% of acid) was drained off and transported to the deto-

luator as described above.

The washed, molten TNT was poured in streams into a granulator, to which

a stream of water was also directed, so as to make two streams collide. TNT

solidified at once in the form of granules at the bottom of the granulator. Water

was run away through a filter, and the TNT, still wet, was unloaded for final puri-

fication. The impurities it contained were:

water about 19.0%

H 2 SO 4 0.3%

HNO 3 1.0%

tetranitromethane 0.15%

Old U. S. S. R. method (according to Gorst)

The main feature of the old method used in the U.S.S.R. is the presence of sepa-

ration columns which are combined with each of the three nitrators. Also the spent

acid from the third nitration stage is kept for some time in a column in which the

nitro compounds swim to the top. The columns are ca. 4 m high and of ca. 2 m

diameter. They are made of sheet iron, clad inside with lead.

The flow-sheet is given in Fig. 81. Toluene flows from the tank (1) through the
measuring tank (2) to the mononitrator (4). The acid flows through the measuring

tank (3). After nitration the products pass through the pressure-egg (5) to the sepa-
rating column (6). The mono-spent acid flows through (7) to denitration, and the MNT

through (8) to the “bubbler” (10) fed through (9) with the spent acid from dinitration.