urbaf2

142 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

When Φ (the quantity of sulphuric acid in the spent acid) is given, it is easy

to calculate the quantity of sulphuric acid to be used.

If GN is the quantity (in kg) of nitric acid of concentration N (% HNO 3 ) and

Gs is the quantity (in kg) of sulphuric acid of concentration S (% HNO 3 ), the

quantity of the spent acid can be expressed as:

TABLE 15

Nitration

Benzene to NB

NB to DNB

Toluene to MNT

MNT to DNT

DNT to TNT:

in the three stage process

in the two stage process

Xylene to DNX

DNX to TNX

Naphthalene to MNN

MNN to DNN

Φ

Quantity of HNO 3

in % of theory

70 103-105

88 110-115

(^70) 103-105
82 110-115
93 180-200
87 170-l 80
72 110-115
90 150-160
61 103-105
72 130-140
Notation: NB - nitrobenzene., DNB - dinitrobenzene, MNT - mononitrotolueoe. DNT - dinitrotoluene,
TNT - trinitrotoluene, DNX - dinitroxylene, TNX - trinitroxylene, MNN - monottitronaphthalene, DNN -
dinitronaphthaleoe.
The quantity of sulphuric acid in the spent acid in per cent Φ can be calculated
as a ratio between the quantity of H 2 SO 4 used for nitration and the
quantity of spent acid:
hence
(according to Orlova [3]).
UTILIZATION OF SPENT ACID
The spent acid from a nitration process is usually re-used in the process, viz. after
being suitably fortsed it is passed from a higher nitration stage to a lower one.
For example, spent acid from the manufacture of trinitrotoluene is used for the