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380 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

water. For this purpose the installation described on p. 364 may be used, in which

a stream of molten TNT ejected under pressure impinges on two streams of cold

water at their point of contact (Fig. 84). Grains of TNT together with water fall

into a tank, and are conveyed to a centrifuge or to a vacuum filter. To remove

water the product is dried in a tunnel or tray drier at 50-60°C, i.e. at a

temperature below its melting point.

FIG. 93. Vessel for drying TNT. FIG. 94. Flaking of TNT.

The water and liquors from washing and sulphitation of TNT contain some

TNT both dissolved and suspended. For recovering the latter the water and wash

liquor are conveyed to “labyrinth” tanks equipped with baffles barring the passage

of suspended TNT, which settles at the bottom. In this way a certain amount of

lower grade TNT may be recovered.

British method

In the British method, crude, granulated TNT prior to sulphitation is washed

either batchwise -an operation not differing from the one described above - or

continuously.
The plant for continuous washing (Fig. 96) consists of a rectangular trough,

8 m long, 1.4 m wide and 1.3 m high. The trough is made of cast iron sections screwed