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442 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

nitronaphthalene is drawn off through a lead or aluminium pipe into a similar tank

(2), containing water heated by live steam to 70°C and is stirred for half an hour.

The lower layer (molten nitronaphthalene) is then drained off into pans (3) arranged

in the form of a stack, where it solidifies.

In this way 400 kg of the raw product ready for further nitration are obtained.

NITRATION OF NAPHTHALENE TO DINITRONAPHTHALENE

German method

The direct nitration of naphthalene to dinitronaphthalene by the method applied

at I. G. Ludwigshafen is carried out in the following way:

A cast or wrought iron jacketed nitrator (of 3.4 m^3 capacity), equipped with

a propeller stirrer (25-26 r. p. m), is charged with the following quantities of acids:

925 kg of 98% H 2 SO 4

610 kg of 53% HNO 3

25 kg of 98% HNO 3

a nitrating mixture of the composition:

HNO 3 22.3%

H 2 SO 4 58.1%

H 2 O 19.6%

being obtained.

As heat is generated during stirring the temperature of the mixture rises to 30°C.

Then 295 kg of naphthalene is introduced through a screw metering tank at a rate

of 14.75-11.8 kg/hr. The naphthalene is added in the following way:

59 kg during the first 4 hr at 34-36°C

118 ,, ,, ,, ,, 8 ,, ,, 36-37°C

59 ,, ,, ,,. ,, 4 ,, ,, 37-38°C

59 ,, ,, ,, ,, 5 ,, ,, 38-44°C

After adding all the naphthalene, the temperature is raised during a period of

4 hr up to 80°C and the nitrator contents are kept at this temperature for another

hour.

The raising of ihe temperature is necessary for keeping the product of nitration

in a molten state, as at this stage it consists of nitro- and dinitro-naphthalenes.

The contents of two nitrators are pumped to a lead-lined stirred tank (of 14.9 m^3

capacity) containing 7000 1. of cold water. The temperature in the tank rises to

40-50°C. Due to constant stirring the product is kept in the form of droplets which,

after cooling to 30°C, solidify giving sand-coloured granules. The contents of the
tank are then conveyed to a vacuum filter of an area of 8 m^2 (6 m^3 capacity).

The spent acid, containing 30% of H 2 SO 4 (sp. gr. 1.220) is disposed to a drain.

The product on the filter is washed with 6 m

3

of cold, then with 12-14 m

3
of warm
water.