Nitroglycerine separation from acid

Originally 2% of water were added to the spent acid and this prevented the separation of nitroglycerine at temperatures from 10 to 15°C. Nevertheless in 1906 a tank filled with this dilute spent acid exploded while being transported. Further experiments showed that nitroglycerine can separate from acid diluted in that way if its temperature falls below 10°C. Addition of 5% water was therefore introduced, to prevent separation of nitroglycerine even at a temperature of 0°C. At the present time this procedure is widely used with new methods of nitration including continuous processes. 

Heat of nitration of glycerin. Suppose we wish to estimate the heat evolved in nitrating 1 mole of glycerin with mixed acid. To simplify this illustrative example we will assume initial mixture — 1 mole glycerin/3 moles 100% nitric acid/6 moles 100% sulfuric acid final mixture -1 mole nitroglycerin completely separated from the spent acid which is now diluted by 3 moles of water the entire heat of dilution is due to 3 moles water dissolving in 6 moles of 100% sulfuric acid. Thus... 

The spent acid leaves the separator from below to flow via a siphon, the height of which can be automatically controlled, to a diluter (6) where 1-2% water is added and then to a spent add mixer (8). Dilute spent acid is pumped to tank (9), and is used for displacement of nitroglycerine from the nitrator and separator after nitration has finished. Most of the dilute acid is sent to denitration. 

After cooling, the emulsion flows into a centrifuge. Here nitroglycerine is separated from the spent acid and transferred to the washing house. 

Separation of nitroglycerine from acid Purification of nitroglycerine Filtering nitroglycerine Transport of nitroglycerine Recovery of stabilizing water The spent acid... 

The intensity of mixing in the nitrator by the turbine is such that the emulsion of nitroglycerine in the acid cannot be initiated by a No. 8 blasting cap. The turbine is driven by V-belts of a motor mounted in a room separated from the nitration unit by a partition wall. 

For analytical purposes, attention must be paid to the solubility of nitroglycerine in acetic acid and in carbon disulphide, since these solvents can be used to separate nitroglycerine from aromatic nitro compounds. Thus nitroglycerine dissolves readily in 65% acetic acid which does not dissolve nitro compounds. In carbon disulphide, nitroglycerine dissolves with difficulty. At room temperature, 100 ml of this solvent dissolve about 1.25 g nitroglycerine. Nitro compounds, on the other hand, are readily dissolved in carbon disulphide. 

---