GB1105466A - Process and apparatus for producing ammonium nitrate - Google Patents

Abstract

Ammonium nitrate solutions of concentrations up to 99.8% NH4NO3 are prepared by reacting aqueous nitric acid with anhydrous ammonia at a temperature and pressure which cause the solution to boil, and recirculating this solution by means of the steam produced in it. As shown, the apparatus consists of three superposed chambers 2, 3 and 4, the upper and lower communicating by a reaction tube 5 which extends well into the lower chamber 4 and is flush with the base of the top chamber 2 and by other tubes 6a and 6b which extend into the top and bottom chambers but not as far down into the bottom chamber as the first tube 5. The middle section contains an inlet 13 and an <PICT:1105466/C1/1> outlet pipe 14 for a fluid (steam or water) and acts as a heat exchanger. The apparatus is filled with ammonia solution and nitric acid is passed into the second set of tubes 6 through diffusers. Reaction occurs in these tubes, and the heat of reaction generates steam which circulates the solution up these tubes and down the reaction tube 5. If nitric acid of less than 62.5% concentration is used heat must be externally supplied by steam through the central vessel 3, if above 62.5% concentration the system is water cooled. Concentrated ammonium nitrate solution is removed from the base of the top chamber 2 and steam from the very top 18, a set of baffles 17 preventing the removal of the nitrate solution through this outlet. The process may be carried out at atmospheric pressure or above or below. The partial pressure of the steam in the reaction vessel may be decreased by the addition of air, gaseous ammonia or a mixture of the two.