PEP Review 82-3-3
Concentrated Nitric Acid (Espindesa Technology)
Published: May 1983
All commercial processes for making concentrated nitric acid fall under one of three general types: extraction of water from weak nitric acid, direct synthesis by oxidation of NO2 to HNO3 with pure oxygen, or fractionation of superazeotropic nitric acid which is made by absorption and reaction of NO2 with weak acid. One economic study shows the fractionation process to be the most economical except in the smaller plants.
A new process employing fractionation of superazeotropic acid has been developed by Espanola de Investigacion y Desarrolla, SA (Espindesa), with the first successful commercial demonstration in 1980. Two additional Espindesa plants are under construction. This paper presents an economic evaluation of the Espindesa process for manufacturing 99% nitric acid. Also, an economic comparison is made between the costs for making concentrated and weak (60%) nitric acids. The incremental costs (concentration difference) are even more than the costs for manufacturing the commercial grade of weak acid.