Method for recovering nitrate ions as nitric acid from nuclear industry effluents

A process for recovering, in the form of nitric acid, the nitrate ions present in a solution of aqueous effluents from the nuclear industry, said solution containing metal nitrates, comprising:

• a) in a first stage, in a contact zone of a reaction chamber, thermomechanical contact is produced between said solution of metal nitrates and a gaseous fluid introduced simultaneously into the reaction chamber, said gaseous fluid being introduced into the reaction chamber in the form of a symmetrical whirled flow coaxial with the main axis of the reaction chamber, thereby converting the solution of metal nitrates into a dispersion of microdroplets, said gaseous fluid being at a temperature that is higher than the decomposition temperature of the nitrates in a dominant proportion in the solution and having a mechanical energy that is sufficiently high to obtain a fine pulverization of the solution and to carry out instantaneously the decomposition of these nitrates with the formation of nitrous vapours of NOx, the instantaneous decomposition temperature of the nitrates being higher than 500° C.;
• b) in a second stage the gaseous NOx are converted into HNO3 by cooling and absorption in an aqueous medium.