METHOD OF PROCESSING MIXTURES OF NITRIC ACID AND NITROGEN OXIDES Russian patent published in 2001 - IPC

FIELD: chemical industry, particularly, processing mixtures of hydrogen fluoride, orthophosphoric acid and/or iodine inhibited nitric acid and nitrogen oxides, preferably rocket fuel oxidizers to give concentrated or conconcentrated nitric acid freed from corrosion inhibitors. SUBSTANCE: method comprises treating mixtures with silicon-containing to give silicon tetrafluoride, distilling off and condensing nitrogen oxides, isolating acid and subsequently distilling off or rectifying nitric acid to finally give purified unconcentrated or concentrated nitric acid in distillate, distillation of nitrogen oxides, treatment with silicon-containing compound to give silicon tetrafluoride or precipitation of iodic acid being carried out at temperatures from 70 to 75 C, condensing nitrogen oxides at minus 10 C, after condensation of nitrogen oxides, treating gases with sodium or potassium nitrate solution in diluted nitric acid to give corresponding hexafluorosilicates, and after distillation or rectification, neutralizing orthophosphoric acid to give corresponding orthophosphoric acid salts. Method makes it possible to process hydrogen fluoride, orthophosphoric acid and/or iodine inhibited oxidizers to give concentrated or diluted nitric acid which meets requirements of current specifications and also makes it possible to use isolated hexafluoro silicates, orthophosphoric acid salts and iodic acid to desired purposes. EFFECT: more efficient processing method. 1 tbl