VERFAHREN ZUR HERSTELLUNG VON SALPETERSAEURE

Continuous nitric acid prodn. comprises (a) using a reaction zone consisting of an extraction zone, a concn. zone and a desorption zone, (b) continuously introducing into the extraction zone a first stream of aq. HNO3 contg. 10-40 wt.% HNO3, at a rate sufficient to maintain a constant level of aq. HNO3 in the desorption zone; (c) continuously leading gaseous prods. from the oxidn. of NH3 with a gaseous oxidising agent, including O2, into the concn zone; (d) reacting the oxidn. prods. of ammonia with the oxidising agent in the presence of the first stream to form gaseous reaction prods. contg. NO2 and liq. reaction products contg. HNO3 which are combined with the first stream so that the HNO3 content of this is increased; (e) maintaining the temp. of the first stream passing through the extraction zone at between 4 degrees and 38 degrees C so that at least the greater part of the gaseous reaction products entering the extraction zone are dissolved in the first stream; (f) maintaining the temp. of the the aq. HNO3 in the desorption zone at >=54 degrees C so that at least the greater part of the dissolved gases are released; (g) withdrawing a second stream enriched in HNO3, from the liq. in the desorption zone at such a rate that the liq. level is maintained at a predetermined level; (h) separating the second stream into a prod. stream and a recycle stream; (i) continuously leading the recycle stream into the rextraction zone to reform a first stream; and (j) adding H2O to the extraction zone so that the concn. of HNO3 in the first zone is maintained at 10-40 wt.%. Process is carried out at atmospheric press. using a relatively small reactor.