Analyzing the Methods of Disposing Spent Acids Obtained in Producing Cellulose Nitrates
Compositions of spent acids used in producing cellulose nitrates were analyzed based on triangular diagrams defining the dependence of the equilibrium nitric acid vapor pressure on the compositions of acids at their boiling points. A line of efficient denitration was obtained, which allows evaluating the possibility of obtaining 98-% HNO3 from spent mixed acids at no extra costs. Two most efficient techniques were identified for recycling spent acids having different compositions. We analyzed potential methods of obtaining ammonium sulfate nitrate by neutralizing the mixed acid with gas ammonia or with the 25-% ammonia liquor with and without using heat as vapor emitted in neutralizing within the further workflow. Testing of mineral fertilizers for metal contents has shown that they contain no elements of the first toxicity class and can be used in agriculture.