METHOD AND INSTALLATION FOR CONCENTRATING SPENT SULPHURIC ACID FROM NITRATION PROCESSES Russian patent published in 2010 - IPC C01B17/94 

FIELD: chemistry.

SUBSTANCE: invention relates to chemistry and can be used to reclaim diluted and contaminated spent sulphuric acid from nitration processes. Spent sulphuric acid from a nitration process I1 is fed into the top part of a first stripping column K1 with external heating and separated into an upper product containing nitric acid and organic nitro compounds and preliminarily purified sulphuric acid. Purified sulphuric acid is fed from the lower part of the first stripping column K1 into the top part of a second stripping column K2 in whose lower part or evaporator diluted sulphuric acid is fed from the unit for obtaining highly concentrated nitric acid through extraction rectification so that in the second stripping column K2, preliminarily purified sulphuric acid from the first stripping column K1 is further purified and pre-concentrated together with diluted sulphuric acid from the nitric acid extraction rectification step. Pre-concentrated sulphuric acid coming out of the evaporator of the second stripping column K2 is further concentrated in one or more evaporation steps at low pressure.

EFFECT: invention enables to obtain highly concentrated nitric acid when reclaiming sulphuric acid.

16 cl, 2 dwg