Processing distn. residues from photographic processing solns.

摘要

Process for processing distn. residues from photographic processing chemical solns. contg. sulphur-, NH4-, K-, Na- and Br cpds. together with a total organic carbon cpd. content of 30-40 wt.%, comprises suspending the distn. residues in water at a solids content of 400-700 g/l; subjecting the suspension to hydrothermal treatment at 120-200 deg C for 5-30 mins. under a partial O2 press. of 20-80 bar, and filtering the resulting crude sulphur out of the suspension; adding lime in a stoichiometric amt. w.r.t. and the SO4 content so that the pH of the suspension is changed from pH 2-4 to a pH greater than 12, and filtering off the pptd. crude gypsum, subjecting the filtrate from gypsum recovery to rectification (stripping) by introducing water or steam at 80-110 deg C for 10-90 mins.; subjecting the filtrate to evapn. with simultaneous conversion of the organic substances to a sec. fuel which is recovered; and recirculating the crude residual condensate to the suspension-forming stage .