Objectif
The project was finalized successfully in regard to the collection of chemical and economical experiences with a new method to treat Zn containing waste solutions from hot dip galvanizing workshops.
The chemistry of the applied extraction process is stable and Zn was removed from spent acid continuously to residual concentrations of less than 0,5 g/l.
Occurring crud formation was not significant and did not disturb the phase separation.
Emulsification effects especially during reextraction were prevented by modifying the pumping and stirring system of the mixer-settlers.
The evaporation of the dilute ZnCl2 solution was carried out with rates of up to 450 l/h. Full capacity of 1000 l/h could not be reached due to wrong evaporator design.
HCl was not recoverable with the tested evaporator. The condensate was completely recycled to the extractant regeneration without severe restraints regarding reextraction efficiency.
The investigated treatment costs for spent pickling acid were 290 DM/m{-3} of acid under Berlin specific conditions. Unless, the costs were more than 40 % lower than those for actual disposal.
The Berlin plant will be moved to another hot dip galvanizing workshop and restarted for spent acid treatment after a repair check.
A concept for the application of the process all over the hot dip galvanizing branch in Germany and Europe will be worked out, which includes a cooperation with a engineering company for the construction of treatment plants with optimized technology basing on the results of the finalized project.
Thème(s)
Data not availableAppel à propositions
Data not availableRégime de financement
CSC - Cost-sharing contractsCoordinateur
30625 Hannover
Allemagne