Rinsing water after the pickling of stainless steel

Sulphuric acid, nitric acid, hydrofluoric acid, surface active agent

During the pickling of stainless steel, acidic, heavy metal contaminated rinsing water accumulates, which must not be directed into the sewerage system. Through treating the rinsing water with the VACUDEST® vacuum distillation process, the distillate can be repeatedly re-used as rinsing water in the cycle. Prior to the VACUDEST®, the rinsing water must be neutralised due to its low pH level. Through this, a better distillation quality is simultaneously achieved, as the creation of azeotropes, and thus obstructions, is not possible. The addition of lime milk or coagulation aids, as in conventional treatments, is not necessary. A processing of disposed pickle in the VACUDEST® is not economical, as the content of metal and acids in the stainless steel pickle is so high that only a slight volume reduction can be achieved.

Through the distillation of the rinsing water, a constant standard of rinsing water quality can be achieved. The re-use of the distillate as rinsing water allows a closed water cycle along with a simultaneous reduction of water usage and disposal costs.