Pickling of stainless steels while continuously reoxidizing catalytically the pickling solution

摘要

In a pickling process for stainless steels or similar ferrous alloys, continuous reoxidation of Fe<2+> to Fe<3+> and/or NOx to nitric acid in the pickling liquor is economically performed by continuously treating a portion of the pickling liquor into a separate reactor where it is contacted with oxygen onto a catalytic bed and recycling the solution so reoxidized into the pickling bath. The need of continuously adding an oxidant in the form of hydrogen peroxide and of stabilizing compounds into the pickling bath is eliminated altogether thus achieving a dramatic reduction of the processing costs.