Study on Acid Evaporation and Valuable Metal Elements Recovery in Stainless Steel Pickling Waste Liquors

Aimed at the disadvantages in relevant techniques of stainless steel pickling waste liquors, evaporation test is carried out to take the rest acid in the waste liquor and recovery the valuable metal element.Different evaporation process with different addtion amount of sulphuric acid are tested.It is found that addition of sulphuric acid can promote the evaporation of HNO₃ and HF obviously.The reasonable propotion of H₂SO₄ addtion is about 10%.The content of valuable metal, such as Ni, Cr, and Fe in residual liquors can be doubled after evaporation treatment.This will be in favor of the effective use.