Water recovery from etching effluents for the purpose of rinsing stainless steel
✍ Scribed by Jacek Wisniewski; Stanislaw Suder
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 503 KB
- Volume
- 101
- Category
- Article
- ISSN
- 0011-9164
No coin nor oath required. For personal study only.
✦ Synopsis
The objective of the study was the choice of unit processes for a treatment train. The wastewater to be treated was the effluem from rinsing of stainless steel which had been etched in nitric acid and hydrofluoric acid. The proposed treatment train involved the following unit processes: electrodialysis (ED1) and cation exchange and electrodialysis (ED2). The ED1 provided removal efficiencies of 75-92%, 65-6g%, and about 99% for iron salts, chromium salts and nickel salts, respectively..'Uae cation exchanger yielded at,. over 99% removal of Feto t and Ni 2+ ions and a 25-31% removal of Cr 3+ ions. The ion-exchange capacity with respect to metals ranged from 0.77 to 0.91 eq./dm 3. The ED2 process enabled removal of residual acids and chromium salts. The effluent contained only small amounts of Cr 3+ ions (7-20 g/m3), and its conductivity varied from ~.0 to 65 pS/cm.