Table of Contents
SRX Engineering
Volume 2010, Article ID 261423, 5 pages
http://dx.doi.org/10.3814/2010/261423
Research Article

Waste Water Treatment after Removal of Thermic Oxides from Stainless Steel Welding Joints

1Department of Welded Structures, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lucica 1, HR-10000 Zagreb, Croatia
2Department of Quality, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lucica 1, HR-10000 Zagreb, Croatia
3Department of Materials, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lucica 1, HR-10000 Zagreb, Croatia

Received 25 August 2009; Revised 29 September 2009; Accepted 13 October 2009

Copyright © 2010 V. Alar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This work describes chemical methods of removal of thermic oxides from stainless steel welding joints, as well as waste water treatment. Thermal oxides were removed from the stainless steel surface using chemical and electrochemical procedures. A pickling paste that contains HNO3 and HF in different ratios was used for chemical cleansing of thermal oxides (A, B, and C). Electrochemical removal was done using an apparatus Magic Cleaner, and as electrolyte a solution H2SO4+H3PO4 was used. Concentrations of chromium, nickel, and iron in the waste water have been determined using Method of Atomic Absorption Spectrophotometrics (AAS). Measured concentrations of Cr, Ni, and Fe are higher than allowed according to legal regulations of the Republic of Croatia. Therefore, an ionic exchange treatment of the waste water is recommended.