engleski

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

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.

removal of thermic oxides; stainless steel; chemical and electrochemical procedures

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