J. Piroskova, J. Trpcevska, D. Orac, M. Laubertova, H. Horvathova, B. Holkova

Production of zinc oxide from hazardous waste – Sal Ammoniac Skimming

J. Min. Metall. Sect. B-Metall. 54 (3) B (2018) 377-384. DOI:10.2298/JMMB180621027P
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This article deals with hydrometallurgical treatment with the subsequent precipitation of zinc from hazardous waste SalAmmoniac Skimming produced in wet hot-dip galvanizing process. Chemical analysis showed that skimming contained 46.64% Zn. X-ray diffraction analysis identified the Zn(OH)Cl phase (96.36%) and NH4Cl (3.64%) in Sal-Ammoniac Skimming. The skimming was first subjected to leaching in order to extract zinc into the solution containing HCl, followed by precipitation of the zinc. The experiments were performed in a medium of HCl at concentrations of 0.25, 0.5, 1 and 2M. Complete dissolution of zinc was achieved in 0.5M HCl solution, at 40°C, L:S=20, max. 30 min. The apparent activation energy of leaching reaction by hydrochloric acid solution was Ea=5.543 kJ mol -1 . Zn precipitation was carried out using Na2CO3 and NaOH. Zinc oxide with a purity of about 99% was obtained directly from the solution of 6M NaOH at a temperature of 60°C – 80°Cat pH 8.8.
Keywords: Sal Ammoniac Skimming; Zinc; Leaching; Precipitation; Zinc Oxide

Correspondence Address:
D. Orac, Technical University of Kosice, Faculty of Materials,
Metallurgy and Recycling, Institute of Recycling Technologies, Kosice, Slovak Republic
email: dusan.orac@tuke.sk

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